34 th Annual MRI Of the Head & Spine 2017: National Symposium

Wednesday, April 5, 2017 The Venetian® | The Palazzo® • Las Vegas, Nevada

Educational Symposia TABLE OF CONTENTS

Wednesday, April 5, 2017

Imaging the Brachial and Lumbar-Sacral Plexus (Wende N. Gibbs, M.D.) ...... 355

MRI of the Cervical Spine - MSK Perspective (William B. Morrison, M.D.) ...... 369

Rheumatoid Arthritis and Seronegative Spondyloarthropathies (Jeffrey J. Peterson, M.D.) ...... 385

MRI of the Foot and Ankle (Mark H. Awh, M.D.) ...... 409

Experiences/Update in Sports MRI of the Shoulder (Charles P. Ho, M.D., Ph.D.) ...... 445

MRI of the Shoulder: Beyond the Cuff (Mark H. Awh, M.D.) ...... 461

SAVE THE DATES - 2018 Spring Symposia 355 356 Objectives

Imaging the Brachial and • Describe imaging features and options for the brachial and lumbosacral Lumbosacral Plexus plexus and peripheral nerves

• Review relevant plexus and regional anatomy

Wende N Gibbs, MD • Discuss indications for imaging Assistant Professor of Radiology University of Southern California, Keck School of Medicine • Evaluate cases of the most commonly encountered pathologies

Plexus and peripheral nerve imaging Peripheral nerve anatomy

• Epineurium: • Nerve: – Dense vascular connective tissue – Morphology – Vasa nervorum – Alterations in caliber, signal, architecture, course • Perineurium: • Regional: – Fascicles have myelinated and unmyelinated axons – Compression from anatomic variant • Endoneurium: – Adjacent mass – Collagenous fibers and fluid • Diagnosis often requires integration of imaging data with patient history • Interfasicular epineurium and clinical exam and electrodiagnostic testing – Fatty material around fascicles • Blood nerve barrier: no enhancement

Peripheral nerve imaging Peripheral nerve imaging

• Symmetric • Abnormal • Normal – Size – Signal – Signal • T1 iso to muscle, T2 hyperintense (like – Morphology • T1 iso to muscle, mildly T2 hyperintense vessels) • enhancement – Signal intensity – Course – Shape / Caliber – Course Fascicular architecture on STIR • Fascicular pattern • Round/oval • Straight, no abrupt change, angles Intrafascicular pattern: • symmetric – Shape / Caliber • Nerve course endoneural fluid and axoplasmic flow – Architecture • Mass-like, nodular, distorted • Fat planes Interfascicular pattern: fibrofatty – Architecture connective tissue

357 Plexus and PNS imaging Pitfalls

• FOV: as small as possible to maintain high resolution (focused based on clinical data) • Differentiating nerves from vessels • Anatomic sequence (T1): high resolution, thin section • Physiologic sequence (T2): • Perineural plexus – edema (fluctuations in endoneural fluid content) • Magic angle effect – SPAIR: uniform fat suppression, better SNR than STIR • 3D (isotropic voxels): nerves with oblique course, treatment planning • Inhomogeneous fat suppression • Contrast: infection or neoplasm

Brachial plexus Anatomy

Anatomy Clinical / Surgical

• Roots: NF to scalene muscles • Supraclavicular: • Trunks: interscalene triangle – roots, trunks • Divisions: sup/post clavicle – Posterior triangle, between • Cords: inferior to clavicle, behind anterior and middle scalene m pectoralis minor m • Retroclavicular: divisions • Branches: distal to pec. minor m • Infraclavicular: cords

358 Roots (and cord) Roots (and cord)

Ventral root

Dorsal root • Most often trauma ganglion Dorsal root • Chronic: cervical spondylitic myelopathy • Nerve roots: – Dorsal (sensory) cell body in DRG DRG • Best evaluated on – Ventral (motor) cell bodies in cord cervical spine MRI or • Spinal Nerve: union of dorsal + ventral roots (distal to DRG) rootlets CT/MR myelogram • Ramus: 1st branch of spinal nerve • Peripheral nerve: neural conduit of one or more rami

Supraclavicular plexus Supraclavicular plexus

Ant. Scalene Anterior scalene Trunks

Mid. Scalene Middle scalene Clavicle Linda et al., Radiographics, 2010 Subclavian A Subclavian V

Roots and Trunks: medial to the scalene muscles Interscalene Triangle

Retroclavicular plexus Infraclavicular plexus

Clavicle Pec Major M Divisions

Cords Clavicle Subclavian A 1st Rib Subclavian V Subclavian A Subclavius M Subclavian V Pec Minor M Pec Major M

Costoclavicular Space Retropectoral Space

359 T2 FS / STIR: T2 FS / STIR: Mildly hyperintense – less than vessels Mildly hyperintense – less than vessels

T1 Pre Indications

• Trauma with plexopathy or nerve injury – Acute phase: MRI cervical spine (not BP) • Tumor T1 FS Post • Post treatment

Recurrent breast cancer • Nerve entrapment or compression • Unexplained plexopathy Normally no enhancement

Protocol Indirect signs of neuropathy

• High Resolution T1 and HR STIR or T2 FS – Coronal: lays out nerves distal to roots • Infiltration of perineural fat – Sagittal or oblique (15 degrees) sagittal – Axial • Perineural edema • 3D T2 fat sat • Muscle edema – Isotropic voxels: MIPs • T1 Post contrast fat sat • Muscle atrophy – Tumor – Infectious/inflammatory

360 Muscle denervation Trauma

• Acute: Normal • Early Subacute: Edema, paradoxical hypertrophy • Late Subacute: Mixed edema and atrophy • Chronic: atrophy

Trauma Pre v Postganglionic

• Adults: high energy force • Primary question in the acute trauma • Peds: traction during delivery setting – always get MRI cervical spine • Preganglionic • Complete avulsion: flail arm – Surgical repair difficult • Complete avulsion can have only partial paralysis due to – Goals: biceps (C6), shoulder mobility (C5) redundant muscle innervation • Postganglionic • Muscle denervation points to abnormal nerve – Intact fascicles: conservative management – Damaged: grafting • Look for associated vascular injury and fractures

Preganglionic

361 Peripheral Avulsion Post ganglionic Most common Traction on arm

Central Avulsion

Cervical spine injury

Moran, 2005 Courtesy of the Mayo Foundation

Seddon and Sunderland Classification

Degree of Prognosis MR Myelin Axon Nerve Injury I Neuropraxia Full recovery -Normal or + / - No -Incr T2 nerve and muscle II Axonotmesis Full recovery Increased T2 nerve Yes Yes Enlarged nerve Muscle denervation III Fair, incomplete Focal nerve enlargement Yes Yes Effaced fascicles Muscle denervation IV Poor Yes Yes V Neurotmesis Very poor Complete nerve discontinuity Yes Yes Muscle denervation

Plexus Injury Malignancy

Neuropraxia Axonotmesis Neurotmesis Endoneurium, Disruption of axon, Transection perineurium, connective tissue epineurium intact sheath intact

Conduction intact in No conduction distal No conduction distal distal and proximal to injury (Wallerian to injury (Wallerian segment, not injured degeneration) degeneration) segment Temporary loss of Recovery possible, Recovery unlikely- function (hours to +/- surgery impossible without months) surgical intervention

362 Neuropathy in Cancer patient Breast

• Compression from mass / lymphadenopathy Cancer • Direct extension – Pancoast • Perineural spread – HN, breast, GI, prostate, cervical – Nodular thickening, enhancement – PET: intense focal uptake • Radiation induced – Mild to moderate enlargement – Variable T2 – PET: Minimal to mild uptake

Squamous Cell Ca Pancoast (Superior Sulcus Tumor)

• Pancoast syndrome: – Severe shoulder/arm pain along C8, T1, T2 nerve trunks – Horner syndrome – Weakness and atrophy of intrinsic hand muscles

Radiation Plexopathy

• Increased T2/STIR SI • Ill-defined enhancement without a discrete mass • Enlarged, ill-defined plexus • Loss of fat planes and stranding • Post RT: 5 – 30 months

363 Benign Tumors Benign Tumor: Schwannoma

Infectious/Inflammatory: Entrapment syndromes CIDP

Entrapment syndromes Entrapment syndromes

• Thoracic outlet syndrome • Thoracic outlet syndrome – Types – Cervical rib • Neurogenic (90-95%) • Vascular – enlarged C7 transverse

– Locations process • Scalene triangle – fibrous bands • Costoclavicular – muscle hypertrophy • Retropectoralis minor space Linda et al., Radiographics, 2010 Magill et al. Neurosurg Focus, 2015

364 Lumbosacral plexus Anatomy

Cejas et al., Radiologia, 2015

Anatomy PNS imaging

• Symmetric – Size – Morphology – Signal intensity (fat sat variations) • Fascicular pattern • Nerve course • Fat planes

Indications Protocol

• Confirmation of involvement and extent in patients with • High Resolution T1 and HR STIR or T2 FS – Coronal oblique tumor – Sagittal or oblique (15 degrees) sagittal • Assess extent of injury – Axial oblique • 3D T2 (CUBE, SPACE) • Evaluate if MRI lumbar spine is indeterminate – Isotropic voxels: MIPs • Exclude mass lesion in patient with unilateral abnormality • T1 Post contrast fat sat on EMG – Axial oblique – Coronal oblique

365 Sciatica Entrapment: Piriformis syndrome

• Herniated disc • Primary neurogenic tumor • Trauma • Piriformis syndrome • Bone tumor or metastasis • Pelvic tumor Entrapment of the sciatic nerve at the greater sciatic foramen: -muscle asymmetry -anatomic variant course of sciatic nerve DW-SSFP

Cancer spread Endometriosis

• From prostate, rectum, bladder, cervix to LS plexus along pelvic autonomic nerves (sup and inf hypogastric plexus • To bony pelvis and musculature

Capek et al. Neurosurg Focus, 2015 Soldatos et al., Radiographics, 2013

Benign Tumor: NF1 Conclusion

• Plexus/peripheral nerve evaluation: – Abnormal imaging findings are the same throughout PNS – Muscle edema, atrophy can point to abnormal nerve • Anatomy: knowledge of plexus anatomy, regional anatomy, and clinical picture all vital to interpretation • Imaging: – a dedicated plexus protocol is not always necessary – good visualization on standard CT/ MR Spine, neck, pelvis, etc
– 18F-FDG PET/CT can help with tumor v radiation plexitis

366 367 368 369 370 MRI of the Cervical Spine MR Technique • T1 – Dark Fluid / Fat bright – Consistent – low artifact – Anatomy – Marrow • Traumatic injury • Tumor – Hematoma William B. Morrison, MD • Acute blood = bright Professor of Radiology Director, Division of MSK Radiology The “TRUTH SEQUENCE” Thomas Jefferson University Hospital, Philadelphia, PA

MR Technique MR Technique

• T2 • “Proton Density” – “Myelogram” – T1 and T2 qualities – Disc / ligament injury – Fat, fluid both bright – Cord injury – High SNR – Good for anatomy • 3-D FSE T2 – Cord lesions (MS)

MR Technique T2 GRE “Gradient Echo” Commonly used Thin cuts – neural foramina • Gradient echo (GRE) Disc vs spurring (DOC) Metal artifact more prominent – Cord hemorrhage – Hemosiderin dark – Bone fragments / disc GRE – 3-D acquisition

371 MR Technique MR Technique: protocol

Sagittal T1 Fell from swing • STIR PD – Bone injury GRE – Soft tissue injury STIR • Cord edema Axial T2 • Ligament injury GRE • Other soft tissues Coronal? Skull base – C2 Coverage – skull base through T3

MRI of hardware: Factors influencing artifact
• Hardware • Alloy type (worst: cobalt chrome, stainless steel) • Complexity • Complex surface: more artifact • Screws, bullet fragments, surgical burring • Metal orientation • Artifact in frequency encoding direction, out of plane • Less artifact in phase plane

T2 Metal Suppression Techniques
Gradient Echo FS T1W FSE T1W IDEAL FSE Metal artifact

GRE GRE NEUROFIBROMATOSIS

Courtesy Garry Gold Stanford

372 Axial images T2

UNCOVERTEBRAL JOINT VERTEBRAL GRE ARTERY

EXITING NERVE ROOT FACET JOINT

Normal Neural Foramen

Cervical discs have a thicker annulus; higher prevalence of Cervical HIZ: Annular Tear Intervertebral disc-osteophyte complex (DOC) Discs

Lumbar

T2

T1 T2

Endplate Changes: Disc dessication Modic 1

T1 T2

373 Modic 2-3 with Schmorl’s Node Formation

DISC BULGES

C-spine Spondylosis Disc Osteophyte Complex (DOC) Disc Herniation: Protrusion Type

Axial confirms focal nature

T1 T2 PD T1 T2 GRE

Herniation: Extrusion Herniation: Protrusion

Protrusion: - Focal Extrusion - Broad base - Focal - At disc level - Narrow base - Extends away GRE from disc level T1 T2

374 Extrusion C-spine: Asymptomatic

• Frequently found – Annular tears – focal disc protrusions • The extruded disc herniation and medullary compression are unusual findings in a symptom-free population

Ernst CW, Stadnik TW, Peeters E, Breucq C, Osteaux MJ. Prevalence of annular tears and disc herniations on MR images of the cervical spine in symptom free volunteers. Eur J Radiol. 2005 Sep;55(3):409-14.

NF Encroachment: Lateral Recess Encroachment: Herniations Uncovertebral Hypertrophy Extruded disc herniation and DOCs

GRE GRE

Cervical Disc Herniation: Pulse Sequences

FSE

GRE

375 DOC C5-6, C6-7 most common DOC

SPONDYLOTIC MYELOPATHY

Spondylolisthesis - Not ‘subluxation’ - Antero- or Retro- - DDD and Facet arthropathy T1 T2

Central Canal Stenosis -Typically multifactorial Developmental

1cm or less Stenosis

T2

• Developmental narrowing & acquired central canal stenosis with cord signal abnormality

376 Spinal Stenosis: Acquired on Developmental Spinal Stenosis Developmental

NO! 70 yearNFL------oldPlayer: male career with chronic ended with neck minor pain; flexionmyelopathic injury sx

“Stinger” Nerve Root Avulsion

• Axial load or lateral bending injury • Acute compression of nerve roots • Transient pain / neuropraxia • MRI: usually no findings except underlying spinal Add Coronal STIR stenosis / NF if suspected -- Asymmetric edema at nerve root

Facet Synovial Joints Acute radiculopathy: C8 Joints - Capsule - Collateral ligaments - Cartilage - Joint fluid

“Sliding” joints

377 Cervical Facet Cervical Facet (Zygoapophyseal) Joints

Note fluid in anterior and posterior recesses (arrows) • Left neck, shoulder pain • Asymmetric left sided facet arthropathy

Facet Facet Joint Edema Arthritis Association with pain with Edema

T2 STIR

Flexion / extension - Can be done in MRI (flexion) Instability Hyperflexion Sprain: MRI T1 STIR

STIR essential in trauma

MRI if Flex/Ext is contraindicated - ie, obtunded

378 Os Odontoideum • Developmental separation of dens • C1-2 Instability • Associated with: ATYPICAL FINDINGS – Down Syndrome, SED, Morquio’s, Klippel-Feil

Hydroxyapetite Deposition (HADD) in Longus Colli Calcific Tendinosis

52 y.o. female with fever, elevated ESR, & sore throat

Calcium Pyrophosphate Deposition (CPPD)

CPPD

379 OPLL CPPD with Ossification of the Posterior Erosion of Dens Longitudinal Ligament - Not uncommon - Older patients - Source of pain - Can cause dens fracture

“Heart Shaped” Canal

DISH Diffuse Idiopathic “Broken DISH” Skeletal Hyperostosis

ALL (anterior longitudinal ligament) ossification

Ankylosing Spondylitis with Fracture Ankylosing Spondylitis

380 Rheumatoid Rheumatoid Arthritis: Spine Arthritis mainly involves cervical spine -Severe disc degen. -Little proliferative change -Pannus at C1-2, • Synovial joints facet joints • Dens erosion • Basilar invagination • Facet involvement

Rheumatoid RA Arthritis Pannus destroying • Atlantoaxial dens instability • Stairstep spondylolisthesis • Little osseous proliferation

Cervical Spine: Atlantoaxial Impaction Spondylodiscitis

• Axial neck pain, headaches • C3-4 spondylodiscitis, staph • Associated epidural abscess

381 Tuberculous DIscitis TB Spondylitis

mass-like destruction 3

Tumor-like Presentation Bone Lesions C2 MASS

Coccidioidomycosis 4

“Stitching” Whole body MRI Algorithm STIR (detection) DWI (characterization) FOR SPINE SURVEY

Metastatic disease

Anatomic Functional

382 “Incidental” Findings Left Arm Pain

www.Jefferson.edu/MSK [email protected]

383 384 385 386 Objectives Rheumatoid Arthritis and the Seronegative • Recognize the common imaging features of Rheumatoid Arthritis Spondyloarthropathies • Identify the various seronegative spondyloarthropathies and the Jeffrey James Peterson, M.D. radiologic manifestations of each Professor of Radiology Vice Chairman for Education Program Director Radiology Residency

Rheumatoid Arthritis Rheumatoid Arthritis

• Chronic, systemic, • Most common purely erosive inflammatory disease inflammatory arthropathy • Chiefly affects the • Characterized by synovial inflammation and articular synovial membranes destruction • Multiple joints • Invariably polyarticular throughout the body

Rheumatoid Arthritis Rheumatoid Arthritis

• Typically arises in young • Exact etiology is unknown to middle aged patients • Considered an autoimmune • ~ 25-55 years of age disease –acquired • F > M - ratio of 3:1 • Genetic factors also appear • Prevalence - 1-2 % of the to play a significant role general population • Found world-wide

387 Rheumatoid Arthritis Rheumatoid Arthritis

• The endocrine system, • Appears that an unknown antigen metabolic and nutritional initiates the autoimmune response factors, geographic, resulting in RA psychologic, and • Suspicion of an infectious origin occupational data have – Included various bacteria and viruses been extensively studied – The exact etiology has remained elusive • No conclusive findings

Clinical Findings Laboratory Tests

• Clinical signs and symptoms may be • Rheumatoid Factor (RF) - not entirely specific continuous or episodic and may be negative early in the disease process but eventually becomes positive in 90-95% – Early mourning stiffness • Erythrocyte Sedimentation Rate (ESR) - – Pain (due to capsular distention) • C-reactive protein (CRP) - nonspecific indicators – Boggy synovial swelling of inflammation - typically elevated with RA and – Periarticular muscle wasting tends to parallel disease activity – Tendon and ligament contractures and rupture

General radiographic description Distribution Soft tissue

• Fusiform soft tissue swelling about joints • Remarkable for its bilateral symmetry – Secondary to effusions and synovitis • Nearly any joint can be affected • Large synovial cysts • Extremities most commonly involved – Communicate with the adjacent joint • Both small and large joints affected • Subcutaneous nodules are common

388 General radiographic description General radiographic description Bone Density Joint Space

• Osteoporosis • Joint spaces in the initial phases of RA – Combination of hyperemia and disuse may be wide due to joint distension • Early cases - juxtaarticular osteoporosis with fluid and synovitis followed later by generalized osteopenia • With cartilage destruction - progressive • Occasionally diffuse osteopenia is the only joint space narrowing initial radiographic abnormality • Occurs in a symmetric uniform pattern

General radiographic description General radiographic description Erosions • Bone Destruction initially is marginal at the • Periostitis and enthesopathy are typically “bare areas” referring to areas which are not prominent features of RA within the joint capsule not protected by • Ankylosis is also not common with RA overlying articular cartilage – When present typically involves • Later with further cartilage destruction, the tarsal and carpal bones subchondral erosions and subchondral cysts • Secondary osteoarthritis is not uncommon develop in the subarticular bone

Advanced Imaging Modalities Advanced Imaging Modalities

• MR and US can detect synovitis and small erosions – Synovitis with RA prior to development • Occurs early of radiographic findings • Strong predictor of bony • Synovial volume - correlates erosion development with joint swelling and • Changes quickly and is tenderness potentially reversible • Predictive of clinical disease

389 Advanced Imaging Modalities Advanced Imaging Modalities

• Erosion – MRI • Erosion – MRI – Sharply marginated bone – T1- loss of normal low lesion with juxtaarticular signal in cortical bone and location and typical signal adjacent marrow characteristics – Gadolinium – rapid – Visible in at least 2 planes enhancement – active – See 6-12 months before pannus in erosion evident on radiographs

Advanced Imaging Modalities Advanced Imaging Modalities

• Bone Marrow Edema – • Bone Marrow Edema – – Ill-defined margins and – May occur alone, signal characteristics surrounding an erosion, consistent with increased or a response to adjacent water content synovitis – T1 – low signal – Stronger predictor of – T2 - high future erosion than synovial volume

Advanced Imaging Modalities Advanced Imaging Modalities

• Sonography • Sonography – Synovitis – Erosions - intraarticular – Abnormal hypoechoic discontinuity of osseous tissue about the joints surface – Hypervascular with – Must be visible in 2 color and power doppler perpendicular planes

390 Extraarticular manifestations Extraarticular manifestations

• Subcutaneous or tendon • Pulmonary manifestations sheath nodules – Pleural effusion • Tenosynovitis or Bursitis – Rheumatoid pulmonary nodules – Diffuse interstitial pneumonitis

Hand and Wrist Hand

• Hand and wrist involvement is seen in • Earliest findings are at the MCP joints – especially at the radial 100% of patients with RA side of the metacarpal head • Proximal disease is the hallmark of • Also early involvement of the RA in the hand and wrist PIP joints • DIP joints are typically spared during the early phases of the disease

Hand Hand

• Characteristic deformities • Boutonniere deformity: of the hand are commonly – PIP hyperflexion seen in later stages of RA – DIP hyperextension • MCP ulnar deviation and volar subluxation

391 Hand Hand

• Hitchhiker’s thumb • Swan neck deformity: • Flexion and subluxation st – PIP hyperextension of 1 CMC joint – DIP hyperflexion • Hyperextension of 1st MCP joint • Flexion of 1st IP joint

Wrist Wrist

• Erosions involve: • Ulnar styloid and lateral – Distal radioulnar joint aspect of the scaphoid – Ulnar and radial styloid • Not covered by cartilage – Waist of the scaphoid • Therefore are vulnerable to early erosion – Triquetrum – Pisiform

Wrist Elbow

• Late changes include intercarpal and • Elbow involvement seen in 30-40% carpometacarpal erosions • Often an effusion - positive fat pad sign • Ulnar translation • Erosions may be present involving the distal • Scapholunate dissociation - DISI humerus, radial head, and coronoid • Distal radioulnar dissociation • Olecranon bursitis my be seen as a mass • Carpal ankylosis posterior to the elbow

392 Shoulder Shoulder • 60% of patients • Early changes typically • Rotator cuff tears are extremely common involve the AC joint in patients with RA • Lysis of the distal clavicle • Secondary signs of rotator cuff rupture • Erosion at the coracoclavicular ligament – Superior translation of the humeral head • Marginal humeral head – Concavity of the undersurface of the acromion erosions – Greater tuberosity – Along the capsular insertion

Feet Ankle

• Ankle involvement not common in early RA • 80-90% of patients • May be seen as a late manifestation • MTP erosive changes – Especially medially • Erosions – plantar and Achilles tendon insertion • 1st IP joint erosions • Retrocalcaneal bursitis may be seen • Lateral deviation at the – Obliteration of the normal pre-achilles fat triangle MTP joints

Knee Hip

• Frequently involved in RA – 80% • 2 features differentiate • Suprapatellar effusions and popliteal synovial cysts seen early in disease RA from OA: – Concentric or axial • Later uniform tricomparmental cartilage joint space narrowing loss, erosion, and subchondral cyst – Protrusio acetabulae formation

393 Spine Atlantoaxial subluxation

• Spinal involvement is • Laxity of the transverse ligament results in seen in 60-80% of instability at the atlantoaxial articulation patients with RA • Subluxation increases with flexion and decreases • Erosions of the with extension odontoid and facet • Atlantoaxial subluxation - indicated by widening joints are the most of the space between the anterior arch of C1 and common findings the odontoid greater than 2.5 mm on flexion view

Atlantoaxial impaction Atlantoaxial impaction

• Arch of C1 usually articulates • The arch of C1 slips with the cranial aspect of the inferiorly and articulates odontoid process with the body of C2 • With RA, C1-2 facet erosions • With collapse of the facet and destruction allows collapse joints the odontoid protrudes of the facets into the foramen magnum • Results in atlantoaxial impaction

Variations

• Felty’s Syndrome – RA, Splenomegaly, and Leukopenia – involves older patients and Seronegative results in various recurrent infections Spondyloarthropathies • Sjogren’s Syndrome – Keratoconjuctivitis sicca, xerostomia, connective tissue disease (typically RA)

394 Seronegative Seronegative Spondyloarthropathies Spondyloarthropathies

• Seronegative spondyloarthopathies share • Ankylosing Spondylitis many features with Rheumatoid Arthritis • Enteropathic Arthropathy • Both involve synovial joints and are • Psoriatic Arthritis associated with significant inflammation of • Reactive Arthritis the synovial membrane

Seronegative Spondyloarthropathies

• Distinguishing features of the seronegative spondyloarthropathies include: ANKYLOSING SPONDYLITIS • 1) Bone mineralization • 2) Bony proliferation and periostitis • 3) Bony Ankylosis • 4) Enthesopathy

Ankylosing Spondylitis Ankylosing Spondylitis

• Derived from Greek • Age of onset - usually 15 – 35 • Spondylos - vertebra • Later onset of disease is typically equated • Ankylos - stiffening of a joint with a better ultimate prognosis • The most common seronegative • Males > Females Ratio 4-10:1 spondyloarthropathy • Radiographic findings tend to be less • Unknown etiology severe in female patients

395 Laboratory tests Distribution

• HLA B27 Positive in greater than 90% • Primarily involving the axial (6-8% normal population) skeleton and large proximal joints • RF negative • Changes initially seen in the SI joints followed by involvement at • Erythrocyte sedimentation rate (ESR) the thoracolumbar and may be increased during disease activity lumbosacral junctions

General radiographic description General radiographic description

• A combination of erosive changes and bony • Ankylosis common in SI joints and spine productive changes are typically seen in AS – Vertebral bodies and posterior elements • Erosions are often smaller and less • Bone density usually normal until the prominent than seen in RA disorder becomes so debilitating that disuse • Periostitis infrequent osteopenia occurs • Enthesopathy common • Bilateral symmetry is a classic feature – Pelvis, patella, and calcaneus – Early disease may occasionally be asymmetric

SI Joints SI Joints

• Classically the initial site • Later sclerosis develops of involvement related to bony • First changes are loss of reparative changes the cortical definition • Finally ankylosis is seen • Followed by erosions and joint space widening

396 SI Joints Spine

• Findings are typically • Abnormalities of the spine in AS most prominent on the classically follows SI joint involvement iliac side of the SI joint • Involvement is typically first seen at the • Involvement may thoracolumbar and lumbosacral junctions initially be asymmetric but rapidly becomes • Vertebral involvement then extends bilateral and symmetric contiguously without skip areas

Spine Spine

• As the erosions heal, • Vertebral involvement reactive sclerosis begins with osteitis develops • Erosive changes at the • “Whitening” or discovertebral junction “Shiny corners” at the anterior corners – Superior and inferior of the vertebral bodies margins of the vertebral body

Spine Spine

• Hallmark of AS in the • “Squaring” - Osteitis leads spine is syndesmophyte to loss of normal concavity of formation the anterior vertebral body • Syndesmophyte - thin vertical ossification – Easier to assess in lumbar spine – Margin of the intervertebral disc within the fibers of the annulus fibrosis

397 Spine Spine

• Syndesmophytes • Later stages of the disease extensive predominate on the syndesmophytes produce the solid anterior and lateral undulating vertebral contour aspects of the spine • Termed “bamboo” spine – Particularly at the thoracolumbar junction • Thin syndesmophytes seen in AS usually can be differentiated from bulky syndesmophytes seen in Reactive and Psoriatic Arthritis

Trolley Track Sign Spine • Fused osteoporitic spine vulnerable to fx • Single central radiodense line on – Even from minor trauma frontal radiographs is related to • When fxs occur “psuedoarthroses” form ossification of supraspinous and • Typically occur anteriorly interspinous ligaments through the disk space • Two lateral vertical linear lines • Continue posteriorly through represent ossification of the facet the posterior elements joint capsules • Most commonly seen at cervicothoracic • Three vertical ossified lines together and thoracolumbar junctions make the “Trolley-track sign”

Hip

• Most common appendicular joint to be involved – Up to 50% of cases ENTEROPATHIC • Concentric joint space narrowing, mild erosions, ARTHROPATHY protrusio acetabuli, and ring osteophytes give an appearance of a combination of RA and OA • Involvement most often bilateral and symmetric

398 Enteropathic Arthropathies Enteropathic Arthropathies

• Musculoskeletal abnormalities in patients • One form occurs with acute GI infections with gastrointestinal disorders are seen with – Salmonella, Shigella, or Yersinia fair frequency – Self limited polyarthritis which typically occurs • These abnormalities have been termed without radiographic abnormalities enteropathic arthopathies because of the • Other form - chronic GI inflammation close association of the articular and – Ulcerative colitis, Crohn’s disease, or intestinal findings Whipple’s disease

Enteropathic Arthropathies Enteropathic Arthropathies

• 50-60% of patients with enteropathic • 10-15% of patients with IBD will arthropathies develop a peripheral develop an arthropathy pauciarticular arthropathy • Etiology of enteropathic arthropathies – Predominantly in the lower extremities is not well understood • 20-30% develop sacroilitis and spinal involvement identical to that of AS – Especially in patients with Ulcerative Colitis

Enteropathic Arthropathies Enteropathic Arthropathies

• Flares of the peripheral arthropathy correlate • Ulcerative colitis is the most common well with the gastrointestinal disease activity inflammatory bowel disease to develop articular manifestations • Sacroilitis and spondylosis does not correlate to inflammatory bowel disease activity • Commonly resembles – Can precede the onset of intestinal changes – Ankylosing Spondylitis • About 10% of cases - demonstrate articular findings prior to onset of GI findings

399 Psoriatic Arthritis

• Literature reports a wide PSORIATIC ARTHROPATHY range of prevalence • 0.5-25% of pts with psoriasis • Most believe 2-6% is an accurate estimate • Typically afflicts young adults • F / M equally affected

Psoriatic Arthritis Clinical Findings

• Most patients a long history of psoriatic • Soft tissue swelling is skin disease prior development of typically seen, especially psoriatic articular disease about the small joints of the hands and feet • Articular involvement - much more • Swelling often involves prevalent in patients with severe skin dz the entire digit which • Arthropathy may coincide or even termed a “sausage digit” antedate skin findings - up to 20%

Clinical Findings Laboratory Tests

• Nail changes are very common patients with • HLA B27 positive in 25-60% PA including thickening, • Negative RF pitting, or discoloration • Elevated ESR • Nail changes correlate well with the severity of disease activity

400 Distribution Radiographic description

• The typical distribution of PA • Erosions begin marginally as in RA but includes the small joints of the progress to include central erosions hands and feet • Productive changes are often seen • w or w/o a spondyloarthropathy peripherally about joints which results in a • Involvement of larger joints is “whiskered” or “paintbrush” appearance at much less common the joint margins – If present, the distal small joints are invariably involved as well

Radiographic description Radiographic description

• Often the affected bone will appear as if it had • Fusiform soft tissue swelling been “gnawed away” or is also commonly seen about “whittled by a pencil the involved joints sharpener” • Swelling of the entire digit is • “Pencil in cup” deformity termed “sausage digit” may be seen which is characteristic of PA

Radiographic description Hand

• Bone mineral density is usually normal in PA • Hand involvement in PA often begins with – An important distinguishing feature from RA DIP erosive changes • Ankylosis is common in the hands and feet – Typically more severe than PIP or MCP joints • Enthesopathy similar to that seen in AS or • Tuft resorption may be evident with Reiter's is frequently seen whittling or penciling of the tuft • Reactive sclerosis of the tufts may result in – “Ivory phalanx”

401 Hand Hand

• Bone proliferation • Bone erosion – Exaggerated healing – Initial – marginal response of injured bone – Late – central – Periostitis – Pencil-in-cup • “Paintbrush” appearance • Ivory phalanx – Ankylosis • IP joints

Hand Hand

• Malalignment and • Tuft resorption subluxation – Nail almost always involved – Telescoping of one bone on another – Subungual calcification • “Opera-glass hand ” – Progressive osteolysis • Skin folded over – Ulnar deviation of digits – Boutonniere and swan-neck deformities

Foot Foot

• The forefoot is commonly affected in PA • Bone proliferation – IP and MTP erosions and proliferative changes – Exaggerated healing response of injured bone • Retrocalcaneal bursitis may be seen in PA – Periostitis – Similar to seen in RA and Reactive Arthritis • “Paintbrush” appearance • “Cloaking” of entire phalanx • Enthesopathy and erosions are common • Ivory phalanx involving the calcaneous – Ankylosis – Insertion of Achilles tendon and plantar fascia • IP joints – Enthesopathy

402 Foot Foot

• Erosions of tufts • Tuft resorption and calcaneus – Nail almost always involved • DIP – Subungual calcification – Progressive osteolysis of the bone

Spine SI Joints

• Spinal involvement is seen in 30-50% of • SI joint involvement seen in 30-50% patients with psoriatic arthropathy • Involvement of the SI joints is usually • Classic appearance of PA consists of large bilateral but asymmetric bulky asymmetric syndesmophytes • Typical findings include widening, erosions, involving primarily the thoracolumbar spine sclerosis, and eventually fusion • Psoriatic Spondylosis may be identical to that seen in Reiter’s syndrome

Reactive Arthritis

• Triad consisting of: REACTIVE ARTHRITIS • (1) Urethritis (cervicitis in females) • (2) Conjunctivitis • (3) Arthritis

403 Reactive Arthritis Reactive Arthritis

• Reiter’s syndrome involves young adults • It appears likely that the disease can be typically between the ages of 15 and 35 transmitted in association with either • Males are afflicted much more commonly epidemic dysentery or sexual intercourse than females (5-50:1) • A high percentage of patients acknowledge • The disorder is seen in greater prevalence in themselves to be sexually promiscuous military personnel • Studies support a close relationship between Reiter’s syndrome and sexual activity

Reactive Arthritis Laboratory Tests

• Urethritis is frequently the initial manifestation of the disease • HLA B27 positive in 80% • The arthropathy only rarely precedes the urethritis or conjunctivitis • RF Negative • Typically an asymmetric arthritis involving • Elevated ESR the lower extremities presents within 1-3 weeks of the inciting episode of urethritis or diarrhea in most cases

Distribution Radiographic Description

• Joint distribution typically • Radiographic abnormalities occur in demonstrates predominantly 60-80% of patients with Reactive Arthritis lower extremity involvement • Soft tissue swelling is often seen and may with changes seen about the be either fusiform about involved joints or calcaneus, ankle, knee and the may involve the entire digit -“sausage digit” small joints of the foot • Juxtaarticular osteoporosis may occur, but • Upper extremity involvement is in a majority of cases the bone mineral uncommon density is normal

404 Radiographic Description Radiographic Description

• Erosions predominate Ankylosis may occur in the sacroiliac joints – Typically progress from marginal to central but is much less common elsewhere than is • Fluffy periosteal proliferation is commonly seen in PA seen about involved joints The spondyloarthropathy and mixed erosive • Enthesopathy is commonly seen in the and productive peripheral arthropathy may pelvis and about the calcaneus be identical to findings seen in Psoriasis

Foot Ankle

• Earliest changes are in the foot • Calcaneal involvement is characteristic of • Involves the MTP and IP articulations Reiter’s syndrome and may be the sole or • Lack of symmetry is commonly seen in the foot early predominant radiographic manifestation in the disease • Retrocalcaneal bursitis is common • Selective and severe first IP erosive disease common • Prominent spur formation and erosive • Sesamoids may undergo significant erosion and changes at the insertion of the Achilles proliferation resulting in irregular cortical margins tendon and plantar fascia

Knees SI Joints

• Radiographic abnormalities are seen • Sacroilitis seen in 10-40% of cases involving the knees in 25-40% • Involvement includes widening, erosions, • Most common abnormality is a joint effusion sclerosis, and eventually fusion • Joint space narrowing, periostitis, erosions, • As with PA, sacroiliac involvement is and enthesopathy are also commonly seen usually bilateral and symmetric although asymmetry is not uncommon

405 Spine Hand

• Although spinal involvement is seen in • Extensive upper extremity involvement is Reiter’s syndrome, it does not occur as distinctly unusual in Reiter’s syndrome, frequently as in PA however in 10-30% of cases, radiographic changes in one or more fingers • Large bulky asymmetric syndesmophytes • PIP involvement is most common followed are seen similar to those found in PA by MCP and DIP abnormalities • Skip segments may be seen • Erosive changes are accompanied by fluffy productive changes

406 407 408 409 410 MR OF THE FOOT AND ANKLE

Mark H. Awh, MD

The complex anatomy at the foot and ankle provides diagnostic and clinical challenges to both the radiologist and the orthopedic surgeon. Through the use of MR, our understanding of the normal and pathologic relationships of the soft tissue and osseous structures at the foot and ankle has grown tremendously.

The Ankle Tendons

Posterior tibial tendon tears typically occur in middle-aged women, presenting with chronic pain and progressive flat foot deformity. A grading system for tears of the posterior tibial tendon has been established. However, in general, it is typically best to simply describe the degree of tendon degeneration you see and the type and extent of any tear that may be present.

The normal posterior tibial tendon is of low signal intensity on all pulse sequences. Tendinosis is most common at the navicular insertion of the tendon, an area of relatively greater stress upon the tendon. A lesser known pitfall to be aware of, however, can also result in increased intratendinous signal near the navicular attachment. A fibrocartilaginous nodule may be present within the tendon near the navicular attachment. When composed of well organized collagen, the nodule remains low signal intensity, but poorly organized collagen may be present, in which case increased signal intensity is present within the tendon. The nodule also results in a bulbous appearance, and overall, the findings can be difficult to distinguish from tendinosis. Signs that indicate that a nodule is likely present include the focal nature of the abnormality, an off center appearance of the signal abnormality, and the characteristic location opposite the spring ligament.

On this fat-suppressed T2-weighted axial image, an abnormally small PTT (white arrow) is noted, consistent with an attritional partial tear.

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A T2-weighted axial view of a complete PTT tear demonstrates a fluid filled posterior tibial tendon sheath (arrow), with only a few edematous irregular tendon fibers visible.

Fibrocartilaginous nodule in a 61 year- old male. Axial proton density-weighted fat-suppressed (top left), axial proton density-weighted (top right), and sagittal T1-weighted (bottom left and bottom right) MR images demonstrate laterally off center intratendinous increased signal intensity (arrow) within the distal posterior tibial tendon, compatible with a fibrocartilaginous nodule.

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The tibialis posterior muscle originates in two heads at the interosseous membrane and the posterior surface of the fibula. It runs within the retromalleolar groove at the ankle and inserts onto the medial aspect of the navicular, with smaller tendon slips inserting onto the cuneiforms and the second, third and fourth metatarsal bases. It inverts and plantar flexes the foot, and supports the medial arch of the foot. This is why chronic tears demonstrate associated flatfoot deformity, with plantar flexion of the talus often seen on sagittal MR images. The site of chronic tears is most commonly at the level of the medial malleolus, where a zone of relative hypovascularity exists. In addition, the tendon is also susceptible to greater mechanical stress and potential impingement as is turns about the medial malleolus. Other etiologic factors for PTT tears include inflammatory arthropathy, obesity, hypertension, an accessory navicular, a cornuate navicular, and congenital flat foot deformity.

Posterior tibial tendon dysfunction may also occur in the younger athletic population where it usually presents as an acutely symptomatic tenosynovitis. Acute ruptures are rare in these patients, and are usually near the navicular insertion. MRI can also localize tears in unusual locations, such as the rare tear of the distal fibers at the level of the cuneiforms and metatarsal bases.

An empty, fluid-filled tendon sheath is noted (arrow) in this case of a complete tear of the distal posterior tibial tendon at the level of the cuneiforms.

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Dislocation of the posterior tibial tendon is rare, and thought to be traumatic. It is usually associated with a torn flexor retinaculum, which allows the tendon to slip out of the retromalleolar groove. An avulsion fracture at the medial malleolar attachment of the flexor retinaculum may be seen in such cases.

Anterior and medial subluxation of the posterior tibial tendon (arrow) is apparent on this T1- weighted axial image.

With chronic rupture of the posterior tibial tendon and failure of the medial longitudinal arch of the foot, increased force is transmitted to other static stabilizers of the arch such as the spring ligament, the ligaments of the sinus tarsi, and the plantar fascia. Abnormalities of all of these structures can be readily seen on MRI and have been demonstrated to occur in association with advanced posterior tibial tendon dysfunction.

The peroneal tendons are positioned posterolaterally and function as evertors and plantar flexors as well as dynamic stabilizers of the foot and ankle. The peroneus longus muscle originates from the upper fibula and courses along the lateral aspect of the ankle before turning medially beneath the cuboid. It courses through the deep plantar aspect of the midfoot, supporting the transverse arch, before inserting onto the medial cuneiform and the base of the first metatarsal. The peroneus brevis originates from the lower fibular shaft and inserts onto the base of the fifth metatarsal. The tendons share a common tendon sheath above the level of the tip of the fibula

414 and are held in place by the superior and inferior peroneal retinacula. The superior peroneal retinaculum (SPR) functions as the primary restraint to peroneal tendon subluxation and is also a secondary restraint to anterolateral ankle instability. It is formed from a confluence of the common peroneal sheath and the superficial fascia of the leg. Anteriorly it attaches to and blends together with the lateral fibular periosteum. Posteriorly it has variable attachments to the Achilles tendon and the calcaneus. The SPR creates a fibro-osseous tunnel for the peroneal tendons contained within their common tendon sheath. .

The superior peroneal retinaculum (SPR) is attached to the lateral fibular periosteum and forms a fibro-osseous tunnel which restrains the peroneus brevis (PB) and peroneus longus (PL) tendons within the peroneal groove. More distally the peroneal tendons have separate fibro-osseous tunnels formed by the inferior peroneal retinaculum (IPR).

On MRI, the normal peroneal tendons typically appear dark on all pulse sequences. On axial sequences at the level of the ankle, the peroneal tendons are found posterior to the lateral malleolus within the peroneal or retromalleolar groove, which is sometimes deepened by a small fibrous ridge at the lateral fibular margin. The groove may alternatively be flat or convex, which can predispose to subluxation. At this level the peroneus brevis tendon is positioned anteromedial to the peroneus longus and is crescentic in cross-section. The peroneus brevis myotendinous junction is lower in position than that of the peroneus longus, and may be seen at the level of the tibiotalar joint. The SPR is seen as a thin dark band posterolateral to the tendons at the level of the lateral malleolus, attaching to the periosteum at the posterolateral margin of the fibula. The uninjured periosteum is thin and indistinct from the bone cortex. Distal to the lateral malleolus, the peroneus brevis courses anterior to the peroneus longus. The peroneal tubercle is variable in size and projects laterally from the anterior process of the calcaneus, separating the positions of the peroneus brevis and longus tendons. Normal variant anatomy in this region may include a peroneus quartus muscle, a low-lying peroneus brevis muscle belly, or an os peroneum.

415 Injury of the superior peroneal retinaculum (SPR) occurs with peroneal dislocation through forceful ankle dorsiflexion and concomitant reflex peroneal muscle contraction. This injury has been described in conjunction with numerous sports activities, particularly snow skiing. The injury can occur when ski tips suddenly become lodged in the snow and the skier’s forward momentum causes passive ankle dorsiflexion. Some controversy exists about the associated role of ankle inversion or eversion.

Patients with chronic injury and recurrent tendon subluxation may present with inability to recall a specific traumatic episode. Nontraumatic dislocations can be seen congenitally, particularly with calcaneovalgus feet, or acquired, such as in patients with neuromuscular disease. Heel valgus may predispose to injury.

The diagnosis of dislocation of the peroneal tendons is made when either or both tendons are not identified in their normal anatomic positions posterior to the lateral malleolus and the diagnosis of complete tendon rupture and retraction is excluded. Evaluating the tendons on serial images allows discrimination between tendon subluxation, dislocation, or tear. Either or both of the peroneal tendons may dislocate, and the determination of which tendon is dislocated must be made by following the tendons distally to their attachments.

With peroneal tendon dislocation, the periosteum is stripped and elevated together with the attached superior peroneal retinaculum, forming a false pouch lateral to the fibular margin. The tendons may reduce, but the SPR remains incompetent, allowing recurrent subluxation and/or dislocation. The resultant abnormal stress leads to tendon degeneration and tearing.

Identification of periosteal stripping and an abnormal pouch is particularly important in patients with recurrent episodes of tendon subluxation, who may have normally positioned tendons at the time of imaging. The SPR should be tightly affixed to the periosteum at the posterolateral margin of the distal fibula. Both peroneal tendons should lie medial to a vertical line drawn from the lateral margin of the distal fibula.

416 Periosteal stripping and SPR insufficiency (Type I SPR injury) with minimal tendon subluxation at time of exam. T2-weighted and T1-weighted images. The SPR (arrowheads) is elevated from its normal attachment to the posterolateral margin of the fibula. The adjacent periosteum is partially stripped and thickened, forming a false pouch which may be filled with fluid or edema (arrow).

Other peroneal tendon pathology may also present with lateral ankle pain and swelling. Most commonly this involves a spectrum of tendon degeneration and tearing, more often involving the peroneus brevis tendon in a longitudinal fashion as it passes under the lateral malleolus. Longitudinal tearing of the peroneus brevis tendon, or “peroneal splits,” can be diagnosed when alteration of the peroneus brevis morphology is seen in the peroneal groove on careful sequential image inspection. The partially torn peroneus brevis split appears as an inverted U shape. This can progress to complete separation into two components, with the peroneus longus tendon interposed between the split peroneus brevis tendon components. Different stages in the continuum of tendinosis, partial tear, and complete tear may coexist in the same tendon at adjacent levels. Care must be taken in not mistaking a normal mildly crescentic peroneus brevis for a partially torn U shaped tendon. The torn tendon is more notably distorted in shape, and often will be accompanied by adjacent segments of tendon degeneration and thickening as well as fluid in the tendon sheath.

Split tear of the peroneus brevis. On this T1- weighted axial image, the peroneus brevis tendon diffusely degenerated and a large split cleaves the tendon into two halves, with the peroneus longus intervening.

Tendinosis less frequently involves the peroneus longus tendon. This may occur at the level of the lateral malleolus, particularly following peroneus brevis tear. Isolated peroneus longus tendon degeneration and tear typically occurs more distally at the midfoot where increased

417 stresses are found as the tendon courses beneath the cuboid, or at the level of the peroneal tubercle, particularly when it is hypertrophied. Acute tears from sports-related injury or trauma are less common.

The Achilles tendon, formed by the confluence of the gastrocnemius and soleus tendons, is the largest and strongest tendon in the body, and is a frequent source of pain at the ankle. Acute rupture of a normal tendon may occur with forced dorsiflexion, or may occur following relatively minor trauma in patients in whom the tendon is already weakened secondary to chronic inflammation or connective tissue disorders. The Achilles tendon does not possess a true tendon sheath, and thus inflammatory disorders are classified as tendinitis, paratendinitis, and peritendinitis. Tendinitis generally manifests on MR as regions of increased signal intensity and/or tendon enlargement on T1 and T2-weighted images. Histologically, Achilles tendinitis is actually more of a degenerative phenomenon, with few inflammatory cells being present. Similar to the rotator cuff, the more correct term for this condition is thus Achilles tendinosis.

The Achilles tendon is severely thickened and demonstrates diffusely increased signal intensity throughout its substance (arrows) on T1-weighted sagittal and T2-weighted axial images from a patient with severe, chronic Achilles tendinosis.

Tears of the Achilles tendon are revealed by the presence of fluid signal intensity within the tendon. Partial tears and longitudinal splits are well seen with MR. Complete Achilles ruptures usually occur approximately 4-5 cm from the calcaneal attachment, that region thought to be a relative watershed zone in the Achilles blood supply. However, trauma to the contracted Achilles musculotendinous unit may result in a distal rupture at the calcaneal attachment.

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A partial tear (arrow) of the Achilles tendon is identified by the presence of fluid signal intensity within medial fibers on a fat-suppressed proton density-weighted coronal view of the posterior ankle.

Rupture of the Achilles tendon may be a dramatic event, particularly when acute and complete. Typical patients are middle-aged men participating in activities requiring forceful push-off maneuvers. Severe pain with localized hemorrhage is often present, and the Thompson test is positive, such that the patient is unable to stand tiptoe on the injured leg and a diminished plantar flexion response to calf squeezing is present.

A T2-weighted sagittal image reveals a complete rupture of the Achilles tendon approximately 4cm above the distal insertion. A small tendon gap (arrow) is readily apparent.

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Ligamentous Injuries

Spring Ligament Tears

Recently, the importance of the static stabilizers of the foot in maintaining the medial longitudinal arch has been emphasized. The calcaneonavicular ligament (spring ligament) complex is a key static stabilizer of the arch and is frequently injured in association with posterior tibial tendon insufficiency. In patients with acquired flatfoot deformity, an isolated repair of the posterior tibial tendon may result in a poor long-term functional outcome, if coexistent abnormalities of the spring ligament are not addressed.

A plantar 3D representation of the midfoot demonstrate the 3 major components of the spring ligament complex, the superomedial (SM-CNL), medioplantar oblique (MPO- CNL), and inferoplantar longitudinal (IPL-CNL) calcaneonavicular ligaments. The posterior tibial tendon (PTT) and tibiospring ligament (TS) are also demonstrated.

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Spring ligament injuries have a high association with posterior tibial tendon tears. Spring ligament tears, like posterior tibial tendon tears, are most commonly seen in middle-aged women and are most often the result of chronic degeneration. Disruption of the spring ligament destabilizes the longitudinal arch, allowing plantar and medial rotation of the head of the talus and valgus alignment of the calcaneus (pes planovalgus). The clinical result is an acquired flatfoot deformity.

The SM-CNL is the most important spring ligament component for providing functional stability of the arch and is also the most frequently injured spring ligament component. Efforts at evaluating the integrity of the spring ligament complex should focus on the SM-CNL. Published reports give a mean thickness for the SM-CNL ranging from 2.5 mm to 4.7mm, suggesting significant interobserver variability and possible inconsistent methods of assessing thickness. In pathologic states the SM-CNL frequently thickens. A measurement of 4 mm has been suggested as the threshold beyond which the spring ligament is abnormal. Our experience suggests this value may be frequently exceeded in the normal population. We prefer to utilize a threshold value of 5 mm or greater in addition to abnormal ligament contour and signal characteristics, and the presence of associated posterior tibial tendon pathology. Atretic ligament tears are also frequently seen and demonstrate an abnormally thinned SM-CNL (<2mm) usually accompanied by discontinuity of the ligament and surrounding edema. In almost all instances of spring ligament tears or laxity, accompanying posterior tibial tendon abnormalities are present.

A T2-weighted axial image demonstrates a large tear of the SM-CNL (arrowheads) at the navicular, resulting in a large ligament gap (small arrows). Note that the posterior tibial tendon (arrow) contacts the medial head of the talus within the the ligament defect.

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Ligamentous injuries at the ankle are well seen with MR, manifesting as abnormal laxity or discontinuity within the affected ligament or as soft tissue thickening and edema about the ligament in cases of partial tearing. Chronically sprained ligaments may be seen as abnormally thickened structures without associated edema.

The lateral ligamentous complex of the ankle consists of three components, the anterior talofibular ligament, the posterior talofibular ligament, and the calcaneofibular ligament. The anterior talofibular ligament is consistently visible on axial MR images, and is the most frequently torn ligament of the lateral complex. The calcaneofibular ligament is usually well seen on coronal MR images, and can also be visualized on axial images, coursing deep to the peroneal tendons. The calcaneofibular ligament, when torn, is typically injured in association with anterior talofibular ligament tears. The posterior talofibular ligament is the strongest and least often torn of the lateral ligaments. It is well seen on coronal and axial MR images, and is usually only injured in cases of severe ankle trauma with dislocation.

A T2-weighted axial image without fat suppression reveals a complete anterior talofibular ligament tear. The ligament is diffusely edematous and lax and the distal fibers are markedly attenuated.

The syndesmotic ligaments include the interosseous, the anterior tibiofibular, the posterior tibiofibular, and the transverse tibiofibular ligaments. These ligaments bind together the distal tibia and fibula. External rotation forces as can occur with downhill skiing and football are the most common cause of syndesmotic injury, with the anterior tibiofibular ligament being the weakest and most frequently injured component of the syndesmotic complex. Injuries to the syndesmotic ligaments are often referred to as “high ankle sprains”, and typically require a longer course of rehabilitation than injuries to the lateral ligamentous complex.

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A T2-weighted axial image (left) reveals irregular, globular soft tissue in the expected location of the anterior tibiofibular ligament, compatible with a complete tear. On the right, a corresponding fat suppressed proton density-weighted sagittal image reveals diffuse edema along the anterodistal fibula, in the region of the interosseous ligaments.

Medially, the deltoid ligament is composed of superficial and deep components. Recent evidence indicates that deltoid ligament injuries are associated with a wide variety of ankle injuries and are more common than earlier studies suggested. Failure to diagnose and appropriately treat deltoid ligament insufficiency may lead to debilitating medial ankle instability, osteoarthritis, and medial ankle impingement syndromes.

The deltoid ligament complex arises from the medial malleolus and is commonly divided into a superficial and deep layer. Conceptually, the superficial layer provides stability to the naviculocalcaneal complex and resists external rotation of the talus relative to the tibia. The deep layer assists in stabilizing the talus and resists posterior translation of the talus, valgus angulation of the talus, and lateral displacement of the talus from the medial malleolus. The tibial attachments of the deep layer arise from the anterior and posterior colliculi of the inner surface of the medial malleolus as well as from the intervening sulcus known as the intercollicular groove. The superficial and deep components of the deltoid ligament complex are composed of multiple fused ligamentous fascicles that are difficult to distinguish on gross inspection. Anatomically, the division of the deltoid ligament complex into discrete components is somewhat artificial, and naming of the ligamentous fascicles is based on the origins and insertions of the ligamentous tissue.

Not surprisingly, there is variation in the agreed upon components of the deltoid ligament complex. The most commonly recognized ligaments of the superficial layer are the

423 tibionavicular ligament (TNL), the tibiospring ligament (TSL), and the tibiocalcaneal ligament (TCL). On anatomic dissection both the TNL and TSL are consistently found.2 The deep layer is comprised of the anterior tibiotalar ligament (ATTL) and the posterior tibiotalar ligament (PTTL) with the PTTL being a constant anatomic finding. Since the deep and superficial components of the deltoid ligament complex serve different stabilizing functions, recognizing which component is injured provides insight into the instability patterns that may be anticipated.

With the superficial layers of the deltoid ligament complex removed, the components of the deep layer of the deltoid ligament complex are demonstrated. The deep layer of the deltoid ligament is formed by a small and variable anterior tibiotalar ligament (ATTL) and a very strong posterior tibiotalar ligament (PTTL).

The superficial layer is a broad and triangular structure composed of multiple fascicles. It is the weakest layer of the deltoid complex. The commonly recognized components of this layer are the tibionavicular ligament (TNL), the tibiospring ligament (TSL), and the tibiocalcaneal ligament

424 (TCL). All three of these fascicles blend with the superomedial portion of the spring ligament complex (SL).

Isolated deltoid ligament tears are very rare. Deltoid ligament injuries are most frequently seen in association with lateral ankle ligament and syndesmotic ligamentous injuries and with fibular and lateral malleolar fractures. Deltoid ligament disruptions are a well-known consequence of pronation-eversion and pronation-abduction injuries at the ankle. In both mechanisms the deltoid ligament or the medial malleolus is the initial structure that fails. However, recent evidence indicates that deltoid ligament injuries are more frequent, less predictable, and occur through a much wider variety of injury mechanisms. For instance, a significant percentage of patients with deltoid ligament complex injuries describe a supination injury as the primary injury or multiple ankle sprains without a clearly identified mechanism. In addition, deltoid complex injuries are more frequent in supination-external rotation (SER) injuries than predicted by the Lauge-Hansen classification of the progression of structural failure. Finally, a high incidence of deltoid ligament complex injuries is demonstrated in patients with inversion sprains of the ankle.

15 year-old female with acute inversion lateral ankle sprain. Axial T1-weighted (left) and coronal proton density- weighted fat-suppressed (right) images demonstrate loss of the normal striations of the PTTL with increased signal indicating edema and contusion (asterisks).

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46 year-old male who suffered a pronation external rotation mechanism of injury one week earlier. Coronal proton density fat-suppressed (left), axial T2-weighted FSE (middle), and sagittal T2-weighted fat-suppressed (right). In this pattern the anterior superficial ligaments fail initially. Proximal (type I) avulsion of the tibionavicular ligament is demonstrated at the anterior margin of the anterior colliculus (arrows) and ill-defined, lax and edematous distal ligament fibers (arrowheads) are apparent. The patient also had a tear of the anterior inferior tibiofibular ligament and a non-displaced spiral fracture of the distal fibular shaft.

Soft tissue impingement may occur after an ankle sprain, and results in chronic pain. Sites of soft tissue impingement include anterolateral, posterior, and syndesmotic, with anterolateral impingement being the most common.

The Tarsal Sinus

Sinus tarsi syndrome is strongly associated with posterior tibial tendon dysfunction and can be an important secondary sign of tendon disease. It can also be seen in inflammatory arthropathy, which may or may not co-exist with posterior tibial tendon pathology and is found in patients with prior lateral ligamentous sprains. Sinus tarsi syndrome is readily detectable on sagittal T1- weighted images when fluid or edema within the sinus tarsi obliterates the normal fat signal intensity surrounding the interosseous and cervical ligaments.

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A sagittal T1-weighted image demonstrates thickening and increased signal intensity filling the sinus tarsi (arrow) in this patient who also had a PTT tear at the medial malleolus (not shown).

The tarsal sinus is well seen between the neck of the talus and the anterior calcaneus on axial, sagittal, and coronal MR images. The normal tarsal sinus contains fat, nerve endings, and arterial anastamoses. The cervical and the interosseous talocalcaneal ligaments can often be visualized within this space. In cases of sinus tarsi syndrome, patients complain of lateral ankle pain and subjective instability, though stress testing reveals no significant instability. MR demonstrates soft-tissue thickening and edema within the tarsal sinus, often obliterating the underlying ligamentous anatomy. Coexistent abnormalities of the lateral ligamentous complex and the posterior tibial tendon are common. Symptomatic relief from injection of local anesthetic into the tarsal sinus is diagnostic in such cases.

Interdigital Neuromas

The most characteristic mass involving the toes is the interdigital neuroma, or Morton’s neuroma. Morton neuroma was originally described in 1876 by Thomas Morton. Because this process was initially thought to be a neoplasm of the interdigital nerve, it was referred to as a neuroma. In actuality, Morton neuroma is non-neoplastic. A true neuroma represents a proliferation of nerve tissue, either as a primary neoplasm or in response to nerve amputation. With Morton neuroma, swelling of the common digital nerve and perineural fibrosis result in mass-like enlargement, but a true neoplasm is not present.

Morton neuroma is felt to most likely represent an entrapment syndrome. The common plantar digital nerve passes deep to the intermetatarsal ligament and into a relatively small space between the metatarsal heads. Entrapment occurs when this confined space is further compromised on a repetitive basis. Morton neuroma most commonly occurs in the third intermetatarsal space, followed by the second intermetatarsal spacei. Anatomically, the second and third intermetatarsal spaces are smaller than the first or fourth intermetatarsal spaces. Young

427 and middle-aged women are most commonly affected, which has been attributed to the belief that poorly fitting shoes in the toe region and high heels contribute to neuroma formation. Athletes who spend a significant portion of their activity on the ball of the foot, such as sprinters, are also at greater risk.

A plantar view of the foot demonstrates the common plantar digital nerves passing plantar to the intermetatarsal ligaments (indicated in blue) in this 3D graphic representation. Morton neuromas arise from the common plantar digital nerves immediately distal to the intermetatarsal ligaments (indicated by red).

The typical clinical presentation for Morton neuroma is progressive pain, throbbing, and numbness radiating from the web space into the toes. There may be a sensation of walking on a marble. A palpable mass may be present, however, physical examination is frequently inconclusive. A wide range of clinical conditions may mimic Morton neuroma, including metatarsal stress fractures, Freiberg's infraction, intermetatarsal bursitis, and synovial cysts. It should be noted that a significant percentage of Morton neuromas (up to 30%) are asymptomatic and demonstrate no gender predilection. These tend to be smaller lesions, whereas larger lesions are more commonly symptomatic3.

The MRI appearance of Morton neuroma is that of a tear-drop shaped soft tissue mass between the metatarsal heads, projecting inferiorly into the plantar subcutaneous fat and located on the plantar side of the intermetatarsal ligament. The mass is typically intermediate in signal intensity on T1-weighted images. On T2-weighted images, fibrosis results in relatively low signal intensity. Fluid may be present in the intermetatarsal bursa secondary to associated

428 inflammation. Although intermetatarsal fluid is common in the asymptomatic population, larger collections (greater than 3mm in transverse dimension) are more likely to be associated with Morton neuroma. Gadolinium-enhanced MRI greatly improves the conspicuity of the neuroma, which typically enhance.

T1-weighted coronal image just distal to the 3rd and 4th metatarsophalangeal joints demonstrates an intermediate signal nodular focus suspicious for a Morton neuroma.

A fat-suppressed T1-weighted coronal image in the same patient following gadolinium administration, demonstrates enhancement of the nodular focus, characteristic of Morton neuroma.

The treatment of Morton neuroma begins with conservative measures. Modification of footware and steroid injections successfully treat most individuals. Surgery is reserved for those patients with a poor response to conservative measures. Surgical approaches include transection of the intermetatarsal ligament and nerve resection. Ironically, in a small percentage of patients, nerve

429 resection may result in a stump neuroma that leads to dysesthesias of the innervated toes. Additional surgery may be required in this subset of patients.

Turf Toe:

The Great Toe is exceeding important in the normal mechanical function of the foot, but its prominent role results in a structure that is prone to injury. As much as 80% of the shock upon the foot when running is absorbed by the great toe. MR easily recognizes causes of pain and dysfunction at the great toe such as sesamoid disorders and osteoarthritis.

The paired medial and lateral sesamoids at the great toe are essential to normal biomechanical function of the metatarsophalangeal joint. Unfortunately, the sesamoids are somewhat prone to injury. MR allows assessment of sesamoid osteochondritis or occult fracture, and aids in differentiating these lesions from a bipartite sesamoid, which is a normal variant.

Injuries to the metatarsophalangeal region of the great toe were once considered relatively uncommon, but now are recognized as a frequent cause of morbidity and lost playing time in the athlete, particularly among American football players. The term “Turf Toe” was first coined by Bowers and Martin in a 1976 article describing capsuloligamentous sprains at the first metatarsophalangeal joint sustained by collegiate football players on artificial turf. Although the hardness and reduced shock absorption of artificial surfaces have impacted the frequency of this injury, it is also recognized that the use of softer soled shoes on artificial turf, allowing greater speed and traction for the athletes, have also had a major contribution, as hyperextension is more likely with these shoes as compared to the harder soled cleats utilized on natural grass. The frequency of turf toe among professional football players is estimated at 30-45%. Although many clinicians originally felt that turf toe represented a relatively minor capsular sprain, the term is now used to describe a wide spectrum of injuries with greatly varying levels of severityii.

Although primarily a hinge joint that flexes and extends, motion at the great toe metatarsophalangeal joint includes rotary and sliding components. The relatively small and shallow articular surface of the proximal phalanx provides little intrinsic stability relative to the metatarsal head. The great toe withstands 40-60% of body weight during normal gait, and this load increases several fold with running or jumping. The toe’s ability to withstand this degree of stress and instability at the metatarsophalangeal joint is dependent upon anatomy that can be referred to as the capsuloligamentous-sesamoid complex.

The paired medial and lateral sesamoids are critical components of normal function at the joint, reducing friction and providing vital shock absorption at the great toe. Much of the complex anatomy at the metatarsophalangeal joint is related to the sesamoids. The sesamoids are embedded in a firm fibrous structure known as the plantar plate, which at its proximal aspect blends with the capsule about the plantar aspect of the distal metatarsal. Distally, the plantar plate attaches to the base of the proximal phalanx, where a small recess is often found. The plantar plate is relatively thin centrally, where it overlies the flexor hallucis longus. The posterior midline aspect of the plantar plate, lying between the sesamoids, may be referred to as the intersesamoidal ligament. At its periphery, where it attaches to the sesamoids, the plantar plate

430 significantly thickens, and these regions are often referred to as the sesamoid phalangeal ligaments. It should be noted that the designation of the intersesamoidal and sesamoid phalangeal regions as “ligaments” is primarily semantic, as these regions are composed of the same type of fibrous tissue as the central plantar plate. The designations are analogous to the use of the terms dorsal and volar radioulnar ligaments to refer to the thicker peripheral regions of the triangular fibrocartilage at the wrist.

In this dorsal 3D depiction of the metatarsophalangeal joint of the great toe, the metatarsal head has been removed and the proximal phalanx is flexed and distracted to better demonstrate the plantar plate and the embedded medial (M) and lateral (L) sesamoids. The sesamoid phalangeal ligaments (arrows) and intersesamoid ligament (asterisk) are seen as thickened regions of the plantar plate.

431

The collateral ligament complexes include main collateral ligaments and accessory sesamoid ligaments, the latter extending from the metatarsal head to the periphery of the respective sesamoids. The medial and lateral heads of the flexor hallucis brevis tendons attach to the sesamoids proximally. The abductor hallucis tendon attaches firmly to the medial aspect of the medial sesamoid with distal contributions blending with the capsule and the plantar plate. Laterally, the transverse and oblique heads of the adductor hallucis form a unified tendon that attaches to the lateral aspect of the lateral sesamoid with distal continuation to the joint capsule. The flexor hallucis longus tendon courses between the sesamoids as it extends to the distal phalanx, but does not actually attach at any point to the sesamoids.

432 Medial (above) and lateral (below) views of the great toe metatarsophalangeal joint with the extensor hood structures removed depicts key structural elements of the plantar capsuloligamentous-sesamoid complex. The main collateral ligament (MC) and accessory sesamoid ligaments (AS) comprise the collateral ligamentous complexes and are found medially and laterally. The abductor hallucis (Ab) tendon inserts on the medial sesamoid and blends with the capsular structures on the medial side of the joint. The transverse (AdT) and oblique (AdO) heads of the adductor hallucis muscle send fibers to the lateral sesamoid, capsule and plantar plate. The medial and lateral heads of the flexor hallucis brevis (FHB) insert on to the sesamoids found along the plantar surface of the metatarsal. The flexor hallucis longus tendon (FHL) is also depicted.

A 3D representation of the plantar aspect of the great toe demonstrates some of the key anatomic structures attaching to the plantar plate and sesamoids including the medial and lateral heads of the flexor hallucis brevis muscles (FHB), abductor hallucis tendon (Ab), and the oblique (AdO) and transverse (AdT) heads of the adductor hallucis muscle. The flexor hallucis longus tendon (FHL) traverses the metatarsophalangeal joint plantar to the plantar plate without an attachment to the sesamoids.

The most common mechanism of injury in turf toe is a hyperextension event with the foot in mild dorsiflexion. A frequent scenario involves a lineman engaged in a block who is injured when another player then falls upon the planted foot, driving the toes downward and hyperextending the great toe. Depending upon the vectors of force, any component of the

433 capsuloligamentous-sesamoid complex can be injured. Associated valgus or varus forces result in a greater likelihood of injuries to the medial and lateral supporting components, respectively.

Normal Great Toe MR Anatomy:

The important anatomical components of the capsuloligamentous-sesamoid complex are well visualized on high quality MR images. The plantar plate is seen as a thin low signal intensity structure on all pulse sequences, with its central portion being best visualized in the sagittal plane. A normal synovial recess is often present at the distal insertion, typically appearing relatively small and smooth, and never full thickness in the normal plantar plate (D). The thicker periphery of the plantar plate which comprises the sesamoid phalangeal ligaments is easily demonstrated in the sagittal plane. Coronal (short axis) images may also provide visualization of the central plantar plate, though visualization is more difficult except for in cases where the plantar plate is thicker than typical. Thicker components such as the sesamoid phalangeal ligaments and the intersesamoidal ligament are well seen in the coronal plane.

A T1-weighted sagittal view demonstrates the normal, thin low signal intensity plantar plate (arrow). The midline location is confirmed by the visualization of the underlying flexor hallucis longus tendon (arrowheads).

434

A fat-suppressed T2-weighted sagittal image demonstrates the normal distal recess (arrow) that is frequently found at the phalangeal insertion of the plantar plate. Note the smooth, fairly small, and well defined appearance of this recess.

A proton density-weighted sagittal image lateral to midline reveals the thick, low signal intensity appearance of the normal lateral sesamoid phalangeal ligament (arrow).

Coronal images at the level of the sesamoids are utilized to confirm the normal position of the sesamoids relative to their facets along the plantar surface of the metatarsal head. The low signal intensity band between the sesamoids, overlying the flexor hallucis longus tendon at this level, represents the intersesamoidal ligament. Contributions to the sesamoids from the abductor and adductor hallucis tendons as well as the sesamoid accessory ligaments are visible in this plane.

435

A T1-weighted coronal view through the metatarsal head reveals normally positioned medial (M) and lateral (L) sesamoids. The flexor hallucis longus tendon (T) lies plantar to the intersesamoidal ligament (I). Normal medial and lateral attachments of the abductor and adductor hallucis tendons and the sesamoid accessory ligaments are also visible (arrowheads).

Initial reports on the use of MR in the evaluation of turf toe described defects, swelling and/or edema in the region of the plantar capsule in patients with injury to the great toe metatarsophalangeal joint. Advances in MR technology and knowledge of anatomy have subsequently led to a much more detailed approach to the evaluation of turf toe, such that numerous types and variations of injuries to the capsuloligamentous-sesamoid complex can be specifically described.

Although clinical studies of turf toe have postulated that tears of the plantar capsule would predominate at a weaker attachment site upon the metatarsal head, our experience and published MR studies suggest that proximal capsular injuries are relatively uncommon. Of patients who present for MR imaging, distal tears of the plantar plate and sesamoid phalangeal ligaments predominate.

436

A STIR sagittal image of collegiate football player with clinical signs of turf toe reveals edema and irregularity (arrows) at the posterior capsular attachment of the medial sesamoid and distal metatarsal.

A midline STIR sagittal image from a collegiate football player following hyperextension injury at the great toe reveals a fluid filled gap (arrow) at the typical distal insertion site of the plantar plate. The gap is too large and irregular to represent a normal recess, and fluid is seen to contact the underlying flexor hallucis longus tendon (arrowhead).

437

A fat-suppressed T2-weighted image of a 23 year-old elite soccer player was obtained at the level of the lateral sesamoid. A large fluid filled gap (arrow) is present at the distal attachment site of the sesamoid phalangeal ligament. The large effusion in this patient aids in detection of the abnormality. With increasingly severe injuries, discrete defects within the plantar plate or sesamoid phalangeal ligaments may not be apparent. Rather, normal structures may simply be replaced by diffuse soft tissue thickening and edema (K). In cases of extensive sesamoid phalangeal ligament disruption, proximal migration of the sesamoids is frequently apparent.

438

A STIR coronal image in an NFL tight end injured during a game demonstrates diffuse soft- tissue thickening and edema (arrows) in the expected location of the medial sesamoid phalangeal ligament. The lateral sesamoid phalangeal ligament (arrowheads) maintains a normal low signal intensity appearance.

A corresponding proton density-weighted sagittal image reveals near complete absence of the normal medial sesamoid phalangeal ligament (arrow). The medial sesamoid (arrowhead) has migrated proximally relative to its normal position.

The same forces that cause soft tissue injuries in turf toe also place osseous structures at risk, primarily the sesamoids. The role of the sesamoids in shock absorption at the toe and their plantar position result in a greater tendency for injury to the sesamoids relative to the metatarsal head or proximal phalanx. The medial sesamoid is at greater risk as it is under a more direct weightbearing load, but either sesamoid may be injured either acutely or due to the chronic repetitive stress that occurs in patients prone to turf toe.

439

A STIR sagittal image from a 21 year-old collegiate football player demonstrates a large midsubstance rupture (arrow) of the plantar plate. The underlying flexor hallucis longus tendon (arrowheads) is evident.

A corresponding sagittal view lateral to midline reveals rupture of the lateral sesamoid phalangeal ligament (arrow) and proximal retraction of the lateral sesamoid. Edema and subtle intramedullary linearity are seen within the mid lateral sesamoid (arrowhead), compatible with a non-displaced fracture, confirmed on additional views (not shown).

In cases of turf toe with significant sesamoid migration, tendinous and capsular injuries are virtually obligatory, and should be carefully assessed. For the sesamoids to migrate proximally, the integrity of the attachments of the ipsilateral capsule, abductor or adductor hallucis tendons, and the accessory sesamoid ligament are quite likely compromised.

440

A coronal T1-weighted image from the same patient as M,N reveals tears at the adductor hallucis and accessory sesamoid ligaments along the lateral side (arrows). Partial tearing is evident at the medial attachment of the abductor hallucis (arrowhead).

Capsular and tendinous avulsions at the great toe may also occur in the absence of sesamoid migration. The most common clinical scenario is in cases where a hyperextension and valgus load are placed upon the toe, resulting in medial soft tissue injuries. In such cases, the plantar plate may remain intact, and the abnormalities may easily be missed if not carefully assessed as part of a thorough search pattern.

Another subset of patients benefitting from surgery includes athletes who fail conservative therapy. These patients may present months after injury with complaints of increased intensity and duration of pain following activity. MR in these patients is able to confirm significant anatomical lesions that require operative repair (R). Such delayed surgeries may be more challenging, as scarring and shortening of retracted structures often occur.

R

441

A T1-weighted sagittal image from a 16 year-old high school football player who complained of increasing pain at the great toe 5 months following initial injury reveals marked proximal migration of the medial sesamoid (asterisk) with associated disruption of the sesamoid phalangeal ligament. A similar appearance was seen at the lateral sesamoid (not shown).

View additional images and discussions of numerous musculoskeletal topics at www.radsource.us

442 443 444 445 446 Experiences in Sports MR Imaging Hockey Injury – Anterior Trauma The Athlete’s Shoulder

Charles P. Ho, PhD, MD

CP Ho – MSK Sports MRI Junior league hockey player, checked into boards CP Ho – MSK Sports MRI

MRI of Shoulder Hockey Injury – Anterior Trauma Rotator Interval Lesions and Associated Injuries

• Long biceps tendon • Biceps pulley – SGHL, CHL • Superior subscapularis – “Hidden lesion” • Anterior supraspinatus • SLAP • SLAC • Microinstability

CP Ho – MSK Sports MRI CP Ho – MSK Sports MRI

Rotator Interval Complete Rotator Interval Disruption

Morag, Y. et al. Radiology 2005;235:21-30

SGHL, CHL, Rotator Interval Capsule contribute to long Biceps Pulley

CP Ho – MSK Sports MRI CP Ho – MSK Sports MRI

447 Rotator Interval Lesion Rotator Interval Lesion “Hidden Lesion” (per Walch)

• SGHL/CHL complex, Biceps pulley tears • Subscapularis tendon tears • Associated Biceps tendon tears and instability • May be difficult to visualize arthroscopically; therefore, “Hidden Lesion”

SGHL and biceps pulley disruption, subscapularis delamination

CP Ho – MSK Sports MRI CP Ho – MSK Sports MRI

Rotator Interval Lesion Long Head Biceps Tendinosis / Hypertrophy “Hidden Lesion” (per Walch) Biceps Pulley Failure

CP Ho – MSK Sports MRI CP Ho – MSK Sports MRI

Long Biceps Intra-Articular Entrapment Long Biceps Intra-Articular Entrapment Intra-Articular Hypertrophy Intra-Articular Hypertrophy “Hourglass Biceps” “Hourglass Biceps” Boileau P, Ahrens PM, Hatzidakis AM. JSES 2004; 13:249-57

• Retrospective review • 21 patients (14 M, 7 F) • Mean age 62 (range 47-69) • Dominant arm 18/21 • Hypertrophic intra-articular LHB tendon • Anterior pain, loss of active and passive elevation averaging 10 – 20 degrees • Associated rotator cuff full-thickness tear 20/21 Boileau P, Ahrens PM, Hatzidakis AM. JSES 2004; 13:249-57

CP Ho – MSK Sports MRI CP Ho – MSK Sports MRI

448 Long Biceps Intra-Articular Entrapment Long Biceps Intra-Articular Entrapment Intra-Articular Hypertrophy Intra-Articular Hypertrophy

59 YO F 75 Y0 F CP Ho – MSK Sports MRI CP Ho – MSK Sports MRI

Long Biceps Intra-Articular Entrapment Intra-Articular Hypertrophy Long Head Biceps Tendinosis / Hypertrophy Biceps Pulley Failure

61 YO M CP Ho – MSK Sports MRI CP Ho – MSK Sports MRI

Long Head Biceps Tendon Tear

NFL Quarterback

CP Ho – MSK Sports MRI CP Ho – MSK Sports MRI

449 Long Head Biceps Tendon Tear

NFL quarterback

62 YO F, Pain, LROM CP Ho – MSK Sports MRI CP Ho – MSK Sports MRI

Adhesive Capsulitis Rotator Interval Lesion Adhesive Capsulitis

• Pain, stiffness, decreased range of motion • Capsule thickened, inflamed, contracted - Anterior superior – Rotator Interval (SGHL, CHL) - Anterior inferior – IGHL - Posterior 61 YO F Frozen shoulder

CP Ho – MSK Sports MRI CP Ho – MSK Sports MRI

Adhesive Capsulitis Massive Irreparable Rotator Cuff Tears

• 2 or more rotator cuff tendons • Severe muscle atrophy, fatty infiltration 60 YO M • Superior migration of humeral head • Pain, weakness, loss of motion/function

With IV contrast

CP Ho – MSK Sports MRI CP Ho – MSK Sports MRI

450 Massive Irreparable Rotator Cuff Tears Massive Irreparable Rotator Cuff Tears Superior Capsular Reconstruction • Latissimus dorsi and other tendon transfers (Arthroscopic SCR)

Variable outcomes • Static stabilizer preventing superior migration
Difficult revisions of humeral head • Reverse total shoulder arthroplasty (rTSA) • Pain relief; reducing painful impingement
Pain relief; some function with deltoid • Some function with deltoid?
Concerns of implant longevity?

Elderly, low-demand patients

(Mihata, et al. Arthroscopy 2013) CP Ho – MSK Sports MRI CP Ho – MSK Sports MRI

Superior Capsular Reconstruction Superior Capsular Reconstruction (Arthroscopic SCR) (Arthroscopic SCR) • 3.5 mm thick human acellular dermal allograft patch • Suture anchors glenoid and humeral fixation (Katthagen, et al. Orthopedics Today 2016.)

65 yo F 65 yo F CP Ho – MSK Sports MRI CP Ho – MSK Sports MRI

Bankart Lesion Labrum

• Most common Capsulo-Labral injury
Deepens socket • Labral Ligamentous
Suction negative pressure seal avulsion with Periosteal disruption
Fusion and insertion site for
Often unable to ligaments determine if periosteum is intact

CP Ho – MSK Sports MRI CP Ho – MSK Sports MRI

451 ALPSA

• Anterior Labral- ligamentous Periosteal Sleeve Avulsion with intact periosteum • Medially displaced and inferiorly shifted Labral- ligamentous attachment • May appear remarkably normal at arthroscopy

CP Ho – MSK Sports MRI CP Ho – MSK Sports MRI

Perthes Lesion

• Labral ligamentous avulsion with intact periosteum • Little or no displacement • May also look remarkably normal at arthroscopy

CP Ho – MSK Sports MRI CP Ho – MSK Sports MRI

Perthes Lesion HAGL Lesion

• Humeral Avulsion of the IGHL, usually anterior band • “J” shaped capsule on coronal images • Uncommon

CP Ho – MSK Sports MRI CP Ho – MSK Sports MRI

452 GAGL BHAGL

CP Ho – MSK Sports MRI CP Ho – MSK Sports MRI

Para-Labral Cyst Para-Labral Cyst

• Arises from capsulo-labral disruption or degeneration, • Compression neuropathy instability lesions
Suprascapular neuropathy • Origin from the joint • Infraspinatus denervation • Original lesion may scar or remain patent/open • Supraspinatus denervation • Symptoms result from • Pain and proprioception fibers original lesion or compression • Mimics rotator cuff tear

CP Ho – MSK Sports MRI CP Ho – MSK Sports MRI

CP Ho – MSK Sports MRI CP Ho – MSK Sports MRI

453 SLAP Lesions Posterior Instability • Superior labrum tear at biceps • Backward force on anchor adducted internally • High signal disrupting labral rotated shoulder substance (not recess) on MRI
Seizures • Forced extension,

Football compression between glenoid and humeral head
Weightlifters • Traction injury • Reverse Bankart • Fall on outstretched hand • Reverse Hill Sachs • Overhead, throwing athlete

CP Ho – MSK Sports MRI CP Ho – MSK Sports MRI

SLAP Lesions SLAP II 4 Types Originally Described

• I degenerative fraying • II unstable, discrete tear, detachment of labrum and biceps anchor • III buckethandle tear • IV buckethandle tear extending into biceps tendon SLAP I

CP Ho – MSK Sports MRI CP Ho – MSK Sports MRI

SLAP III SLAP IV

CP Ho – MSK Sports MRI CP Ho – MSK Sports MRI

454 SLAP Lesions Additional Variants Internal Impingement Overhead Activity • V Bankart lesion dissecting upward to biceps anchor • VI unstable radial, flap tear involving • Undersurface attrition/tear of posterior separation of biceps anchor supraspinatus /anterior infraspinatus • VII SLAP extending to involve middle • Posterosuperior labral fraying/tear glenohumeral ligament (Posterior peelback) • VIII type II SLAP + entire posterior • Posterosuperior lateral humeral head labral tear bone pitting/cysts, osteitis • IX circumferential labral tear (from repetitive impaction, • X extension into rotator interval structures differentiate from Hill Sachs lesion)

CP Ho – MSK Sports MRI CP Ho – MSK Sports MRI

Internal Impingement Posterior Peelback • Posterior labral, capsule tearing, stripping, scarring • Posterior glenoid remodeling osteophyte enthesophyte - Bennett’s lesion

Baseball Pitcher CP Ho – MSK Sports MRI CP Ho – MSK Sports MRI

INTRA-ARTICULAR CONTRAST FOR MRI ARTHROGRAPHY INTRA-ARTICULAR CONTRAST FOR MRI ARTHROGRAPHY • Invasive → Informed Consent • Morbidity – Pain, Synovitis • Logistical Difficulties, Delay • Distends Joint Capsule • Leakage or Missed Injections • Diluted Gadolinium Solution vs. Saline • Limited to Injected Compartment • Passive Contrast • Limited Pressurization of Joint

CP Ho – MSK Sports MRI CP Ho – MSK Sports MRI

455 Gadolinium MR Arthrogram

Quarterback – severe pain 2 days later CP Ho – MSK Sports MRI CP Ho – MSK Sports MRI

Gadolinium MR arthrogram

Baseball pitcher – pain after MRA, lost to team for a week after

CP Ho – MSK Sports MRI CP Ho – MSK Sports MRI

MRI, non-contrast

16 YO M, persistent pain, catching 16 YO M, persistent pain, catching CP Ho – MSK Sports MRI CP Ho – MSK Sports MRI

456 Gadolinium MR Arthrogram 1 week later MRI, non-contrast

15 YO M, football 16 YO M, persistent pain, catching

CP Ho – MSK Sports MRI CP Ho – MSK Sports MRI

INTRAVENOUS GADOLINIUM Gadolinium MR Arthrogram 1 month later CONTRAST MRI • Delayed Post-Contrast, Post-Exercise Imaging (Indirect Arthrography) - Logistical Issues - Becomes Passive Contrast - Less Distention

15 YO M, football • Immediate Contrast-Enhanced Imaging

CP Ho – MSK Sports MRI CP Ho – MSK Sports MRI

INTRAVENOUS GADOLINIUM IMMEDIATE INTRAVENOUS GADOLINIUM IMMEDIATE CONTRAST-ENHANCED MRI CONTRAST-ENHANCED MRI • Physiologic Information → Enhanced Areas of Hyperemia, Inflammation • Minimally Invasive
Granulation Tissue • Minimal Logistical Difficulties or Delay
Synovitis, synovial overgrowth • Immediate Active Contrast Enhancement around injured structures

Scar (Vascularized)

CP Ho – MSK Sports MRI CP Ho – MSK Sports MRI

457 Intravenous gadolinium immediate contrast-enhanced MRI

Pre T1 weighted image Post T1 weighted image INTRAVENOUS GADOLINIUM IMMEDIATE CONTRAST-ENHANCED MRI

• Applies Throughout Imaged Area/Field of View -- Not Limited to Single Injected Joint Compartment • Points To Soft Tissue & Bone Injuries/Tears

Volleyball player

CP Ho – MSK Sports MRI CP Ho – MSK Sports MRI

CP Ho – MSK Sports MRI CP Ho – MSK Sports MRI

Intravenous gadolinium contrast-enhanced MRI Pre PD Pre T2* FFE Post FS T1

Football lineman (history of previous MR arthrogram)

CP Ho – MSK Sports MRI CP Ho – MSK Sports MRI

458 Intravenous gadolinium contrast-enhanced MRI T2* FFE FS T1

Baseball pitcher - new pain, weakness CP Ho – MSK Sports MRI CP Ho – MSK Sports MRI

Intravenous gadolinium contrast-enhanced MRI Experiences in Sports MR Imaging

FS T1 T2* FFE

Thank You

Acute dislocation (gadolinium MR arthrogram requested)

CP Ho – MSK Sports MRI CP Ho – MSK Sports MRI

459 460 461 462 MR OF THE SHOULDER: BEYOND THE CUFF

Mark H. Awh, MD www.radsource.us

MR has revolutionized the diagnostic approach to imaging the shoulder. Previously, plain films, arthrography, and CT were the mainstays of the diagnostic armamentarium. None of these examinations provide the soft tissue contrast necessary to optimally evaluate the complex anatomy of the shoulder. Traditionally, evaluation of the rotator cuff and impingement syndrome have by far been the most common indication for shoulder MR. However, as our understanding of pathology and anatomy at the shoulder continues to evolve, numerous additional entities have proven appropriate and indeed preferable for the use of MR in diagnosis and evaluation.

Labrum and Instability

The glenohumeral joint is a synovial-lined ball-in-socket joint that has the greatest range of motion of any joint in the human body. The glenohumeral joint is the most commonly dislocated joint, attributed to the much larger articular surface area of the humeral head and the smaller, shallow glenoid fossa. The glenoid labrum is a fibrocartilaginous cuff surrounding the glenoid fossa. The labrum deepens the fossa and increases the articular surface area of the glenoid. The osseous rim of the glenoid and the fibrocartilaginous labrum are sites of attachment for the glenohumeral ligaments and long head biceps tendon, which can be injured individually or in tandem.

Glenohumeral stability is provided by dynamic and static “restraints”. Dynamic restraints include the rotator cuff and the long head biceps brachii tendon. Static restraints include the glenohumeral ligaments, glenohumeral joint capsule (including the rotator cuff interval capsule), the coracohumeral ligament, the glenoid labrum, and the bones. The attachments of the glenohumeral ligaments and the long head biceps anchor to the labrum are stronger than the attachment of the labrum to the glenoid rim. Therefore, the glenoid labrum is commonly torn or avulsed when excessive force is applied to a glenohumeral ligament or the long head biceps. These injuries have classic appearances, and are associated with multiple acronyms (such as ALPSA and SLAP) and eponyms (like the Hill Sachs deformity).

463 Relevant anatomy:

Lateral view of the shoulder with the humerus removed demonstrates the restraints of the glenohumeral joint. Inferior glenohumeral ligament (IGHL), middle glenohumeral ligament (MGHL), superior glenohumeral ligament (SGHL), long head of the biceps (LHB), and coracohumeral ligament (CHL). The supraspinatus (Sup), infraspinatus (Is), subscapularis (Sub), and teres minor (Tm), and coracoacromial ligament (CAL) are indicated.

The glenohumeral ligaments (inferior, middle, and superior) are thickened bands of the joint capsule that extend from the inferior and anterior glenoid and glenoid labrum, to the anatomic neck region of the humerus, protecting against extreme range of motion.

The inferior glenohumeral ligament (IGHL) is a hammock-like structure that attaches to the inferior glenoid, glenoid labrum, and the humeral neck. Thickened portions of the IGHL anteriorly and posteriorly are referred to as the anterior and posterior bands. Anterior inferior shoulder dislocation is the most common cause of shoulder instability, and the anterior band of the inferior glenohumeral ligament is believed to represent the major passive stabilizer of the glenohumeral joint.

464

A fat suppressed axial T1- weighted MR arthrogram image demonstrates the anterior band of the inferior glenohumeral ligament (arrow).

A fat suppressed oblique sagittal T1-weighted MR arthrogram image, demonstrating the anterior and posterior bands of the inferior glenohumeral ligament (arrows).

465 The middle glenohumeral ligament (MGHL) is the most variable of the glenohumeral ligaments. It varies in thickness and is associated with labroligamentous anatomic variations such as in the Buford complex. The MGHL can share a common origin with the superior glenohumeral ligament, can be absent in approximately one tenth to one third of shoulders, and functions to help stabilize the shoulder anteriorly from 0-45 degrees of abduction and external rotation.

A fat suppressed oblique sagittal T1-weighted MR arthrogram image demonstrating the middle glenohumeral ligament (arrow).

The superior glenohumeral ligament (SGHL) is the smallest of the glenohumeral ligaments and acts with the coracohumeral ligament to stabilize the glenohumeral joint and prevent posterior and inferior translation of the humeral head. The SGHL can have a common attachment with the long head biceps anchor to the superior glenoid/superior labrum. The long head biceps tendon can also attach along the anterior, posterior, or along both the anterior and posterior superior glenoid/labrum.

466

A fat suppressed axial T1-weighted MR arthrogram image demonstrates the superior glenohumeral ligament (arrow), the glenoid labrum (arrowhead), the long head biceps tendon (short arrow), and the coracohumeral ligament (curved arrow).

For localization purposes, the labrum is divided into four zones, six zones, or according to the location on a clock face. The four zones are superior, anterior, inferior, and posterior. Further subdivision of the labrum into six zones includes: superior, anterosuperior, anteroinferior, inferior, posteroinferior, and posterosuperior. By convention, when utilizing the clock face, the mid superior labrum is denoted as 12 o’clock and the mid inferior labrum as 6 o’clock. There is controversy regarding 3 o’clock and 9 o’clock, as radiologists tend to classify the anterior labrum as 3 o’clock regardless of side, whereas some of the orthopaedic literature assumes 3 o’clock as anterior at the right shoulder but posterior at the left shoulder. For this reason, we favor utilizing a descriptive method of localization, utilizing zones and the use of equator as a designation of the mid anterior or posterior labrum.

A fat suppressed oblique sagittal T1 weighted MR arthrogram image, demonstrating the six labral zones of the glenoid labrum.

467 The normal labrum demonstrates low signal intensity on all pulse sequences, due to the lack of mobile protons in this dense fibrocartilage. On cross sectional imaging, the normal labrum is most commonly triangular, but can also be round, cleaved, notched, flat, or absent.

MRI diagnosis of labral tears is based on abnormalities in the signal intensity, morphology, and location (displacement) of the labrum. The labrum may be frayed, crushed, avulsed, or torn. Tears are classified by morphology, displaced or nondisplaced, and by location. Labral tears can extend into the biceps anchor as well as the glenohumeral ligaments. MRI criteria for diagnosing labral tears include surface irregularity, increased signal within the substance of the labrum that extends to the labral surface, fluid or contrast imbibed into the substance of the labrum, and labral avulsions. Secondary signs of labral tears include paralabral cysts, periosteal stripping and tearing, labral associated bone injuries such as Hill Sachs and Osseous Bankart lesions, and hyaline cartilage injuries such as the GLAD lesion.

An axial gradient echo image demonstrates increased signal intensity in the anterior labrum that extends through the labrum to the articular and non- articular surfaces (arrowheads), consistent with an anterior labral tear.

468

A fat suppressed oblique coronal T1-weighted MR arthrogram image demonstrates contrast extending into the superior labrum, consistent with a superior labral tear (arrow).

Multiple acronyms and eponyms are used to describe labral, glenohumeral ligament, and associated shoulder injuries. A Bankart lesion is a tear of the anteroinferior glenoid labrum with an associated tear of the anterior scapular periosteum, with or without associated fracture of the anterior inferior glenoid rim. (Some radiologists and surgeons use the term Bankart lesion to describe all tears of the anteroinferior labrum.)

A fat suppressed axial proton density- weighted image of a classic Bankart lesion, with tears of the anteroinferior labrum (arrow) and the adjacent scapular periosteum (arrowhead).

469 Illustration depicting the components of the classic Bankart lesion consisting of a tear of the anteroinferior labrum (L) and periosteum (P). Inferior glenohumeral ligament (IGHL), humerus (H), and glenoid (G).

A Perthes lesion is a variant of the Bankart, where the anteroinferior labrum is avulsed from the glenoid and the scapular periosteum remains intact but is stripped medially.

A fat suppressed axial T1-weighted MR arthrographic image of a Perthes lesion demonstrates an avulsed anteroinferior labrum (arrow). The scapular periosteum remains intact but is stripped medially (arrow head).

470

The Perthes is a Bankart variant in which the labrum (L) is torn and the periosteum is stripped (P) but remains intact. Inferior glenohumeral ligament (IGHL), humerus (H), and glenoid (G).

A HAGL lesion is humeral avulsion of the glenohumeral ligament that occurs from shoulder dislocation, with avulsion of the inferior glenohumeral ligament from the anatomic neck of the humerus. A BHAGL is a bony HAGL, or a HAGL lesion that involves a bone fragment.

Fat suppressed oblique coronal T1-weighted MR arthrogram images of a HAGL lesion. The axillary pouch in a normal patient is typically “U” shaped. This patient’s axillary pouch has an abnormal inverted “J” shape (arrowheads). There is fraying of the inferior glenohumeral ligament (arrow), and cortical irregularity along the humeral neck (short arrows) consistent with a humeral avulsion of the glenohumeral ligament.

The GLAD lesion (R) refers to glenolabral articular disruption, which involves a tear of the anterior inferior labrum with an associated glenoid chondral defect.

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A gradient-echo axial MR image of a GLAD lesion. The anterior labrum is torn (arrowhead) and there is an adjacent glenoid chondral defect (arrow).

The POLPSA lesion is a posterior labrum periosteal sleeve avulsion lesion. The POLPSA lesion is associated with posterior glenohumeral instability and most commonly occurs with posterior dislocation. In the POLPSA lesion, the posterior labrum is torn and the posterior scapular periosteum is intact but stripped from the posterior glenoid. The POLPSA lesion is similar to the ALPSA lesion, however it occurs posteriorly

SLAP is an acronym for superior labral tears, that propagate anterior and posterior in reference to the biceps anchor. Originally, SLAP lesions were classified by Snyder et al, based on arthroscopic evaluation. Additional categories of SLAP tears were described by Maffet et al, Morgan et al, Resnick and Beltran. Although the classification of SLAP tears is useful in terms of prognosis and treatment, a careful description of the type and location of labral tear can provide equivalent information.

SLAP Classification Type Location (clock face) Description I 11-1 Fraying II 11-1 Tear with biceps instability IIA 11-3 Tear with biceps instability -associated with repetitive overhead motion -similar to Type X IIB 9-11 Tear with biceps instability -associated with infraspinatus tear IIC 9-3 Tear with biceps instability

472 -associated with infraspinatus tear III 11-1 Bucket-handle tear with intact biceps IV 11-1 Bucket-handle tear with biceps extension V 11-5 Bankart lesion with superior extension, or SLAP with anterior inferior extension VI 11-1 Anterior or posterior flap tear, with tear of the bucket handle component VII 11-3 Middle glenohumeral ligament extension VIII 7-1 Similar to IIB, but more extensive -associated with acute posterior dislocation IX 7-5 Globally abnormal labrum -likely post traumatic X 11-1+ Rotator interval extension

Snyder et al, Maffet et al, Morgan et al, Resnick and Beltran. Adapted from Mohana- Borges, Chung, and Resnick16

A fat suppressed oblique coronal T2-weighted MR image demonstrates a Type II SLAP lesion. Note fluid signal extending through the superior labrum (arrow) consistent with a superior labral tear.

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A fat suppressed oblique coronal T1-weighted MR indirect arthrogram image demonstrates a Type IV SLAP lesion, with increased signal undercutting the superior labrum (arrow) and extending into the biceps tendon (arrowhead).

A fat suppressed oblique sagittal MR arthrogram image demonstrates a global labral abnormality (arrowheads) consistent with Type IX SLAP lesion. Also note tearing and fraying of the labral/glenoid attachment of the middle glenohumeral ligament (arrow).

474 The vast majority of shoulder instability is anterior, with posterior instability estimated to affect 2-10% of unstable shoulders. Although anterior shoulder dislocations have been recognized since the dawn of medicine, the first medical description of posterior shoulder dislocation did not occur until 1822. In modern times, posterior shoulder instability is still a commonly missed diagnosis, in part due to a decreased index of suspicion for the entity among many physicians. It is, however, becoming more frequently recognized, particularly in athletes such as football players and weightlifters, in which posterior glenohumeral instability has achieved increased awareness. As McLaughlin stated in 1963, “the clinical diagnosis is clear-cut and unmistakable, but only when the posterior subluxation is suspected”. Modern imaging techniques, in particular MRI, have greatly increased our ability to accurately diagnose posterior glenohumeral instability, and accurate recognition and characterization of the relevant abnormalities are critical for proper diagnosis and patient management.

A normal glenoid labrum has a laterally pointing edge and normal posterior labral morphology. Mild glenoid hypoplasia results in a rounded contour of the posterior glenoid with normal or only mildly thickened posterior labral tissue. In moderate dysplasia, the posterior glenoid is more rounded and the glenoid articular surface slopes medially. The posterior labrum is enlarged to replace the deficient glenoid rim. In cases of severe dysplasia, advanced rounding and posterior sloping of the posterior glenoid is seen, and pronounced thickening of the labrum and other adjacent posterior soft tissues is apparent.

475 A fat-suppressed proton density-weighted axial image in a 14 year-old female with shoulder instability reveals findings of severe glenoid hypoplasia. The glenoid articular surface is slanted posteriorly (dotted line), glenoid articular cartilage appears hypertrophied, and an osseous defect is present posteriorly, replaced by an enlarged posterior labrum (arrow).

The posterior shoulder capsule plays a significant role in preventing posterior shoulder dislocation, particularly at the extremes of internal humeral rotation, the position in which most posterior dislocations occur. As a result, in cases of posterior shoulder instability, particularly dislocation, capsular tears are frequently identified on MR imaging. The posterior capsule injuries most commonly involve the humeral attachment inferiorly, in the region known as the posterior band of the inferior glenohumeral ligament. However, posterior capsular tears may also be seen in the midsubstance or at the humeral attachment of the posterior capsule. A useful indirect sign to be aware ofis to recognize that normally the shoulder capsule should only be outlined by fluid along its inner margin. Fluid should not lie along both sides of the shoulder capsule. If this appearance is present, a capsular tear should be strongly suspected. Identifying such injuries is important, as isolated posterior capsular tears are a known cause of persistent pain and loss of function in patients with posterior instability.

In a 39 year-old weightlifter with persistent posterior shoulder pain and instability, the axial image reveals the posterior capsule outlined by arthrographic fluid along both sides of the capsule, strongly suggestive of a capsular tear.

476 Labroligamentous anatomic variants can mimic pathology, but their appearance and typical location can aid in making the correct diagnosis. Labral variations most commonly occur anterosuperiorly, at the 11 o’clock to 3 o’clock position. The sublabral recess or sulcus is seen at the 11 o’clock to 1 o’clock position, at the junction of the biceps labral complex, but it does not extend posterior to the biceps anchor. The sublabral recess is differentiated from a labral tear by the specific location, the smooth margin, and the fact that it follows the contour of the glenoid. Sublabral recess occurrence increases with increasing patient age, suggesting that sublabral recesses are an age dependant degenerative phenomenon.

A fat suppressed oblique coronal T1 MR arthrogram of a sublabral recess. Contrast undercuts the normal labrum and follows the contour of the glenoid cartilage (arrow heads), but does not extend posterior to the biceps anchor.

A sublabral hole, or foramen, occurs between the anterosuperior labrum and the adjacent glenoid cartilage at the 12 o’clock to 3 o’clock position. It occurs most commonly at the 2 o’clock position, and in patients with a “pear shaped” glenoid.

A fat suppressed T1-weighted MR arthrogram of a sublabral hole (arrow). Sublabral holes/foramina occur anterosuperiorly (1 o’clock to 3 o’clock position). Note the smoothly contoured, otherwise normal appearing anterior superior labrum (arrow head), and middle glenohumeral ligament (short arrow).

477 The Buford complex is an anatomic variant that is seen anterosuperiorly, when the anterosuperior portion of the labrum is absent and the middle glenohumeral ligament is thick and cordlike.

An axial fat suppressed T1- weighted MR arthrogram of a Buford complex. Note absence of the anterior superior labrum (arrowhead) and a thick, cord-like middle glenohumeral ligament (arrow).

Miscellaneous Pathology of the Shoulder

A variety of disease processes that affect the rotator cuff musculature and tendons can be evaluated with MR. Many of these entities produce clinical signs and symptoms that are indistinguishable from impingement syndrome and rotator cuff tears. MR allows characterization of the true nature of the cuff pathology in such cases.

With trauma, muscle contusions and/or tears can occur at the rotator cuff in the absence of tendon tears. Such injuries are well seen as areas of intramuscular edema and fluid signal intensity within the involved muscles. Similarly, occult osseous injuries at the humeral head may mimic the symptoms of a rotator cuff tear. The avulsion injury at the greater tuberosity at the site of supraspinatus tendon attachment is a common example. An uncommon and diagnostically challenging injury is the rotator cuff contusion. In the setting of acute trauma, edema and hemorrhage within the tendons of the rotator cuff may result in high signal intensity that is extremely difficult to distinguish from a full- thickness rotator cuff tear. Careful attention to the lack of tendon retraction and the appropriate clinical context are the keys to accurate MR interpretation in these cases.

478 Rotator interval injuries involve the space between the subscapularis tendon and the supraspinatus tendon. Within the rotator interval, the anterior joint capsule is reinforced by the coracohumeral ligament and the superior glenohumeral ligament. Rotator interval injuries are thought to be important in the development of shoulder instability. MR images reveal edema and soft tissue thickening in the rotator interval region. Fluid extension across the interval into the subcoracoid bursa may also be noted.

The shoulder is the most common site of calcific tendinitis , also known as Hydroxyapatite Deposition Disease (HADD). In one study that examined the prevalence of calcific tendinitis in the general population, 2.7% of study participants had calcified deposits (presumed CHA deposits) in the rotator cuff complex. Of these patients, only 34% to 45% had problems that could be associated with the CHA deposits. In this study, women were more often symptomatic than men and disease occurred most commonly between the ages of 31 and 40. The shoulder is said to account for 60% of cases of acute calcific periarthritis. HADD can involve any of the components of the rotator cuff complex (D) and the supraspinatus tendon is most commonly involved. HADD can also involve adjacent tendon structures including the long and short heads of the biceps tendon, the coracobrachialis tendon, the triceps tendon and pectoralis tendon..

A coronal oblique T2- weighted fat suppressed image shows a deposit of CHA crystals (arrow). Prominent subdeltoid bursitis is also present (arrowheads).

Adhesive capsulitis or “frozen shoulder” is an inflammatory condition of the glenohumeral joint synovium and capsule leading to a restricted range of motion. It is most commonly encountered in female patients who are 40 to 60 years of age. Primary or idiopathic adhesive capsulitis is encountered in the absence of preceding trauma. Secondary adhesive capsulitis or post-traumatic arthritis results from antecedent injury, low-level repetitive trauma, surgery, or rheumatologic conditions. Although poorly understood, adhesive capsulitis is felt to begin as an inflammatory hypervascular

479 synovitis, which prompts a progressive fibroblastic response in the adjacent capsule. Capsular thickening and contraction ensue. At arthroscopy, synovial inflammation or capsular thickening may be seen. The abnormalities most commonly involve the rotator interval capsule, the biceps tendon root, and the inferior and posterior capsule.

The clinical diagnosis of idiopathic adhesive capsulitis relies on the detection of a global decreased range of motion at the glenohumeral joint, absence of previous major trauma, and a normal joint space on plain radiographs. However, these diagnostic criteria are nonspecific, as the clinical features of rotator cuff pathology and impingement often mimic those of adhesive capsulitis.

MRI effectively demonstrates the rotator interval and the axillary recess, which are sites commonly affected by adhesive capsulitis. The rotator interval lies between the supraspinatus muscle and tendon posterosuperiorly and the subscapularis muscle and tendon anteroinferiorly. The rotator interval capsule is composed of the coracohumeral ligament and the superior glenohumeral ligament. The coracohumeral ligament is readily identified on sagittal and coronal T1-weighted or T2-weighted FSE images as a curvilinear low-signal structure surrounded by fat, lateral to the coracoid process. The thickness of the capsule of the axillary recess is best demonstrated on coronal images at the mid glenoid level. .

A coronal T2-weighted image following an MR arthrogram demonstrates the normal thickness of the inferior glenohumeral ligament (arrow).

The MRI findings that suggest adhesive capsulitis include soft tissue thickening in the rotator interval, which may encase the coracohumeral and superior glenohumeral ligaments, and soft tissue thickening adjacent to the biceps anchor. A thickened inferior glenohumeral ligament greater than 4 mm is often seen in the axillary pouch. Loss of definition of the inferior capsule secondary to edema and synovitis may also be demonstrated. IV gadolinium enhancement increases the specificity of the diagnosis by demonstrating enhancement of the rotator interval capsule and enhancement of the

480 capsuloligamentous structures in the axillary recess. MR Arthrography has also been utilized as a means of making the diagnosis of adhesive capsulitis. However, this procedure is relatively invasive and offers no specific or reproducible signs of adhesive capsulitis.

Post IV gadolinium enhanced sagittal T1- weighted image with fat- suppression demonstrates enhancement in the rotator interval region (arrows), confirming the diagnosis of adhesive capsulitis. The long biceps tendon (short arrow), supraspinatus muscle (Sup), subscapularis (Sub), and Coracoid (Cor) are indicated.

Denervation injuries at the rotator cuff result in pain and weakness that may mimic a rotator cuff tear. The most common type of denervation injury at the shoulder is caused by suprascapular nerve entrapment, often secondary to the presence of a ganglion cyst within the spinoglenoid notch. Edema and perhaps fatty atrophy of the infraspinatus and/or the supraspinatus muscles is seen in these patients. Similarly, compression of the axillary nerve within the quadrilateral space may result in isolated atrophy and edema within the teres minor muscle. Recent data indicate that isolated teres minor atrophy, however, is more commonly due to shoulder instability and resultant traction injury to the axillary nerve.

Pectoralis ruptures:

Rupture of the pectoralis major muscle is rare injury that is becoming more frequent due to increasing numbers of intense weight-training and high-performance athletes. While the diagnosis is usually suspected clinically, assessment of the extent and location of the

481 injury is often limited in the acute setting. With an understanding of the complicated anatomy of the pectoralis major musculotendinous unit, MRI provides the anatomic detail necessary to allow accurate localization and characterization of the pectoralis major musculotendinous injury.

The pectoralis major muscle is a fan shaped muscle with 3 heads originating from clavicular, sternal and abdominal origins. The clavicular head takes origin from the medial one half to two thirds of the clavicle. The upper portion of the sternal head arises from the manubrium and sternum and ribs 2-4. The lower portion of the sternal head arises from the distal body of the sternum and ribs 5-6. The abdominal head arises from the external oblique muscle fascia. Although indistinguishable by MR, the pectoralis tendon is composed of two laminae: the clavicular lamina and the sternal lamina. The clavicular lamina is composed of fibers from the clavicular head and the upper sternal head fibers with the tendon fibers arising from the clavicular head being most superficial. The distal inserting fibers of the clavicular lamina blend with the distal deltoid inserting fibers. The sternal lamina is composed of the lower sternal and abdominal heads and insert deep and proximal to the clavicular lamina contributing to the long biceps tendon sheath. The fibers from the abdominal head undergo a 180 degree rotation before inserting on the humerus. Thus the tendon fibers from the abdominal head are most superior in their insertion onto the lateral aspect of the bicipital groove.

The multiple muscle head origins and crossing pattern of insertion allows the pectoralis major muscle to exert a wide range of actions on the humerus. Depending on the position of the humerus, the pectoralis major muscle can adduct, flex, and internally rotate the humerus against a stable thorax. Against a fixed humerus, the pectoralis muscle acts as a climbing muscle, pulling the thorax upward. It is also an accessory muscle of respiration when the shoulders are fixed in an elevated position.

A coronal oblique T1-weighted image demonstrates normal anatomy of the pectoralis major muscle. The pectoralis muscle is made up of three heads: the clavicular head (CH), the sternal head (SH), and the abdominal head (AH). The clavicular head fibers (blue) combine with the superior sternal head fibers (green) to form the clavicular head lamina. The lower sternal head fibers (red)

482 and abdominal head fibers (yellow) form the sternal lamina and insert deep to the clavicular head lamina with the abdominal head fibers (yellow) inserting most superiorly. The cephalic vein (arrow) is a reliable landmark separating the anterior deltoid (D) from the clavicular head (H) of the pectoralis major. The humeral head (HH) and Biceps muscle (B) are also indicated.

The pectoralis tendon is best seen on axial T1 and T2-weighted images as a curvilinear low-signal band inserting onto the lateral ridge of the bicipital groove of the humerus. The superior-most inserting fibers can be identified curving anterior to the biceps tendon at the approximate level of the quadrilateral space. The tendon length is variable ranging from 5 to 15 mm and the fibers insert over a cephalocaudal distance of 4-6 cm. The distal extent of tendon insertion is typically seen just proximal to the deltoid tubercle. The pectoralis major muscle is the most superficial muscle group along the superior chest wall, separated from the anterior deltoid by the deltopectoral groove which contains the cephalic vein.

Axial T1-weighted image at the level of the quadrilateral space (Q) demonstrates the pectoralis major tendon (arrow) curving anterior to the coracobrachialis and short biceps muscles (CB) to insert on the lateral ridge of the biceps groove. The clavicular head of the pectoralis major muscle (CH) and the deltoid muscle (D) are also identified.

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MRI offers multiplanar imaging and fluid sensitive sequences that are ideal for evaluating acute pectoralis major muscle and tendon injuries. Fluid sensitive sequences are valuable for detecting the site of injury demonstrating edema and hemorrhage in the muscle, tendon and in the surrounding soft tissues. The multiplanar capabilities of MRI allow optimal depiction of the portions of the pectoralis major muscle and tendon involved.

Incomplete ruptures of the pectoralis major are most common and typically occur at the musculotendinous junction or muscle belly of the sternal head. Edema and hemorrhage are seen at the site of the musculotendinous tear. The muscle may be retracted, but the inserting pectoralis major tendon fibers remain intact without associated hemorrhage or edema.

Axial T2-weighted fat- suppressed image demonstrates a musculotendinous rupture (arrow) of the sternal head (SH) which is mildly retracted. The pectoralis major tendon is normal at it humeral insertion (arrowhead). The clavicular head (CH) demonstrates mild edema at this level indicating muscle strain. The asterisk indicates the cephalic vein. The deltoid muscle (D) and coracobrachialis and short biceps muscles (CB) are indicated.

Complete ruptures occur most commonly at the distal tendon or its insertion. Hemorrhage and edema are seen anterior to the humerus without visualization of the inserting pectoralis major tendon fibers. The biceps tendon may be slightly displaced from its normal location anterior to the humerus because of associated biceps sheath injury and periosteal hemorrhage and edema.

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Axial fat-suppressed proton-density weighted image at the level of the quadrilateral space (Q) demonstrates hemorrhage and edema anterior to the humerus (black arrow) representing periosteal stripping at the site of tendon avulsion. The pectoralis major muscle tendon (white arrow) is mildly retracted. With disruption of the pectoralis major tendon insertion the long biceps tendon (arrowhead) is mildly displaced from the biceps groove.

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