Synovial Diseases in Children

A. Carl Merrow, MD Corning Benton Chair for Radiology Education Department of Radiology Cincinnati Children’s Hospital Medical Center Disclosures • Pediatrics Lead Author for Amirsys-Elsevier – Royalties/Fees

• Lecture heavily weighted for MRI

Overview • Anatomy • Imaging: Techniques and value • Specific diseases – Etiology – Distribution of joints – Acute & chronic manifestations – Useful imaging clues Anatomy: Types of Joints • Synarthroses (immovable) • Amphiarthrosis (slightly movable) • Diarthrosis (freely movable) Anatomy: Diarthrodial Joints • Cartilage • Capsule – Ligaments – Fibrous tissue • Synovium – Lines capsule, not cartilage – Invests intra-articular ligaments & tendons

Anatomy: Synovium • Two layers – Intima • Synovial lining cells (synoviocytes, SLCs) • Discontinuous layer 1-3 cells thick • Incomplete basement membrane – Subintima • Loose connective tissue • Merges with fibrous capsule

Anatomy: Synovium • Purposes – Fluid formation – Nutrition of cartilage – Movement

Synovium also found… • Bursae • Tendon sheaths • Synovial cysts • NOT synovial sarcoma

Joint pathophysiology • Variety of processes may incite synovitis • Single vs. recurrent event  destructive cycle • Long term effects – Bone – Articular cartilage – Growing epiphysis

Imaging: Why? • Establish diagnosis • Localize/define extent of involvement – Within single joint – Tendon sheath/bursa – Additional unsuspected joints • Pick up complications early • Optimize management

General imaging: Radiographs • Pros – Baseline – Exclude other etiologies – Cheap, quick • Cons – No early cartilage damage – No synovial detail General imaging: Radiographs • Secondary findings – Synovial hypertrophy • Effusion/synovial complex • Osteoporosis • Epiphyseal changes – Osteocartilaginous damage • Joint space loss • Erosions • Ankylosis

General imaging: Ultrasound • Pros – No radiation/sedation – Readily available – Easy contralateral comparison – Great for effusions, synovitis – May demonstrate osteocartilaginous changes • Cons – Operator dependent – Limited window General imaging: MRI • Pros – Most sensitive, specific method for all tissues – Entire joint – Early changes (even asymptomatic) – Quantitative assessments • Cons – Sedation (age dependent) – IV contrast – Comparison not readily available without planning – Time intensive – Scheduling – Cost Specific Diseases Case 1 Differential: Intra-articular “loose” bodies

2+ 2+ • Tiny, numerous, no Ca • Larger, single, +/- Ca – Rice bodies/necrotic – Osteochondral fragment synovium • OCD • JIA • Acute trauma • Granulomatous diseases – Retained foreign body • Other? – Chondromatosis

Differential: Intra-articular “loose” bodies

2+ 2+ • Tiny, numerous, no Ca • Larger, single, +/- Ca – Rice bodies/necrotic – Osteochondral fragment synovium • OCD • JIA • Acute trauma • Granulomatous diseases – Retained foreign body • Other? – Chondromatosis Is it really loose vs. attached?

Juvenile Idiopathic Arthritis • Most common chronic pediatric arthropathy

• 16-150/100,000 children worldwide

• Most common 1-3YO, less 8-10YO Juvenile Idiopathic Arthritis • Arthritis of unknown etiology – Onset prior to 16YO – Lasts at least 6 weeks • 9-83% persistent disease into adulthood • Mortality < 0.3%

JIA: ILAR Classification • Systemic arthritis (10-20%) • Oligoarthritis (50-60%) • Polyarthritis (Rh factor negative) (30-35%) • Polyarthritis (Rh factor positive) • Psoriatic arthritis (<15%) • Enthesis-related arthritis (<7%) • Undifferentiated arthritis

JIA JIA JIA JIA

Differential: Distorted epiphyses • Synovitis • Prior infection • Syndromic • Gorham disease • AVN

JIA 2004

2007 2004 2007 JIA JIA

JIA JIA JIA JIA JIA: Imaging • Radiographs – Periarticular soft tissue swelling, effusion – Periarticular osteoporosis – Accelerated maturation of secondary ossification centers – Periosteal reaction – Joint space loss, erosions – Subluxation, dislocation (ligamentous laxity) – Ankylosis (wrist, c-spine), degeneration JIA: Imaging • Radiographs—Specific joints – Knee: Widened intercondylar notch, flat patella – Phalanges: Bouttonniere, Swan Neck, flexion – Hip: Protrusio acetabuli, osteonecrosis – Spine: Atlanto-axial instability, fusion of posterior elements, hypoplastic vertebral bodies JIA: Imaging • MRI – Fat pad edema – Prominent lymph nodes – Effusion, synovial thickening – Cartilage wear, bony edema, erosions – Enthesitis – Tenosynovitis, tendon rupture – Synovial cyst (popliteal or “Baker’s” cyst) – Specific joints: • Knee: Hypoplastic menisci, cruciate ligament atrophy Grading System of Knee: JAMRIS • Synovial hypertrophy • Bone marrow changes • Cartilage lesions • Bone erosions

Hemke R et al. Reliability and responsiveness of the Juvenile Arthritis MRI Scoring (JAMRIS) system for the knee. Eur Rad (2013) 23: 1075- 1083. Hemke R et al. Contrast-enhanced MRI compared with the physical examination in the evaluation of disease activity in juvenile idiopathic arthritis. Eur Rad (2014) 24: 327-334. OMERACT 11 • Special interest group on MRI in JIA • Further develop MRI as outcomes marker • Established goals include – Age-based MRI atlas of normal joint development – Standard protocols – Clinically-validated imaging grading scales • Knee, ankle (large) • Wrist, hand (small) • TMJ OMERACT 12 • JIA SIG plus Health-e-Child Radiology group – Knee and wrist • Agreements on protocols and scoring – Terminology/Definitions – Locations – Scales JIA MRI Protocol • T1 no FS • T2 with FS • Pre/post T1 with FS (subtraction) – Immediate, dynamic vs. 5/10 minutes • Others? – DWI/ADC – 3D imaging • GRE or PD (cartilage)

JIA Quantitative Imaging • MRI – Synovial volumes – Dynamic enhancement – BOLD – Cartilage mapping (T2, T1rho, dGEMRIC) • US – Hyperemia – Cartilage/bone erosions JIA TMJ • Mild enhancement, small amount of fluid may be normal • Surrounding soft tissue enhancement abnormal – Other than normal posterior venous plexus • Active disease – Signal to noise ratios pre/post – Dynamic enhancement – Condylar edema Whole Body Screening • MRI • PET

Ultrasound Features • Non-compressible hypoechoic synovium • Compressible hypo/anechoic effusion • Hypo/anechoic tissue in tendon sheath • Hypoechoic, thickened bony insertions of – Tendons – Ligaments – Capsule • Cartilage thickness • Bone erosions • Doppler

JIA Therapies • NSAIDs • Steroids (systemic or local injections) • DMARD – Methotrexate, sulfasalazine, leflunomide • Biologics (monoclonal antibodies, soluble receptors) – TNF-α inhibitors – IL-1, IL-6 • Stem Cell Transplant

Case 2

Differential: Intra-/peri-articular calcifications • Synovial chondromatosis Smaller, • Synovial venous malformation Intraarticular • Neuropathic joint • Synovial sarcoma • Injection granulomas

• Heterotopic ossification

• Osteosarcoma • Dermatomyositis Larger, • Tumoral calcinosis Periarticular

Synovial Chondromatosis • Benign subsynovial neoplasia – Hyaline cartilage nodules – May mineralize (60%) and/or become loose • Usually monoarticular process – Knee (50%)>elbow, hip, shoulder – Bilateral knee involvement <10% • M:F 2:1 • Most common 3rd-5th decades • Rare malignant transformation

Synovial Chondromatosis: Imaging • Radiographs: – Joint fullness • With/without calcified nodules • Nodules typically uniform in size – May have erosions (esp. tight capsule joints) – Late secondary DJD

Synovial Chondromatosis: Imaging • MRI: – Appearance depends on nodule content • Cartilaginous – Intermediate T1/high T2 – Low signal intensity septa enhances • Mixed cartilage/calcification – Small foci of low T1/T2 signal within nodules • Ossified with fatty marrow: – Follows fat signal (high T1, low w/ fat suppression) Neuropathic joint Dermatomyositis Tumoral calcinosis Tumoral calcinosis Osteosarcoma Case 3 Differential: Intra-articular hemosiderin • Hemophilia (or other systemic bleeding disorder) • Pigmented villonodular synovitis • Synovial venous malformation

PVNS • Classification – Intra-articular diffuse • Knee 80%, hip, ankle, shoulder, elbow – Intra-articular localized – Extra-articular (GCTTS) • M=F • Most commonly 3rd-4th decade • Benign neoplastic process PVNS • Radiographs: – Soft tissue mass – Late demineralization and joint space loss – Erosions • Prominent in joints with tight capsule (hip & ankle) • Prefer bare areas (rather than subchondral) – Periosteal reaction, calcifications <10% PVNS • MRI – Low signal • Secondary to hemosiderin deposition • GRE (T2*) accentuates susceptibility – May be components of variable T1/T2 signal due to: • Mix of hemosiderin/fat/fibrovascular elements • Recent hemorrhagic effusion (subacute blood products) • Inflamed synovium PVNS PVNS (GCTTS) Differential: Focal articular/tendon sheath mass • Clot • Foreign body granuloma • PVNS • Venolymphatic malformation • Pannus • Synovial lipoma • Synovial sarcoma • Fibroma of tendon sheath Synovial sarcoma Case 4 Differential: Fat-containing mass • Synovial lipoma/lipoma arborescens • Lipoblastoma • Fibrous hamartoma • Involuted hemangioma • Venous malformation

Lipoma Arborescens/Synovial Lipoma • Monoarticular – Usually knee, suprapatellar – Rarely bilateral • Subsynovial tissue replaced by fat cells, inciting synovial proliferation • Metaplasia (not neoplasia)

Lipoma Arborescens/Synovial Lipoma • Usually chronic – Gradual swelling – Painless – Recurrent effusions – Rarely restricted movement – Most common 5th-7th decade – Can be secondary to JIA, trauma

Lipoma Arborescens: Imaging • Radiographs – Radiolucent foci • Ultrasound – Echogenic mass – May be frond-like and mobile • MRI – Follows fat signal on all sequences – Nonfatty portions and synovium may enhance – May be accompanied by effusion – Chemical shift artifact at fat-fluid interface

Lipoma Arborescens Case 5 Septic Arthritis • Often < 10YO • Knee, hip > elbow, ankle, shoulder • Sources: – Adjacent osteomyelitis • Is effusion a septic joint or sterile reactive fluid? • Is marrow signal reactive edema vs. osteomyelitis? – Hematogenous seeding – Direct penetration Septic Arthritis • Joint injury by – Lytic enzymes – Increased pressure • Imaging – Initially by radiographs, US – Correlated with clinical & laboratory parameters (Kocher) – Tapped, taken to OR, IV antibiotics – MR if no improvement in 48 hours for osteomyelitis • Other infections – Granulomatous disease – Lyme disease

Septic arthritis Remote septic arthritis

TB 3 months later… ? Infection • Toxic Synovitis • Hip (bilateral 25%) • Limp, pain, stiffness • Self-limiting, 3-10 days • 3-10YO • Imaging – Ultrasound cannot distinguish – MRI suggests septic joint if periarticular soft tissue or bone marrow signal abnormalities

Toxic synovitis

Case 6

2001 2006

Hemophilia • X-linked recessive diseases – A: factor VIII deficiency – B: factor IX deficiency • Manifest by spontaneous or traumatic hemorrhage: – Intracranial – Intra-abdominal, retroperitoneal – Musculoskeletal • Joints (up to 85% of bleeding episodes) • Muscle • Bone • Fascia Hemophilic arthropathy • Synovial bleeding into joint • Originates at subsynovial vascular plexus • Chronic deposition of hemosiderin • Synovial hypertrophy, inflammation, hyperemia – Osteoporosis – Epiphyseal overgrowth – Physeal fusion Hemophilic arthropathy • Articular cartilage damaged by: – Intra-articular blood products – Enzymes breaking down hemosiderin – Increased intracapsular pressure • Subchondral cysts – Intraosseus hemorrhage • Fibrosis – Capsular fibrosis, joint contractures

Hemophilic arthropathy: Imaging • Radiographs – General: • Increased density effusions • Osteoporosis, epiphyseal enlargement, physeal fusion • Subchondral cysts • Degenerative changes • Flexion deformities

Hemophilic arthropathy: Imaging • Radiographs: – Specific joints • Knee: Wide intercondylar notch, elongated patella • Elbow: Wide trochlear notch and olecranon fossa • Ankle: Tibiotalar slanting, flattened talar dome • Hip: Protrusio acetabuli, SCFE, coxa valga Hemophilic arthropathy: Imaging • MRI: – Thickened, low signal synovium on all sequences (most pronounced on T2*) – Enhancement post-contrast Case 7 Synovial Venolymphatic Malformation • Usually monoarticular • Knee most common • Pain, swelling, hemarthrosis • Focal mass vs. diffuse venous abnormality – Malformation may extend through soft tissues to another joint Synovial Venolymphatic Malformation: Imaging • Radiographs: – 50% normal – May have phleboliths • MRI: – Lobulated mass or serpiginous components – High T2 signal – Low T1 phleboliths – May have fluid-fluid levels – May have T2* effect from hemosiderin – Variable enhancement Venolymphatic Malformation (Many) Other causes of synovitis • Trauma/foreign body • SCFE • Infarction • Tumors • Leukemia Foreign body LCP ABC Chondroblastoma Summary • Variety of processes may incite synovitis • Significant long term effects on intra-articular structures • Overlapping imaging features – Look for specific clues • Loose bodies • Calcifications • Hemorrhage • Fat • Marrow abnormalities – Always think about septic arthritis! Thank you! References

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