Disclosures: Ultrasound of the Knee • Consultant: Bioclinica Jon A. Jacobson, M.D. • Book Royalties: Elsevier • Advisory Board: GE, Philips Professor of Radiology Director, Division of Musculoskeletal Radiology University of Michigan Note: all images from the textbook Fundamentals of Musculoskeletal Ultrasound are copyrighted by Elsevier Inc.
Pathology: Tendon Abnormalities • Tendon • Tendinosis: • Ligament –Swollen, hypoechoic, no inflammation • Cartilage • Tear: • Fluid collections and cysts –Partial-thickness tear • Peripheral nerves –Full-thickness tear: retraction • Miscellaneous
Quadriceps Tendon: tendinosis Quadriceps Tendon • Full-thickness tear Patella – Complete tendon disruption – Tendon retraction: dynamic imaging – Joint fluid extending through tear Femur
La et al. AJR 2001; 22:1323
Long Axis
1 Quadriceps Femoris Tear: Quadriceps Tendon: full-thickness tear dynamic imaging
Patella
Long Axis Sagittal PDw Long Axis
Patellar Tendon: tendinosis Patellar Tendinosis: • Jumper’s knee • Hypoechoic swelling • Mucoid degeneration, possible Long Axis Short Axis interstitial tearing • Hyperemia: neovascularity • No inflammatory cells
color Doppler power Doppler Radiology 1996; 200:821
Patellar Tendon: full-thickness tear Patellar Tendon Tear • Full-thickness tear – Hypoechoic – Posterior shadowing at ends of torn tendon Patella – Tendon retraction – Patellar alta Long Axis Sagittal PDw AJR 2001; 176:1535
2 Patellar Tendon: full thickness tear Pathology: • Tendon Prox Distal • Ligament • Cartilage • Fluid collections and cysts • Peripheral nerves • Miscellaneous
Longitudinal
MCL: full-thickness tear MCL: sprain
m Tibia MCL Femur
Femur
Longitudinal Coronal T2w
Short Axis
Lateral Collateral Ligament Injury Pathology: • Tendon Fibula • Ligament P • Cartilage LM Tibia • Fluid collections and cysts Femur • Peripheral nerves • Miscellaneous Longitudinal
3 Meniscus: Accuracy Meniscus: • 35 patients • Normal: hyperechoic • Sensitivity / Specificity = 86% / 69% • Degeneration: hypoechoic • PPV / NPV = 83% / 75% • Tear: defined hypoechoic cleft to • Most studies: articular surface – US is markedly limited
*Invest Radiol 1986; 21:332 *JBJS-Br 2008; 90-B:1045.
Meniscus: tear PHMM: degeneration
Tibia Femur
Sagittal Sagittal PDw
Meniscus: chondrocalcinosis Pathology: • Tendon • Ligament • Cartilage • Fluid collections and cysts • Peripheral nerves • Miscellaneous
4 Suprapatellar Recess and Gutters Joint Effusion
• Suprapatellar recess – Superior • Prefemoral & quadriceps fat pad separation • Distends with partial knee flexion – Medial and lateral to patella • Distends with knee extension • Transducer pressure displaces joint effusion
From: Miller PJ et al. Am J Sports Med 2001;29:822.
Joint Effusion: transverse plane Joint Effusion: sagittal plane
Patella Patella
Quadriceps Femur Patella Femur *
* Femur Sagittal T2w
Transverse
Knee Bursae
*Suprapatellar Joint Effusion: Patella Recess Baker knee extension Quad Cyst Prepatellar Bursa Semimembranosus -Tibial Collateral Deep Ligament Bursa Infrapatellar Bursa Pes Patella Patella Anserinus Superficial Bursa Infrapatellar Bursa Femur Femur
5 Prepatellar Bursa: aseptic fluid Anterior Knee Bursa: • Prepatellar bursa • Superficial infrapatellar bursa Patella PT PT • Deep infrapatellar bursa
Sagittal Axial
Superficial Infrapatellar Bursa Deep Infrapatellar Bursa
PT PT
PT
Tibia Tibia Tibia
Normal Abnormal Case #1 Case #2
Baker Cyst Baker Cyst: • Semimembranosus-medial gastrocnemius bursa • 50% over age of 50 have Medial communication with knee joint Gastrocnemius • Cyst communication to posterior knee between SM-MG tendons required SM
AJR 2001; 176:373 Axial Axial T2w
6 Baker Cyst Baker Cyst: rupture + hemorrhage
MG SM MG MG SM
Longitudinal Transverse
Transverse Longitudinal
Baker Cyst: intra-articular body Baker Cyst: rupture
Longitudinal Coronal T2w Transverse Sagittal PDw
Baker Cyst: rupture Pes Anserinus
• Pes anserinus: “goose foot” – Sartorius – Gracilis – Semitendinosus • Bursa: – Deep to conjoined tendon – Adjacent to proximal tibia
Radiology 1995; 194:525
7 Pes Anerinus: bursal fluid Adventitious Bursae:
• Site of friction G • Myxomatous degeneration of Medial G S Epicondyle T fibrous tissue • Medial epicondyle: – Rider’s bursa: horseback riding – Limbo-dancing Tibia • Trinidadian art form of limbo Longitudinal Transverse dancing
Pathology: Nerve Entrapment • Tendon • US findings: • Ligament – Nerve enlargement proximal to entrapment • Cartilage • Best appreciated transverse to nerve – Abnormally hypoechoic • Fluid collections and cysts • Especially the connective tissue layers • Peripheral nerves – Variable enlargement or flattening at • Miscellaneous entrapment site
Common Fibular Nerve: entrapment Common Fibular Nerve: entrapment
Fibularis Longus
Fibula
Long Axis Long Axis
8 Common Fibular Nerve: entrapment Peroneal Intraneural Ganglion
• Joint fluid from proximal tibiofibular joint – Enters peroneal nerve via articular nerve branches – Shown at MR arthrography after exercise – Extends proximal via epineurial sheath1 • May also form via tibial nerve2 Asymptomatic Atrophy
1Spinner et al. Clin Anatomy 2007; 20:826 Extensor Musculature (Short Axis) 2Spinner et al. Skeletal Radiol 2006; 35:172
Peroneal Intraneural Ganglion Peroneal Intraneural Ganglia
Fibula
From: Spinner et al. From: Spinner et al. Skeletal Radiol 2008;37:1091 Clin Anatomy 2007;20:826
Intraneural Ganglion
Nerve Transection • Neuroma formation: >15 cm – Disorganized and tangled nerve end – Normal response to nerve transection – After amputation: • US important to determine if symptomatic
Atrophy Asymptomatic J Clin Ultrasound 1997; 25:85
9 Stump Neuroma Transection Neuroma: sciatic
Longitudinal Transverse
Deep Venous Thrombosis Pathology: • Hypoechoic thrombus • Tendon • Not compressible • Ligament Tibial Nerve • No flow • Cartilage • Fluid collections and cysts • Peripheral nerves V A • Miscellaneous
Take Home Points: • Common indications: – Fluid, cysts, extensor tendon • Very limited: – Meniscus, cartilage, cruciate ligaments • Suprapatellar recess: – Look all around patella • Baker cyst: often communicates with joint See www.jacobsonmskus.com for syllabus
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