Ultrasound of the Knee

Transcription

1 Ultrasound of the Knee Jon A. Jacobson, M.D. Professor of Radiology Director, Division of Musculoskeletal Radiology University of Michigan Disclosures: Consultant: Bioclinica Book Royalties: Elsevier Advisory Board: GE, Philips Note: all images from the textbook Fundamentals of Musculoskeletal Ultrasound are copyrighted by Elsevier Inc. Tendon Abnormalities Tendinosis: Swollen, hypoechoic, no inflammation Tear: Partial-thickness tear Full-thickness tear: retraction Quadriceps Tendon: tendinosis Quadriceps Tendon Full-thickness tear Complete tendon disruption Tendon retraction: dynamic imaging Joint fluid extending through tear La et al. AJR 2001; 22:1323 1

2 Quadriceps Tendon: full-thickness tear Quadriceps Femoris Tear: dynamic imaging Sagittal PDw r Tendinosis: Jumper s knee Hypoechoic swelling Mucoid degeneration, possible interstitial tearing Hyperemia: neovascularity No inflammatory cells r Tendon: tendinosis Short Axis Radiology 1996; 200:821 color Doppler power Doppler r Tendon Tear Full-thickness tear Hypoechoic Posterior shadowing at ends of torn tendon Tendon retraction r alta AJR 2001; 176:1535 r Tendon: full-thickness tear Sagittal PDw 2

3 Prox r Tendon: full thickness tear Distal MCL: sprain MCL: full-thickness tear MCL m Coronal T2w Short Axis Lateral Collateral Ligament Injury P LM Fibula 3

4 Meniscus: Normal: hyperechoic Degeneration: hypoechoic Tear: defined hypoechoic cleft to articular surface *Invest Radiol 1986; 21:332 Meniscus: Accuracy 35 patients Sensitivity / Specificity = 86% / 69% PPV / NPV = 83% / 75% Most studies: US is markedly limited *JBJS-Br 2008; 90-B:1045. PHMM: degeneration Meniscus: tear Sagittal Sagittal PDw Meniscus: chondrocalcinosis 4

5 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: sagittal plane Joint Effusion: transverse plane Quadriceps * * Sagittal T2w Knee Bursae Joint Effusion: knee extension Quad *Suprapatellar Recess Prepatellar Bursa Deep Infrapatellar Bursa Superficial Infrapatellar Bursa Baker Cyst Semimembranosus -l Collateral Ligament Bursa Pes Anserinus Bursa 5

6 Anterior Knee Bursa: Prepatellar bursa Superficial infrapatellar bursa Deep infrapatellar bursa Prepatellar Bursa: aseptic fluid PT PT Sagittal Axial Superficial Infrapatellar Bursa Deep Infrapatellar Bursa PT PT PT Case #1 Case #2 Normal Abnormal Baker Cyst: Semimembranosus-medial gastrocnemius bursa 50% over age of 50 have communication with knee joint Cyst communication to posterior knee between SM-MG tendons required SM Medial Gastrocnemius Baker Cyst AJR 2001; 176:373 Axial Axial T2w 6

7 Baker Cyst Baker Cyst: rupture + hemorrhage MG SM MG MG SM Baker Cyst: intra-articular body Baker Cyst: rupture Sagittal PDw Coronal T2w 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

8 Pes Anerinus: bursal fluid Adventitious Bursae: G S G T Site of friction Myxomatous degeneration of fibrous tissue Medial epicondyle: Rider s bursa: horseback riding Limbo-dancing Trinidadian art form of limbo dancing Medial Epicondyle Nerve Entrapment US findings: Nerve enlargement proximal to entrapment Best appreciated transverse to nerve Abnormally hypoechoic Especially the connective tissue layers Variable enlargement or flattening at entrapment site Common Fibular Nerve: entrapment Common Fibular Nerve: entrapment Fibularis Longus Fibula 8

9 Common Fibular Nerve: entrapment Peroneal Intraneural Ganglion Asymptomatic Atrophy Joint fluid from proximal tibiofibular joint Enters peroneal nerve via articular nerve branches Shown at MR arthrography after exercise Extends proximal via epineurial sheath 1 May also form via tibial nerve 2 Extensor Musculature (Short Axis) 1 Spinner et al. Clin Anatomy 2007; 20:826 2 Spinner et al. Skeletal Radiol 2006; 35:172 Peroneal Intraneural Ganglia Peroneal Intraneural Ganglion Fibula From: Spinner et al. Skeletal Radiol 2008;37:1091 From: Spinner et al. Clin Anatomy 2007;20:826 Intraneural Ganglion Nerve Transection >15 cm Neuroma formation: 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

10 Stump Neuroma Transection Neuroma: sciatic Deep Venous Thrombosis Hypoechoic thrombus Not compressible No flow l Nerve V A 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 for syllabus 10