Download MRI of the Elbow:Current Concepts

MRI of the Elbow:Current Concepts
Russell C. Fritz, M.D.
National Orthopedic Imaging Associates
San Francisco, CA
ANATOMY
lateral collateral ligament (LCL) complex
radial collateral ligament
annular ligament
lateral ulnar collateral ligament (LUCL)
medial collateral ligament (MCL) complex
anterior bundle
posterior bundle
transverse ligament
common flexor tendon
common extensor tendon
biceps tendon & bicipital aponeurosis (lacertus fibrosus)
triceps tendon
PATHOLOGY
Valgus stress injury
Medial tension overload: extraarticular injury
medial collateral ligament sprain
flexor-pronator muscle strain
medial epicondylitis
ulnar traction spurs
ulnar neuritis
Lateral compression overload: intraarticular injury
bone contusions
osteochondritis dissecans of the capitellum or radial head
loose body formation
degenerative arthritis
Medial collateral ligament injury
-anterior bundle of the MCL is the most important stabilizing ligament to valgus stress
-midsubstance rupture of the MCL requires reconstruction in throwers
-undersurface partial tears of the distal MCL may occur in throwers
-intraarticular contrast may improve detection of these partial MCL tears
Medial epicondylitis
-secondary to tendinosis of the common flexor tendon
-may progress to complete avulsion
-often associated with ulnar neuritis
Ulnar neuritis
-anatomic variations of the cubital tunnel retinaculum (CTR) may contribute to ulnar
neuropathy
-CTR may be absent in 10%, allowing anterior dislocation of the nerve over the medial
epicondyle during flexion with subsequent friction neuritis
-CTR may be replaced by an anomalous muscle, the anconeus epitrochlearis, in 11%
resulting in static compression of the ulnar nerve
-thickening of the MCL and medial bony spurring may undermine the floor of the cubital
tunnel
Osteochondritis dissecans
-commonly occurs within the anteroinferior aspect of the capitellum
-lesions may fragment and result in loose bodies
-adolescent pitchers or gymnasts at risk due to repetitive valgus stress
Lateral epicondylitis
-secondary to tendinosis of the common extensor tendon
-primarily involves the extensor carpi radialis brevis (ECRB) tendon
-macroscopic tears of the common extensor tendon in 35% at surgery
-unsuspected tears of the LCL may accompany tendon injury
-LCL injury may be iatrogenic due to an overaggressive extensor tendon release
-LCL injury may result in posterolateral rotatory instability and a “trick elbow”
Posterior dislocation injury
-coronoid process fracture suggests posterior dislocation/subluxation
-LCL & MCL rupture, anterior capsular injury, and brachialis muscle strain are typically
seen in posterior dislocation of the elbow
Distal biceps impingement syndrome
-tendinosis from mechanical impingement and poor blood supply
-tendinosis precedes rupture
-rupture typically occurs adjacent to the radial tuberosity
-the lacertus fibrosus usually tears in association with biceps rupture
-partial tears and cubital bursitis are less common than rupture
-enlargement of the bursa adjacent to the radial tuberosity (radio-bicipital bursa) may
occasionally present as an antecubital fossa mass that may entrap the radial nerve
-fibers from the short head attach distally on the radial tuberosity and flex the elbow,
fibers from the long head attach proximally on the radial tuberosity and supinate the
forearm
Triceps tendon injury
-tendinosis precedes rupture
-rupture typically occurs adjacent to the olecranon
-rupture may follow or accompany olecranon bursitis
REFERENCES
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Fritz RC. MR imaging of sports injuries of the elbow. MRI Clin North Am 1999,
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ligament injury in the throwing athlete: evaluation with saline-enhanced MR
arthrography. Radiology 1995; 197:297-9.
4.
Seiler JG, Parker LM, Chamberland PDC, Sherbourne GM, Carpenter WA. The
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imaging of the elbow. Clin Sports Med 23:567-80, 2004.
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Fritz RC. The Elbow. In: Edelman R, Hesselink J, Zlatkin M (eds): Clinical
Magnetic Resonance Imaging, third edition, 2006, 3280-3308.
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