Case 6

History
The patient noted a snapping sound followed by pain while moving a heavy object.

Diagnosis?

Diagnosis
Biceps brachii, complete tendon disruption.

Findings
Sagittal STIR image (Fig 1) shows a wavy longitudinally oriented low signal intensity structure with surrounding edema anteriorly above the elbow. There is retraction of the biceps tendon and muscle proximally. Axial T2 (Fig 2) shows absence of tendon insertion at the radial tuberosity.

Discussion
Distal biceps tendon tears account for three to 10 percent of all biceps tears. The dominant arm is involved in 80 percent. The common mechanism is contraction of the biceps against resistance or rapid forced extension against a flexed arm. Clinical diagnosis is often evident but diagnosis may be difficult, particularly if the bicipital aponeurosis (lacertus fibrosis) is intact and the bicipital tendon is only minimally retracted. If this aponeurosis is intact, flexion of the elbow may be preserved, however supination will be weakened. Biceps tendonosis usually precedes tear and may be multifactoral in origin. MRI is the choice for imaging of the distal biceps tendon and may be useful in distinguishing tendinosis from partial and complete tears. Ultrasound is also of aid, particularly for those unable to undergo MRI.

References
Fritz RC, Steinbach LS, Tirman PF, Martinez S. Imaging of the elbow. An update. Radiology Clinics of North America 1997; 35: 117-44.
Miller TT, Adler RS. Sonography of tears of the distal biceps tendon. AJR 2000; 175:1081-1086.

Submitted by: Paul Clifford, M.D.
Reviewed by: Robert Martinez, M.D.