Flexor tendon tears in the hand: Use of MR imaging to diagnose degree of injury in a cadaver model

OBJECTIVE. Treatment of flexor tendon lacerations of the finger partly depends on the degree of injury, which is difficult to determine clinically. We used a cadaver model to investigate the potential of MR imaging in evaluating these injuries. MATERIALS AND METHODS. A scalpel was drawn transversely across the volar surface of four cadaver hands, producing various flexor tendon injuries. MR imaging of each hand was performed using axial two-dimensional spin-echo and three-dimensional gradient-recalled-echo sequences. The three-dimensional data sets were interactively reformatted along the long axis of each tendon. The hands were then dissected; injury to each digit was categorized, measured, and compared with the prospective MR interpretations. RESULTS. Twelve high-grade flexor tendon tears (10 complete tears, with 1- to 14-mm separation of the torn ends, and two partial tears involving 50% or more of the total tendon cross-sectional area) and two partial tears of less than 50% of tendon area were produced; four tendons were not injured. Using MR imaging, we diagnosed 11 of the 12 high-grade lesions (those involving at least 50% of the total tendon cross-sectional area); the MR images did not show one complete tear whose separation measured 2 mm long at dissection. All intact tendons were correctly identified. We underestimated the extent of five lesions but overestimated none. Using the reformatted images, we reduced the number of errors that we would have made interpreting the transverse images alone. CONCLUSION. In this cadaver model, using MR imaging we accurately distinguished different degrees of flexor tendon tears. The potential of this technique for noninvasively diagnosing flexor tendon injury in patients awaits clinical studies.