PMC6005791_01
Physical examination. The patient cannot flex her distal (a) or proximal (b) phalangeal joint actively because of the flexor tendon rupture. She is able to flex the metacarpophalangeal joint (c) by using intrinsic muscles.
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One month prior to the visit of our unit, her left little finger had been extended passively when she tried to pick up something but could not be flexed afterward without help (Fig. 1).
Clinical examination. Dorsal tilt at the distal radius and volar dislocation of the ulnar head are seen on plain radiography (a) and computed tomography (arrowhead) (c). (b) Magnetic resonance image indicates discontinuity of the flexor tendon of the fifth finger (*).
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Radiographs of the left wrist joint exhibited an old malunion in which the distal part of radial shaft tilted 11 , and the ulnar head had dislocated toward the volar side (Fig. 2a). As on the radiographs, computed tomography (CT) showed a dorsal tilt of the radius and DRUJ osteoarthritis with a bone spur (Fig. 2c). Magnetic resonance imaging revealed that the distal stump of the flexor digitorum profundus (FDP) of the fifth digit was on the volar aspect of the fifth metacarpal diaphysis (Fig. 2b) with mild proliferation of synovial tissue around the injured wrist joint.
Intraoperative findings. (a) The fourth flexor tendon was not damaged (*), but the fifth tendon was not seen in the carpal tunnel. (b) The distal stump of the fifth flexor tendon (profundus) had degenerated and was involved with synovial tissue. (c) There is a pinhole-like discontinuity at the volar aspect of the joint capsule (arrowhead). (d). We transferred the distal stump of the fifth flexor tendon to the fourth flexor tendon (<).
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The fifth FDP was identified and found to be completely ruptured in zone V, and its flexor digitorum superficial (FDS) was denatured (Fig. 3a). The proximal stamp was not found within the width of the skin incision (Fig. 3b). Contrary to our preoperative inspection, there was pinhole-size discontinuity of the DRUJ capsule and no more than mild spur protrusion at the discontinuation of the capsule (Fig. 3c). Hence, the fifth FDP was transferred to the fourth FDP at the level of metacarpophalangeal joint using interlacing sutures (the fourth and fifth A1 pulleys were incised longitudinally) (Fig. 3d).
At the 12-month (final) follow-up, the patient actively achieved full flexion.
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Regarding activities of daily living, she could perform light work, such as folding paper, knitting a sweater, or cutting food (Fig. 4).