The Journal of hand surgery
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Since 1959, 22 patients have had wrist extension restored by transfer of the pronator teres to the extensor carpi radialis longus and brevis, common finger extension by transfer of the superficialis of the long finger, independent thumb and index finger extension by transfer of the superficialis of the ring finger, and abduction of the thumb by transfer of the flexor carpi radialis at the wrist joint level. Twenty-one of 22 patients have been evaluated from 8 months to 15 years after operation, with an average follow-up of 4.5 years. ⋯ Sixteen patients obtained full, independent thumb-index finger extension, three had fair function, and two obtained thumb-index extension by tenodesis of the transfer. This procedure allows full metacarpophalangeal extension independent of wrist position, provides thumb-index finger extension independent of the ulnar three digits, and maintains the dorsal-radial-to-volar-ulnar plane of functional motion of the wrist by retaining the flexor carpi ulnaris.
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Seven hundred and fifty normal thumbs were examined to determine the normal range of radioulnar mobility of the metacarpophalangeal joint with the joint in full extension, 15 degrees of flexion, and full flexion. Full flexion was the position of greatest stability. ⋯ However, further sectioning of the ulnar collateral ligament revealed marked ulnar instability most significantly when the thumbs were examined in full metacarpophalangeal flexion. Finally, division of the adductor aponeurosis, dorsal capsule, ulnar collateral ligament, accessory collateral ligament, and volar plate resulted in complete instability of the metacarpophalangeal joint in all positions tested.