Tendon Transplantations In Median-nerve And Ulnar-nerve Paralysis

1. The typical claw-hand deformity is caused by non-functioning interossei and lumbricales resulting from median-nerve and ulnar-nerve involvement regardless of the etiology. Function of the long flexors and extensors is still present and the resulting imbalance gradually causes the deformity to develop. 2. According to Bunnell's and Fowler's concepts of finger extension, both the long extensors and the intrinsics (interossei and lumbricales) act synergistically to extend the distal two phalanges. Fowler further states that either the long extensors alone or the interossei alone can extend the distal two phalanges, provided the proximal phalanges are not allowed to extend beyond 180 degrees. 3. Bunnell's and Fowler's concepts are partly proved by splinting in radial-nerve paralysis. Here the only force applied is extensor force on the proximal phalanges and full finger extension is possible. It is done by the intrinsic function still remaining. In combined median-nerve and ulnar-nerve paralysis, full extension of the distal two phalanges can be restored by block of the proximal phalanx at 180 degrees or less of extension, proving that the long extensors can extend the distal two phalanges if the proximal phalanges are stabilized. 4. The Bunnell multiple sublimis transplantation for paralysis of the median and ulnar nerves gives excellent results in those cases in which there are sublimis muscles suitable for transplantation and in which the deformity is of recent origin. 5 The Fowler operation for restoration of full extension in median-nerve and ulnar-nerve paralysis consists in transplanting the extensor-indicis proprius and extensor digiti quinti through the interosseous space, through the lumbrical canal anterior to the transverse metacarpal ligament, and inserting it into the combined intrinsic extensor aponeurosis. This procedure gives excellent results in those cases in which the sublimis muscles are not suitable for transplantation, and in which the deformity is severe or has been present for a long time. The limitation of wrist flexion resulting from this procedure is helpful in overcoming the claw deformity. 6. The same force can be exerted by a pure tenodesis operation in which one half of the extensor carpi radialis longus and one half of the extensor carpi ulnaris are used. Each tendon is split into two slips and inserted in the same manner as in the Fowler transplantation. The tenodesis procedure described here is recommended for those cases in which insufficient extensor power is present to allow use of the extensor indicis proprius and extensor digiti quinti for the Fowler transplantation and those in which the sublimis muscles are too weak for the Bunnell transfers. 7. The three methods of tendon transplantation for the correction of the claw-hand of median-nerve and ulnar-nerve paralyses discussed here can be used in nearly all cases. The only cases not suitable for such tendon transplantations are those with secondary skin contractures and fixed joint contractures; these require joint arthrodeses. It should be obvious that great care must be exercised in selecting the proper procedure for each individual case.