The tails are then extended using free tendon grafts and attached to the radial lateral bands of the small, ring and long fingers and the ulnar lateral band of the index finger (Brand). Clawing of all four digits (as seen in a combined ulnar and low median nerve palsy) can be treated using the FCR, or ECRB tendon split into two to four tails according to the number of fingers being addressed. Alternatively, the FDS of the long finger can be transected 2 cm proximal to its insertion and retracted from the tendon sheath proximally and then rerouted distally deep to the intermetacarpal ligament and inserted into the radial lateral bands of the small and ring fingers (Stiles-Bunnell). The FDS slips of the affected finger can be transected 2 cm proximal to their insertion and sutured back to themselves proximally creating a lasso around the A1 pulley (Zancolli lasso). This is accomplished by MCP capsulodesis or tenodesis. Unlike procedures to reinnervate muscles, tendon transfers do not depend on the viability of the motor endplate of the dysfunctional muscle and so can be performed at any time.Ĭlawing is corrected by blocking MCP hyperextension which allows for the transmission of the EDC extensor forces distally to the PIP and IP through the extensor hood. In the setting a non-displaced distal radius fracture, integrity of the EPL can be tested by having the patient place their hand flat on a table, inability to lift their thumb off of the table is consistent with an EPL rupture.Īn EMG can help determine nerve injury severity and likelihood of recovery. In ulnar nerve palsy, when the patient attempts to pinch an object, the thumb MP hyperextended the, and the IP flexes in an attempt by the EPL and FPL respectively to compensate for the deficiency of the adductor pollicis, 1st dorsal interosseus, and deep head of the flexor pollicis brevis (FPB). This is called Froment sign. Also, the normal extensor force to the PIP and DIP joints through the extensor hood of the ring and small fingers is deficient secondary to weakness of the interossei and ulnar two lumbricals.Ī low ulnar nerve palsy results in a more severe claw hand because the FDP to the ring and small fingers are intact, worsening the imbalance of flexion forces across the PIP and DIP joints. The extended posture of the MP joint prevents extension forces from the EDC from being transmitted to the PIP and DIP joints. Ulnar claw hand occurs because of unopposed extension forces by the EDC and EDM on the small and ring finger MP joints with no counter flexion force by the interossei and ulnar two lumbricals innervated by the ulnar nerve. Wrist, hand, and finger range of motion testing is important since the full passive range of motion should be achieved before tendon transfers. An abnormal exam can indicate isolated tendon injuries. Wrist passive tenodesis test should be performed by taking the wrist passively from flexion to extension. With a normal test, the digits transition from an extended posture in wrist flexion to a flexed posture in wrist extension with fingers maintaining symmetrical cascade. Motor strength and sensory testing will distinguish lesions and appropriate indications for correction according to above categories.
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