14: Distal Anterior Interosseous Nerve Transfer to Motor Branch of Ulnar Nerve

Procedure 14 Distal Anterior Interosseous Nerve Transfer to Motor Branch of Ulnar Nerve



Pao-Yuan Lin, Sandeep J. Sebastin, Kevin C. Chung


imageSee Video 12: Distal Anterior Interosseous Nerve Transfer to Motor Branch of Ulnar Nerve



Indications




image For recovery of intrinsic muscle function in a patient with a high ulnar nerve injury (near or above the elbow) to shorten the distance between the donor nerve and the recipient muscles


• In patients with ulnar nerve injuries at the mid-distal forearm, direct nerve repair or nerve grafts are more suitable options than nerve transfers.

• In patients with demyelinating neuropathy such as leprosy, nerve transfer procedures are not indicated.


Examination/Imaging



Clinical Examination




image Check motor function of the anterior interosseous nerve (AIN).


• The patient is examined to ensure that the function of the flexor pollicis longus (FPL) (flexion of thumb interphalangeal joint) and the flexor digitorum profundus (FDP) of the index finger (flexion of index finger distal interphalangeal joint) is preserved. These two muscles are innervated by the AIN and can be checked by asking the patient to make the OK sign.

• The other muscle that is innervated by the AIN is the pronator quadratus (PQ). This is done by testing pronation of the forearm with the elbow in full flexion (to eliminate the contribution of the pronator teres).

image Check the joints of the ring and small fingers. The joints of the hand should be supple. If mild contractures of the joints are discovered, the patient will require hand therapy before any nerve transfer procedures are performed.



Imaging




image Electromyography of the ulnar and median nerves should be performed if the nerve-muscle function is not clear.



Surgical Anatomy




image The ulnar nerve enters the anterior (flexor) compartment of the forearm between the two heads of flexor carpi ulnaris (FCU) and innervates one and a half muscles (FCU and medial half of FDP to the ring and small fingers). It runs along the ulna with the ulnar artery, and the two travel distally under the FCU. Proximal to the wrist, the fascicles of the motor branch lie ulnar to the sensory fascicles. The ulnar nerve and artery pass superficial to the flexor retinaculum into the Guyon canal. In the Guyon canal, the ulnar artery is radial to the ulnar nerve. At the radial side of the pisiform bone, the ulnar nerve is divided into the superficial and deep branches. The deep branch of the ulnar nerve curves laterally to supply the hypothenar muscles and runs across the palm with the deep palmar arch; it terminates by supplying the first dorsal interosseous and the deep head of the flexor pollicis brevis (Fig. 14-1).


image The AIN is a branch of the median nerve that supplies the deep muscles on the front of the forearm. It accompanies the anterior interosseous artery and runs on the anterior surface of the interosseous membrane in the interval between the FPL and FDP, supplying the whole of the former and the radial half of the latter. The AIN terminates in the volar capsule of the wrist joint after it innervates the PQ (see Fig. 14-1).


image

FIGURE 14-1

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Mar 5, 2016 | Posted by in Hand surgery | Comments Off on 14: Distal Anterior Interosseous Nerve Transfer to Motor Branch of Ulnar Nerve

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