Isolated injury to a major branch of the posterior interosseous nerve of the forearm with surgical repair

Neglected posterior interosseous nerve injury

Posterior interosseous nerve (PIN) injury is uncommon due to its anatomically deep location. We report a neglected, rare case of PIN injury presenting the loss of extension of thumb, index, and small fingers with weakness of thumb abduction in a 49-year-old male patient. The patient sustained a penetrating injury to his right forearm caused by a kitchen knife that was repaired primarily through an emergency surgery under general anesthesia. During the regular follow-up on the 52nd postoperative day, the patient presented 20° of extension lags in the right thumb and index finger and 30° in the small finger. Wrist extension was intact, and there was no sensory deficit. We explored the wound and traced the PIN completely, identifying a club-shaped neuroma formation at the proximal cut end of the PIN. Delayed nerve repair was performed with a double-strip cable graft. Hand surgeons should be aware of the probable PIN injury in certain situations of forearm-penetrating injury and perform proper preoperative physical examination to rule out neurovascular deficits. Careful exploration and immediate repair of severe PIN are mandatory, even in emergency situations.

Penetrating injury to the terminal branches of the posterior interosseous nerve with nerve grafting

We report two cases of penetrating injuries to the terminal branches of the posterior interosseous nerve in the forearm. Repair using nerve grafts in both cases were followed by complete recovery.

Isolated paralysis of the extensor digitorum communis associated with the posterior (Thompson) approach to the proximal radius

Seven patients presented with an isolated extensor digitorum communis (EDC) palsy immediately after undergoing surgery in which the posterior (Thompson) approach to the proximal radius was used. All had normal neurologic examination findings documented prior to surgery. In an attempt to localize this lesion, the authors studied the arborization of the terminal motor branches of the posterior interosseous nerve (PIN) at the distal edge of the supinator. A common innervation pattern to the superficial extensor muscles was observed in 29 of 30 cadaveric limbs. In 10 of 10 specimens, when the EDC was subdivided into its individual bellies, a reproducible pattern emerged: the proximal EDC muscles of the middle and ring fingers were supplied primarily by the recurrent nerve branch(es) and the EDC muscles of the index and little fingers, by separate nerve branches. Consistent with our anatomic findings, perioperative stimulation of the recurrent branch in 1 neurologically intact patient resulted in middle and ring finger extension. Electromyography in 8 normal limbs showed that the middle and ring fingers could be activated together without the index and little fingers in all cases. We believe that these patients with isolated EDC nerve palsy may have sustained an iatrogenic injury to EDC motor branches, distal to the supinator rather than to a PIN fascicle near the proximal supinator.