Case report: Double nerve transfer of the anterior and posterior interosseous nerves to treat a high ulnar nerve defect at the elbow

Double neurotization of the deep branch of ulnar nerve (DBUN) and superficial branch of ulnar nerve using the anterior interosseous nerve (AIN) and the recurrent (thenar) branch of the median nerve was first described by Battiston and Lanzetta. This article details the postoperative results after 18 months of a patient who underwent this technique using the posterior interosseous nerve (PIN) instead of the recurrent branch of the median nerve for sensory reconstruction. A 35-year-old, right-handed man suffered major trauma to his right upper limb following a serious motor vehicle accident. One year later, a pseudocystic neuroma of the ulnar nerve was evident on ultrasound examination and MRI. After the neuroma had been resected, the nerve defect was estimated at 8 cm. One and a half years after the initial trauma, with the patient still at M0/S0, we transferred the AIN and PIN onto the deep and superficial branches of the ulnar nerve respectively. Nerve recovery was monitored clinically every month and by electromyography (EMG) every three months initially and then every six months. At 18 months postoperative, 5th digit abduction/adduction was 28 mm. Sensation was present at the base of the 5th digit. The patient was graded M3/S2. Clear re-innervation of the abductor digiti minimi was demonstrated by EMG (motor conduction velocity 50 m/s). Given that the ulnar nerve could not be excited at the elbow, this re-innervation had to be the result of the double nerve transfer. Neurotization of the DBUN using the AIN produces functional results as early as 1 year after surgery. Using PIN for sensory neurotization is easy to perform, has no negative consequences for the donor site, and leads to good recovery of sensation (graded as S2) after 18 months.