An analysis of results after selective tendon transfers through the interosseous membrane to provide selective finger and thumb extension in chronic irreparable radial nerve lesions

Purpose We present the results of a modified tendon transfer for the restoration of wrist and finger extension in irreparable radial nerve lesions. Methods Restoration of wrist extension, finger extension, thumb extension, and thumb abduction was done in 29 patients (20 males and 9 females; age range: 10-58 years) with isolated, irreparable radial nerve palsy. We used a modified tendon transfer technique using the flexor digitorum superficialis (FDS) 3 (to extensor indicis proprius [EIP] and extensor pollicis longus [EPL]) and FDS 4 (to extensor digitorum communis 2-4 [EDC]) as donors for the reconstruction of selective finger and thumb extension (all patients) and pronatorteres (PT) for wrist extension (25 patients). Thumb abduction was achieved by transferring the palmaris longus (PL) tendon to the abductor pollicis longus (APL) (all patients). Results Results show that near-normal wrist extension was achieved in 22 of 25 patients with extension strength of M4+. In the other 3 patients, wrist extension strength did not exceed M3 (1 patient) or M4 (2 patients). Extension of long fingers with a completely extended wrist joint was achieved in 12 of 29 patients. In the remaining 17 patients, full-range finger extension was possible only with the wrist in neutral. The advantage of the selective tendon transfer (FDS 3 to EIP and EPL and FDS 4 to FDC 2-4) resulted in selective extension of the index finger and thumb, as well as other digits, in all patients. Thumb abduction and rotation was achieved in all. Conclusions Tendon transfers are indicated in longstanding, irreparable, isolated radial nerve lesions. Selective tendon transfer of FDS 3 to EIP and EPL and FDS 4 to EDC through the interosseous membrane results in reliable selective extension of these digits. The sacrifice of FDS 3 and 4 to reconstruct finger extension results in bowing of the donor digits.