[Transfer of the flexor digitorum superficialis tendons of the middle and ring fingers to restore extension of fingers and thumb (Boyes' transfer)].

Objectives: Restoration of extension in the metacarpophalangeal joints of the fingers as well as in the interphalangeal joint of the thumb by transfer of the superficial flexor tendons of the long and ring fingers (flexor digitorum superficialis III and IV).
Indications: The indications for surgery are substantial loss and palsy of muscles innervated by the radial nerve and its roots.
Contraindications: The procedure is contraindicated by reversible radial palsy, palsy or substantial loss of flexors, limited passive mobility due to contracture, ankylosis or instability of the affected joints, instability of the wrist joint, palsy of the wrist flexors, ankylosis of the wrist joint in an unfavorable position, adhesions of flexor or extensor tendons, insufficient soft tissue coverage or soft tissue defects and passage of transposed tendons through scarred tissue.
Surgical Technique: The surgical technique involves division of the superficialis tendons of the long and ring fingers proximal to Camper's chiasm and routing of the tendons to the dorsum of the hand through separate fenestrations of the interosseus membrane. The flexor digitorum superficialis tendon III is interwoven into the tendons of the extensor pollicis longus und extensor indicis and the flexor digitorum superficialis IV is interwoven into the extensor digitorum tendons.
Postoperative Management: Forearm splinting in 20° wrist extension including the metacarpophalangeal joints of the fingers in extension and the thumb in the automatic stop position for 4 weeks leaving the proximal and distal interphalangeal joints free.
Results: From March 1999 to January 2010 a Boyes' transfer was performed in 13 patients (8 female and 5 male) and the right side was affected in 8, the left side in 5 and the dominant hand in 7 cases. The patient age at the time of surgery was an average of 47 ± 17 (13-73) years. The interval between radial palsy and tendon transfer was an average of 79 ± 144 (4-543) months. The final follow-up was performed at an average of 82 ± 35 (32-165) months. According to the Haas scoring system finger extension was excellent in 5, good in 5, fair in 3 and unfavorable in 4 cases and thumb extension was excellent in 5, good in 3, fair in 1 and unfavorable in 5 patients. The mean disabilities of the arm, shoulder and hand (DASH) score was 36 ± 24 (11-85) points. Although disability of varying degrees persisted in all patients, Boyes' transfer is considered to be a safe procedure to restore finger and thumb extension with excellent and good functional results, a high degree of patient satisfaction and few complications.