A, Two incisions made at wrist. B, Through volar incision, flexor sublimis tendon to ring finger and flexor carpi ulnaris tendon are exposed. Through ulnar incision, extensor carpi ulnaris is exposed. Flexor carpi ulnaris tendon is divided 4 cm from its insertion, and free end of distal segment is sutured to extensor carpi ulnaris. Flexor digitorum sublimis tendon to ring finger is exposed through transverse incision at proximal flexor crease of finger, and its two slips are divided. C, Tendon of flexor digitorum sublimis to ring finger is drawn proximally through volar incision at wrist, threaded through pulley, and passed through subcutaneous tissue to metacarpophalangeal joint of thumb. D, Two slips of transferred tendon are secured to base of proximal phalanx. Hole is made through proximal phalanx in ulnar-to-radial direction and is enlarged on ulnar side to accept loop of one tendon slip, which is secured with pull-out suture. E, After transfer has been secured to thumb phalanx, tension is adjusted (see text), and proximal segment of flexor carpi ulnaris tendon is sutured to transferred tendon.