Transfer of the Fifth Finger to Replace an Amputated Thumb: A Preliminary Study

Introduction: Amputation of the thumb causes not only loss of significant functional use of the hand but also psychological and social problems. The procedures of toe-to-thumb transfer, pollicization, or metacarpal extension are recognized and well-documented options in totally amputated thumb reconstruction. Although these techniques have been successfully applied, they have some disadvantages. There is no record in the literature supporting the transfer of the fifth finger for thumb reconstruction. This study aims to test the suitability of the fifth finger for thumb reconstruction. We planned to transfer the fifth finger to the amputated thumb site in ten cadaver hands by preserving its digital artery, nerve, and flexor tendon.

Methodology and Material: The fifth finger was released following exploration of the digital artery, vein, nerve, and flexor and extensor tendons including the flexor retinaculum. The digital vein and the extensor tendon of the fifth finger were separated at the level of the metacarpophalangeal joint. The proximal phalanx of the fifth finger was cut smoothly at the level of the metacarpophalangeal joint with a saw. Two digital arteries on the flexor surface, two digital nerves, and the deep flexor tendons were protected. The ulnar side of the digital artery of the fourth finger was cut to release the fifth finger. The proximal phalanx of the released fifth finger was fixed to the first metacarpal bone. The extensor tendon of the first finger was sutured to that of the fifth finger. The digital vein of the first finger was anastomosed to the digital vein of the fifth finger by microsurgery. Angiography was done after the transfer.

Results: Exploration till the flexor retinaculum enabled thumb transfer without any restriction of movement in all ten cadaver fingers. The average time taken for dissection was 90 minute and the average transfer time was 45 minute.

Conclusions: Transfer of the fifth finger enables functional thumb reconstruction by preserving digital arteries and nerves in a relatively short time. Flow from both radial and ulnar arteries was demonstrated in the transferred fifth finger by angiography. This technique is shown to be possible in cadavers, but detailed clinical trials are needed for routine application.