The thumb accounts for 50% of the total hand function. This study reports the functional outcomes and complications of people with traumatic thumb amputations who underwent toe-to-thumb reconstruction.From 2013-01 to 2018-01, 29 patients with second-degree thumb defect underwent thumb reconstruction with distal phalangeal braided toenail flap. The footscan foot pressure gait analysis system was used to measure the index changes of the same foot before and after one, three and six months. The contact area, peak pressure, impulse value, contact time of each gait phase, centre of gravity coordinate and foot balance were analysed statistically. Twenty-nine cases of thumb reconstruction recovered well. After following up for 6-15 months, the appearance of the reconstructed thumb was close to normal, and the sensation was restored to S3+. The two-point discrimination was 6-8 mm, and the function of the thumb was good. The function of the donor foot was well restored, and no skin ulceration, pain and claudication were noted during walking. Compared with that before operation, the biomechanical indices of the donor foot were basically restored to normal six months after operation. Only the stress and impulse values of the third metatarsal head were significantly increased, forming a stress concentration area centred on the third metatarsal head.This study confirmed that the toe nail flap with distal phalangeal bone restored the second-degree thumb defect without destroying the main functional structure of the sole. The biomechanical indices of the donor foot were basically restored to normal six months after operation. Only the stress concentration area centred on the third metatarsal head, and the pain on the forefoot was induced after the operation. Discomfort, callus formation, metatarsal fasciitis, etc. can lead to fatigue fracture of the third metatarsal bone in severe cases, which requires further follow-up and observation.

Inclusion Criteria:

1. patients with second-degree thumb defect；
2. without any foot disease or deformity before injury；
3. Written informed consent to undergo the surgical procedure；

Exclusion Criteria:

1. Concomitant phalanx fractures or other injuries needing immobilization；
2. Loss of skin substance requiring grafts or flaps
3. Uncompensated diabetes, neoplasia, haemocoagulative alterations, psychic disorders
4. Smokers

The causes of injury were as follows: 2 cases of amputation and loss, 21 cases of machine rolling damage, 5 cases of rotational tear and replantation failure and 1 case of childhood traumatic defect. The patients included 19 males and 10 females with age of 17-46 years (mean 29.1 years), height of 156-179 cm (average 170.4 cm), weight of 50-80 kg (average 62.3 kg) and foot length of 23-26 cm (average 24.5 cm). The defect cases included 12 on the left side of the toe and 17 on the right side.