Objective:To investigate the therapeutic effect of reverse proximal segment dorsal flap of radial digital artery of the thumb in repairing thumb tip defects.Methods:A retrospective case series study was conducted to analyze the clinical data of 56 patients with thumb tip defects admitted to Renqiu People 's Hospital from February 2010 to October 2020. There were 37 males and 19 females，aged 17-66 years［（37.8±12.2）years］. The injury on the right side was observed in 35 patients and on the left side in 21 patients. All of them were thumb tip defects with exposed distal phalanx. Dimension of skin defects was 2.9 cm×1.8 cm-3.3 cm×2.6 cm.The reverse proximal segment dorsal flap of thumb radial digital artery was used，with the dorsal digital nerve sutured with the proper digital nerve. The donor site was repaired with free skin graft from the ulnar side of the affected forearm. The time of flap harvesting，operation time and healing of the flap were measured. At the last follow-up，the shape，texture，sensory recovery and complications of the flap were observed. One month after operation and at the latest follow-up，the upper limb function evaluation standard set up by hand surgery branch of Chinese Medical Association and Vancouver Scar Scale（VSS）score were used to evaluate the recovery of sensory function of the flap and scar formation of the donor sites，respectively. Results:All patients were followed up for 6-26 months［（13.2±6.4）months］. The time of flap harvesting ranged from 20 to 35 minutes［（26.0±5.3）minutes］. The operation time was 1-2 hours［（1.3±0.3）hours］. Blisters appeared at the distal end of the flap in 2 patients after operation，but they were not treated. After 7 days，the blisters subsided and the flaps survived. The other flaps survived successfully. The donor sites healed by first intention. At the last follow-up，the flaps showed relatively cosmetic appearance，similarities in texture，elasticity and color to the surrounding area and good sensory recovery，without scar contracture and dystrophy of interphalangeal joint. According to the upper limb function evaluation standard set up by hand surgery branch of Chinese Medical Association，56 patients exceeded S3 grade compared to none at postoperative 1 month（ P<0.01），and the VSS score was 3-7 points［（5.0±1.4）points］compared to 6-12 points［（8.8±1.5）points］at postoperative 1 month（ P<0.01）. The donor site left a linear scar，which had no significant effect on its shape and function. Conclusion:The reverse proximal segment dorsal flap of the radial digital artery of the thumb can be used to repair thumb tip defects，for it has advantages of easy operation，a high survival rate as well as good appearance and sensory function recovery，with less damage to the donor area.

Objective:To report our clinical efficacy of pedicled transplantation of proximal thumb dorsal transverse flap to repair tissue defects at thumb pulp and fingertip.Methods:From February 2010 to November 2020, 97 patients with tissue defects at thumb pulp and fingertip were treated by pedicled transplantation of proximal thumb dorsal transverse flap at Department of Orthopedics, People's Hospital of Renqiu. They were 55 men and 42 women, aged from 17 to 66 years (average, 41.3 years). Altogether 55 right and 42 left sides were affected. The size of soft tissue defects ranged from 2.8 cm×1.8 cm to 3.9 cm×2.8 cm. Postoperatively, flap survival, shape, color and sensory recovery at the recipient area were observed; wound healing, function and complications at the donor site were also observed.Results:All the 97 flaps survived and all the wounds healed at the first stage. Blisters appeared at the distal end of the flap in only 2 cases but subsided 7 days after operation with no special treatment and the flaps survived smoothly. All the skin grafts at the donor site survived uneventfully. The 97 patients were followed up for 6 to 26 months (average, 10.7 months). Their flaps were not swollen, finger abdomen was full, finger appearance satisfactory, and finger feeling recovered well. The two-point discrimination at the last follow-up ranged from 4 to 11 mm (average, 7.6 mm). By the trial criteria for assessment of upper limb function suggested by Hand Surgery Society of Chinese Medical Association, sensory function of the affected finger was assessed as S 4 in 21 cases and as S 3+ in 76 cases at the last follow-up. No scar contracture was observed at the donor site and no movement restriction at the interphalangeal joint. Conclusion:Proximal thumb dorsal transverse flap is a reliable choice for reconstruction of complex tissue defects at thumb pulp and fingertip because of the advantages of easy harvest, constant vascular anatomy, full appearance and good sensory function at the recipient site, and limited damage to the donor site.