[Efficacy of precisely designed first dorsal metacarpal artery flap under the guidance of high-frequency color Doppler ultrasound in repairing small-sized skin and soft tissue defects in the thumb].

Objective: To explore the efficacy of precisely designed first dorsal metacarpal artery flap under the guidance of high-frequency color Doppler ultrasound in repairing small-sized skin and soft tissue defects in the thumb. Methods: This study was a retrospective observational study. From January 2021 to August 2023, 29 patients with small-sized skin and soft tissue defects in the thumb who met the inclusion criteria were admitted to the Department of Hand Surgery of the Second Hospital of Tangshan. There were 16 males and 13 females, with ages ranging from 22 to 65 years. The wound area after debridement ranged from 2.5 cm×1.5 cm to 3.0 cm×2.0 cm. Before flap transplantation, the body surface projections of the anastomotic branches between the first metacarpal radial dorsal artery and the radial proper digital artery of the affected finger measured by high-frequency color Doppler ultrasound examination were recorded. During surgery, the first dorsal metacarpal artery flap was harvested to repair the defects in the thumb, with the harvested flap area of 3.0 cm×2.0 cm to 3.5 cm×2.5 cm. The superficial branch of radial nerve carried by the flap was anastomosed with the proper digital nerve in the recipient area. The wound in the flap donor site was directly sutured. It was observed whether the body surface projections of the anastomotic branches between the first metacarpal radial dorsal artery and the radial proper digital artery of the affected finger measured by preoperative high-frequency color Doppler ultrasound examination were consistent with the intraoperative findings. After surgery, the wound healing and suture removal time in the donor and recipient sites, as well as the flap survival were observed. At the last follow-up (6-12 months postoperatively), the function of the affected finger was evaluated according to the trial criteria for evaluation of partial function of upper extremity by the Hand Surgery Society of Chinese Medical Association, and the excellent and good rate was calculated. The satisfaction scoring of flap efficacy was performed. Additionally, the two-point discrimination distance of flap was measured, and Semmes-Weinstein monofilament test was performed to evaluate flap sensory function. Results: The body surface projections of the anastomotic branches between the first metacarpal radial dorsal artery and the radial proper digital artery of the affected finger of 29 patients measured by preoperative high-frequency color Doppler ultrasound examination were all consistent with the intraoperative findings. After surgery, all wounds in the donor and recipient sites healed well, the suture removal time was 14-16 days postoperatively. The flaps survived completely in 26 patients, and the partial flap necrosis occurred in 3 patients. At the last follow-up, the functional score of the affected finger was 88±8, with the excellent and good rate of 96.6% (28/29). The satisfaction scoring of flap efficacy was 7.4±1.0, the two-point discrimination distance of flap was (6.9±0.7) mm, and the Semmes-Weinstein monofilament test result was (3.46±0.19) g. Conclusions: The application of precisely designed first dorsal metacarpal artery flap under the guidance of high-frequency color Doppler ultrasound in repairing small-sized skin and soft tissue defects in the thumb has the advantages of high flap survival rate, good functional recovery of the affected finger, and high satisfaction with flap efficacy.