ABSTRACT
Objective:To observe the path and anatomic distribution of cutaneous branch of second dorsal metacarpal artery(SDMA) from the back of hand to the web of the fingers, and to explore the feasibility and clinical effect on the transfer of free flap of SDMA.Methods:Between June 2018 and September 2018, with perfusion of red latex, 22 hand specimens were dissected to explore the course, vessel calibre and distribution of cutaneous branches of SDMA, and to discover the existence of an innervation of cutaneous nerve in Department of Hand Surgery of Tangshan Second Hospital. Later on, from February 2019 to July 2020, 2 thumb pulp defects of 2 patients were reconstructed with the free flaps of SDMA. One defect was in the left thumb and the other in the right, both were male and compression injuries. Size of thumb pulp and a skin defect was at 3.5 cm×2.0 cm in 1 patient, and 2.0 cm×2.5 cm in the other. There was no neurovascular injury, but 1 patient had a distal phalangeal fracture and a nail bed laceration. The sizes of the flaps were 3.8 cm×2.3 cm and 2.8 cm×2.5 cm. Functional exercises started from 3 weeks after surgery. Patients attended postoperation follow up regularly by outpatient visit, telephone or internet interviews. Follow-up observations included the appearance, texture, sensory recovery of the flaps and thumb functions.Results:Multiple perforating branches (4-9 branches) were found from SDMA, which distributed in the distal 1/3 of SDMA in the anatomic study. It was found that the outer diameter of SDMA was 0.76 mm±0.25 mm at the intersection of extensor tendon of index finger and that of the digital web artery was 0.71 mm±0.12 mm. The length of digital web artery was 11.00 mm±1.27 mm. The 2 surgically transferred flaps were all survived. One patient showed the function of thumb in excellent with two-point discrimination (TPD) at 7.0 mm, at 18 months of follow-up. The other patient showed good thumb movement, soft and elastic skin of the flap and with a 7.5 mm in TPD, at 15 months of follow-up. According to the Evaluation Standard of Upper Limb Partial Functional of Hand Surgery of Chinese Medical Association, the results of the 2 flaps were all excellent.Conclusion:The flap of SDMA has a constant cutaneous nerve and a long vascular pedicle with an ideal vessel size. It is suitable for free transfer and can be used to reconstruct soft tissue defects of thumb.