This retrospective cohort study adhered to the principles of the Helsinki declaration and was approved by Jilin University, China (license number: SCXK (Ji) 20140084). Patients with soft-tissue defects on the volar surface of the finger caused by trauma from March 2014 to March 2017 were included. All patients’ medical history was recorded. Detailed clinical examination and radiography were performed to assess the skeletal effects and arterial duplex scanning was performed to assess the vascular pattern of the hand.
Those who had systemic diseases, including diabetes mellitus, vascular sclerosis, and peripheral vascular disease, those who could not withstand lengthy operation, and those who had a smoking history were excluded from this study, along with those with accompanied fractures or tendon ruptures. Patients were informed about the merits and demerits of each method and made the choice themselves. Written informed consent was obtained from all patients.
A total of 28 patients were included, of these 4 (3 DDMF and 1 MPAF) were lost to follow-up and 24 were eventually included in the study with an average age of 38.9 years (20–65 years); Eighteen patients were men (75%), and six were women (25%). All skin and soft-tissue defects were caused by trauma. The defects were localized at the volar surface of the finger with exposed flexor tendons. The patients were divided into two groups: MPAF group and DDMF group, and all procedures were performed by a single surgeon. The locations of the defects were as follows: thumb, seven; index finger, four; middle finger, four; and ring finger, nine. Among the patients, 13 had only skin and soft-tissue defects, and the other 11 (MPAF: 6 cases; DDMF: 5 cases) had nerve defects/injury. Nerve repair was performed using different methods (MPAF: nerve bridging, DDMF: flap with neurovascular bundle or the proper digital dorsal nerve was anastomosed with the digital nerve). Demographic data of the patients is presented in Table 1.
A survey was undertaken at least 12 months after the surgery to investigate and record the operation time and complications, including flap necrosis, graft loss, infection, paresthesia, and donor-site morbidity. The Michigan Hand Outcomes Questionnaire (MHQ)  was used to assess patient satisfaction with the surgical result. The questionnaire consists of five domains, including hand function, activities of daily living, work performance, esthetics, and satisfaction with hand function and was scored on a scale from 0–to 100 (0 = worst result, 100 = best result). In particular, the esthetic appearance also measured with Modified Vancouver Scar Scale (VSS), the total score was 18, including pigmentation (0-3), vascularity (0-3), pliability (0-5), Height (0-3), Pain (0-2) and Prutitus (0-2) [12-14]. Differences between independent parametric variables were assessed using an independent samples t-test. The group were also divided two subgroups with and without nerve damage and the 2PD test [15.16] always started from a greater distance between the spikes of the discriminator and then the distance was gradually reduced, generally from 10 mm to the smallest distance. The smallest distance the patient recognized as a sensation of two points was recorded in millimeters and used for analysis.
The overall function was graded as excellent, good, or poor. We defined the criteria for excellent results as flap survival and mean MHQ score of ≥ 85 without complications; flap survival with mean MHQ score of 60–84 and minimum complications were the criteria for good results. A result was considered poor when an alternative reconstructive procedure was required or the mean MHQ score was < 60.
The wound was subjected to radical debridement before reconstruction because most cases were a result of trauma. Necrotic tissue was removed, and antibiotic therapy was administered on the basis of microbiology results until the local wound bacterial culture confirmed the absence of infection. Thereafter, flap and nerve bridging were performed to repair the soft-tissue and nerve defects in the second stage.
The operation was performed under general anesthesia or nerve block. The pneumatic tourniquet was applied to provide a bloodless field. Surface marker measurement and preoperative imaging were performed; antibiotics were injected intravenously before tourniquet application.
MPAF is located in the non-weight-bearing area of the plantar on both sides of the axis and behind the head of the metatarsal bone. The size and shape of the flap can be designed and dissected as per the wound size, but it generally cannot be more than 4 × 8 cm [17,18]. The medial plantar artery and t medial plantar nerve can be identified between the abductor hallucis and flexor digitorum brevis. The flap was then elevated at the superficial muscle membrane of the abductor hallucis and isolated in the distal to the proximal direction. The medial plantar artery was anastomosed with the digital proper arteries or the common palmar digital arteries; the dorsal veins of the finger or palm were anastomosed with the accompanying vein of the plantar metatarsal artery. To ensure that the flap was sensate, the branches supplying the flap were isolated and teased out from the main trunk of the medial plantar nerve. The proximal and distal ends of the flap nerve should be sutured with the proper digital nerve. The donor site of the flaps was primarily grafted with a split-thickness skin graft. Fig 1.
DDMF was located between the metacarpals and with the rotation point located at the proximal phalanx level. It was designed on the intermetacarpal spaces as an ellipse centered over the dorsal metacarpal arteries that were ligated at the proximal margin of the flap. The flap was elevated in the interosseous fascial plane. The pivot point of the flap was located at the mid-point of the proximal phalanx where the proximal dorsal branch of the digital artery anastomoses with the dorsal digital artery. It can be transferred to the defect through an open tunnel, and the secondary defect was closed primarily or with a skin graft. Fig 2.
Data are presented as the mean ± standard error of the mean. The incidence of complications, functional outcomes, and other qualitative parameters were compared using Fisher’s exact test. The mean operation time between the two groups and other quantitative variables were analyzed using the t-test. The level of significance was set at p < 0.05.