Flap transfer for traumatic defects of the upper extremity: experience of 35 cases


 Background Despite advances in microsurgical techniques of flap transfer, complex upper extremity trauma reconstruction remains a challenge for surgeons. Methods We retrospectively analyzed data from patients undergoing subacute upper extremity flap reconstruction, including flap choices, complications and success of flap reconstructions. Results Thirty-five patients underwent free flap procedures, including 24 anterolateral thigh flaps (68.57%), five latissimus dorsi flaps (14.29%) and six lateral arm flaps (17.14%). Flap sizes ranged from 3 × 4 to 33 × 11 cm 2 . The mean time of flap reconstruction was 14 days (range 5–29). Two flaps developed partial necrosis, both of which were later treated with skin-grafting. Traumatic wound infections occurred in three patients. All upper limb trauma was completely covered. Conclusions All three types of skin flaps used to reconstruct severe upper limb soft tissue defects achieved satisfactory function and appearance with negligible complications and low amputation rates during the subacute period.


Introduction
With the development of microsurgical technologies, plastic surgery has undergone tremendous advances. Operations previously requiring several procedures now can be completed in one operation, and some wounds that were difficult or even impossible to repair can be repaired successfully. Nevertheless, because of the complexity of severe upper limb trauma, wound coverage after severe limb injury remains challenging for surgeons. Furthermore, compared to the lower limbs, The concept of the perforator flap was first proposed by Koshima(1) in 1989. The technique entails only minimal damage to the donor area of the flap while obtaining the best appearance and function.
For this reason, the technique is widely used in plastic surgery for soft tissue reconstruction. There are many perforator vessels throughout the body, and the best perforator flap donor area can be selected according to the particular situation of the recipient area. Chimeric skin flaps can be designed to repair wounds with muscle and bone defects or severe infections. In recent years, the survival rate of flaps covering upper limb trauma have been above 90%. Vitse (2)  Although the timing of tissue transfer has been hotly debated for years, the effects of timing remain uncertain with respect to patient outcomes. It was originally suggested by Godina(4) that microsurgical reconstructions of the wounds within 3 days would decrease the rate of infection and shorten hospital stay and bone-healing time. Since then, 72 hours has been considered the "golden window" for flap reconstruction (5). However, in recent years, with improvements in preoperative management, especially with the application of Vacuum Sealing Drainage (VSD) negative pressure aspiration, researchers have found that the time of flap transplantation beyond the golden window achieved satisfactory outcomes(6). Derderian (7)  Despite the high success rate of skin flaps, some issues remain unresolved. To begin resolving these issues, we reported our experience using flap transfer for traumatic defects for the upper extremity during the past several years. We analyzed the flap choices, the timing, incidence of complications, and success of flap reconstructions used for devastating upper extremity injuries.

Patients And Methods
We performed a retrospective study of patients who came to our hospital for treatment of complex

Results
The three upper extremity reconstructive tissue transfers used were anterolateral thigh flaps (698.57%), latissimus dorsi flaps (14.29%), and lateral arm flaps (17.14%). Five defects of the major arteries were reconstructed with the ALT flaps using a flow-through pattern. Four defects were reconstructed with the ALT flaps using split skin paddles flaps. Three defects were reconstructed with ALT flaps without the fascia lata. The dimensions of the ALT flaps ranged from 8 to 33 cm in length and 6 to 11 cm in width. Latissimus dorsi flaps ranged from 28 to 36 cm in length and 7 to 9 cm in width. The lateral arm flaps ranged from 4 to 10 cm in length and 3 to 6 cm. Flap procedures were performed during the subacute period, with an average time to reconstruction of 14 days (range, 5-29 days). Some defects were not completely covered and were grafted with split-thickness skin grafts secondarily.
All but two of 35 flaps survived completely with three flaps requiring microvascular re-exploration.
The hospital stays ranged from 12 to 103 days (average, 39 days). The two lost partial flaps were an anterolateral thigh flap and a latissimus dorsi flap, both because of deficient blood supply.
Traumatized wound infections occurred in three patients, and further debridement was performed in two patients except one healed after five change dressings at his bedside. Two resulted from progressive muscle and soft-tissue necrosis of the wounds. Rehabilitation training was performed by physical therapists within 7 days of admission. The follow-up periods ranged from 19 to 62 months.

Discussion
High-energy injuries are associated with loss of muscle, nerve, blood vessels, and bone, making it difficult to treat the wounds left after primary debridement. With the development of surgical techniques, especially microsurgery, many limbs have been preserved instead of being amputated. Therefore, the focus has shifted to how to improve the appearance and function of the preserved limbs.
For severely complex upper limb wounds, selecting the tissue with adequate blood supply to cover the wound is most important (8,9). In our study, three kinds of flap were used to reconstruct upper Because of inter-individual variations in perforator anatomy, preoperative vascular mapping was introduced to help identify the dominant perforator. In our study, we performed computed tomography angiography (CTA) or color doppler sonography (CDS) to map perforators before applying an ALT perforator flap to repair soft tissue defects. According to our previous study (13), CTA had a higher sensitivity than CDS for detecting vessels. Therefore, we typically used CTA first to create clear 3D images of the vessels and surrounding structures, as well as to mark the skin. If the patient was allergic to iodine had renal insufficiency, they would undergo CDS to determine the position, path, caliber, and quality of the perforator vessels, and to mark the skin. We depended on the results of CTA and CDS to identify the best perforators to design the ALT perforator flaps. If the perforators are located precisely, the surgeon can identify the path of the perforator in the surrounding area and minimize incisions of the muscle and deep fascia during the operation, thereby reducing complications at the donor site. Furthermore, this makes the surgeon's task easier.
There has been no consensus regarding the most appropriate time to cover upper limb wounds using skin flap transplantation. As early as 1986, early covering of the wound was suggested by Godina (4); it was suggested that if flap transplantation should be carried out within 72 hours to close the wound, the necrosis rate of the flap would be 0.75%, greatly reducing the postoperative infection rate and hospital stays. However, since 1990, several studies have shown that secondary tissue transplantation can achieve better effects. In particular, there has been application of the negativepressure wound therapy technique (14). The benefits of negative-pressure wound therapy include increased perfusion, fresh granulation tissue, promotion of angiogenesis, wound area reduction, cellular proliferation, decreased bacterial contamination, and reduction of the inhibitory effects of wound exudates (12,15). According to Derderian (7), covering the wound using tissue transplantation on the 6th and 21st day after injury has obvious advantages over other times; flap necrosis rates, postoperative infection rates, incidences of osteomyelitis and nonunion were lower and the one-stage operation time was shortened, making patients more tolerant of the secondary operations. Delayed closure of the wound prevents proliferation of anaerobic bacteria while allowing sufficient time to identify the tissue that survives during primary debridement, avoiding more radical scavenging of surviving tissue, or leaving possible necrotic tissue resulting in late wound deferred. However, the later the wound is closed, the worse the function of the affected limb, resulting in heavier psychological and economic burdens. The reasons for this can be summarized as follows: (1) Wound infections correlate with longer exposure times. Despite the fact that the VSD negative pressure sealing technique keeps the wound closed, it can only guarantee effective sealing for 3 days; (2) Long-term inflammatory stimulation causes edema and adhesion of surrounding tissues, leading to stiffness and tissue organization; (3) Long-term exposure of bony tissue can easily lead to nonunion, necrosis and bone infections, increasing the difficulty of bone tissue repair at the later stages; (4) Long-term bed-rest leads to disuse atrophy of muscle and late limb dysfunction; (5) Inflammation stimulates peripheral blood vessels and nerves, causing edema and adhesions with surrounding tissue, resulting in increased graft necrosis rates of the late flap.
Of the 35 patients we treated, individualized treatments were developed according to the patient's condition and injury, as well as their condition on admission. In the subacute stage, the wound was closed by tissue transplantation. Therefore, we believe that subacute wound closure, if possible within 5-30 days after emergency surgery, remains a better choice. Emergency flap transplantation is not recommended unless there are important vessels and nerves that must be repaired. Mundi (16) suggested that primary wound closure is best for fractures with less severe soft-tissue injuries, to allow for tension-free closure. For those injuries requiring delayed closure, definitive coverage should not be delayed beyond seven days, even in the setting of negative-pressure wound therapy. We

Availability of data and materials
The datasets used and analyzed during the current study are available from the corresponding author on reasonable request.