Clinical Application Of Sural Neurofasciocutaneous Flap And Analysis Of The Influencing Factors Contributing To The Partial Necrosis Rate Of The Flap

Objective: To introduce using antegrade-retrograde combined method to harvest distally based sural neurofasciocutaneous flap and explore its advantages; investigate the characteristics and indications of distally based sural neurofasciocutaneous flap with adipofascial flap for the reconstruction of soft tissue defect; analyze the influencing factors contributing to the partial necrosis rate of the flap.Method: Between April of 2001 and April of 2008, 114 distally based sural neurofasciocutaneous flaps were performed in 111 patients. Eighty-eight patients were male, and 23 were female. Ninety-six soft tissue defects were caused by trauma, Other 15 defects were caused by disposing the unstable scars, contractures, chronic ulcer, and tumors. All the defects complicate with the exposed bone, joint, muscle tendon and Achilles tendon. The defects repaired lie in calcar pedis and Achilles (78), middle and inferior segment of leg (36). The size of flaps ranged from 5 cm x 4cm to 20 cm x 15 cm. Thirty-six flaps were harvested by retrograde method; Seventy-eight flaps were harvested by antegrade-retrograde combined method since July 2005, namely, the perforating branches of peroneal artery in fascia pedicle are exposed by antegrade-retrograde combined method, then the flap is harvested retrogradely. Seventeen distally based sural neurofasciocutaneous flaps with distal adipofascial flaps were used to repair the soft tissue defects with larvaceous cavities, the distal adipofascial flaps being used to tamponade the cavities. The leg length (the distance between lateral malleolar sharp and transverse striation of the popliteal fossa) is separated to 9 portions equally, and the flap location is defined as leg zonation that the flap extremity distal to pedicle lies in. The definition of the flap length-width ratio is that the length of flap and pedicle is divided by the width of pedicle. The statistics was used to analyze the influencing factors contributing to the partial necrosis rate of the 114 flaps retrospectively. There are several influencing factors analyzed, such as sex, age, defect, process character, pivot point site, flap length plus pedicle length, flap length-width ratio, flap location, flap width and pedicle length-width ratio. Statistics analytical method: t-test and chi square test are used for mono-factor analysis; Logistic regression analysis is adopted for multi- factor analysis.Result: Among these 111 patients (114 flaps), 87 flaps survived uneventfully; distal superficial necrosis took place in 13 flaps, whose wound surfaces healed by changing dressings, secondary suture, or skin grafting; partial necrosis took place in 13 flaps, whose wound surfaces healed by secondary suture, skin grafting, or other flaps; bulk necrosis took place in only 1 case and the patient received a above knee amputation after operation because of the deep venous thrombosis and thromboangitis obliterans (TAO) of the affected limb. The partial necrosis rate of the flaps harvested by antegrade-retrograde combined method (7.7%, 6/78)is lower than that by retrograde method(22.2%, 8/36)(P>0.05) . Among 17 distally based sural neurofasciocutaneous flaps with adipofascial flaps, 14 flaps survived uneventfully; distal superficial and partial necrosis took place in 3 flaps, whose wound surfaces healed by changing dressings, skin grafting, or the other flap. Through 1 to 26 months following up of the 17 cases, the outlook of all those flaps was satisfactory and there is no suppuration relapse, no ulcer or sore or no dysfunction of donor site. There are three influencing factors contributing to the partial necrosis rate of the flap according to our analysis: the width, length-width ratio, and the location of the flap. The width of the flaps of survival group and partial necrosis group is analyzed by two-sample t-test (t=2.274,p<0.05); the partial necrosis rate of the length-width ratio less than 5 group(4.84%, 3 / 62) is lower than that of the length-width ratio more than and equal to 5 group(21.15%, 11/52) (P=0.005) ; the partial necrosis rate of the flap location less than 7/9 group(2.04%, 1 / 49)is lower than that of the flap location more than 7/9 group(20.00%, 13/ 65) (P=0.009) ; the partial necrosis rate of the flap location less than 8/9 group(8.60%, 8 / 93)is lower than that of the flap location more than 8/9 group (28.57%, 6/21) (P=0.032).Conclusion: (1) The antegrade-retrograde combined method can locate perforating branches of peroneal artery accurately, and position of the flap can be regulated if necessary, thus the partial necrosis ratio can be degraded. The method is especially suitable in the condition that there is no color-Doppler equipment or perforating branches of peroneal artery is not located by color-Doppler scan before operation. (2) The distally based sural neurofasciocutaneous flap with distal adipofascial flap is suitable to repair soft tissue defect in heel with a cavity. The advantage of the flap is easy to annihilate suppurative wound and reserve the function of heel's weight loading part. (3) With the length-width ratio of flap increasing, the partial necrosis rate of the flap increases. More proximal the location of the flap is, lower the partial necrosis rate of the flap is. While the length-width ratio is less than 5: 1and the location of the flap is lower than or equal to the 7/9 part of leg, the flap can survive uneventfully. These 2 factors can be used as a guidance to predict the survival rate of the flap.