[Relationship between proximal-tip location and partial necrosis in distally based sural neuro fasciocutaneous flap: an analysis of 157 flaps].

Objective: To explore the influence of proximal-tip location on partial necrosis in distally based sural neuro fasciocutaneous flap.

Methods: From April 2001 to May 2009,157 distally based sural neuro fasciocutaneous flaps were conducted to repair the soft tissue defect in distal region of lower leg, ankle and feet in 153 patients. Date of the flaps and the patients were retrospectively analyzed. From the tip of lateral malleolus to the popliteal crease, posterior aspect of the lower leg was equally divided into 9 regions that were 1st to 9th region from inferiorly to superiorly, respectively. The flaps were divided into 2 groups: survival group (including uneventfully survived flaps, flaps with distally epidermal necrosis and with wound dehiscence) and partial necrosis group. Based on the location of the proximal tip of flaps, the flaps were stratified into 4 groups: flaps with the proximal tip locating in the 6th or lower region (group A), the 7th region (group B), the 8th region (group C) and the 9th region (group D). Harvesting the flaps started from exploring the perforator of peroneal vessel in the adipofascial pedicle, then the flaps were elevated retrogradely.

Results: Of the 157 flaps, 125 survived uneventfully,8 showed distal epidermal necrosis,wound dehiscence occurred in 6 flaps, 18 flaps (11.5%) showed distal partial necrosis. Partial necrosis occurred in zero of 19 flaps in group A (0), 1 of 44 flaps in group B (2.3% ), 7 of 62 flaps in group C (11.3% ) and 10 of 32 flaps in group D (31.3% ). The differences in partial necrosis rate between group A and group B , group B and group C, were not statistically significant (P > 0.05). Partial necrosis rate was higher in group D than in group C (P = 0.012), it was lower in group A + group B (1.6%) than in group C + group D (18. 1% ) (P = 0. 001).

Conclusions: Distally based sural neuro fasciocutaneous flap can survive reliably when the proximal tip of flap is not beyond the junction between lower 7/9 and upper 2/9 of the lower leg, whereas probability of partial necrosis occurring in the flap increase significantly when the proximal tip of flap locates in upper 1/9 of the lower leg.