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[Clinical study of modified technique to reduce partial necrosis rate of distally pedicled sural flap].

Objective
To investigate whether the technical modifications regarding the risk factors related to the partial necrosis of the distally pedicled sural flap could reduce the partial necrosis rate of the flap.


Methods
A clinical data of 254 patients (256 sites) (modified group), who used modified technique to design and cut distally pedicled sural flaps to repair the distal soft tissue defects of the lower limbs between April 2010 and December 2019, was retrospectively analyzed. Between April 2001 and March 2010, 175 patients (179 sites) (control group) who used the traditional method to design and cut the skin flap to repair the distal soft tissue defects of the lower limbs were compared. Various technical modifications were used to lower the top-edge of the flap, reduce the length-width ratio (LWR) of the flap and width of the skin island. There was no significant difference in gender, age, etiology, duration from injury to operation, site and area of the soft tissue defect between groups ( P>0.05). The length and width of the skin island and adipofascial pedicle, the total length of the flap and LWR, and the pivot point position were measured and recorded. The top-edge of the flap was determined according to the division of 9 zones in the posterior aspect of the lower limb. The occurrence of partial necrosis of the flap and the success rate of defect reconstruction were observed postoperatively.


Results
There was no significant difference in the length and width of the skin island, the length of the adipofascial pedicle, total length and LWR of the flap, and pivot point position of the flap between groups ( P>0.05). The width of the adipofasical pedicle in modified group was significant higher than that in control group ( t=-2.019, P=0.044). The top-edge of 32 flaps (17.88%) in control group and 31 flaps (12.11%) in modified group were located at the 9th zone; the constituent ratio of the LWR more than 5∶1 in modified group (42.58%, 109/256) was higher than that in control group (42.46%, 76/179); and the constituent ratio of width of skin island more than 8 cm in control group (59.78%, 107/179) was higher than that in modified group (57.42%, 147/256). There was no significant difference in the above indicators between groups ( P>0.05). In control group, 155 flaps (86.59%) survived completely, 24 flaps (13.41%) exhibited partial necrosis. Among them, 21 wounds healed after symptomatic treatments, 3 cases were amputated. The success rate of defects reconstruction was 98.32% (176/179). In modified group, 241 flaps (94.14%) survived completely, 15 flaps (5.86%) exhibited partial necrosis. Among them, 14 wounds healed after symptomatic treatments, 1 case was amputated. The success rate of defect reconstruction was 99.61% (255/256). The partial necrosis rate in modified group was significantly lower than that in control group ( χ 2=7.354, P=0.007). There was no significant difference in the success rate between the two groups ( P=0.310). All patients in both groups were followed up 1 to 131 months (median, 9.5 months). All wounds in the donor and recipient sites healed well.


Conclusion
The partial necrosis rate of the distally based sural flap can be decreased effectively by applying personalized modified technical for specific patients.