Objective:To analyze the feasibility of applying transcutaneous electrical nerve stimulator and high-frequency ultrasound in superficial nerve positioning for detection anatomical location in the area of lateral lip of the iliac crest by lateral cutaneous branch of subcostal nerve(LCSN). The significance of using the nerve as a free sensory superficial circumflex iliac artery perforator flap was discussed.Methods:The data of patients who underwent the repair of defects on limbs with free perforator flap or composite flap of superficial iliac circumflex artery carrying sensory nerve and the volunteers who agreed to have the location of the LCSN measured between October, 2018 and October, 2020 were collected. The LCSN were located by percutaneous electrical nerve stimulation and ultrasound, and the patients were measured and located during surgery. Using Passing-Bablok regression and Bland-Altman graph to evaluated the consistency between transcutaneous electrical nerve stimulation, ultrasound and the surgical positioning.Results:A total of 43 subjects, including 22 patients and 21 volunteers, were selected for locating the LCSN. Thirty-nine males and 4 females, with an average age of 39 years old and an average BMI of 24.08. The operation time of percutaneous nerve electrical stimulation was(6±1) min, and the detection distance was(80.7±5.9) mm. The high-frequency ultrasound was(23±4) min, and the distance was(81.2± 6.6) mm. The average operation time of surgical measured distance was(80.9±8.2)(65-100) mm, the diameter of nerve was(2.3±0.8)(1.0-4.0) mm, and the operation time was(5±1) min. A 95% CI of Passing-Bablok regression intercept and slope of operation, percutaneous electrical nerve stimulation and ultrasoundincluded 0 and 1, respectively. The points on Bland-Altman plot were distributed on both sides, and 95% CI of total mean difference, total intercept and slope included 0. Therefore, it was can be considered that the application of percutaneous electrical nerve stimulation and ultrasound in LCSN localization has good consistency.Conclusion:The location point of the LCSN crossing the iliac crest which detected by transcutaneous electrical nerve stimulation and high-frequency ultrasound detection was close to the measurement taken during the operation. It was also showed that both of them can be used for preoperative locationing of the sensory branch of the sensory nerve flap, optimizing the design of the flap, shortening the operation time, and reducing the unnecessary injury in operation.

BACKGROUND:Calcaneal defects are common in clinical practice.It is difficult for surgeons to evaluate the effect of calcaneal reconstruction due to the complex anatomical structure and motor function of the heel.Finite element analysis has become an effective method for biomechanical behavior simulation and numerical analysis. OBJECTIVE:To compare the clinical effect and biomechanical characteristics of total calcaneal reconstruction with the Ⅱ-shaped and V-shaped fibular flap. METHODS:CT images of one left foot of a healthy 50-year-old male were acquired.Mimics software was used to obtain the preliminary three-dimensional model.Geomagic software was used to trim and curve the model.The model was imported into Solidworks software to simulate calcaneal reconstruction and complete the pre-processing of finite element calculation.Finally,Ansys software was used to solve the problem.The simulation results were compared with previous literature results to verify the effectiveness of the model.The surgical effect and biomechanical characteristics of the foot in different gait phases based on the simulated stress results were analyzed. RESULTS AND CONCLUSION:(1)Both Ⅱ-shaped and V-shaped fibular flaps could be used to reconstruct completely missing calcaneus,which could restore the length,width and height of normal calcaneus,and fill up the missing calcaneus bone.(2)Compared with the normal calcaneus,both configurations of fibular flaps showed a tendency for over-concentration of stress after loading.The normal calcaneus stress was mostly concentrated around the calcaneus nodule,the subtalar process and the calcaneus groove,while the stress of the two fibular flaps was mostly concentrated at the junction between the bone flap with the talus and cuboid bones.(3)The maximum stress of calcaneus was different between the two models and normal calcaneus under different simulation conditions,with statistically significant differences(P＜0.05).Compared with the V-shaped fibular flaps,Ⅱ-shaped fibular flaps had less force change in different gaits and were closer to the normal calcaneus.The V-shaped fibular flap bore excessive stress during the period of push-off,and the grafted bone material may yield under this condition and have the risk of fractures.