Surgical anatomy of the common peroneal nerve in the Kenyan population: A cadaveric study

Abstract

Background: The common peroneal nerve (CPN) is a branch of the sciatic nerve in the leg, at most risk of injury around the fibular neck as it is almost subcutaneous. With increasing procedures around the knee, there is increasing incidence of possible injuries to the nerve intraoperatively resulting in post operative complications. The nerve has been studied in Caucasian populations and findings published, unlike the case in Kenyan population. Objective: To describe the surgical anatomy of the CPN in the Kenyan population. Methods: The study was conducted in the Human Anatomy Laboratory at Moi University, School of Medicine, and using anatomical descriptive cross- sectional study design. Study population of forty three right sided formalin fixed limbs of unascertained origin was dissected, using lateral approach. CPN was identified and tagged. Its distance from the Gerdy’s tubercle was plotted at 3 points: d I-(from Gerdy’s tubercle to the CPN at the back of the head of the fibula); d II- (from Gerdy’s tubercle to the starting point of the superficial branch of the CPN); and d III- (from Gerdy’s tubercle to anterior recurrent genicular branch). Its branches were identified. Photographs showing the course of the nerve and its branches were taken. Measurements of d I, d II, d III and the length of the nerve main trunk were taken and recorded into data collection sheets, and later fed into an electronic database with restricted access. Data analysis was done and results were presented using tables and graphs. Results: Forty three (32 males, 11 females) cadaveric formalin fixed lower limbs were used. CPN trunk was noted winding around the neck of fibula and disappeared into substance of peroneus longus muscle. The measurements for all cadaveric limbs in mm (Median (IQR)) were: d I=58 (54, 62); d II= 54 (47, 58); and d III= 49 (44, 53). The mean radius was 57.6±5.0 mm. The d I, d II and d III for all limbs and even by gender categorization however were all statistically not significant (p> 0.05). The CPN main trunk had median (IQR) lengths in mm of 153 (138, 230) and was statistically significant (Shapiro-Wilk test: W= 0.717; p< 0.001). Photographic findings showed the nerve arose from the sciatic nerve at different locations (2.3% intrapelvic; 9.3% proximal third of the thigh; 18.6% middle third of the thigh and 69.8% distal third of the thigh) and divided into its branches inside the peroneus longus muscle in 91% of limbs, and outside the muscle in 9% of limbs. The branches included: sural communicating; superior, inferior and recurrent genicular; deep and superficial peroneal nerves. The variations in the course of the nerve and the branches were displayed in photographs. Conclusion: The mean radius for Gerdy’s safe zone and the length of the main trunk in Kenyan population were greater than in other studied populations. However, no comparison can be made for the median (IQR) length of main trunk as it lacked in other studies. The number of branches and branching patterns were as in other studies with only in 9% of limbs- division outside the peroneus longus. Recommendations: Orthopaedics surgeons in Kenya can use the findings of this study to plan and carry out various procedures safely in proximal tibia (Gerdy’s safe zone). The exact origin of the limbs could not be ascertained. Therefore further study can be carried out in ascertained different populations for comparison.