Anatomical Probability Model for Tibial and Peroneal Motor Entry Points

Hyperselective neurectomy requires accurate localization of terminal motor branches and their neuromuscular entry points in the lower leg. This descriptive cadaveric study was designed to establish proportional anatomical reference zones for motor branches of the tibial, superficial peroneal, and deep peroneal nerves.

Fresh-frozen adult lower-limb specimens without prior trauma or prior surgical intervention were examined. One extremity per cadaver was selected by coin toss. Standardized posterior, lateral, and anterior compartment dissections were performed to identify the tibial nerve and the common peroneal nerve, trace the superficial and deep peroneal divisions, and follow terminal motor branches to the point at which each branch entered the corresponding muscle.

For tibial nerve branches, branch location was referenced to the posterior border of the tibia at the midpoint of the proximal epiphysis. For superficial and deep peroneal branches, the proximal reference point was the most superior aspect of the fibular head on its anterior surface. The distal reference point was the point of entry into the target muscle. Total leg length was measured from the knee joint line to the ankle joint line. The motor entry point was calculated as the distance to the entry point divided by total leg length. Distributions were evaluated separately for each muscle using the Shapiro-Wilk test. Means and standard deviations were calculated, and probability intervals corresponding to mean plus or minus one standard deviation and mean plus or minus two standard deviations were used to define the most likely anatomical zones of motor branch entry. When required, logarithmic, square-root, or power transformations were used to approximate normality, with results expressed on the original proportional scale.