Anatomical Probability Model for Tibial and Peroneal Motor Entry Points

Anatomical Probability Model for Tibial and Peroneal Motor Entry Points

This completed descriptive cadaveric study mapped the motor entry points of lower-leg muscles supplied by the tibial, superficial peroneal, and deep peroneal nerves. Twenty fresh-frozen adult lower-limb specimens without prior trauma or surgery were examined. One extremity from each cadaver was selected by coin toss. Investigators performed standardized posterior, lateral, and anterior compartment dissections, followed each terminal motor branch to the point where it entered the target muscle, and measured its location relative to total leg length. For each muscle, motor entry point location was expressed as a proportion of leg length and summarized using the mean, standard deviation, and probability intervals corresponding to mean plus or minus one and two standard deviations. The study was designed to provide quantitative anatomical reference zones that may support surgical planning for hyperselective neurectomy and related lower-leg procedures.

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.

Inclusion Criteria:

• Adult cadaveric specimen (age at death 18 years or older)
• Fresh-frozen lower-limb specimen made available under institutional standards for cadaveric research
• No prior trauma involving the selected lower limb
• No prior surgical intervention involving the selected lower limb

Exclusion Criteria:

• Cadaveric specimen from an individual younger than 18 years at death
• Prior trauma involving the lower limb
• Prior surgical intervention involving the lower limb