Computer-assisted measurements of the histological structure of the tibial nerve and its terminal branches.

Abstract

The aim of this study was to analyse the histological structure (cross-sectional area [CSA] and number of nerve bundles) of the distal part of the tibial nerve and its terminal branches (medial plantar nerve, lateral plantar nerve) using computer-assisted image analysis. The tibial nerve and its distal branches (medial and lateral plantar nerves) were dissected from the fresh cadavers. Each nerve was harvested 5 mm proximally and respectively 5 mm distally from the tibial nerve bifurcation, marked, dehydrated, embedded in paraffin, sectioned at 2 μm slices and stained with haematoxylin and eosin. Then photographed and analysed using Olympus cellSens software. The studied group comprised 28 female and 32 male feet (mean age 68.1 ± 15.2 years). The mean CSA and the number of nerve bundles were respectively 17.86 ± 4.57 mm2, 33.88 ± 6.31 for the tibial nerve, 9.58 ± 1.95 mm2, 23.41 ± 7.37 for the medial plantar nerve and 7.17 ± 2.36 mm2, 15.06 ± 5.81 for the lateral plantar nerve in males and 12.27 ± 2.45 mm2, 26.32 ± 8.87 for the tibial nerve, 7.81 ± 1.41 mm2, 17.71 ± 5.28 for the medial plantar nerve and 5.83 ± 1.25 mm2, 11.50 ± 3.72 for the lateral plantar nerve in females. Both CSA and number of nerve bundles of the tibial, medial plantar and lateral plantar nerves revealed no statistical differences when comparing foot side of the individual. The statistical difference was related to the gender, showing significantly bigger CSA and number of nerve bundles in males (CSA: p = 0.000, p = 0.000, p = 0.016; number of nerve bundles: p = 0.01, p = 0.003, p = 0.004, respectively). A positive correlation was found between the donor age and the tibial nerve CSA (r = 0.44, p = 0.000). A significant statistical difference was found between the medial and lateral plantar nerves both in CSA and number of nerve bundles (p < 0.001, p < 0.001, respectively). The CSA and the number of nerve bundles in the distal part of the tibial nerve and its branches are significantly larger in males with no differences between right and left foot of the individual. The tibial nerve shows increasing CSA with advanced age. The medial plantar nerve has larger CSA and more nerve bundles than the lateral plantar nerve.