Morphologic and morphometric bilateral analysis and sexual dimorphism in sciatic nerves of adult cadaveric specimens in Uganda

Abstract

Background: The Sciatic nerve (SN) exhibits distinct sex and side-related differences, which have significant implications for clinical practice. The study investigated the sex and side-related morphologic and morphometric variations of the nerve using cadavers.

Methods: This is a cross-sectional cadaveric study involving 62 Ugandan cadavers. Continuous variables were reported using descriptive statistics and discrete variables were reported as percentages. Ordinary two-way ANOVA was used to compare the dimensions and proportion of the patterns of the SN.

Results: The study identified six categories of exit patterns of the SN, type A ("Below and undivided") occurred in a majority of cases (62.9%). A penta-furcate branching pattern dominated the whole population. Bifurcate termination pattern was found in most SNs (90.3% and 87.1% for right and left limbs respectively) while the rest have the trifurcate termination pattern, with no side or sex-related variations. The average dimensions of SN were within normal ranges, and showed no side-related differences but with a sex difference (significantly higher in males than females), mean length of the SN in centimetres (length A: Males, right limbs = 30.58 ± 9.00; left limbs = 31.30 ± 6.20; Females, right = 26.07 ± 6.58; left = 26.30 ± 5.56). The difference in the length "A" for the males left limb and females right limb was statistically significant with a p-value of 0.0195.

Conclusions: Most of the examined SNs showed normal anatomical characteristics with rare cases of sex-related dimorphism in the termination level and morphometry (length and diameter) of the nerve. The observed sexual dimorphisms in sciatic nerves are of clinical and surgical interest; hence, suggesting the need for further investigations in different populations, especially using advanced techniques such as ultrasonography anatomic techniques.

Keywords: Anatomic variations; Cadaveric sciatic nerves; Sciatic nerve dimensions; Sciatic nerve dimorphism; Sciatic nerve injury; Sciatic nerve patterns; Sciatic nerve topography; Sciatic nerve variant; Ugandan population.

Fig. 1

Photographs of the gluteal and posterior aspects of the thigh representing: the exit patterns (A-F); branching patterns (G); and terminations patterns (a&b) of the cadaveric sciatic nerves in the general Ugandan population. N = 62. A. Type A (Below and undivided); undivided SN goes inferior to the piriformis.B. Type B (Below and divided); division of SN occurring below the piriformis with one part passing in front of the muscle and the other part below it. C. Type C (Above and undivided); undivided SN goes superior to the piriformis.D. Type D (Above and divided); division of SN occurring above the piriformis with one part passing in front of the muscle and the other part above itE. Type E (Within and undivided); course of SN undivided through the piriformis muscle. F. Type F (Within and divided); course of SN divided through the piriformis muscle. G.The “Pentafurcate branching pattern”; SNshowedfive divisions during its course in the posterior compartment of the thigh.a. Birfucate termination pattern; SN divides into two terminal branches.b. Trifurcate termination pattern; SN divides into three terminal branches. Abbreviations. CPN = common peroneal nerve; SN = sciatic nerve; TN = tibial nerve. N = the total number of the sample