Evaluation of anatomical and histological characteristics of human peripheral nerves: as an effort to develop an efficient allogeneic nerve graft.

Management of peripheral nerve defects is a complicated problem in clinical contexts. Autologous nerve grafting, a gold standard for surgical treatment, has been well known to have several limitations, such as donor site morbidity, a limited amount of available donor tissue, and size mismatches. Acellular nerve allografts (ANAs) have been developed as an alternative and have been applied clinically with favorable outcomes. However, because of the limited availability of commercialized ANAs due to supplier-related issues and high costs, efforts continue to produce alternative sources for ANAs. The present study evaluated the anatomical and histological characteristics of human peripheral nerves using 25 donated human cadavers. The length, diameter, and branching points of various peripheral nerves (median, ulnar, tibial, lateral femoral cutaneous, saphenous, and sural nerves) in both the upper and lower extremities were evaluated. The cross-sectional area (CSA), ratio of fascicular area, and numbers of fascicles were also evaluated via histologic analysis. CSA, the ratio of fascicular area, and the number of fascicles were analyzed statistically in correlation with demographic data (age, sex, height, weight, BMI). The mean length of all evaluated nerves ranged from 17.1 to 41.4 cm, and the mean diameter of all evaluated nerves ranged from 1.2 to 4.9 mm. Multiple regression analysis revealed correlations between the ratio of fascicular area and sex (p = 0.005) and BMI (p = 0.024) (R2 = 0.051). The results of the present study will be helpful in selecting necessary nerve allograft sources while considering the characteristics of each nerve in the upper and lower extremities during ANAs production.

The anatomy of the saphenous and sural nerves as a source of processed nerve allografts.

As an alternative to autologous nerve donors, acellular nerve allografts (ANAs) have been studied in many experiments. There have been numerous studies on processing ANAs and various studies on the clinical applications of ANA, but there have not been many studies on sources of ANAs. The purposes of the present study were to evaluate the course of the saphenous and sural nerves in human cadavers and help harvest auto- or allografts for clinical implications. Eighteen lower extremities of 16 fresh cadavers were dissected. For the saphenous nerve and sural nerve, the distances between each branch and the diameters at the midpoint between each branch were measured. In the saphenous nerve, the mean length between each branch ranged from 7.2 to 28.6 cm, and the midpoint diameter ranged from 1.4 to 3.2 mm. In the sural nerve, the mean length between each branch ranged from 17.4 to 21 cm, and the midpoint diameter ranged from 2.3 to 2.8 mm. The present study demonstrates the length of the saphenous and sural nerve without branches with diameters larger than 1 mm. With regard for the clinical implications of allografts, the harvest of a selective nerve length with a large enough diameter could be possible based on the data presented in the present study.