gms | German Medical Science

Objectives/Interrogation: Nerve injuries in the hand are common and continue to pose a challenge to the upper extremity surgeon. Depending on the injury, means of coaptation include primary repair, hollow-tube (conduit) repair, and repair with autograft or allograft. Appropriate size matching, related to nerve diameter, is important for many of these techniques. The aims of this study were to 1) describe the nerve diameters of the hand and their relative differences and 2) investigate if there is a relationship between nerve diameter and external hand dimensions or body mass index (BMI).

Methods: We utilized eighteen freshly-frozen cadaveric hands from adult donors aged 20-86 of both sexes for this study. External hand dimensions were measured across three axes: length, width, and span. Two independent observers measured nerve diameter to the nearest 0.1mm using a digital caliper. Using the flexor zones as boundaries, we performed a total of 33 nerve measurements for each cadaveric hand (Fig 1). Provided values are based on the mean measurement of these two observers.

Results and Conclusions: Nerve diameter increased from the distal to the proximal flexor zones. The internal common digital nerves in flexor zone three were larger than the external digital nerves. The median nerve was found to be nearly two times larger than the ulnar nerve at two locations within the wrist. There was a positive correlation between BMI, hand span, hand width, and nerve diameter at several measured locations.

This study provides reference values for nerve diameters of the hand and wrist and describes their relative differences. It is important for surgeons to be aware of these differences and to consider this information as we advance our efforts to reconstruct the hand and develop technologies for nerve repair.