Radial nerve location at the posterior aspect of the humerus: an anatomic study of 100 specimens.

PURPOSE: Radial neuropathy represents a devastating complication in a posterior approach to the distal humerus. This study aimed to propose "safe zones" regarding the radial nerve (RN) location at the posterior aspect of the humerus to minimize the risk of iatrogenic injury.

METHODS

In 100 embalmed specimens, the distances of the proximal edge of the olecranon fossa (OF) to the radial nerve at the medial edge (R1), at the center (R2) and at the lateral edge (R3) of the posterior aspect of humeral shaft were measured. Humeral length (HL) and transcondylar width (TW) were evaluated and correlated to R1, R2 and R3.

RESULTS

R1 was 15.0 (±2.1; 10.6-19.5) cm, R2 averaged 12.7 (±1.6; 8.9-15.7) cm, R3 was 10.6 (±1.3; 7.6-13.7) cm. HL was 30.8 (±1.9) cm. TW averaged 6.3 (±0.6) cm. TW and HL correlate with R1, R2, R3 (r = 0.451-0.565 [95% CI 0.279-0.685]). The mean ratio was 2.3 (±0.18) for HL/R1, 2.6 (±0.23) for HL/R2 and 3.1 (±0.31) for HL/R3. The ratio averaged 2.2 (±0.20) for R1/TW, 1.9 (±0.18) for R2/TW and 1.6 (±0.15) for R3/TW.

CONCLUSIONS

We present the OF as an osseous landmark to reduce the risk of iatrogenic radial neuropathy. HL and TW can be reliably used to estimate the RN location. The consistent "safe zones" of the RN in relation to the OF are 10.5 cm at the medial edge, 9 cm at the center and 7.5 cm at the lateral edge of the posterior aspect of the humeral shaft.