Ulnar nerve strains at the elbow: the effect of in situ decompression and medial epicondylectomy.

Strains were measured in the ulnar nerve at the elbow in 10 unembalmed, intact cadavers by using a microstrain gauge. In each cadaver, strains in the ulnar nerve behind the medial epicondyle, occurring between 60 degrees and 140 degrees flexion, were calculated for the following 3 conditions: (1) initial strain before in situ decompression, (2) strain after in situ decompression, and (3) strain after in situ decompression plus medial epicondylectomy. The average strain for each group was compared by using the paired Students t-test with multiple comparisons. The average initial percent strain was not significantly reduced by in situ decompression alone (5.3% to 4.3%). However, the average percent strain after medial epicondylectomy and in situ decompression was -0.54%, which was a significant reduction from the initial percent strain and after decompression alone. In situ decompression of the ulnar nerve at the elbow alone does not relieve the tensile strains at the elbow, which may contribute to cubital tunnel syndrome. Medial epicondylectomy after in situ decompression eliminates ulnar nerve strains with elbow flexion.