Effect of partial, distal epicondylectomy on reduction of ulnar nerve strain: a cadaver study

Abstract

Purpose: To compare the decrease in ulnar nerve strains using a modification of medial epicondylectomy by removing the distal half of the medial epicondyle with in situ decompression and partial medial epicondylectomy.

Methods: Using 20 elbows of 10 fresh human cadavers, we measured the strain on the ulnar nerve using a microstrain gauge before and after in situ decompression. Then, we repeated the measurements after partial medial epicondylectomy on left elbows, and after distal medial epicondylectomy on right elbows. We compared the mean strain values with 2-way analysis of variance.

Results: The decrease in mean ulnar nerve strain with in situ decompression from 5.4% to 5.2% on the right side and 5.4% to 5.0% on the left was not statistically significant. The decrease to 2.9% on the left elbows after partial and to 1.9% on the right elbows after distal medial epicondylectomy was statistically significant. In addition, the remaining ulnar nerve strain after distal medial epicondylectomy was significantly less compared with that after partial medial epicondylectomy. We observed nerve subluxation only with partial medial epicondylectomy.

Conclusions: In situ decompression alone does not change ulnar nerve strains. The significant change in ulnar nerve strain with partial or distal medial epicondylectomy underlines the role of medial epicondyle on stretching of the ulnar nerve. Excision of the distal half of the medial epicondyle sets the contact point of the nerve with the bone proximally and decreases the strain on ulnar nerve more effectively than partial epicondylectomy. However, its efficacy and complications need to be studied clinically.

Clinical relevance: The results of the present cadaveric study suggest that excision of the distal half of the medial epicondyle in cubital tunnel syndrome may decrease ulnar nerve strain effectively. The clinical effect of decrease in nerve strain and the indications for the procedure need to be investigated.