The effect of operative technique on ulnar nerve strain following surgery for cubital tunnel syndrome.

Background: The aim of this study is to compare the amount of strain on the ulnar nerve based on elbow position after in situ release, subcutaneous transposition, submuscular transposition, and medial epicondylectomy.

Methods: Six matched cadaver upper extremity pairs underwent ulnar nerve decompression, transposition in a sequential fashion, while five elbows underwent medial epicondylectomy. A differential variable reluctance transducer (DVRT) was placed in the ulnar nerve. An in situ release, a subcutaneous transposition, and a submuscular transposition were performed sequentially with the strain being measured after each procedure in neutral, full elbow flexion, and extension positions. The strain was then averaged and compared for each procedure. Five cadavers underwent medial epicondylectomy and were similarly tested.

Results: After the in situ release, there was no statistically significant change in strain in either flexion or extension. After a subcutaneous transposition, there was a statistically significant decrease in strain in full elbow flexion but not in extension. Similarly after a submuscular transposition, there was a statistically significant decrease in strain in full flexion but not in extension. There was not a statistically significant change in strain with medial epicondylectomy.

Conclusion: An in situ release of the ulnar nerve at the elbow may relieve pressure on the nerve but does not address the problem of strain which may be the underlying pathology in many cases of ulnar neuropathy at the elbow (UNE). Transposition of the ulnar nerve anterior to the medial epicondyle addresses the problem of strain on the ulnar nerve. In addition, it does not create an increased strain on the ulnar nerve with elbow extension.