Risk Factors for Ulnar Nerve Instability Resulting in Transposition in Patients With Cubital Tunnel Syndrome

Purpose To assess the incidence of ulnar nerve instability in patients undergoing in situ decompression and to identify preoperative risk factors to predict the need for transposition. Methods Using our surgical database, we retrospectively identified 363 patients who were candidates for in situ ulnar nerve decompression for the treatment of cubital tunnel syndrome over a 5-year period. During this time, the 3 participating surgeons considered ulnar nerve instability to be a contraindication for in situ ulnar nerve decompression. We collected demographic data including sex, age, weight, height, and body mass index. We recorded the number of patients who underwent ulnar nerve transposition owing to ulnar nerve instability and evaluated whether ulnar nerve instability was diagnosed before, during, or after surgery. Results Of the 363 patients who were considered for in situ ulnar nerve decompression, 76 patients (21%) underwent ulnar nerve transposition secondary to ulnar nerve instability. Twenty-nine patients (8%) were identified with instability before surgery, and 44 patients (12%) were identified with instability during surgery following in situ decompression. Three patients (1%) were not diagnosed with instability until after surgery and subsequently underwent secondary transposition. Patients who underwent transposition owing to instability were more likely to be male and to be younger. Conclusions A notable percentage of patients with a stable nerve before surgery will have ulnar nerve instability following decompression. Identification of factors correlating to instability and the potential need for transposition can aid surgeons and patients in preoperative planning. (Copyright (C) 2016 by the American Society for Surgery of the Hand. All rights reserved.)