Abstract
Objectives: Knowledge is scarce about the outcome of revision surgery for recurrent or persistent ulnar nerve entrapment at the elbow (UNE). We studied the outcome of subcutaneous (SCT) and submuscular (SMT) ulnar nerve transpositions due to UNE, analyzing both primary and revision surgeries, aiming to identify predictors for revision surgery.
Methods: All surgically treated UNE cases (2004-2008) at our department were studied retrospectively. The initial population of surgically treated patients included 285 primary and 52 revision surgeries. Forty-three of the former were transpositions (15 SCT and 28 SMT) and 44 (7 SCT and 37 SMT) of the latter, which were the ones included in the present study. Medical records, including electrophysiological protocols, were reviewed and the postoperative outcome was graded as 1) cured/improved, and 2) unchanged/exacerbated symptoms, based on the patient-reported and surgeon-evaluated outcome.
Results: The frequency of concomitant systemic diseases (p<0.001), musculoskeletal conditions (p=0.029) and CTS (p=0.048) was higher in revision than in primary surgery cases. Both primary (79%) and revision SMT (76%) cases had a high frequency of ulnar nerve subluxation. Primary SMT cases had a higher frequency of ulnar nerve impact found through electrophysiological examination (p=0.045), while revision SMT cases had normal electrophysiological findings or reduced ulnar nerve conduction velocity (not significant; p=0.10). The satisfaction rate was 79-93% of primary transposition surgeries and 73-86% of revision transposition surgeries.
Conclusion: Patients with comorbidity with other systemic diseases, musculoskeletal conditions or concomitant CTS have a higher risk of UNE relapse and need revision surgery. Surgeons should assess any tendency for peroperative subluxation at primary surgery for UNE, proceeding with concomitant transposition of the nerve to minimize the need for revision surgery.

Key words: Ulnar nerve, entrapment, submuscular ulnar nerve transposition, subcutaneous ulnar nerve transposition, electrophysiology, outcome