Purpose: To evaluate the significant factors leading to major median and ulnar nerve injury after carpal tunnel release (CTR). We hypothesize that operative technique and redo carpal tunnel releases are the most significant factors resulting in nerve injury.

Methods: A retrospective chart analysis identified patients who were referred to our institution between 1990 and 2001 with partial or complete injury to the median or ulnar nerves during CTR. All patients complained of pain, parasthesias, and loss of sensibility consistent with major nerve injury. Complete evaluations of all patients included history, physical examination, and electrodiagnostic studies. Carpal tunnel re-exploration documenting the location of nerve injury and necessary repairs were performed.

Results: Ten (8 female and 2 male) patients were identified with major nerve injury following carpal tunnel release. All patients were referred to the hand specialists at our institution after their initial operation. Average age was 48.7 (range 33-75). Patients were referred an average of 4.1 months (range 1- 9) following initial operation. None of the patients had had previous CTR or wrist operations prior to the initial operation resulting in nerve injury. 90% (n=9) had partial median nerve transection and 10% (n=1) had ulnar nerve transection. 60% (n=6) had a standard open release through a linear incision, 30% (n=3) had endoscopic release, and 10% (n=1) had a mini open technique. The initial surgeon’s training was 50% (n=5) orthopedic surgery, 20% (n=2) general surgery, 10% (n=1) neurological surgery, 10% (n=1) osteopathic medicine, and 10% (n=1) hand surgery.

Conclusion: The results of this study suggest that major median and ulnar nerve injury after CTR are not related whether open or endoscopic techniques were used. In contradiction to our hypothesis, we found more injuries with the open approach than with the endoscopic approach. Also, nerve injuries were not associated with redo CTR. However, of significance, was the fact that ninety percent of the patients with nerve injury were operated on by surgeons with no formal hand surgery training.

Significance: Although CTR is in theory a simple operation, in this series, the most significant factor resulting in nerve injury was the operative surgeons lack of specialized training in hand surgery.