Anatomic Anomalies Encountered in 467 Open Carpal Tunnel Surgeries

Purpose: Carpal tunnel syndrome is the most common compression neuropathy and carpal tunnel surgery is the most frequently performed hand surgery. Anatomic anomalies may predispose the median nerve to compression. The aim of the current study was to search for anatomic anomalies in open carpal tunnel surgeries through a cross-sectional study. Methods: During a cross-sectional study in a one-year period, 436 consecutive patients (307 females and 129 males) with the average age of 50.3 2.4 years underwent 467 classic open carpal tunnel surgeries. Thirty-one patients had bilateral surgeries. A thorough inspection of the incisions was conducted to search for vascular, neural, tendon and muscular anomalies. Results: Forty-two (8.9%) hands (14 males and 28 females) had anomalies. The average age of the patients with discovered anomalies was 48.6 7.6 years. Ten anomalies were seen on the left hands and 32 anomalies were seen on the right hands. Among the 42 anomalies, there were 16 persistent median arteries, 14 anomalies of the median nerve, 7 intratunnel intrusion of the flexor and lumbrical muscle bellies and 5 anomalies of the origin of the thenar muscles. There was no correlation between the discovered anomalies and the age, gender or hand sides. Conclusion: Anatomical anomalies are not uncommon in carpal tunnel surgeries. However, the frequencies of the reported anomalies vary among different studies. Familiarity with these anomalies increases the safety of the operation.