Previous studies have demonstrated that the volume of the carpal canal increases after open and endoscopic surgery in patients with carpal tunnel syndrome. There is some controversy regarding the contribution of the postoperative widening of the carpal arch to the increment in carpal canal volume. The objectives of this study were to: 1) evaluate the degree of variation in the angles formed by the borders of the carpal arch following the surgical division of the transverse carpal ligament; and 2) determine if there are differences in the variation of these angles after the classical open surgery versus endoscopic carpal tunnel release.
The authors prospectively studied 20 patients undergoing carpal tunnel syndrome surgery: 10 patients were treated via the standard open technique, and 10 underwent endoscopic carpal tunnel release. The angles of the carpal arch were measured on CT scans of the affected hand obtained before and immediately after the surgical procedures. Measurements were performed at the level of the pisiform-scaphoid hiatus and at the level of the hook of the hamate-trapezium hiatus.
There was widening of the postoperative angles of the carpal arch after open and endoscopic division of the flexor retinaculum; however, the difference between pre- and postoperative angulations reached statistical significance only in those patients treated by means of the open procedure. The mean (± SD) values for the postoperative increase in the angles at the level of the pisiform-scaphoid hiatus were 5.1 ± 0.4° after open surgery and 2.5 ± 0.3° after the endoscopically assisted procedure (p < 0.05). At the level of the hook of the hamate-trapezium hiatus, the mean values for the widening of the angles were 6.2 ± 0.6° for the open surgery group and 1.2 ± 0.4° for those patients treated by means of the endoscopic technique (p < 0.05).
The widening of the postoperative angles of the carpal arch is a phenomenon observed at the proximal and distal levels of the carpal canal, and it can be noted after both open and endoscopically assisted carpal tunnel release. The endoscopic procedure yielded less increase in these angles than the open surgery.