Surgical Technique for Performing Endoscopic Carpal Tunnel Release without Converting to an Open Technique, and Analysis of the Reasons for Conversion.

Objective: Endoscopic carpal tunnel release (ECTR) has advantages over open carpal tunnel release (OCTR); however, complications with ECTR are more likely to occur if the surgeon continues the procedure despite encountering difficulties. Techniques to minimize the need for conversion to OCTR have been infrequently discussed in the literature. This study aims to present a technique for performing ECTR without conversion to the open approach and to analyze the reasons for such conversions.

Methods: A total of 1160 hands in 771 patients who underwent single-portal ECTR between January 2001 and December 2020 were analyzed. We evaluated the rate and reasons for conversion and compared clinical severity and electrodiagnostic grades between the ECTR and OCTR conversion groups to identify patient characteristics associated with conversion.

Results: A total of 18 hands in 17 patients required conversion to OCTR (1.56%). In the first 5 years, 9 out of 251 ECTRs (3.59%) were converted, but since then, the conversion rate significantly decreased with increasing surgical experience. The most common reasons for conversion were poor visualization of the transverse carpal ligament due to the transbursal approach with a hypertrophic synovial membrane. As the preoperative clinical grade worsened, the conversion rate significantly increased. The OCTR conversion rate also tended to rise with more severe electrodiagnostic grades. Outcomes for all 18 wrists were successful at the 6-month follow-up.

Conclusions: A thorough subligamentous extrabursal approach is essential for achieving a clear endoscopic view of the transverse carpal ligament and performing ECTR without the need for conversion to open surgery.