Intraoperative Conversion From Endoscopic to Open Carpal Tunnel Release: A Systematic Review and Case Series

Predictive Factors for Converting Endoscopic to Open Carpal Tunnel Release

Introduction: Both open and endoscopic methods of carpal tunnel release are accepted treatments for carpal tunnel syndrome. The objective was to determine the endoscopic to open conversion rate of all carpal tunnel surgeries. We evaluated potential predictive factors for an increased rate of conversion. Methods: The IRB/IRBnet approved (#20210613/1639264) a retrospective chart review of all attempted endoscopic carpal tunnel surgeries performed from July 1, 2012 through June 30, 2021. Charts were reviewed for procedure, age, sex, body mass index (BMI), electromyograph (EMG) reading, wrist arthritis on x-ray, preoperative steroid injections, trainee as surgeon, diabetes, hand dominance, and operated side. Conversion rate was noted. A chi-square test using a P-value of <0.05 was used to determine the statistical significance of the patients' age, sex, BMI, EMG severity, the presence of wrist arthritis, preoperative steroid injections, resident as surgeon, diabetic status, and operated hand dominance as predictive factors for conversion. Results: The plastic surgery service attempted 1053 endoscopic carpal tunnel releases using the Chow dual port technique over a 9-year period. Forty-five cases converted to an open release. Median age (P = 0.54), sex (P = 0.43), median BMI (P = 0.76), EMG severity (P = 0.20), wrist arthritis (P = 1.0), preoperative steroid injections (P = 0.65), resident surgeon (P = 0.53), diabetes (P = 0.50), and operated hand dominance (P = 0.36) were not statistically significant predictive risk factors. Nineteen of 45 converted cases had a future successful contralateral endoscopic release. Conclusion: Our study found a 4.27% endoscopic to open conversion rate. No identifiable risk factors could predict conversion. Prior conversion does not determine a future contralateral conversion.

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.

Early Rates of Revision Surgery in Endoscopic and Open Carpal Tunnel Release

PURPOSE

To compare rates of revision surgery between primary endoscopic carpal tunnel release (ECTR) and open carpal tunnel release (OCTR). In addition, we aimed to assess the influence of fellowship training on revision rates. We hypothesized that ECTR would not be associated with higher rates of revision surgery.

METHODS

We conducted a retrospective, single-center replication study of a recently published comparative assessment of ECTR and OCTR. All patients between 18 and 75 years old undergoing primary ECTR or OCTR over a 6-year period were included if they were seen within 1 year after surgery. To control for confounding, adjusted binary logistic regression models were inverse-weighted by propensity scores. Early (12 months) and overall revision rates were compared between ECTR and OCTR, as were revision rates relative to surgeon training.

RESULTS

A total of 4,160 patients and 63 surgeons were included. Eighty-one percent underwent OCTR. Nine patients (0.21%) underwent revision within 12 months of index CTR at a mean of 231 days postoperatively. The early revision rate for OCTR and ECTR were 0.24% and 0.13%, respectively. After adjusting for patent characteristics and confounding, ECTR cases were 0.28 times (95% confidence interval, 0.09-0.90) less likely to undergo revision. Early OCTR revision rates for hand surgeons were similar to nonhand surgeons (0.23% vs 0.24%); however, statistically significant higher revision rates were noted for nonhand surgeons (1.04%) compared to hand surgeons (0.42%) for revisions beyond 12 months.

CONCLUSIONS

Within a single health care system, the early revision rate after primary CTR was 0.21%. When adjusting for patient characteristics and controlling for confounding, ECTR was 0.28 times less likely to undergo revision compared to OCTR. Hand fellowship training was associated with lower OCTR revision rates beyond 1 year. These data highlight the need for future investigations to clearly define indications for, and outcomes following, revision CTR.

TYPE OF STUDY/LEVEL OF EVIDENCE

Prognostic II.

A Comparison of Amyloid Deposition in Endoscopic and Open Carpal Tunnel Release

PURPOSE

Previous investigations assessing the incidence of amyloidosis detected with biopsy during carpal tunnel release (CTR) have focused on open CTR (OCTR). Prior authors have suggested that biopsy may be more technically challenging during endoscopic carpal tunnel release (ECTR). Our purpose was to compare differences in the incidence of amyloid deposition detected during ECTR versus OCTR.

METHODS

We reviewed all primary ECTR and OCTR during which a biopsy for amyloid was obtained between February 2022 and June 2023. All procedures were performed by five upper-extremity surgeons from a single institution. Congo red staining was used to determine the presence of amyloid deposition in either the transverse carpal ligament (TCL) or tenosynovium. All positive cases underwent subtype analysis and protein identification through liquid chromatography-tandem mass spectrometry. Baseline demographics were recorded for each case, and the incidence of positive biopsy was compared between ECTR and OCTR cases.

RESULTS

A total of 282 cases were included for analysis (143 ECTR and 139 OCTR). The mean age was 67 years, and 45% of cases were women. Baseline demographics were similar except for a significantly higher incidence of diabetes in OCTR cases (13% vs 33%). Overall, 13% of CTR cases had a positive biopsy. There was a statistically significant difference in the incidence of amyloid deposition detected during biopsy in ECTR cases (3.5%) compared with OCTR cases (23%).

CONCLUSIONS

Biopsy performed during ECTR may result in a lower incidence of amyloid detection. Future basic science investigation may be necessary to determine histologic differences between tenosynovium proximal and distal to the leading edge of the TCL. When surgeons plan a biopsy during surgical release of the carpal tunnel, an open approach may be advantageous.

TYPE OF STUDY/LEVEL OF EVIDENCE

Prognostic II.

A Comparison of Early Complication Rates of Endoscopic Carpal Tunnel Release With and Without Resident Involvement

PURPOSE

The purpose of this study was to compare the complication rates of endoscopic carpal tunnel release (ECTR) relative to orthopedic resident trainee involvement in the procedure.

METHODS

All patients undergoing isolated, elective ECTR by two attending surgeons within a 59-month period were analyzed. Cases were categorized as the following according to the degree of resident involvement: ECTR performed by attending with either no resident or a resident as an assistant (group 1), resident performing a portion of the procedure (group 2), and resident performing the entire procedure (group 3). Early postoperative complications and/or intraoperative conversion to an open procedure were the outcomes of interest. We used a noninferiority design, hypothesizing that resident involvement would not be associated with inferior outcomes compared with cases without resident involvement. Multiple logistic regression models, adjusted for patient demographic and surgical characteristics, were fit to assess the relationship between resident involvement groups and complication/conversion outcomes.

RESULTS

A total of 1,167 ECTR cases (895 patients) were performed and returned for postoperative follow-up for at least 2 weeks after surgery. Operative time was significantly shorter for group 1 cases versus group 2 and 3 cases. The early postoperative complication and conversion rates were 1.7% and 1.0%, respectively. Superficial infection (1.2%), deep infection (0.3%), and transient neuropraxia (0.3%) occurred infrequently and did not differ relative to resident involvement. No differences in the odds of complication and/or conversion relative to resident involvement were observed.

CONCLUSIONS

The results of ECTR performed entirely or in part by attending-supervised resident trainees were not inferior to ECTR performed by an attending surgeon regarding the odds of experiencing complications or conversion to an open procedure. With appropriate supervision, ECTR can be performed safely by orthopedic and plastic surgery residents.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic II.