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Endoscopic Release Superficial Rather Than Deep to the Transverse Carpal Ligament for Carpal Tunnel Syndrome Improves Immediate Postoperative Transient Symptomatic Exacerbation With Fewer Absences From Work

  • Ruihong Wei
    Affiliations
    Division of Hand and Microvascular Surgery, Department of Orthopedic Surgery; Shenzhen Key Laboratory of Musculoskeletal Tissue Reconstruction and Function Restoration, Shenzhen People's Hospital, Second Clinical Medicine College of Jinan University, First Affiliated Hospital of Southern University of Science and Technology, Shenzhen, Guangdong
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  • Chao Chen
    Affiliations
    Division of Hand and Microvascular Surgery, Department of Orthopedic Surgery; Shenzhen Key Laboratory of Musculoskeletal Tissue Reconstruction and Function Restoration, Shenzhen People's Hospital, Second Clinical Medicine College of Jinan University, First Affiliated Hospital of Southern University of Science and Technology, Shenzhen, Guangdong
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  • Yingnan Liu
    Affiliations
    Division of Hand and Microvascular Surgery, Department of Orthopedic Surgery; Shenzhen Key Laboratory of Musculoskeletal Tissue Reconstruction and Function Restoration, Shenzhen People's Hospital, Second Clinical Medicine College of Jinan University, First Affiliated Hospital of Southern University of Science and Technology, Shenzhen, Guangdong
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  • Zhaokang Liu
    Affiliations
    Division of Hand and Microvascular Surgery, Department of Orthopedic Surgery; Shenzhen Key Laboratory of Musculoskeletal Tissue Reconstruction and Function Restoration, Shenzhen People's Hospital, Second Clinical Medicine College of Jinan University, First Affiliated Hospital of Southern University of Science and Technology, Shenzhen, Guangdong
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  • Hongtao Xiong
    Affiliations
    Division of Hand and Microvascular Surgery, Department of Orthopedic Surgery; Shenzhen Key Laboratory of Musculoskeletal Tissue Reconstruction and Function Restoration, Shenzhen People's Hospital, Second Clinical Medicine College of Jinan University, First Affiliated Hospital of Southern University of Science and Technology, Shenzhen, Guangdong
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  • Xu Zhang
    Affiliations
    Hand Surgery Department, Third Hospital of Hebei Medical University, Shijiazhuang, Hebei China
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  • Yongqing Zhuang
    Correspondence
    Address correspondence to Yongqing Zhuang, Division of Hand and Microvascular Surgery, Department of Orthopedic Surgery; Shenzhen Key Laboratory of Musculoskeletal Tissue Reconstruction and Function Restoration, Shenzhen People's Hospital, Second Clinical Medicine College of Jinan University, First Affiliated Hospital of Southern University of Science and Technology, Shenzhen, Guangdong, 518020, China.
    Affiliations
    Division of Hand and Microvascular Surgery, Department of Orthopedic Surgery; Shenzhen Key Laboratory of Musculoskeletal Tissue Reconstruction and Function Restoration, Shenzhen People's Hospital, Second Clinical Medicine College of Jinan University, First Affiliated Hospital of Southern University of Science and Technology, Shenzhen, Guangdong
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Open AccessPublished:October 05, 2022DOI:https://doi.org/10.1016/j.arthro.2022.09.013

      Purpose

      To determine the endoscopic release superficially rather than deep to the transverse carpal ligament to reduce the incidence of transient symptomatic exacerbation and postoperative absence from work in patients with carpal tunnel syndrome.

      Methods

      From January 2012 to January 2018, patients with idiopathic carpal tunnel syndrome who underwent one-portal endoscopic release superficial to the transverse carpal ligament (ERSTCL) were analyzed. For comparison, a cohort treated with the conventional Chow endoscopic release between February 2008 and October 2013 were included. Transient worsening of symptoms, discrimination sensation, and days off work were assessed. The minimal clinically important difference was calculated for discrimination sensation. Severity of symptom and functional status also were assessed using the Levine-Katz Questionnaire. Significance was set at P < .05.

      Results

      There was a significant difference between the ERSTCL group and the control group regarding the incidence of symptomatic exacerbation 1 week after surgery (2% vs 9%; P = .003) but no difference in other time intervals within the initial 3 months. There was a significant difference in 2-point discrimination 1 week (mean change = –0.13, 95% confidence interval [CI] –0.30 to 0.04, P = .01) and 2 weeks after surgery (mean change = –0.18, 95% CI –0.36 to –0.01, P = .033). Postoperative 1 and 2 weeks, 28% and 35% patients in ERSTCL group achieved a minimal clinically important difference, respectively. Compared with control group, the difference in frequencies was statistically significant (28% vs 45%; P = .027; 35% vs 57%; P = .015). The difference between the 2 groups in postoperative absence from work was statistically significant (95% CI 1.083-4.724; P = .002), with an average reduction in sick leave of 3 days in ERSTCL group. At a mean follow-up of 3 years, no significant difference was found between the groups regarding symptom and function statuses.

      Conclusions

      Endoscopic release superficial rather than deep to transverse carpal ligament for carpal tunnel syndrome improves immediate postoperative transient symptomatic exacerbation, which allows the patients to return to work earlier.

      Level of Evidence

      Level III, retrospective comparative study.
      Carpal tunnel syndrome (CTS) is the most common disabling condition of the upper extremity and affects more than 60 million people worldwide.
      • Chammas M.
      Carpal tunnel syndrome.
      ,
      • Devana S.K.
      • Jensen A.R.
      • Yamaguchi K.T.
      • et al.
      Trends and complications in open versus endoscopic carpal tunnel release in private payer and Medicare patient populations.
      Endoscopic carpal tunnel release (CTR) is commonly used for idiopathic CTS. However, nerve irritation is the major concern because the procedure requires the insertion of a video camera, instruments, and tools into the carpal tunnel.
      • Kang H.J.
      • Koh I.H.
      • Lee T.J.
      • Choi Y.R.
      Endoscopic carpal tunnel release is preferred over mini-open despite similar outcome: A randomized trial.
      • Castillo T.N.
      • Yao J.
      Prospective randomized comparison of single-incision and two-incision carpal tunnel release outcomes.
      • Chen L.
      • Duan X.
      • Huang X.
      • Lv J.
      • Peng K.
      • Xiang Z.
      Effectiveness and safety of endoscopic versus open carpal tunnel decompression.
      Accumulating studies have shown that endoscopic CTR is associated with faster recovery and fewer complications when compared with standard open surgery.
      • Sayegh E.T.
      • Strauch R.J.
      Open versus endoscopic carpal tunnel release: A meta-analysis of randomized controlled trials.
      • Li Y.
      • Luo W.
      • Wu G.
      • Cui S.
      • Zhang Z.
      • Gu X.
      Open versus endoscopic carpal tunnel release: A systematic review and meta-analysis of randomized controlled trials.
      • Ayeni O.
      • Thoma A.
      • Haines T.
      • Sprague S.
      Analysis of reporting return to work in studies comparing open with endoscopic carpal tunnel release: A review of randomized controlled trials.
      • Chow J.C.Y.
      Carpal tunnel syndrome.
      • Teng X.
      • Xu J.
      • Yuan H.
      • He X.
      • Chen H.
      Comparison of wrist arthroscopy, small incision surgery, and conventional surgery for the treatment of carpal tunnel syndrome: A retrospective study at a single center.
      • Okutsu I.
      • Ninomiya S.
      • Takatori Y.
      • Ugawa Y.
      Endoscopic management of carpal tunnel syndrome.
      • Chow J.C.
      Endoscopic carpal tunnel release: two-portal technique.
      • Trumble T.E.
      • Diao E.
      • Abrams R.A.
      • Gilbert-Anderson M.M.
      Single-portal endoscopic carpal tunnel release compared with open release: A prospective, randomized trial.
      • Atroshi I.
      • Larsson G.U.
      • Ornstein E.
      • Hofer M.
      • Johnsson R.
      • Ranstam J.
      Outcomes of endoscopic surgery compared with open surgery for carpal tunnel syndrome among employed patients: Randomised controlled trial.
      • Zhang X.
      • Huang X.
      • Wang X.
      • Wen S.
      • Sun J.
      • Shao X.
      A randomized comparison of double small, standard, and endoscopic approaches for carpal tunnel release.
      Currently, there are 1-portal and 2-portal endoscopic techniques.
      • Okutsu I.
      • Ninomiya S.
      • Takatori Y.
      • Ugawa Y.
      Endoscopic management of carpal tunnel syndrome.
      ,
      • Chow J.C.
      Endoscopic carpal tunnel release: two-portal technique.
      Among them, the Chow 2-portal endoscopic technique is most commonly used. These techniques require the insertion of a camera and other instruments into the carpal tunnel, carrying a risk of nerve injuries to the patient.
      • Kang H.J.
      • Koh I.H.
      • Lee T.J.
      • Choi Y.R.
      Endoscopic carpal tunnel release is preferred over mini-open despite similar outcome: A randomized trial.
      ,
      • Saw N.L.
      • Jones S.
      • Shepstone L.
      • Meyer M.
      • Chapman P.G.
      • Logan A.M.
      Early outcome and cost-effectiveness of endoscopic versus open carpal tunnel release: A randomized prospective trial.
      ,
      • Thoma A.
      • Veltri K.
      • Haines T.
      • Duku E.
      A meta-analysis of randomized controlled trials comparing endoscopic and open carpal tunnel decompression.
      To avoid this drawback, we developed endoscopic release superficial to the transverse carpal ligament (ERSTCL) for CTS to improve nerve irritation (Fig 1). This retrospective study aimed to determine endoscopic release superficial rather than deep to transverse carpal ligament, to reduce the incidence of transient symptomatic exacerbation and postoperative absence from work (POAFW) in patients with CTS.
      Figure thumbnail gr1
      Fig 1(A) The conventional endoscopic carpal requires to insert instruments into the carpal tunnel. The red arrow shows the entry point; the red dotted line shows the operative tunnel. (B) The ERSTCL is performed without need to insert the instruments into the carpal tunnel. (ERSTCL, endoscopic release superficial to the transverse carpal ligament; TCL, transverse carpal ligament).

      Methods

      The institutional review boards of the participating hospital review the study and approved the protocol. Informed consent was obtained from each patient. From January 2012 to January 2018, 224 patients with CTS were selected and examined at our hospital. Our eligibility criteria for ERSTCL group were as follows: (1) patients between 20 and 59 years of age; (2) a confirmed diagnosis of CTS based on Evidence for Surgical Treatment issued by the British Society for Surgery of the Hand
      • McCabe S.J.
      Diagnosis of carpal tunnel syndrome.
      ; (3) idiopathic CTS with symptoms that have lasted for at least 2 months or inadequate responses to the nonsurgical treatments ≥3 months; (4) moderate-to-severe symptoms based on the Levine–Katz Questionnaire (1 = best to 5 = worst)
      • Levine D.W.
      • Simmons B.P.
      • Koris M.J.
      • et al.
      A self-administered questionnaire for the assessment of severity of symptoms and functional status in carpal tunnel syndrome.
      ; and (5) normal contralateral hand as the baseline. Our exclusion criteria were as follows: (1) mild symptoms; (2) bilateral CTS lacking a comparison; (3) a combined or multiple nerve compression; (4) inflammatory neuropathy caused by infection, gout, diabetes, or chronic renal failure; (5) patients who refused to attend the study; (6) revision CTR; and (7) incomplete or interrupted follow-up (Fig 2). Patients older than 60 years were excluded because assessing days off work was difficult after retirement, which was an important factor in this study. Posttraumatic compression also was excluded because dissection in scar tissues is difficult and unsafe. The operations were performed by the same senior hand surgeon (Y.Q.Z.).
      Figure thumbnail gr2
      Fig 2Flowchart of trial participants and the outcome measures. (CTR, carpal tunnel release; ERSTCL, endoscopic release superficial to the transverse carpal ligament.).
      For comparison, we selected another cohort of patients (control group) undergoing CTR in our hospital from February 2008 to October 2013. The CTR was performed with Chow endoscopic technique. The patients met the same selection criteria of ERSTCL group (Fig 2). All operations were performed by the same 2 senior hand surgeons (Y.Q.Z. and R.H.W.).

      Surgical Technique

      One-Portal ERSTCL

      The operation was performed under brachial plexus blocking anesthesia and with upper arm tourniquet control. In the palm of the hand, we drew the first line along the radial border of the ring finger. The second line was drawn from the apex of the first web space to the ulnar palm and perpendicular to the first line. The portal was located at the crosspoint of the 2 lines (Fig 3). A 1-cm longitudinal incision was made at the crosspoint. We inserted tunneling forceps into the subcutaneous layer and made a subcutaneous tunnel to the ulnar edge of palmaris longus tendon at the distal wrist crease, i.e., the proximal edge of transverse carpal ligament (TCL). The tunneling forceps was replaced with a dilator. The subcutaneous tunnel was enlarged with the dilator. A video camera (Smith & Nephew Endoscopy, Andover, MA) also was inserted into the tunnel (Fig 4). With the aid of the dilator, we identified the TCL and palmar aponeurosis through the camera (Fig 5). The distal edge of the TCL was opened using Metzenbaum scissors. The median nerve and TCL were then divided proximally using a curved dissector. Under camera visualization, we divided the full length of TCL and palmar aponeurosis using Metzenbaum scissors. This procedure was performed in a distal-to-proximal sequence and along the ulnar border of the median nerve to avoid injuries to the motor nerve branch. Complete release was confirmed when the median nerve was completely exposed in the tunnel without compression fibers or lesion. The compression site was identified, and nerve edema were assessed (Fig 6). The tourniquet was released, and hemostasis was achieved by electric coagulation as needed. The wound was closed with one or two stitches.
      Figure thumbnail gr3
      Fig 3The design of entry point (red arrow). Surface projection of the operative tunnel (red dotted line).
      Figure thumbnail gr4
      Fig 4A video camera is inserted into the subcutaneous tunnel superficial to the TCL. With the aid of the video camera, the TCL is divided using Metzenbaum scissors. (TCL, transverse carpal ligament).
      Figure thumbnail gr5
      Fig 5A view superficial to the TCL showing the TCL (arrow). The camera is focusing on the proximal edge of TCL. (TCL, transverse carpal ligament).
      Figure thumbnail gr6
      Fig 6The TCL is divided and the median nerve (∗) is demonstrated.

      Chow Two-Portal Endoscopic Technique

      To summarize, as described by Chow et al.,
      • Chow J.C.
      Endoscopic carpal tunnel release: two-portal technique.
      the operation was performed under regional anesthesia associated with general intravenous sedation, and tourniquet control. A proximal portal was made 1 to 2 cm proximal to the distal wrist crease, in the midline, ulnar to the palmaris longus. A distal portal was established along a line bisecting an angle created by the intersection of the ulnar border of the abducted thumb and the third web space.
      • Chow J.C.Y.
      Carpal tunnel syndrome.
      A curved dissector was inserted into carpal canal and used to push soft tissue from the bottom surface of TCL. The slotted cannula assembly was gently inserted into the space between TCL and dissected soft tissue, passed downward and pointed towards the distal portal. The trocar was pushed through distal portal. The scope was inserted proximally into the cannula, and a probe was inserted distally. When the distal edge of TCL was identified by a probe, a sequence of cuts was made to release TCL. The cuts began by using the probe knife and cutting proximally to release the distal edge of TCL. The triangle knife was then inserted to cut through the midsection of TCL. Next, the triangle knife was positioned in this second cut and drawn distally to join the first cut. When the release of the distal half of the ligament was completed, the scope was then removed from the proximal portal and inserted into distal portal, and the instrument was brought in proximally. The uncut proximal half of the ligament was identified and the probe knife was used to cut the proximal edge of TCL. Finally, a retrograde knife was inserted into the midsection and cut proximally to complete the release of TCL. The trocar was then reinserted and the slotted cannula was removed from the hand. The 2 incisions were sutured.

      Outcome Evaluation

      An independent observer performed the assessments during office visits and household interviews. Based on hand strength, repetition, and wrist activity, we categorized the occupations into blue collar (manual labor), white collar (managerial, administrative, professional, and technician), and self-employed (sales and service) jobs.
      • Atroshi I.
      • Larsson G.U.
      • Ornstein E.
      • Hofer M.
      • Johnsson R.
      • Ranstam J.
      Outcomes of endoscopic surgery compared with open surgery for carpal tunnel syndrome among employed patients: Randomised controlled trial.
      ,
      • Katz J.N.
      • Amick 3rd, B.C.
      • Keller R.
      • et al.
      Determinants of work absence following surgery for carpal tunnel syndrome.
      We defined transient worsening of symptoms as numbness and/or tingling of any severity involving at least 1 of the radial 3 digits and the radial half of the ring finger, and restored to a preoperative condition within 3 months after operation (the symptoms are induced by median nerve irritation due to camera and instrument insertion rather than iatrogenic injuries). Sensibility of those fingers was measured on the pulps using the static 2-point discrimination (2PD) test
      • Crosby P.M.
      • Dellon A.L.
      Comparison of two-point discrimination testing devices.
      and Semmes–Weinstein monofilament (SWM) test
      • Wong K.H.
      • Coert J.H.
      • Robinson P.H.
      • Meek M.F.
      Comparison of assessment tools to score recovery of function after repair of traumatic lesions of the median nerve.
      preoperatively and at the ends of the first, second, fourth, sixth, eighth, tenth, and twelfth postoperative weeks. Severity of the symptoms and functional status was assessed using the Levine–Katz Questionnaire
      • Levine D.W.
      • Simmons B.P.
      • Koris M.J.
      • et al.
      A self-administered questionnaire for the assessment of severity of symptoms and functional status in carpal tunnel syndrome.
      preoperatively and at the final follow-up. We measured the grip and pinch strength of the hand using a Jamar hand dynamometer and a Jamar hydraulic pinch gauge, respectively. To exclude any discrepancy between dominant and nondominant hand strength, we based the scores for analysis on the premise that the grip strength was 15% greater on the dominant sides compared with the nondominant sides; and no correction was required for left-handed individuals.
      • Incel N.A.
      • Ceceli E.
      • Durukan P.B.
      • Erdem H.R.
      • Yorgancioglu Z.R.
      Grip strength: Effect of hand dominance.
      Patients reported scar pain (0 = no pain, 100 = severe pain) using the 100-mm visual analog scale.
      • Zimmerman R.M.
      • Jupiter J.B.
      • González del Pino J.
      Minimum 6-year follow-up after ulnar nerve decompression and submuscular transposition for primary entrapment.
      Patient satisfaction was assessed based on the Short Assessment of Patient Satisfaction.
      • Tuzuner S.
      • Inceoglu S.
      • Bilen F.E.
      Median nerve excursion in response to wrist movement after endoscopic and open carpal tunnel release.
      ,
      • Wei R.
      • Zhuang Y.
      • Ye F.
      • Xiong H.
      • Fang X.
      • Zhuang Y.
      Anatomical study on minimally invasive treatment of carpal tunnel syndrome by palmar single-hole approach.
      POAFW is defined as the number of days from surgery until partial or total return to work. Patients were advised to return to work when they themselves felt that the discomfort in their hand had improved sufficiently to allow safe practice at their workplace. To determine whether there was a meaningful 2PD improvement, we calculated the minimal clinically important difference (MCID) with 1/2 standard deviation of the change within the initial 3 postoperative months.
      • Cancienne J.M.
      • Beck E.C.
      • Kunze K.N.
      • et al.
      Two-year patient-reported outcomes for patients undergoing revision hip arthroscopy with capsular incompetency.
      ,
      • Nwachukwu B.U.
      • Chang B.
      • Adjei J.
      • et al.
      Time required to achieve minimal clinically important difference and substantial clinical benefit after arthroscopic treatment of femoroacetabular impingement.

      Statistical Analysis

      The Student t-test (symmetric distribution) or the Mann–Whitney U test (asymmetric distribution) was applied to compare the 2 groups in relation to the quantitative outcomes. The Pearson χ2 test was applied to compare nominal categorical variable. We performed a mixed model of repeated measures on the postoperative sensation within the initial 3 months. The group as a fixed factor, age, sex, the dominance of hand, and each dependent variable’s preoperative value as covariates. At the final follow-up, we compared the postoperative sensation, symptom severity and functional status, and strength scores for the 2 groups with analysis of covariance adjusting for their preoperative scores. We used Statistical Package for Social Sciences 20.0 (IBM, Corp., Armonk, NY) and a 2-sided threshold of .05 for statistical significance. We performed mixed effects analysis using lme4 in R (version 3.5.3).

      Results

      Based on the inclusion and exclusion criteria, 123 patients were included in ERSTCL group, and 69 patients were included in control group. No wound infection was observed in the 2 groups. No patients required a reoperation due to the recurrence of the symptoms.
      We did not find significant differences between the 2 groups in age, sex, hand dominance, and follow-up period (P > .05) (Table 1). Within the initial 3 postoperative months, the incidences of symptomatic exacerbation were 2% (n = 2) after 1 week, 2% (n = 2) after 2 weeks, and 1% (n = 1) after 4 weeks in ERSTCL group; and the data were 9% (n = 6), 7% (n = 5), and 4% (n = 3) in control group. We found a significant difference between the 2 groups at 1 week postoperatively (P = .003). We did not find significant differences in other time intervals (Fig 7; Table 2). In both groups, discrimination sensation improved 12 weeks postoperatively. We found significant differences in static 2PD between the 2 groups 1 week (mean change = –0.13, 95% CI –0.30 to 0.04, P = .010) and 2 weeks after surgery (mean change = –0.18, 95% CI –0.36 to –0.01, P = .033) (Table 3). The MCID threshold values for the changes of static 2PD 1 and 2 weeks postoperatively specific to ERSTCL group were 0.18 and 0.31, and 28% and 35% of the patients achieved MCID. The changes in static 2PD for MCID scores in control group were 0.16 and 0.20, and 45% and 57% of the patients achieved MCID. A statistically significant difference was found in the frequency of patients achieving MCID 1 and 2 weeks after surgery (P =.027 and P =.015) (Table 4). Furthermore, we did not find differences in SWM at all follow-up visits (Appendix Fig 1, available at www.arthroscopyjournal.org).
      Table 1Demographic and Clinical Characteristics of Patients in Two Groups
      Clinical ValuesERSTCL (n = 123)Control (n = 69)P Value
      Age, mean (range), y45 (33-58)44 (32-57).535
      t test.
      Sex, male:female31:9219:50.724
      Pearson’s χ2 test.
      Side affected, dominant:nondominant85:3844:25.450
      Pearson’s χ2 test.
      Follow-up time, mean (SD), mo36.1 (1.0)35.8 (1.1).079
      t test.
      ERSTCL, endoscopic release superficial to the transverse carpal ligament; SD, standard deviation.
      t test.
      Pearson’s χ2 test.
      Figure thumbnail gr7
      Fig 7Graphs showing the changes of the incidences of symptomatic exacerbation (A) and discrimination sensation (B) within the initial 12 postoperative weeks. (2PD, 2PD, static 2-point discrimination; ERSTCL, endoscopic release superficial to the transverse carpal ligament.).
      Table 2Comparison of Symptomatic Exacerbation (%) in Two Groups Undergoing CTR Within Postoperative 12 Weeks
      ERSTCL (n = 123)Control (n = 69)P Value
      Pre-00
      Post 1-wk1.68.7.003
      Post 2-wk1.67.2.100
      Post 4-wk0.84.3.133
      Post 6-wk02.8.127
      Post 8-wk00
      Post 10-wk00
      Post 12-wk00
      CTR, carpal tunnel release; ERSTCL, endoscopic release superficial to the transverse carpal ligament.
      Table 3Hand Sensation Within Postoperative 12 Weeks
      2PD (Mean)Mean Change (95% CI)P ValueSWM testMean Change (95% CI)P Value
      ERSTCLControlERSTCLControl
      Post 1-wk5.35.5–0.13 (–0.30 to 0.04).0103.193.21–0.02 (–0.12 to 0.08).686
      Post 2-wk5.05.2–0.18 (–0.36 to –0.01).0333.153.130.02 (–0.08 to 0.13).640
      Post 4-wk4.74.8–0.06 (–0.25 to 0.12).4733.103.15–0.05 (–0.16 to 0.05).328
      Post 6-wk4.54.5–0.08 (–0.25 to 0.09).3333.133.120.01 (–0.09 to 0.10).968
      Post 8-wk4.34.4–0.07 (–0.25 to 0.10).3613.083.070.01 (–0.09 to 0.10).872
      Post 10-wk4.34.3–0.01 (–0.19 to 0.18).9793.083.050.03 (–0.07 to 0.13).582
      Post 12-wk4.24.3–0.03 (–0.22 to 0.15).6836.063.040.02 (–0.09 to 0.152).763
      NOTE. “Mean Change” indicates adjusted mean between-group difference in change over time.
      2PD, static 2-point discrimination; CI, confidence interval; ERSTCL, endoscopic release superficial to the transverse carpal ligament; SWM, Semmes-Weinstein monofilament.
      Table 4MCID Rates of 2PD Change for Patients in Two Groups
      ERSTCLControlP Value
      Post 1-wk28%45%.027
      Post 2-wk37%57%.015
      Post 4-wk67%77%.189
      Post 6-wk97%94%.461
      Post 8-wk99%97%.294
      Post 10-wk100%99%.359
      Post 12-wk100%99%.359
      2PD, static 2-point discrimination; ERSTCL, endoscopic release superficial to the transverse carpal ligament; MCID, minimal clinically important difference.
      We did not find a significant difference between the 2 groups in type of work performed by patients (Table 5). The mean POAFW was 17 ± 5 days in the ERSTCL group and 20 ± 8 days in the control group. A significant difference was found between the 2 groups in POAFW (95% CI 1.083-4.724; P =.002) (Table 5).
      Table 5Work Absence After the Operation
      ERSTCL (n = 123)Control (n = 69)P Value
      Type of work, No. (%) of patients
       Blue collar82 (66.7)43 (62.3)
       White collar30 (24.4)19 (27.5)
       Self employed11 (8.9)7 (10.1).368
      Pearson χ2 test.
      Work absence, d17.2 ± 4.720.1 ± 8.1.002
      t test.
      NOTE. A value P < 0.05 was set as statistically significant.
      ERSTCL, endoscopic release superficial to the transverse carpal ligament.
      Pearson χ2 test.
      t test.
      We did not find postoperative progressive atrophy of the thenar muscles induced by recurrent motor branch laceration in 2 groups. Symptom severity and functional status improved significantly at the final follow-up visit (34-36 months in ERSTCL group; 33-37 months in control group; P = .079). We did not find significant differences in sensation, strength, scar pain, and patient satisfaction (Appendix Tables 1 and 2, available at www.arthroscopyjournal.org).

      Discussion

      The ERSTCL technique produces a low incidence of symptomatic exacerbation and good digital discrimination sensation in the initial several postoperative weeks. Compared with the Chow technique, ERSTCL is associated with a short POAFW. Both techniques produce similar long-term satisfactory outcomes.
      Surgery for CTS is one of the most often performed procedures, and the greatest proportion is done in working people.
      • Atroshi I.
      • Larsson G.U.
      • Ornstein E.
      • Hofer M.
      • Johnsson R.
      • Ranstam J.
      Outcomes of endoscopic surgery compared with open surgery for carpal tunnel syndrome among employed patients: Randomised controlled trial.
      POAFW after CTS is therefore important for these patients, because the economic consequences of POAFW can be substantial.
      • Katz J.N.
      • Amick 3rd, B.C.
      • Keller R.
      • et al.
      Determinants of work absence following surgery for carpal tunnel syndrome.
      In a comparison study among the mini-open, open, and endoscopic techniques, Zhang et al.
      • Zhang X.
      • Huang X.
      • Wang X.
      • Wen S.
      • Sun J.
      • Shao X.
      A randomized comparison of double small, standard, and endoscopic approaches for carpal tunnel release.
      treated 73 patients with the mini-open CTR, resulting in a mean POAFW of 14 ± 8 days, and treated 69 patients with Chow endoscopic CTR and found a mean POAFW of 12 ± 9 days. Trumble et al.
      • Trumble T.E.
      • Diao E.
      • Abrams R.A.
      • Gilbert-Anderson M.M.
      Single-portal endoscopic carpal tunnel release compared with open release: A prospective, randomized trial.
      and Saw et al.
      • Saw N.L.
      • Jones S.
      • Shepstone L.
      • Meyer M.
      • Chapman P.G.
      • Logan A.M.
      Early outcome and cost-effectiveness of endoscopic versus open carpal tunnel release: A randomized prospective trial.
      reported a mean POAFW of 18 days after one-portal endoscopic CTR. Atroshi et al.
      • Atroshi I.
      • Larsson G.U.
      • Ornstein E.
      • Hofer M.
      • Johnsson R.
      • Ranstam J.
      Outcomes of endoscopic surgery compared with open surgery for carpal tunnel syndrome among employed patients: Randomised controlled trial.
      treated 63 patients and found the mean POAFW was 28 days after 2-portal endoscopic CTR. Although POAFW may differ in different countries based on the health insurance system, labor rules, sickness compensation, etc.,
      • Katz J.N.
      • Amick 3rd, B.C.
      • Keller R.
      • et al.
      Determinants of work absence following surgery for carpal tunnel syndrome.
      this would have similarly influenced both groups in our study. Compared with the conventional endoscopic CTR, the ERSTCL technique showed 3 days earlier return to work, suggesting the selection of ERSTCL for working people with CTS is a valuable option.
      In a prospective study of 52 consecutive patients with bilateral idiopathic CTS by Kang et al.,
      • Kang H.J.
      • Koh I.H.
      • Lee T.J.
      • Choi Y.R.
      Endoscopic carpal tunnel release is preferred over mini-open despite similar outcome: A randomized trial.
      one hand was randomized to undergo endoscopic CTR and the other to undergo mini-incision release. The authors found that mini-open CTR was associated with a lower incidence of transient worsening symptoms than endoscopic CTR. Thoma et al.
      • Thoma A.
      • Veltri K.
      • Haines T.
      • Duku E.
      A meta-analysis of randomized controlled trials comparing endoscopic and open carpal tunnel decompression.
      reviewed 13 randomized controlled trials and found endoscopic CTR produced a greater incidence of transient neuropraxia than open CTR. ERSTCL technique does not require to insert instruments into the carpal tunnel, and thus minimizing nerve irritation, resulting in a low incidence of transient neuropraxia. In addition, some surgeons argued whether endoscopic CTR carries greater risks of nerve injury and permanent disability than open CTR. Accumulating studies have shown endoscopic CTR is a safe procedure with minimal complications.
      • Kang H.J.
      • Koh I.H.
      • Lee T.J.
      • Choi Y.R.
      Endoscopic carpal tunnel release is preferred over mini-open despite similar outcome: A randomized trial.
      ,
      • Tarfusser I.
      • Mariacher M.
      • Berger W.
      • Tarfusser T.
      • Nienstedt F.
      Endoscopic carpal tunnel release without invading the tunnel: A new transretinacular technique.
      ,
      • Williamson E.R.C.
      • Vasquez Montes D.
      • Melamed E.
      Multistate comparison of cost, trends, and complications in open versus endoscopic carpal tunnel release.
      The advantages include a minimally invasive procedure, minimal nerve irritation, and less reversible neuropraxia. The disadvantage is limited visualization of the operating field.

      Limitations

      Our study has limitations. First, the lack of power analysis and small sample size precludes to establish an effect size for evaluating a low incidence of nerve injury. Second, the retrospective design limits our ability to determine the cause and effect of CTR. Although severe never injuries are not noted in our study, the outcomes may vary in larger cohorts. In addition, surgeons’ preferences, experience, and ability may influence ascertaining the effects of the techniques. Patient-reported assessments may affect the actual outcomes.

      Conclusions

      Endoscopic release superficial rather than deep to TCL improves immediate postoperative transient symptomatic exacerbation with lower absence from work in patients with CTS.

      Acknowledgments

      This work was supported by Sanming Project of Medicine in Shenzhen (SZSM201111015), Shenzhen Key Medical Discipline Construction Fund (SZXK024), Science and Technology Innovation Commission of Shenzhen (ZDSYS20200811143752005).

      Appendix

      Figure thumbnail fx1
      Appendix Fig 1Graph showing the changes of SWM test within the initial 12 postoperative weeks after 2 methods of carpal tunnel release. (ERSTCL, endoscopic release superficial to the transverse carpal ligament; SWM, Semmes–Weinstein monofilament.)
      Appendix Table 1Outcomes at Follow-up in Two Groups
      MeanAdjust Mean of Post- (95% CI)P Value
      Pre-Post-
      2PD—thumb
       ERSTCL5.54.14.0 (3.9-4.2).303
       Control5.44.24.1 (4.0-4.3)
      2PD—index
       ERSTCL5.34.34.3 (4.2-4.5).597
       Control5.64.44.4 (4.2-4.6)
      2PD—middle
       ERSTCL5.74.24.2 (4.0-4.4).480
       control5.64.34.3 (4.1-4.5)
      SWM test—thumb
       ERSTCL3.23.03.0 (2.9-3.1).982
       Control3.13.13.0 (2.8-3.1)
      SWM test—index
       ERSTCL3.23.03.0 (2.9-3.1).613
       Control3.23.03.0 (2.9-3.1)
      SWM test—middle
       ERSTCL3.23.03.1 (3.0-3.2).563
       Control3.23.13.0 (2.9-3.2)
      Levine-Katz Symptom
       ERSTCL3.61.31.3 (1.2-1.4).951
       Control3.71.31.3 (1.2-1.4)
      Levine-Katz Function
       ERSTCL3.21.41.4 (1.3-1.5).560
       Control3.31.41.4 (1.3-1.6)
      Grip strength
       ERSTCL41.743.743.8 (43.5-44.1).272
       Control42.443.343.5 (43.1-43.9)
      Pinch strength
       ERSTCL8.39.29.2 (9.1-9.3).177
       Control8.29.19.1 (9.0-9.2)
      2PD, static 2-point discrimination; CI, confidence interval; ERSTCL, endoscopic release superficial to the transverse carpal ligament; SWM, Semmes–Weinstein monofilament.
      Appendix Table 2Outcomes After 3 Years
      ERSTCL (n = 123)Control (n = 69)P Value
      Scar pain, No. (%),7 (5.7)5 (7.2).613
      SAPS, mean (SD),23.6 (1.4)23.3 (1.7).504
      ERSTCL, endoscopic release superficial to the transverse carpal ligament; SAPS, Short Assessment of Patient Satisfaction; VAS, 100-mm visual analog scale.

      Supplementary Data

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