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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
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
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
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
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
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
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.
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
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.
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.
Accumulating studies have shown that endoscopic CTR is associated with faster recovery and fewer complications when compared with standard open surgery.
Comparison of wrist arthroscopy, small incision surgery, and conventional surgery for the treatment of carpal tunnel syndrome: A retrospective study at a single center.
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.
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.
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).
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
; (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)
; 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.).
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.
Fig 3The design of entry point (red arrow). Surface projection of the operative tunnel (red dotted line).
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).
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.
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.
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
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
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.
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.
Time required to achieve minimal clinically important difference and substantial clinical benefit after arthroscopic treatment of femoroacetabular impingement.
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
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.).
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).
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.
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.
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.,
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.,
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.
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.
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
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.)
ERSTCL, endoscopic release superficial to the transverse carpal ligament; SAPS, Short Assessment of Patient Satisfaction; VAS, 100-mm visual analog scale.
Comparison of wrist arthroscopy, small incision surgery, and conventional surgery for the treatment of carpal tunnel syndrome: A retrospective study at a single center.
Time required to achieve minimal clinically important difference and substantial clinical benefit after arthroscopic treatment of femoroacetabular impingement.
The authors report that they have no conflicts of interest in the authorship and publication of this article. ICMJE author disclosure forms are available for this article online, as supplementary material.
Rui-hong Wei and Chao Chen contributed equally to this work.
The authors have applied for registration at ClinicalTrials (ClinicalTrials.gov Identifier: NCT05094778).
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