Mini Open Carpal Tunnel Release: Technique, Feasibility, And Clinical Outcomes Compared With Conventional Surgery In Long-Term Follow-up - ZhongXing

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We sought to evaluate the results of our anatomical landmark-based minimal open surgery (MCTR) by the palmar approach and compared its results and utility with the conventional approach (OCTR).The study consisted of 100 matched patients (n = 50 MCTR, n = 50 OCTR) followed for at least three years.Outcomes were characterized by the Arm, Shoulder, and Hand Disability Score (DASH), Symptom Severity Scale (SSS), Functional Status Scale (FSC), and Visual Analog Scale (VAS).All adverse events were observed.An alpha of 0.05 and a confidence level of 95% were set for statistical analysis.Both techniques showed comparable functional outcomes over the long term (mean follow-up MCTR: 60 months and OCTR: 54 months).Mean MCTR vs OCTR: DASH: 4.6/8.3 (p = 0.398), SSS: 1.3/1.2 (p = 0.534), FSC: 1.3/1.2 (p = 0.617), VAS: 0.4/0.7 (p = 0.246) .MCTR was relatively convincing to OCTR by lower scar sensitivity (MCTR: 0% vs. OCTR: 12%, 0/50 vs. 6/50; p = 0.007) and strut pain, and shortened recovery and procedure times .Low complication rates were observed in both groups, and recurrences were not recorded.The MCTR procedure showed favorable clinical outcomes similar to conventional techniques.MCTR is a minimally invasive, reliable, fast and simple procedure with clear benefits for scar sensitivity.
Carpal tunnel syndrome (CTS) is the most common compressive neuropathy1,2,3,4,5,6 with a reported prevalence of 3.8% in the general population7.The described prevalence of CTS varies according to the diagnostic criteria used7.It is well known that certain risk factors8 as well as occupational factors influence its prevalence9.
Conservative treatment algorithms including splinting, non-steroidal anti-inflammatory drugs, and topical corticosteroid injections are typically initiated after diagnosis by characteristic symptoms and electroneurograms3,5,10.In cases where conservative treatment fails, surgical carpal tunnel release (CTR) is necessary.Open carpal tunnel release (OCTR) is the generally accepted method3.Although this procedure enables direct visualization, reliable segmentation of the flexor retinaculum, and the ability to identify anatomical variations; it includes postoperative wound pain, scar sensitivity, and the possibility of strut pain.To overcome these complications, several endoscopic and small incision approaches have been developed in recent years2,11.Endoscopic carpal tunnel release can be performed as a single-port or double-port technique5.It has been reported to reduce postoperative pain5, reduce wound-related complications (including scar sensitivity, columnar pain, or hypertrophic scarring), and allow earlier return to work and activities of daily living5,10,12.However, it includes an increased risk of median nerve and vascular injury or incomplete division of the retinaculum of the flexor muscles.Mini-open carpal tunnel release (MCTR) combines the advantages of both techniques and has been reported to have a lower complication rate13.
The aim of this study was to evaluate the long-term follow-up of MCTR based on previously described anatomical landmarks14 by the palmar approach and to compare it with conventional OCTR.Therefore, we assume that the safety and utility between MCTR and OCTR are similar.More specifically, we sought to determine whether MCTR was superior to conventional techniques in terms of patient satisfaction and functional recovery.
Fifty patients who had undergone unilateral MCTR between January 1, 2008 and December 31, 2015 in our level III trauma center were included in the study.The 50 patients who received conventional OCTR during the same period were matched for age and sex to the MCTR group.Each surgical group was treated by an experienced trauma consultant and hand specialist (MCTR group: MP, OCTR group: AK).The type of surgical procedure is not random.The minimum follow-up period between surgery and patient visit was three years for final reassessment.
The diagnosis of CTS is based on the presence of sensory disturbance and/or weakness in the area supplied by the median nerve and a unique history of pain.All patients obtained preoperative EMG confirming median nerve neuropathy.Conservative treatment, including prior physiotherapy and splint application, failed in all patients.
Exclusion criteria included signs of local or systemic inflammation, anatomical deformation, nerve or soft tissue defects, previous wrist and hand surgery, and bilateral CTS symptoms and symptom duration greater than one year.Patients with other comorbidities such as insulin-dependent diabetes mellitus, polyneuropathy, smoking, or rheumatoid arthritis were excluded.
Standardized protocols were used in both groups.Each group underwent surgery with a consistent technique, with any specific differences in each surgical procedure described below.All procedures were performed in the operating room with regional anesthesia and the use of an upper arm tourniquet.All hands were placed in the supine position and immobilized with lead hand splints.Insert a micro-suction drainage tube and leave it in place systematically for one day.Wound closure was performed with nonabsorbable 5.0 suture {Polyamide, ETHILON 668H, Johnson & Johnson Medical GmbH, Norderstedt, Germany} without Leukostrips.All wounds were covered with gauze swabs {Lohmann & Rauscher International GmbH & Co. KG, Rengsdorf, Germany} for direct compression.A dressing consisting of a gauze swab was used as a pad roll after a moderate stretch bandage {Lenkelast, Lohmann & Rauscher International GmbH & Co. KG, Rengsdorf, Germany} before loosening the tourniquet on the upper arm.After the surgery, the hands remained in this fist bandage for a day.Early dressing removal, including microsuction flow removal and clinical control, was performed by the surgeon 24 hours postoperatively.Then, a cast {Cosmopor, Hartmann AG, Heidenheim, Germany} was applied and the patient was discharged.Begin free functional aftercare on the first postoperative day and avoid heavy lifting for two weeks.The sutures were removed 14 days after surgery (first follow-up).
For the OCTR technique, a 3.5 cm longitudinal incision is made proximal to the palmar crease and stops 0.5 cm distal to the wrist crease.After subcutaneous dissection, the transverse carpal ligament and the thenar branch of the median nerve were shown, and the ligament was severed proximally at its ulnar edge.
For the MCTR group, both styloid processes were palpated and connected to a horizontal line by using a pen.Then, draw a parallel line in the palm from the proximal end of the first mesh, called the Kaplan baseline.In previous papers15, 16, 17, this line was used as a surface marker for the superficial palmar arch safety zone.
Next, draw vertical longitudinal lines on the radial side of the ring finger.This line terminates directly in the palmar longus tendon of the distal forearm (if present).The intersection of these lines in the palm is used as the reference point (A).The skin incision extends one third distally from the reference point and the other two thirds proximally (see Figures 1 and 2).
Schematic representation of the skin incision for MCTR and both techniques: the blue circle area represents the skin incision area for MCTR and the black circle represents the skin incision area for OCTR.The red line represents the longitudinal direction line of the ring finger, and the blue line marks the horizontal line of the styloid process.The green line shows the maximum dimension of the transverse carpal ligament as in Hohenberger et al.14 has been described.MCTR Mini Open Carpal Tunnel Releaser, OCTR Open Carpal Tunnel Releaser.
(A) Preoperative planning and (B) MCTR postoperative results: The following lines were drawn: 1. Horizontal line between the two styloid processes 2. Horizontal parallel line – Kaplans baseline: 3. Longitudinal line on the radial side of the ring finger.(A) The intersection of these two lines (2. and 3.) marks the reference point for the skin incision.(B) Suture closure for micro-open surgery—extending no more than 1-1.5 cm—and its positioning as shown.MCTR Mini Open Carpal Tunnel Release.
A 1-1.5 cm palmar incision was made in a proximal longitudinal fashion, in each case from the ulna through the thenar crease.After the Dupuytren’s aponeurosis is opened, the transverse carpal ligament is traversed proximally above and below it using the Hegar dilator (see Figure 3).The arch of the superficial palmar artery and the thenar branch of the median nerve are delineated and protected (see Figure 4).
Instrument system of MCTR: It consists of two parts: A. Special cutting knife, B. Protective guide rail.{SafeGuard Mini Carpal Tunnel Release System, Art.-No. 08-0001 and 08-0003, INTEGRA LifeSciences Corporation, USA}.”Hegar” dilators are labeled C. {KARL STORZ SE & Co. KG, Art.-No. 28147 SA, Germany} D. Fomon retractor, E. Mini suction tube, F. Mosquito forceps.{MEDICON eG, Art.-No. 20.50.05, Germany; MEDICOPLAST International GmbH, Art.-No. 770 (107867), Germany; MEDICON eG, Art.-No. 15.45.12, Germany}.MCTR Mini Open Carpal Tunnel Release.
Intraoperative pictures of MCTR: The exit point of the median nerve thenar exit is fully visible in the operative field.The superficial palmar arterial arch is protected and visible through the skin incision and in the proximal direction of the split.{MEDICON eG, Art.-No. 20 May 2005, Germany}.MCTR Mini Open Carpal Tunnel Release.
The first incision in the distal part of the transverse carpal ligament was made under direct vision with a No. 15 surgical scalpel blade {Dahlhausen & Co. GmbH, Köln, Germany}.Next, insert a protective guide into the carpal tunnel in a proximal direction below the remaining transverse carpal ligament.Insert a special cutter into its groove and pass proximally until complete release of the remaining transverse carpal ligament is achieved (see Figures 3, 5, and 6).
Intraoperative picture of MCTR: A protective guide has been inserted to protect the median nerve.During exposure, two Fomon retractors were used laterally and one Ragnell retractor proximally.{SafeGuard Mini Carpal Tunnel Release System, Art.-No. 08-0001, INTEGRA LifeSciences Corporation, USA; MEDICON eG, Art.-No. May 20, 2005, Item No.20.12.20, Germany}.MCTR Mini Open Carpal Tunnel Release.
Intraoperative picture of MCTR: The release of the transverse carpal ligament is achieved.The median nerve can be seen to ensure full release.Further final examination of the perineural scar tissue can be performed without problems.{MEDICON eG, Art.-No. May 20, 2005, Art. No.20.12.20, Germany}.MCTR Mini Open Carpal Tunnel Releaser, OCTR Open Carpal Tunnel Releaser.
Retrospectively assessed data were collected prospectively in a specialized hospital database.Basic characteristics involving age, sex, affected side, duration of surgery, and preoperative symptoms were recorded from the respective patient files.
Patients were followed up two weeks after surgery.Early follow-up was assessed by the respective surgeon (MP or AK).Here, the presence of wound healing impairment, infection, scar sensitivity and the corresponding visual analog scale (VAS) was assessed.
Final follow-up was done by two trauma surgeons (AS and GH) to document changes in symptoms and signs and/or adverse events.During the final follow-up period, all patients completed the VAS, Arm, Shoulder, and Hand Disability Score (DASH) and Boston Carpal Tunnel Syndrome Questionnaire, including Symptom Severity Scale (SSS) and Functional Status Scale (FSC).In addition, patients were asked about scar sensitivity and/or column pain at the surgical site.The assessment of scar sensitivity was defined as follows: The patient was asked about discomfort in the scar area, such as burning discomfort on palpation, hypersensitivity, or superficial pain.Scar sensitivity is classified as the presence of one or more symptoms.Pillar pain is defined as deep pain in the thenar and/or hypothenar region associated with hand use, such as clenching.During the examination, strut pain was tested by simultaneously compressing the thenar and hypothenar eminences, as if separating the carpal tunnel.
The duration from surgery to restitution and return to the workplace (excluding retirees) was assessed.Restitution was defined as the subjective time after surgery that the patient was able to perform activities of daily living without pain.The occurrence and recurrence of adverse events (hematoma, infection, neurovascular or tendon injury) were assessed.Relapse refers to the recurrence of symptoms and/or the need for symptom-related reoperation after a period of temporary relief.In addition, revision rates and causes and the time interval from initial surgery to revision surgery (if applicable) were assessed.
Statistical analysis was performed using SPSS software {IBM SPSS Statistics version 26, Armonk, USA}.Continuous parameters are expressed as mean, standard deviation (SD), and categorical or quantitative data.Descriptive statistics are used for demographic variables; continuous variables are summarized using SD and/or by ranges of minimum and maximum values.
Nonparametric tests were used for data analysis for significance.To investigate differences between the MCTR and OCTR groups, the Mann-Whitney U test was used.Chi-square tests were used to compare remaining targets and/or adverse events.A P value (p) below 0.05 was set as statistically significant, and a 95% confidence interval was calculated.Post hoc power analysis was performed using G*Power 3.1.18.With an alpha of 0.05, a sample size of 0.88 was calculated based on a two-tailed significance test19.
Ethical approval was granted by the Institutional Review Board of the Austrian Workers’ Compensation Board (AUVA-EK 03/2019).Although included, patients consented to the study protocol and obtained informed consent for research purposes.All experimental protocols and methods were performed in accordance with the provisions and principles of the Declaration of Helsinki and the ICH-GCP guidelines.
The MCTR group consisted of 72% female (36/50) and 28% (14/50) male patients with a mean age of 61.2 years (SD: 13.3; range: 36-81).64% (32/50) were right-handed and 36% (18/50) were left-handed.The mean duration of symptoms was 4.9 months (standard deviation: 2.2; range: 3-12).The mean duration of surgery was 9.2 minutes (SD: 2.7; range: 6-18).The mean final follow-up in the MCTR group was 60 months (SD: 23.1; range: 36-108).
In the OCTR group, 74% (37/50) were women and 26% (13/50) were men.The mean age on the day of surgery was 59.0 years (SD: 16.7; range: 20-84).62% (31/50) of right hands and 38% (19/50) of left hands received CTR.The mean operation time was 12.0 minutes (standard deviation: 3.3; range: 7-21).The mean duration of symptoms was 5.4 months (standard deviation: 1.8; range: 4-12).The mean final follow-up in the OCTR group was 54 months (SD: 24.3; range: 37-101).
There was a statistically significant difference between the duration of surgery (p = 0.001), but not between the groups in terms of age (p = 0.621) and follow-up time (p = 0.623).
Two weeks after the operation, there were no adverse reactions in either group.In the MCTR group, scar sensitivity was present in 3 patients (MCTR: 3/50; 6%), with a mean VAS score of 1.4 (SD: 2.1; range: 0-7).In the OCTR group, scar sensitivity was assessed in 13 patients (OCTR: 13/50; 26%) and the mean VAS score was 1.7 (SD: 2.8; range: 0-8).Comparing the two groups at early follow-up, scar sensitivity was significantly reduced after MCTR (MCTR: 3/50; 6% vs OCTR: 13/50; 26%; p = 0.002).There was no statistically significant difference in VAS (p = 0.327).
There were no statistically significant differences in assessment scores between the groups (see Table 1).All postoperative progression can be ignored in Table 2.Of these, scar sensitivity was significantly reduced in the MCTR group (0%) compared to the OCTR group (12%, 6/50) (p = 0.007).
The perioperative adverse events are shown in Table 3.No recurrence was observed in either group.The revision rate was 2% (1/50) in the MCTR group and 4% (2/50) in the OCTR group.In both samples, patients with infection underwent a single revision surgery.The mean time from primary surgery to revision surgery was 2 weeks in the MCTR group and 6.3 weeks in the OCTR group (range: 3.5-9).
In the entire group, no iatrogenic vascular, nerve branch, or tendon injuries were recorded.Partial injury to the volar median nerve was validated in the MCTR group, followed by microneurosurgery techniques to enlarge the incision and repair the nerve directly.Complete neurological function was achieved two years postoperatively and was confirmed clinically and electromyographically.Overall, the overall complication rate was 4% (4/100 in total or 2/50 in each group).
The aim of this study was to evaluate the long-term follow-up of minimally invasive CTR by the palmar approach and to compare its results with conventional surgery.There were no significant differences in functional scores between groups in our sample.Scar sensitivity was significantly reduced after MCTR compared with OCTR at early (p = 0.002) and long-term follow-up (p = 0.007).
Paine20 describes the first device in 1955 used as a support belt cutter.This device has been used until now, as recently reported by Fernandes et al. 21 .The authors21 looked at short- and long-term outcomes and reported favorable clinical outcomes in more than 500 patients over a 17-year period.Palmar incision for CTR has been used for a long time, and various strategies have been reported over time.Aryan et al22 reported a representative case series from 1977 in which 429 patients improved.Using a similar retinal slicer, our findings address a gap in the literature.There are few existing studies23,24 on long-term outcomes after MCTR.
Bai et al2 performed a retrospective analysis of prospectively collected data involving 85 patients who had undergone MCTR or OCTR, including incisions similar to those performed in the current study.The mean duration of symptoms was 6.6 months (MCTR) and 6.4 months (OCTR), respectively, which was comparable to our sample (MCTR: 4.9 months; OCTR: 5.4 months).The mean procedure duration was not significantly different between the two groups (p = 0.130) (MCTR: 25.1 minutes; OCTR: 23.5 minutes), which varied in our collective (MCTR: 9.2 minutes; OCTR: 12.0 minutes; p = 0.001).In our sample, the authors found no statistically significant difference in VAS and DASH between the two groups (VAS: p = 0.246, DASH: p = 0.398).At 12-month follow-up, the rate of scar pain was 4.7% in the OCTR group, whereas no patients experienced wound pain after MCTR (p = 0.490).Likewise, in our long-term results, scar sensitivity was significantly increased in the OCTR group (12%) compared to our MCTR group (0%) (p = 0.007).
Aslani et al25 divided their sample of 105 patients into three subgroups (MCTR, OCTR, and the group receiving endoscopic CTR).The mean return to work interval was significantly longer (p = < 0.05) in OCTR (mean: 21.1 days) compared to MCTR (mean: 12.7 days).We also assessed shorter absences and a non-statistically significant advantage in the MCTR group (MCTR: mean 14 days; OCTR: mean 20 days; p = 0.142).On the basis of earlier resumption of work, this can be considered as a positive cost benefit.
Zhang et al23 analyzed 207 patients randomized through two small incisions (n ​​= 73) to MCTR, OCTR (n = 65), and endoscopic CTR (n = 69).The mean symptom duration in the MCTR and OCTR groups was 6 months, which was very similar to our sample (MCTR: 4.9 months; OCTR: 5.4 months).At the last follow-up of three years, there was no statistically significant difference between MCTR and OCTR in the outcomes of the Boston Carpal Tunnel Syndrome Questionnaire.Here, the mean SSS and FSC for both groups was 1.2 points.These values ​​are very similar to our results.
Recurrent nerve compression occurs in less than 2% to as high as 25%26, 27, 28, 29, 30, 31 and may occur years after surgery.Recurrence rates in long-term follow-up studies have been reported to range from 3.7%27 to 57%32.However, the lack of a consistent definition of recurrence in the literature could explain this range.Some authors define recurrence of any preoperative symptoms32, others define the need for reoperation27 to be considered a recurrence.Cresswell et al24 reported a higher immediate complication rate and higher recurrence rate in patients after MCTR compared with conventional surgery.The authors24 assessed outcomes at 7 years postoperatively.In contrast, no recurrence was observed in our two groups, with a minimum follow-up of 3 years and a shorter final follow-up (mean final follow-up for MCTR: 60 months, OCTR: 54 months).This may be traced back to our shorter follow-up interval and bias in the questionnaire returned by Cresswell et al24, which may not reflect the entire cohort.
A common and major indication for recurrent nerve compression may result in incomplete division of the transverse ligament and/or postoperative fibrosis30,33.It is believed that post-operative fibrosis may have a positive effect, as we did with an early exercise regimen from the first postoperative day.Complete disintegration of the wrist ligaments is a factor associated with surgery.Kilinc34 showed that recurrent CTS is unlikely after sufficient division of the transverse ligament.In addition, similar low adverse events were observed in both groups.Regardless, these facts indicate positive validity and allow for inferences that MCTR represents a reliable approach to CTR.
Another technical advantage represents the direct visualization of the thenar branch of the median nerve.In addition, iatrogenic injury to the superficial palmar arch does not occur due to the proximal directional release.In this regard, we emphasize that we must have observed a partial median nerve tear in a patient with high adhesions around the median nerve in the MCTR group.Similarly, Cresswell et al24 reported 1 median nerve injury in 53 patients.Lee and Strickland17 observed two median nerve injuries in their 694 releases using the support band knife.Summarizing our findings and the two studies, median neuropathy was a notable major complication, occurring in less than 1% of all three study groups.Based on our observations and experience, we strongly recommend widening the skin incision for patients with severe adhesions.
This study has several limitations.We only compared MCTR with OCTR, excluding the endoscopic group.In addition, random assignments were not calculated for individual groups.Furthermore, although we used prospectively collected data, the study was still retrospective.A randomized controlled trial is recommended to re-evaluate this technique in the future.Patients generally prefer minimally invasive procedures, although patients and hand surgeons may have conflicting decisions regarding treatment.These factors were not addressed in the study.Finally, no review was made regarding the cost of materials or the localization of performed surgery or the financial impact of inpatient versus outpatient settings.
As the strength of this study is the long time frame.To specifically confirm surgical technique, we used matched patients and a single-surgeon study design performed by experienced practitioners.Furthermore, the surgical procedure is easy to repeat because it is based on superficial anatomical landmarks.The further importance of this minimally invasive approach represents the simplicity of the approach and intraoperative visibility of two structures at risk – namely, the thenar branch of the median nerve and the superficial palmar arch.Our method was developed in the context of anatomical landmarks containing well-known anatomical safety zones and micro-opening techniques, as demonstrated by Hohenberger et al.In Anatomical Studies 14.
In conclusion, our proposed and preferred MCTR technique via the palmist approach has been shown to be effective.Patients after MCTR achieve the same functional long-term outcomes as conventional surgery.The complication rate of MCTR surgery is low, and the two techniques are comparable in this regard.Enlarged skin incisions are recommended for patients with high adhesions.
Using the technique we described, no patients with relapse or suffering from strut pain were observed.In addition, it combines the advantages of shortened recovery and surgery time.The patient-specific primary benefit was reduced scar sensitivity due to small incisions of 1–1.5 cm and its positioning, which was convincingly statistically significant compared to the OCTR group.These positive effects may be traced back to the reduction of soft tissue damage while preserving the adjacent structures of ownership.Thus, MCTR is a quick, practical, minimally invasive, and less technically difficult procedure that allows direct visualization of at-risk anatomy.
Anbarasan, A., Thevarajah, N. & Sadagatullah, A. Functional outcomes of mini carpal tunnel release.J. Hand Microsurgery.Rev. 09, 006–010 (2017).
Bai, J. et al.Carpal tunnel release was a retrospective cohort study using the new small incision approach compared to the traditional approach.Interpretation.J. Surgery Journal.52, 105–109 (2018).
Kim, P.-T., Lee, H.-J., Kim, T.-G.& Jeon, I.-H. Current treatments for carpal tunnel syndrome.clinical.orthopedics.Surgery Journal.6, 253 (2014).
Logli, AL, Bear, BJ, Schwartz, EG, Korcek, KJ & Foster, BJ A prospective randomized trial of splints after release of the minor carpal tunnel.J. Hand Surgery.43(775), e1-775.e8(2018).


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