Biomechanical and anatomical consequences of carpal tunnel release

Snapping Wrist From Bowstringing of the Digital Flexors After Carpal Tunnel Release: A Case Report

Symptomatic bowstringing of digital flexor tendons is a rare complication of carpal tunnel release (CTR). Two weeks after open CTR, a 47-year-old man with severe carpal tunnel syndrome had relief of his preoperative median paresthesia but complained of new-onset painful snapping of the wrist and transient ulnar paresthesia occurring with wrist dorsiflexion and concomitant digital flexion. Physical examination localized the audible snapping to the hook of hamate (HOH) where manual pressure eliminated the wrist motion-induced snapping and the associated ulnar paresthesia. Wrist radiographs showed stage III scapholunate advanced collapse (SLAC) with marked palmar subluxation of the lunate. Wrist magnetic resonance imaging revealed palmar and ulnar subluxation of the digital flexors over the HOH due to the mass effect of the palmarly displaced lunate and the chronic carpal malalignment. The snapping wrist and accompanying ulnar paresthesia resolved after HOH excision, and no additional treatment for the asymptomatic SLAC wrist deformity was required. Satisfactory clinical outcome was observed at 5-year follow-up.

Surgical Interventions for the Management of Carpal Tunnel Syndrome: A Narrative Review

Carpal tunnel syndrome (CTS) is a severe condition that affects the hand, causing pain, numbness, paresthesia, and autonomic dysfunction caused by increased pressure, damage, and demyelination of the median nerve in the carpal tunnel. The most effective treatment for CTS is carpal tunnel release (CTR) via transverse carpal ligament (TCL) transect. We can apply decompression through endoscopic procedures; standard open techniques and minimally invasive wrist incisions can all be used to accomplish decompression. Superior outcomes have been reported in many studies, including patient satisfaction, symptom relief, improvements in multiple assessment modality results, and fewer complications. Soreness at the incision site, tenderness around the site of ligament release, transitory loss of motor or sensory function, and the need for a repeat operation are all postoperative consequences. There is minimal and low-quality evidence to support the effectiveness of postoperative rehabilitation, such as wrist orthoses, dressings, exercise, and ice therapy, which have benefited patients anecdotally.

Non-Surgical Carpal Arch Space Augmentation for Median Nerve Decompression

The carpal tunnel is a tightly bounded space, making the median nerve prone to compression and eventually leading to carpal tunnel syndrome. Carpal tunnel release surgery transects the transverse carpal ligament to expand the tunnel arch space, decompress the median nerve, and relieve the associated symptoms. However, the surgical procedure unavoidably disrupts essential anatomical, biomechanical and physiological functions of the wrist, potentially causing reduced grip strength, pillar pain, carpal bone instability, scar tissue formation, and perineural fibrosis. It is desirable to decompress the median nerve without surgically transecting the transverse carpal ligament. This paper is to review several approaches we have developed for nonsurgical carpal arch space augmentation (CASA), namely, radio ulnar wrist compression, muscle-ligament interaction, palmar pulling, and collagenolysis of the transverse carpal ligament. Briefly summarized is the research work on the CASA topic about theoretical considerations, in vitro and in situ experiment, computational modeling, and human subject studies with asymptomatic and carpal tunnel syndrome hands.

Treatment of Intractable Pillar Pain With Excision of the Hook of Hamate

Introduction: A common consequence of carpal tunnel release (CTR) is ulnar palmar pain termed pillar pain. Some (very rare) patients do not improve with conservative treatment. We have been treating recalcitrant pain with excision of hook of the hamate. Our purpose was to evaluate a series of patients undergoing excision of the hook of the hamate for post CTR pillar pain. Methods: A retrospective review of all patients undergoing hook of hamate excisions over a 30-year period was performed. Data collected included: gender, hand dominance, age, time-to-intervention, preoperative and post-operative pain scores, and insurance. Results: Fifteen patients were included with a mean age of 49 (range 18-68) years, 7 female (47%). Twelve (80%) of the patients were right handed. Mean time between CTR and excision hook of hamate was 7.4 months (range 1-18 months). Pain prior to surgery was 5.44 (range 2-10). Post-operative pain was 2.44 (range 0-8). Mean follow-up was 4.7 months (range 1-19 months). Patients with a good clinical outcome were 14 (93%). Conclusions: Excision of hook of hamate seems to provide clinical improvement in patients who remain painful despite exhaustive conservative treatment. It may be considered as a very last resort for persistent pillar pain after CTR.

Carpal tunnel mechanics and its relevance to carpal tunnel syndrome

The carpal tunnel is an elaborate biomechanical structure whose pathomechanics plays an essential role in the development of carpal tunnel syndrome. The purpose of this article is to review the movement related biomechanics of the carpal tunnel together with its anatomical and morphological features, and to describe the pathomechanics and pathophysiology associated with carpal tunnel syndrome. Topics of discussion include biomechanics of the median nerve, flexor tendons, subsynovial tissue, transverse carpal ligament, carpal tunnel pressure, and morphological properties, as well as mechanisms for biomechanical improvement and physiological restoration. It is our hope that the biomechanical knowledge of the carpal tunnel will improve the understanding and management of carpal tunnel syndrome.

Ultrasound-guided percutaneous release procedures in the transverse carpal ligament by acupotomy: A cadaveric study

Objective

This study aimed to determine the safety and accuracy of ultrasound-guided acupotomy percutaneous loosening of the transverse carpal ligament.

Methods

The 100 upper limb specimens were equally divided into the ultrasound-guided acupotomy group (U) and the nonultrasound-guided acupotomy group (N). For the U group, we simulated ultrasound-guided acupotomy loosening of the transverse carpal ligament in a human specimen, and for the N group, we performed the loosening of the transverse carpal ligament through the same approach under nonultrasound-guided conditions. The safety and accuracy of the two methods were compared through measurement.

Results

In the ultrasound-guided group, the injury rate of nerves, blood vessels and tendons caused by needle-knife release was 0%. In the non-ultrasound-guided group, the rate of nerve, blood vessel and tendon damage was 6 percent, 12 percent and 20 percent, respectively. χ ² test (Fisher exact test) was performed for the nerve and blood vessel damage rates in the two groups (P_N  > 0.05, P_A  < 0.05), the difference in nerve damage rates was not statistically significant, but the difference in blood vessel damage rates was statistically significant. Pearson's χ ² test was performed on the tendon injury rates of the two groups (P_F  < 0.05), and the difference was statistically significant. In the ultrasound-guided group, the proportion of acupotomy marks greater than or equal to half of the width of the transverse carpal ligament was 86%, and the non-ultrasound-guided group was 36%. The accuracy of the two surgical methods was tested by Pearson's χ ² test (P_L  < 0.05), and the difference was statistically significant. According to the measurement, the ultrasound-guided acupotomy technology had high safety and accuracy.

Conclusion

In this study, we designed a new method for cutting the transverse carpal ligament under ultrasound guidance, which is different from surgery. These results indicate that this is a safe and accurate method of interventional treatment of carpal tunnel syndrome.

A preliminary study of radioulnar wrist compression in improving patient-reported outcomes of carpal tunnel syndrome

Previous studies have shown radioulnar wrist compression augments carpal arch space. This study investigated the effects of radioulnar wrist compression on patient-reported outcomes associated with carpal tunnel syndrome. Subjects underwent thrice-daily (15 min each time 45 min daily) wrist compression over 4 weeks with an additional four weeks of follow-up without treatment. Primary outcomes included Boston Carpal Tunnel Questionnaire symptom and functional severity scales (SSS and FSS) and symptoms of numbness/tingling based on Visual Analog Scales. Our results showed that radioulnar wrist compression improved SSS by 0.55 points after 2 weeks (p < 0.001) and 0.51 points at 4 weeks (p < 0.006) compared to the baseline scale. At the four-week follow-up, SSS remined improved at 0.47 points (p < 0.05). Symptoms of numbness/tingling improved at two and 4 weeks, as well as the follow-up (p < 0.05). Hand motor impairment such as weakness had a lower frequency across carpal tunnel syndrome sufferers and does not significantly improve (p > 0.05). Radioulnar wrist compression might be an effective alternative treatment in improving sensory related symptoms in patients with mild to moderate carpal tunnel syndrome.

Thenar and Hypothenar Muscle Coverage on the Transverse Carpal Ligament

Background  The purpose of the study was to examine the coverage of thenar and hypothenar muscles on the transverse carpal ligament (TCL) in the radioulnar direction through in vivo ultrasound imaging of the carpal tunnel. We hypothesized that the TCL distance covered by the thenar muscle would be greater than that by the hypothenar muscle, and that total muscle coverage on the TCL would be greater than the TCL-alone region. Methods  Ultrasound videos of human wrist were collected on 20 healthy subjects. Automated algorithms were used to extract the distal cross-sectional image of the trapezium-hamate level. Manual tracing of the anatomical features was conducted. Results  Thenar muscles covered a significantly larger distance (11.9 ± 1.8 mm) as compared with hypothenar muscles (1.7 ± 0.8 mm) ( p  < 0.001). The TCL covered by thenar and hypothenar muscles was greater than the TCL-alone length ( p  < 0.001). The thenar and hypothenar muscle coverage on the TCL, as normalized to the total TCL length, was 61.0 ± 7.5%. Conclusions  More than 50% of the TCL at the distal carpal tunnel is covered by thenar and hypothenar muscles. Knowledge of muscular attachments to the TCL improves our understanding of carpal tunnel syndrome etiology and can guide carpal tunnel release surgery.

Efficacy of extracorporeal shock wave therapy for pillar pain after open carpal tunnel release: a double-blind, randomized, sham-controlled study

Background

Pillar pain may develop after carpal tunnel release surgery (CTRS). This prospective double-blinded randomized trial investigated the effectiveness of extracorporeal shock wave therapy (ESWT) in pillar pain relief and hand function improvement.

Methods

The sample consisted of 60 patients with post-CTRS pillar pain, randomized into two groups. The ESWT group (experimental) received three sessions of ESWT, while the control group received three sessions of sham ESWT, one session per week. Participants were evaluated before treatment, and three weeks, three months, and six months after treatment. The pain was assessed using the visual analogue scale (VAS). Hand functions were assessed using the Michigan hand outcomes questionnaire (MHQ).

Results

The ESWT group showed significant improvement in VAS and MHQ scores after treatment at all time points compared to the control group (P < 0.001). Before treatment, the ESWT and control groups had a VAS score of 6.8 ± 1.3 and 6.7 ± 1.0, respectively. Three weeks after treatment, they had a VAS score of 2.8 ± 1.1 and 6.1 ± 1.0, respectively. Six months after treatment, the VAS score was reduced to 1.9 ± 0.9 and 5.1 ± 1.0, respectively. The ESWT group had a MHQ score of 54.4 ± 7.7 before treatment and 73.3 ± 6.8 six months after. The control group had a MHQ score of 54.2 ± 7.1 before treatment and 57.8 ± 4.4 six months after.

Conclusions

ESWT is an effective and a safe non-invasive treatment option for pain management and hand functionality in pillar pain.

Presentation and outcome of carpal tunnel syndrome with mini incision open carpal tunnel release

Background: To document the clinical presentation of carpal tunnel syndrome (CTS) and evaluate the outcome of mini-incision open carpal tunnel release in terms of surgical complications, relief/persistence of symptoms at 4 months, and recurrence at 1 year. Methods: This prospective case series included patients of all genders and ages who presented with CTS. They underwent release of transverse carpal ligament (TCL) under local anesthesia and tourniquet control on day care basis. Mini-incision of 2 cm to 2.5 cm was employed. The data were subjected to statistical analysis using SPSS version 21 (SPSS Inc). The percentages of key categorical variables were compared by employing the chi square test, and a P value of less than.05 was regarded as statistically significant. Results: There were 67 patients with 77 CTS affected wrists. A Significant majority of the patients (n = 54; 80.59%) were females, whereas 13 (19.40%) patients were males. The age range was 26 to 69 years, with a mean age of 41.01 ± 11.70 years. The CTS was found to be moderate among 34 (44.15%) and severe among 43 (55.84%) patients. The majority of patients had no operative complications. At 4 months follow-up, the majority of patients (n = 74; 96.10%) reported symptomatic relief, whereas 3 (3.89%) patients continued to have persistent severe symptoms. All the cases with persistent symptoms had diabetes mellitus of more than 5 years duration. There was no case of recurrence at one year follow-up. Conclusion: CTS predominantly affected women aged 30 to 45 years. The open carpal tunnel release with mini-incision yielded good results in terms of relieving symptoms among the majority of patients and was associated with no critical complications or recurrence at 1 year.

Morphologic Analysis of the Carpal Tunnel and Median Nerve Following Open and Endoscopic Carpal Tunnel Release

Background: Endoscopic carpal tunnel release (ECTR) has purported advantages over open release such as reduced intraoperative dissection and trauma and more rapid recovery. Endoscopic carpal tunnel release has been shown to have comparable outcomes to open release, but open release is considered easier and safer to perform. Previous studies have demonstrated an increase in carpal tunnel volume, regardless of the technique used. However, the mechanism by which this volumetric increase occurs has been debated. Our study will determine through magnetic resonance imaging (MRI) analysis the morphologic changes that occur in both open carpal tunnel release (OCTR) and ECTR, thereby clarifying any morphologic differences that occur as a result of the 2 operative techniques. We hypothesize that there will be no morphologic differences between the 2 techniques. Methods: This was a prospective study to compare the postoperative anatomy of both techniques with MRI. Nineteen patients with clinical and nerve conduction study-confirmed carpal tunnel syndrome underwent either open or endoscopic release. Magnetic resonance imaging was performed preoperatively and 6 months postoperatively in all patients to examine the volume of the carpal tunnel, transverse distance, anteroposterior (AP) distance, divergence of tendons, and Guyon's canal transverse and AP distance. Results: There was no significant difference in the postoperative morphology of the carpal tunnel and median nerve between OCTR and ECTR at 6-month follow-up on MRI. Conclusion: We conclude that there are no morphologic differences in OCTR and ECTR. It is an increase in the AP dimension that appears to be responsible for the increase in the volume of the carpal tunnel.

Surgical intervention for carpal tunnel syndrome in individuals with spinal cord injuries-patient characteristics, diagnostic considerations, and treatment outcomes

STUDY DESIGN

A retrospective chart audit.

OBJECTIVES

To characterize SCI patients with carpal tunnel syndrome (CTS) and evaluate the diagnostic rationale for surgical decision-making.

SETTING

Swiss Paraplegic Centre, Nottwil, Switzerland.

METHODS

Retrospective investigation of medical history, diagnostics, surgeries, and outcomes of surgical treatments of CTS in patients with para- and tetraplegia.

RESULTS

We identified a total of 77 surgeries for CTS in 55 patients: 16 females (25 surgeries) and 39 males (52 surgeries) with spinal cord injury. The majority (47 persons, 68 surgeries) were paraplegic (level of lesion Th2 and below); 8 persons (9 surgeries) were tetraplegic (level of lesion Th1 and above). ASIA scores in the tetraplegic group were A: 0, B: 1, C: 4, D: 3 while complete lesions predominated in the paraplegic group (A: 32, B: 4, C: 5, D: 6). Sixty-six out of 77 patients reported total relief of symptoms. Neither nerve conduction velocity nor motor amplitude correlated well with the severity of CTS. Co-morbidity and specific risk factors were rare.

CONCLUSIONS

SCI patients with CTS respond well to surgical decompression of median nerve regardless of level and type of spinal cord lesion and risk factors. Nerve conduction parameters and clinical findings can provide additional diagnostic support of CTS although nocturnal hand paresthesia, wrist pain at and after loading as well as failed conservative treatment are the main indications for surgical interventions. Based on symptomatology, clinical findings, and nerve conduction studies, we propose a decision-making tree for suggesting surgery or not.

Modification of intra-carpal tunnel pressure after Z-lengthening of the transverse carpal ligament

Background Flexor retinaculum reconstruction techniques or simply Flexor Retinaculum Z-lengthening have been proposed to preserve Flexor Retinaculum continuity after carpal tunnel release. Their effectiveness is based solely on symptom relief. There has been no analysis of the effects on intra-carpal tunnel pressure of Flexor Retinaculum-lengthening techniques. Objective was to compare intra-carpal tunnel pressure outcomes between complete division and Z-lengthening of the Retinaculum in a cadaveric model of carpal tunnel release. Methods Experimental study of carpal tunnel pressure after surgical Flexor Retinaculum modification in 10 fresh-frozen forearm and hand cadaveric specimens. The Kyphon™ Balloon Kyphoplasty system was used to measure the pressure before and after infusing 1, 2, 3, 4 and 5 ml of saline solution when untreated (Flexor Retinaculum continuity stage I), when Z-lengthened (Flexor Retinaculum continuity stage II), and after complete Flexor Retinaculum division (Flexor Retinaculum continuity stage III). Finding Intra-carpal tunnel pressure increased with larger volume of infused saline solution, although mean pressures were lower after Z lengthening or complete division of the Retinaculum than at baseline. Analysis of linear regression coefficients indicated significant differences as a function of FR continuity stage (F(2,18) = 18.38, p < 0.001), while the Bonferroni test revealed significant differences in slopes between stages I and III (p = 0.003), between stages I and II (p < 0.02), but not between stages II and III (p > 0.05). Interpretation The effectiveness of carpal tunnel release and the reduction in intra-carpal tunnel pressures obtained by Z-lengthening of the FR were similar to those observed after its complete division, while preserving FR continuity.

The Influence of Self-Reported Hand-Arm Vibration Exposure on Functional Outcomes Following Carpal Tunnel Release

PURPOSE

This study describes the impact of self-reported hand-arm vibration (HAV) exposure on patient-reported outcomes, health-related quality of life, and satisfaction after carpal tunnel release.

METHODS

We prospectively collected data from Quick-Disabilities of the Arm, Shoulder, and Hand (QuickDASH), patient satisfaction, and 5-level EuroQol-5D questionnaires before and after surgery. Patient-reported outcomes were available for 475 patients (78% follow-up at a mean of 14 months). Fifteen patients were excluded, giving a final cohort of 460 patients.

RESULTS

A total of 119 patients reported HAV exposure (26%). Median postoperative QuickDASH and QuickDASH improvement were significantly worse in the HAV-exposed group, although both groups improved after surgery. Multivariable linear regression revealed a significantly worse postoperative score and change in QuickDASH in HAV-exposed patients. There was no difference in satisfaction, but after surgery, the 5-level EuroQol-5D score was significantly worse in HAV-exposed patients.

CONCLUSIONS

Carpal tunnel release in HAV-exposed patients results in a significantly lower improvement in self-reported disability compared with patients without HAV exposure. This study provides important prognostic information for patients with previous HAV exposure undergoing carpal tunnel release.

TYPE OF STUDY/LEVEL OF EVIDENCE

Prognostic III.

Biometry of thenar muscle origins on the flexor retinaculum

The transverse carpal ligament (TCL), the main part of the flexor retinaculum, serves as an anchor for the thenar muscles: abductor pollicis brevis (APB), superficial head of the flexor pollicis brevis (sFPB), and opponens pollicis (OPP). Biomechanically, the thenar muscles rely on their TCL anchoring to transmit muscle contractions distally for thumb force and motion production, and reciprocally, muscle contraction interacts with the TCL at the proximal end through the origins. However, scarce knowledge exists regarding the distribution pattern of the thenar muscle origins. The purpose of this study was to understand the anatomical interface between the thenar muscles and TCL by examining the origin distributions of the individual muscles. Ten cadaveric specimens were dissected for digitization of the muscle origins and TCL volar surface. Digitized data were used for mesh reconstruction and calculation of surface areas and centroids. The origin areas for APB, sFPB, and OPP were 105.8 ± 30.3, 64.6 ± 15.2, and 245.9 ± 70.7 mm² , respectively. The surface area of the TCL was 386.2 ± 86.9 mm² . The origin areas of APB and OPP on the TCL were comparable, 18.4 ± 4.8% and 17.3 ± 9.6% of the TCL area, respectively. The origin locations for APB, sFPB, and OPP were in proximal-radial quadrant of the TCL, on distal aponeurosis outside the TCL, and around the ridge of trapezium, respectively. The knowledge of the anatomical interface provides a foundation for the understanding of biomechanical interactions between the muscles and ligaments and pathomechanical implications.

Changes of median nerve conduction, cross-sectional area and mobility by radioulnar wrist compression intervention in patients with carpal tunnel syndrome

BACKGROUND

Owing to the compressive nature of the neuropathy, patients with carpal tunnel syndrome (CTS) have prolonged distal motor latency (DML), sensory nerve latency (SNL), median nerve swelling and restricted median nerve mobility. The purpose of this study was to noninvasively augment carpal tunnel space using radioulnar wrist compression (RWC) and evaluate its effects on median nerve pathological properties in patients with CTS. It was hypothesized that the RWC intervention would reduce the median nerve DML, SNL and cross-sectional area (CSA) and enhance longitudinal median nerve mobility in patients. with CTS.

METHODS

Eleven patients diagnosed with CTS participated in this study. A portable RWC intervention splint was developed to apply 10 N of compressive force across the wrist. Three daily sessions of RWC were performed over 4 weeks of intervention (15 min per session, 45 min per day, 7 days per week). Each 15-min session consisted of three 5-min blocks of RWC, with a 1-min rest in between consecutive blocks. Patients were evaluated at Week 0 (baseline), Week 2 (mid-intervention) and Week 4 (end of intervention). DML and SNL of the median nerve were evaluated using established nerve conduction study techniques. Median nerve CSA at the distal wrist crease was obtained by ultrasound imaging. Median nerve motion associated with finger flexion/extension was captured by dynamic ultrasound imaging and quantified using a speckle cross-correlation algorithm. Finger flexion/extension was recorded using an electrogoniometer. The slope of the regressed linear equation of median nerve displacement as a function of finger flexion angle was used to quantify nerve mobility.

RESULTS

Patients with CTS showed significantly decreased DML (p = 0.048) and median nerve CSA (p < 0.001) and increased nerve mobility (p < 0.001) at mid-intervention compared to baseline. However, DML, CSA and mobility of the median nerve did not differ significantly between Weeks 2 and 4 (p = 0.574, 1.00 and 0.139, respectively). Median nerve SNL was not significantly affected throughout the 4-week intervention (p = 0.330 for Week 0 vs. 2; p = 1.00 for Week 2 vs. 4).

CONCLUSION

This study revealed that RWC intervention with 10-N force applied to the wrist in the radioulnar direction could restore impaired neurophysiological and biomechanical functions of the median nerve. The beneficial effects of RWC intervention for the median nerve were in evidence after a relatively short period of two weeks. These functional improvements could be explained by intermittent decompression of the median nerve via RWC-induced augmentation of the carpal arch.

THE TRANSLATIONAL POTENTIAL OF THIS ARTICLE

Biomechanically manipulating the carpal tunnel by RWC decompresses the median nerve and has the potential to become an alternative treatment for CTS.

Extracorporeal Shockwave Therapy in Pillar Pain after Carpal Tunnel Release: A Prospective Randomized Controlled Trial

Background

The aim of this study was to evaluate the effect of extracorporeal shockwave therapy (ESWT) on pillar pain after carpal tunnel release.

Materials and Methods

In this prospective randomized controlled trial, forty patients with pillar pain for at least 1 month after carpal tunnel release surgery were randomly assigned in two groups. ESWT group received four sessions of ESWT at weekly intervals, and patients in the control group received sham ESWT treatment at the same intervals, involved sound but no energy. At baseline, 1^st month, and 3^rd month, hand function (using Brief-Michigan Hand Outcome Questionnaire) and pain score were assessed and compared between groups.

Results

At baseline, pain score and hand function score were similar in both groups. After 1^st month, pain score in ESWT and control groups was 3.7 versus 4.7, respectively (P = 0.066), and hand function score was 60.7 versus 52.2, respectively (P = 0.032). After 3 months, pain score in ESWT group was significantly lower than the control group (1.6 versus 3.6, respectively, P < 0.0001), hand function score in ESWT group was significantly better than the control group (75.4 vs. 63.7, respectively, P < 0.0001). Trend of decrease in pain score between groups was significantly different, but trend of increase in hand function score was not significantly different.

Conclusion

After ESWT, hand function and pain score in patients with pillar pain improved faster compared to control patients. Hence, ESWT can be used as a safe and effective noninvasive technique in patients with pillar pain after carpal tunnel release.

Preoperative Pain Sensitization Is Associated With Postoperative Pillar Pain After Open Carpal Tunnel Release

BACKGROUND

Postoperative pillar pain (deep-seated wrist pain worsened by leaning on the heel of the hand) sometimes occurs after carpal tunnel release (CTR), leading to weakness in the hand and delayed return to work. Increased pain sensitivity has been found to be associated with worse symptoms and poorer treatment response in a number of chronic musculoskeletal conditions, but few studies have investigated the association of pain sensitization with pillar pain after CTR.

QUESTIONS/PURPOSES

(1) Is preoperative pain sensitization in patients with carpal tunnel syndrome (CTS) associated with increased severity of pillar pain after open CTR? (2) What other demographic, electrophysiological, or preoperative clinical characteristics are associated with pillar pain after CTR?

METHODS

Over a 35-month period, one surgeon performed 162 open carpal tunnel releases. Patients were eligible if they had sufficient cognitive and language function to provide informed consent and completed a self-reported questionnaire; they were not eligible if they had nerve entrapment other than CTR or if the surgery was covered by workers compensation insurance. Based on these criteria, 148 (91%) were approached for this study. Of those, 17 (9%) were lost to followup before 12 months, leaving 131 for analysis. Their mean age was 54 years (range, 32-78 years), and 81% (106 of 131) were women; 34% (45 of 131) had less than a high school education. We preoperatively measured pain sensitization by assessing the patients' pressure pain thresholds by stimulating pressure-induced pain in the pain-free volar forearm and administering a self-reported Pain Sensitivity Questionnaire minor subscale, an instrument that assesses pain intensity in daily life situations. We evaluated postoperative pillar pain using the "table test" (having the patient lean on a table with their weight on their hands placed on the table's edge with elbows straight) with an 11-point ordinal scale at 3, 6, and 12 months after their surgical procedures. We conducted bivariate and multivariable analyses to determine whether the patients' clinical, demographic, and pain sensitization factors were associated with their postoperative pillar pain severity after CTR.

RESULTS

After controlling for relevant confounding variables such as age, education level, and functional states, we found that increased pillar pain severity was associated with the pressure pain threshold (β = -1.02 [-1.43 to -0.61], partial R = 11%, p = 0.021) and Pain Sensitivity Questionnaire minor (β = 1.22 [0.73-1.71], partial R = 17%, p = 0.013) at 3 months, but by 6 months, only Pain Sensitivity Questionnaire minor (β = 0.92 [0.63-1.21], partial R = 13%, p = 0.018) remained an associated variable for pillar pain. Additionally, gender (women) was associated with increased pain severity at 3 (β = 0.78 [0.52-1.04], partial R = 9%, p = 0.023) and 6 months (β = 0.72 [0.41-1.01], partial R = 8%, p = 0.027). At 3 months, pressure pain threshold, Pain Sensitivity Questionnaire minor, and gender (women) collectively accounted for 37% of the variance in pillar pain severity; at 6 months, Pain Sensitivity Questionnaire minor and gender (women) accounted for 21% of the variance, but no relationship between those factors and pillar pain was observed at 12 months.

CONCLUSIONS

Gender (women) and preoperative pain sensitization measured by pressure pain threshold and self-reported Pain Sensitivity Questionnaire were associated with pillar pain severity up to 3 and 6 months after CTR, respectively. However, the influence of pain sensitization on pillar pain was diminished at 6 months and it did not show persistent effects beyond 12 months. Pain sensitization seems to be more important in the context of recovery from surgical intervention (in the presence of a pain condition) than in healthy states, and clinicians should understand the role of pain sensitization in the postoperative management of CTS. Future research may be needed to determine if therapeutic interventions to reduce sensitization will decrease the risk of pillar pain.

LEVEL OF EVIDENCE

Level III, prognostic study.

Comparison of the efficacy of lidocaine and betamethasone dipropionate in carpal tunnel syndrome injection

BACKGROUND

Carpal tunnel syndrome (CTS) is a commonly seen peripheral nerve mononeuropathy. Corticosteroid injection within the carpal tunnel is among the conservative treatment options. The exact mechanism of action of steroids is not fully clear; decreased inflammation surrounding nerves or tendons is thought to be the main effect. Lidocaine has been shown to have anti-inflammatory effects on certain cells (monocytes, macrophages, neutrophils etc.). The aim of this study is to evaulate the efficacy of lidocaine treatment as a alternative to corticosteroid treatment in carpal tunnel syndrome.

METHODS

A total of 67 carpal tunnel syndrome patients who were diagnosed with physical examination and EMG were evaluated. Twenty-nine patients received a mixture of normal saline solution and lidocaine (0.5 cc of normal saline solution and 0.5 cc of lidocaine) while 38 patients were administered betamethasone dipropionate (1 cc). Quick DASH (Disabilities of the Arm, Shoulder and Hand) and Visual Analog Scale (VAS) scores were noted in 1st, 3rd and 6th month follow-ups.

RESULTS

There were no significant difference between saline solution + Lidocaine group and betamethasone dipropionate groups; initial, 1st, 3rd and 6th month VAS scores and QDASH scores (p > 0.05).

CONCLUSION

Considering the potential side effects of corticosteroid, lidocaine injection is a good alternative treatment of carpal tunnel syndrome instead of corticosteroids.

A Clinical Study of the Modified Thread Carpal Tunnel Release

BACKGROUND

Previous studies have indicated that the thread carpal tunnel release (TCTR) is a safe and effective technique. Through a study on 11 cadaveric wrists, the TCTR procedure was modified and the needle control accuracy was improved to 0.15 to 0.2 mm, which is precise enough to preserve superficial palmar aponeurosis (SupPA), Berrettini branch, and common digital nerves. The aim of the present study was to verify the modified TCTR clinically.

METHODS

The modified TCTR was performed on 159 hands of 116 patients. The Boston Carpal Tunnel Syndrome Questionnaire was used for assessing the outcomes. Statistical analyses were used to compare the outcomes with the available data from the literature for the open and endoscopic techniques.

RESULTS

TCTR led to significant improvement in the short-term results, and the outcomes were better in long-term results compared with the open or endoscopic release. The SupPA, Berrettini branch, and common digital nerves were protected. There was no neurovascular complication for any case. Significant relief of symptoms was observed 3 to 5 hours post procedure. Most patients used their hands on the day of the procedure for simple daily activity. Patients reported their sleep quality was improved on the surgical day. Most patients with office jobs were able to return to work on postoperative day 1, and those with repetitive jobs returned to work in about 2 weeks. The statistical evidence proves that the modified TCTR procedure results in improved clinical outcomes as compared with open carpal tunnel release (CTR) and endoscopic CTR.

CONCLUSIONS

The TCTR procedure has been shown to be a safe and effective technique for CTR. The modified TCTR procedure minimizes postoperative complications, such as pillar pain, scar tenderness, or functional weakness, by avoiding unnecessary injuries to the surrounding structures around the transverse carpal ligament during the procedure.

Thickness and Stiffness Adaptations of the Transverse Carpal Ligament Associated with Carpal Tunnel Syndrome

The purpose of this study was to investigate the morphological and mechanical properties of the transverse carpal ligament (TCL) in patients with carpal tunnel syndrome (CTS). Thickness and stiffness of the TCL in eight female CTS patients and eight female control subjects were examined using ultrasound imaging modalities. CTS patients had a 30.9% thicker TCL than control subjects. There was no overall difference in TCL stiffness between the two groups, but the radial TCL region was significantly stiffer than the ulnar region within the CTS group and such a regional difference was not found for the controls. The increased thickness and localized stiffness of the TCL for CTS patients may contribute to CTS symptoms due to reduction in carpal tunnel space and compliance. Advancements in ultrasound technology provide a means of understanding CTS mechanisms and quantifying the morphological and mechanical properties of the TCL in vivo.

Carpal arch and median nerve changes during radioulnar wrist compression in carpal tunnel syndrome patients

The purpose of this study was to investigate the morphological changes of the carpal arch and median nerve during the application of radiounlarly directed compressive force across the wrist in patients with carpal tunnel syndrome. Radioulnar compressive forces of 10 N and 20 N were applied at the distal level of the carpal tunnel in 10 female patients diagnosed with carpal tunnel syndrome. Immediately prior to force application and after 3 min of application, ultrasound images of the distal carpal tunnel were obtained. It was found that applying force across the wrist decreased the carpal arch width (p < 0.001) and resulted in increased carpal arch height (p < 0.01), increased carpal arch curvature (p < 0.001), and increased radial distribution of the carpal arch area (p < 0.05). It was also shown that wrist compression reduced the flattening of the median nerve, as indicated by changes in the nerve's circularity and flattening ratio (p < 0.001). This study demonstrated that the carpal arch can be non-invasively augmented by applying compressive force across the wrist, and that this strategy may decompress the median nerve providing symptom relief to patients with carpal tunnel syndrome. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:1234-1240, 2016.

Changes in carpal tunnel compliance with incremental flexor retinaculum release

Background

Flexor retinaculum transection is a routine surgical treatment for carpal tunnel syndrome, yet the biomechanical and clinical sequelae of the procedure remain unclear. We investigated the effects of flexor retinaculum release on carpal tunnel structural compliance using cadaveric hands.

Methods

The flexor retinaculum was incrementally and sequentially released with transections of 25, 50, 75, and 100 % of the transverse carpal ligament, followed by the distal aponeurosis and then the antebrachial fascia. Paired outward 10 N forces were applied to the insertion sites of the transverse carpal ligament at the distal (hamate-trapezium) and proximal (pisiform-scaphoid) levels of the carpal tunnel. Carpal tunnel compliance was defined as the change in carpal arch width normalized to the constant 10 N force.

Results

With the flexor retinaculum intact, carpal tunnel compliance at the proximal level, 0.696 ± 0.128 mm/N, was 13.6 times greater than that at the distal level, 0.056 ± 0.020 mm/N. Complete release of the transverse carpal ligament was required to achieve a significant gain in compliance at the distal level (p < 0.05). Subsequent release of the distal aponeurosis resulted in an appreciable additional increase in compliance (43.0 %, p = 0.052) at the distal level, but a minimal increase (1.7 %, p = 0.987) at the proximal level. Complete flexor retinaculum release provided a significant gain in compliance relative to transverse carpal ligament release alone at both proximal and distal levels (p < 0.05).

Conclusions

Overall, complete flexor retinaculum release increased proximal compliance by 52 % and distal compliance by 332 %. The increase in carpal tunnel compliance with complete flexor retinaculum release helps explain the benefit of carpal tunnel release surgery for patients with carpal tunnel syndrome.

Adaptation of the Transverse Carpal Ligament Associated with Repetitive Hand Use in Pianists

The transverse carpal ligament (TCL) plays a critical role in carpal tunnel biomechanics through interactions with its surrounding tissues. The purpose of this study was to investigate the in vivo adaptations of the TCL’s mechanical properties in response to repetitive hand use in pianists using acoustic radiation force impulse (ARFI) imaging. It was hypothesized that pianists, in comparison to non-pianists, would have a stiffer TCL as indicated by an increased acoustic shear wave velocity (SWV). ARFI imagining was performed for 10 female pianists and 10 female non-pianists. The median SWV values of the TCL were determined for the entire TCL, as well as for its radial and ulnar portions, rTCL and uTCL, respectively. The TCL SWV was significantly increased in pianists relative to non-pianists (p < 0.05). Additionally, the increased SWV was location dependent for both pianist and non-pianist groups (p < 0.05), with the rTCL having a significantly greater SWV than the uTCL. Between groups, the rTCL SWV of pianists was 22.2% greater than that of the non-pianists (p < 0.001). This localized increase of TCL SWV, i.e. stiffening, may be primarily attributable to focal biomechanical interactions that occur at the radial TCL aspect where the thenar muscles are anchored. Progressive stiffening of the TCL may become constraining to the carpal tunnel, leading to median nerve compression in the tunnel. TCL maladaptation helps explain why populations who repeatedly use their hands are at an increased risk of developing musculoskeletal pathologies, e.g. carpal tunnel syndrome.

Comparison of short wrist transverse open and limited open techniques for carpal tunnel release: a randomized controlled trial of two incisions

The purpose of this randomized controlled trial was to compare outcomes of limited open and short wrist transverse techniques in patients with carpal tunnel syndrome. In a single centre randomized controlled trial, 84 patients with idiopathic carpal tunnel syndrome were randomized before surgery to limited open or short wrist transverse open carpal tunnel release. The patients were evaluated at 6 weeks, 3 months, 6 months, and 1 and 2 years after surgery. At every follow-up, the Brigham and Women's Carpal Tunnel Questionnaire scores, scar discomfort, and subjective patient satisfaction were evaluated. Two years after surgery, five patients were lost to follow-up. The groups had similar Brigham and Women's Carpal Tunnel Questionnaire Symptom Severity and Functional Status scores and subjective satisfaction scores. The incidence of scar discomfort was not significantly different between the two groups on serial postoperative follow-up. Short wrist transverse open release surgery showed similar early postoperative symptoms and subjective and functional outcomes to limited open release.

LEVEL OF EVIDENCE

II.

Tensile properties of the transverse carpal ligament and carpal tunnel complex

BACKGROUND

A new sophisticated method that uses video analysis techniques together with a Maillon Rapide Delta to determine the tensile properties of the transverse carpal ligament-carpal tunnel complex has been developed.

METHODS

Six embalmed cadaveric specimens amputated at the mid-forearm and aged (mean (SD)): 82 (6.29) years were tested. The six hands were from three males (four hands) and one female (two hands). Using trigonometry and geometry the elongation and strain of the transverse carpal ligament and carpal arch were calculated. The cross-sectional area of the transverse carpal ligament was determined. Tensile properties of the transverse carpal ligament-carpal tunnel complex and Load-Displacement data were also obtained. Descriptive statistics, one-way ANOVA together with a post-hoc analysis (Tukey) and t-tests were incorporated.

FINDINGS

A transverse carpal ligament-carpal tunnel complex novel testing method has been developed. The results suggest that there were no significant differences between the original transverse carpal ligament width and transverse carpal ligament at peak elongation (P=0.108). There were significant differences between the original carpal arch width and carpal arch width at peak elongation (P=0.002). The transverse carpal ligament failed either at the mid-substance or at their bony attachments. At maximum deformation the peak load and maximum transverse carpal ligament displacements ranged from 285.74N to 1369.66N and 7.09mm to 18.55mm respectively. The transverse carpal ligament cross-sectional area mean (SD) was 27.21 (3.41)mm(2).

INTERPRETATION

Using this method the results provide useful biomechanical information and data about the tensile properties of the transverse carpal ligament-carpal tunnel complex.

Morphological and positional changes of the carpal arch and median nerve during wrist compression

BACKGROUND

The carpal tunnel is a fibro-osseous structure containing the median nerve and flexor tendons. Its cross-sectional area has been shown to increase during compressive force application to the carpal bones in modeling and in vitro studies. The purpose of this study was to investigate the morphological and positional changes of the carpal arch and median nerve while in vivo compressive force was applied in the radioulnar direction across the wrist.

METHODS

Ultrasound images of the carpal tunnel and its contents were captured for 11 healthy, female volunteers at the distal tunnel level prior to force application and during force application of 10 and 20N.

FINDINGS

With applied force, the carpal arch width significantly decreased, while the carpal arch height and area significantly increased (P<0.001). The median nerve shape became more rounded as the compressive force magnitude increased, reflected by decreases in the nerve's flattening ratio and increases in its circularity (P<0.001). The applied force also resulted in nerve displacement in the radial-volar direction.

INTERPRETATION

This study demonstrates that noninvasively applying radioulnar compressive force across the wrist may potentially provide relief of median nerve compression to patients suffering from carpal tunnel syndrome.

Carpal tunnel release: do we understand the biomechanical consequences?

Carpal tunnel release is a very common procedure performed in the United States. While the procedure is often curative, some patients experience postoperative scar sensitivity, pillar pain, grip weakness, or recurrent median nerve symptoms. Release of the carpal tunnel has an effect on carpal anatomy and biomechanics, including increases in carpal arch width and carpal tunnel volume and changes in muscle and tendon mechanics. Our understanding of how these biomechanical changes contribute to postoperative symptoms is still evolving. We review the relevant morphometric and biomechanical changes that occur following release of the transverse carpal ligament.

Biomechanical role of the transverse carpal ligament in carpal tunnel compliance

The transverse carpal ligament (TCL) is a significant constituent of the wrist structure and forms the volar boundary of the carpal tunnel. It serves biomechanical and physiological functions, acting as a pulley for the flexor tendons, anchoring the thenar and hypothenar muscles, stabilizing the bony structure, and providing wrist proprioception. This article mainly describes and reviews our recent studies regarding the biomechanical role of the TCL in the compliant characteristics of the carpal tunnel. First, force applied to the TCL from within the carpal tunnel increased arch height and area due to arch width narrowing from the migration of the bony insertion sites of the TCL. The experimental findings were accounted for by a geometric model that elucidated the relationships among arch width, height, and area. Second, carpal arch deformation showed that the carpal tunnel was more flexible at the proximal level than at the distal level and was more compliant in the inward direction than in the outward direction. The hamate-capitate joint had larger angular rotations than the capitate-trapezoid and trapezoid-trapezium joints for their contributions to changes of the carpal arch width. Lastly, pressure application inside the intact and released carpal tunnels led to increased carpal tunnel cross-sectional areas, which were mainly attributable to the expansion of the carpal arch formed by the TCL. Transection of the TCL led to an increase of carpal arch compliance that was nine times greater than that of the intact carpal tunnel. The carpal tunnel, while regarded as a stabile structure, demonstrates compliant properties that help to accommodate biomechanical and physiological variants such as changes in carpal tunnel pressure.

Carpal tunnel syndrome - Part II (treatment)

The treatments for non-deficit forms of carpal tunnel syndrome (CTS) are corticoid infiltration and/or a nighttime immobilization brace. Surgical treatment, which includes sectioning the retinaculum of the flexors (retinaculotomy), is indicated in cases of resistance to conservative treatment in deficit forms or, more frequently, in acute forms. In minimally invasive techniques (endoscopy and mini-open), and even though the learning curve is longer, it seems that functional recovery occurs earlier than in the classical surgery, but with identical long-term results. The choice depends on the surgeon, patient, severity, etiology and availability of material. The results are satisfactory in close to 90% of the cases. Recovery of strength requires four to six months after regression of the pain of pillar pain type. This surgery has the reputation of being benign and has a complication rate of 0.2-0.5%.

Use of the Accordion Severity Grading System for negative outcomes of carpal tunnel syndrome

A universal classification of the negative outcomes of carpal tunnel release surgery does not, as yet, exist. In order to avoid the use of arbitrary factors we have applied the Accordion Severity Grading System, which uses rigorously defined qualitative terms to classify complications. It also provides a uniform manner for grading the severity of complications, enabling outcome comparisons between centres. We analysed the negative outcomes of 500 device-assisted carpal tunnel releases performed over a 2-year period in the author's department. In order to establish a standardised list of complications we used the terms employed within the guidelines of the American Academy of Orthopaedic Surgeons. Most of these terms were subsequently defined using the data variables and definitions taken from the American College of Surgeons National Surgical Quality Improvement Program or the Medical Subject Headings of the National Library of Medicine. We also adopted the quantitative severity weighting, as proposed by the Accordion system, in order to determine the postoperative morbidity index for our assisted carpal tunnel releases. The most common complications were pain and reversible damage to peripheral nerves. Other common negative events, other than complications, included hand weakness, which we classified as a sequela of the procedure, and incomplete retinaculum release, which we classified as failure to cure. The overall postoperative morbidity index for complications was 0.014. Although the Accordion system was developed for more complex procedures, it may also be adopted for carpal tunnel release surgery where it provides an objective and universal method for the classification of complications.

Pressure-morphology relationship of a released carpal tunnel

We investigated morphological changes of a released carpal tunnel in response to variations of carpal tunnel pressure. Pressure within the carpal tunnel is known to be elevated in patients with carpal tunnel syndrome and dependent on wrist posture. Previously, increased carpal tunnel pressure was shown to affect the morphology of the carpal tunnel with an intact transverse carpal ligament (TCL). However, the pressure-morphology relationship of the carpal tunnel after release of the TCL has not been investigated. Carpal tunnel release (CTR) was performed endoscopically on cadaveric hands and the carpal tunnel pressure was dynamically increased from 10 to 120 mmHg. Simultaneously, carpal tunnel cross-sectional images were captured by an ultrasound system, and pressure measurements were recorded by a pressure transducer. Carpal tunnel pressure significantly affected carpal arch area (p < 0.001), with an increase of >62 mm(2) at 120 mmHg. Carpal arch height, length, and width also significantly changed with carpal tunnel pressure (p < 0.05). As carpal tunnel pressure increased, carpal arch height and length increased, but the carpal arch width decreased. Analyses of the pressure-morphology relationship for a released carpal tunnel revealed a nine times greater compliance than that previously reported for a carpal tunnel with an intact TCL. This change of structural properties as a result of transecting the TCL helps explain the reduction of carpal tunnel pressure and relief of symptoms for patients after CTR surgery.

Narrowing carpal arch width to increase cross-sectional area of carpal tunnel--a cadaveric study

BACKGROUND

Carpal tunnel morphology plays an essential role in the etiology and treatment of carpal tunnel syndrome. The purpose of this study was to observe the morphological changes of the carpal tunnel as a result of carpal arch width narrowing. It was hypothesized that carpal arch width narrowing would result in increased height and area of the carpal arch.

METHODS

The carpal arch width of eight cadaveric hands was narrowed by a custom apparatus and cross-sectional ultrasound images were acquired. The carpal arch height and area were quantified as the carpal arch width was narrowed. Correlation and regression analyses were performed for the carpal arch height and area with respect to the carpal arch width.

FINDINGS

The carpal tunnel became more convex as the carpal arch width was narrowed. The initial carpal arch width, height, and area were 25.7 (SD1.9) mm, 4.1 (SD0.6) mm, and 68.5 (SD14.0) mm(2), respectively. The carpal arch height and area negatively correlated with the carpal arch width, with correlation coefficients of -0.974 (SD0.018) and -0.925 (SD0.034), respectively. Linear regression analyses showed a 1mm narrowing of the carpal arch width resulted in proportional increases of 0.40 (SD0.14) mm in the carpal arch height and 4.0 (SD2.2) mm(2) in the carpal arch area.

INTERPRETATION

This study demonstrates that carpal arch width narrowing leads to increased carpal arch height and area, a potential mechanism to reduce the mechanical insult to the median nerve and relieve symptoms associated with carpal tunnel syndrome.

The Effect of an Open Carpal Tunnel Release on Thumb CMC Biomechanics

Purpose. We have observed worsening thumb pain following carpal tunnel release (CTR) in some patients. Our purpose was to determine the effect of open CTR on thumb carpometacarpal (CMC) biomechanics. Methods. Five fresh-frozen cadaver arms with intact soft tissues were used. Each specimen was secured to a jig which fixed the forearm at 45° supination, and the wrist at 20° dorsiflexion, with thumb pointing up. The thumb was axially loaded with a force of 130 N. We measured 3D translation and rotation of the trapezium, radius, and first metacarpal, before and after open CTR. Motion between radius and first metacarpal, radius and trapezium, and first metacarpal and trapezium during loading was calculated using rigid body mechanics. Overall stiffness of each specimen was determined. Results. Total construct stiffness following CTR was reduced in all specimens but not significantly. No significant changes were found in adduction, pronation, or dorsiflexion of the trapezium with respect to radius after open CTR. Motion between radius and first metacarpal, between radius and trapezium, or between first metacarpal and trapezium after open CTR was not decreased significantly. Conclusion. From this data, we cannot determine if releasing the transverse carpal ligament alters kinematics of the CMC joint.

Ultrasound assessment of transverse carpal ligament thickness: a validity and reliability study

The transverse carpal ligament (TCL) forms the palmar boundary of the carpal tunnel and plays an important role in carpal tunnel mechanics. TCL hypertrophy has been observed for individuals with carpal tunnel syndrome (CTS) and postulated as a potential etiologic factor. Ultrasound is particularly advantageous for TCL imaging because of its capability of detecting the interfaces between the TCL and other tissues. The purposes of this study were to develop an ultrasound based method to measure the TCL thickness and to test the validity and reliability of this method. Three operators conducted two sessions of ultrasound examination on eight cadaveric specimens and eight healthy volunteers. A custom script was used to calculate TCL thickness along the TCL length from the ultrasound images. The ultrasound based TCL thickness of the cadaveric specimens was compared with the dissection based TCL thickness for validation. The results showed Pearson's correlation coefficients of 0.867-0.928, intraclass correlation coefficient (ICC) values of 0.726-0.865, a standard error of measurement of 0.02-0.07 mm and a minimal detectable difference of 0.05-0.15 mm. The high correlation coefficients and small errors indicate that the ultrasound based method is valid for measuring TCL thickness. Furthermore, ultrasound measurements showed excellent intraoperator and interoperator reliability with ICC values as 0.826-0.933 and 0.840-0.882, respectively. The ultrasound based TCL thickness was in the range of 0.93-2.34 (1.54 ± 0.33) mm and agreed well with previous studies. The ultrasound method developed in this study is a valuable tool to examine morphologic properties of healthy and pathologic TCLs.

Fiber orientation of the transverse carpal ligament

The transverse carpal ligament is the volar roof of the carpal tunnel. Gross observation shows that the ligament appears to have fibers that roughly orient in the transverse direction. A closer anatomical examination shows that the ligament also has oblique fibers. Knowledge of the fiber orientation of the transverse carpal ligament is valuable for further understanding the ligament's role in regulating the structural function of the carpal tunnel. The purpose of this study is to quantify collagen fiber orientation within the transverse carpal ligament using the small angle light scattering technique. Eight transverse carpal ligament samples from cadaver hands were used in this study. Individual 20-μm sections were cut evenly along the thickness of the transverse carpal ligament. Sections of three thickness levels (25%, 50%, and 75% from the volar surface) were collected for each transverse carpal ligament. Fibers were grouped in the following orientation ranges: transverse, longitudinal, oblique in the pisiform-trapezium (PT), and oblique in the scaphoid-hamate (SH) directions. In analyzing the fiber percentages, the orientation types for the different thickness levels of the ligament showed that the transverse fibers were the most prominent (>60.7%) followed by the PT oblique (18.6%), SH oblique (13.0%), and longitudinal (8.6%) fibers.

Ulnar subluxation of the median nerve following carpal tunnel release: a case report

Complications of carpal tunnel release, while infrequent, include incomplete release resulting in persistent symptoms or recurrence due to postoperative scarring, as well as iatrogenic damage to nerves and vessels. We present the case of a patient who underwent carpal tunnel release with resolution of symptoms in the immediate postoperative period. At one and a half years post release he started to experience numbness and tingling in a median nerve distribution triggered by repetitive ulnar to radial deviation of the wrist, with no symptoms at rest. Dynamic ultrasound showed a subluxation of the median nerve from one side of the palmaris longus tendon to the other. The patient's symptoms were triggered as the median nerve squeezed in between the palmaris longus and flexor digitorum superficialis tendons.

Bilateral ulnar neuropathy secondary to volar displacement of flexor tendons following open carpal tunnel release: case report

We report a case of bilateral ulnar neuropathy after bilateral open carpal tunnel release. Displacement of the flexor tendons anterior to the hook of hamate caused impingement on the ulnar nerve. Symptoms resolved after hook of hamate resection.

GENDER DIFFERENCE IN CARPAL TUNNEL COMPLIANCE

The purposes of this study were to investigate the mechanical properties of the carpal tunnel and to examine carpal tunnel compliance as it related to gender difference. Twelve male and twelve female subjects without any neuromusculoskeletal disorders in the upper extremities participated in the study. Indentation testing was manually performed on the wrist volar to the transverse carpal ligament. Effective compliance was defined as the slope of the regression analyses of indentation force and displacement data. In the tested indentation force range (2.45–19.60 N), the displacement of females was 1.38 ± 0.25 mm, significantly smaller than that of the males, 1.82 ± 0.30 mm (p < 0.001). Regression analyses in the force range showed that the effective compliance for females, 0.075 ± 0.012 mm/N, was 26.3% lower than that for males, 0.101 ± 0.018 mm/N (p < 0.005). It was concluded that females have less compliant carpal tunnel than males. The gender difference in carpal tunnel mechanics may predispose females to detrimental compression of the median nerve and carpal tunnel syndrome.

Carpal tunnel and transverse carpal ligament stiffness with changes in wrist posture and indenter size

This study investigated the effects of loading and posture on mechanical properties of the transverse carpal ligament (TCL). Ten fresh-frozen cadaver arms were dissected to expose the TCL and positioned in the load frame of a servo-hydraulic testing machine, equipped with a load cell and custom made indenters. Four cylindrical indenters (5, 10, 20, and 35 mm) loaded the TCL in three wrist postures (30° extension, neutral and 30° flexion). Three loading cycles with a peak force of 50 N were applied at 5 N/s for each condition. The flexed wrist posture had significantly greater TCL stiffness (40.0 ± 3.3 N/mm) than the neutral (35.9 ± 3.5 N/mm, p = 0.045) and extended postures (34.9 ± 2.8 N/mm, p = 0.025). TCL stiffness using the 10 and 20 mm indenters was larger than the 5 mm indenter. Stiffness was greatest with the 20 mm indenter, which had the greatest indenter contact area on the TCL. The 35 mm indenter covered the carpal bones, compressed the carpal tunnel and produced the lowest stiffness. The complexity of the TCL makes it an important part of the carpal tunnel and the mechanical properties found are essential to understanding mechanisms of carpal tunnel syndrome. 

Extracorporeal shock wave therapy in pillar pain after carpal tunnel release: a preliminary study

"Pillar pain" is a relatively frequent complication after surgical release of the median nerve at the wrist. Its etiology still remains unknown although several studies highlight a neurogenic inflammation as a possible cause. Pillar pain treatment usually includes rest, bracing and physiotherapy, although a significant number of patients still complain of painful symptoms two or even three years after surgery. The aim of this study was to investigate the efficacy of low-energy, flux density-focused extracorporeal shock wave therapy (ESWT) in the treatment of pillar pain. We treated 40 consecutive patients with ESWT who had pillar pain for at least six months after carpal tunnel release surgery, and to our knowledge, this is the first study that describes the use of ESWT for treating this condition. Our results show that in all of the treated patients, there was a marked improvement: the mean visual analogue scale (VAS) score decreased from 6.18 (±1.02) to 0.44 (±0.63) 120 d after treatment, and redness and swelling of the surgical scar had also decreased significantly.

Predictors of scar pain after open carpal tunnel release

PURPOSE

To identify the predictors of scar pain after open carpal tunnel release (CTR).

METHODS

We enrolled 83 patients with idiopathic carpal tunnel syndrome treated by open CTR. All patients completed the Brigham and Women's (Boston) carpal tunnel questionnaire (BCTQ) preoperatively. We assessed levels of depression preoperatively using the Center for the Epidemiological Study of Depression (CES-D) scale, and pain anxiety using the Pain Anxiety Symptoms Scale. At 3 months after surgery, patients were asked to self-assess treatment satisfaction and scar pain using a 10-point ordinal scale and to complete the BCTQ.

RESULTS

The mean BCTQ-symptom (BCTQ-S) score decreased significantly from 2.7 ± 1.1 preoperatively to 1.6 ± 1.0 at 3 months postoperatively, and mean BCTQ-function score decreased significantly from 2.4 ± 1.1 to 1.4 ± 1.0. Overall, scar pain intensity at 3 months postoperatively ranged from 0 to 8 (mean, 2.4 ± 2.2), and overall satisfaction ranged from 2 to 10 (mean, 7.6 ± 2.6). The intensity of the scar pain was significantly correlated with the CES-D scale and BCTQ-S. Multivariable regression analysis showed that depression, assessed using the CES-D scale, and postoperative symptoms, assessed using the BCTQ-S, predicted scar pain intensity, which accounted for 38% of scar pain intensity variance.

CONCLUSIONS

Depression score and postoperative symptoms predicted scar pain intensity after open CTR. However, the most important contributor to scar pain intensity variance remains unidentified.

TYPE OF STUDY/LEVEL OF EVIDENCE

Prognostic I.