Histology of the transverse carpal ligament and flexor tenosynovium in idiopathic carpal tunnel syndrome

A Comparison of Tenosynovial and Transverse Carpal Ligament Biopsy for Amyloid Detection in Open Carpal Tunnel Release

PURPOSE

Our purpose was to compare differences in the incidence of amyloid deposition in tenosynovium (TS) versus transverse carpal ligament (TCL) biopsies obtained during open carpal tunnel release. We hypothesized that the incidence of amyloid would be similar between TCL and TS when obtaining both specimens from the same patient.

METHODS

All primary, elective open carpal tunnel release cases that underwent biopsy for amyloid between January 2022 and September 2023 were reviewed. Tenosynovial and TCL specimens were independently evaluated by a pathologist to assess for amyloid. Demographic data were collected, and incidence of amyloid deposition was compared between the two samples. Agreement statistics, sensitivity, and specificity were calculated for TCL, using TS as the reference standard.

RESULTS

A total of 196 cases met either Tier 1 (n=180) or Tier 2 (n=16) biopsy criteria. Forty-eight cases were excluded for missed biopsies or laboratory processing errors, leaving 148 cases available for analysis. Amyloid deposition was present in 31 out of 148 (21%) TS specimens and 33 out of 148 (22%) TCL specimens. Overall, the results of the TS biopsy agreed with TCL biopsy in 138 out of 148 cases (93%). In the 10 cases for which the results of the TCL and TS biopsy differed, six cases had (+) TCL and (-) TS, and four cases had amyloid deposition in TS without evidence of deposition in the TCL. Sensitivity and specificity values for the TCL specimen were 87% and 95%, respectively. Positive and negative predictive values were 82% and 97%, respectively.

CONCLUSIONS

For cases of open carpal tunnel release undergoing biopsy, amyloid deposition was noted in 21% of TS specimens and 22% of TCL specimens. Results of TS and TCL biopsies obtained from the same patient agreed in 93% of cases. Single-source biopsy for amyloid represents a reasonable diagnostic approach. Future cost analyses should be performed to determine whether the addition of two biopsy sources to improve diagnostic accuracy is justified.

TYPE OF STUDY/LEVEL OF EVIDENCE

Prognostic II.

Being a Better Starfish Thrower, Carpal Tunnel Syndrome, and Cardiac Amyloidosis: The Hand Surgeon's Opportunity to Make a Profound Difference

In recent years, there is increasing literature in cardiac and hand surgery journals demonstrating a stronger association between seemingly idiopathic carpal tunnel and amyloidosis. Despite this, it can be difficult for hand surgeons to identify who need biopsies, and this is further complicated by the cost of a biopsy and the low likelihood that a patient has cardiac amyloidosis. In patients with cardiac amyloidosis and carpal tunnel syndrome (CTS), CTS is typically diagnosed 5-10 years prior. Early diagnosis of cardiac amyloidosis is crucial, as current medications work to slow disease progression, but do not treat existing amyloid deposits. Hand surgeons can play an essential role in early diagnosis. The patient case discussed describes a man who had a carpal tunnel biopsy because of his bilateral CTS, recurrent trigger fingers, and his age. After confirmation of amyloidosis, he was referred for cardiac amyloidosis evaluation. Testing confirmed this diagnosis, and he was started on tafamidis, which studies show provide patients an opportunity for increased survival and quality of life. The responsibility falls on cardiologists and hand surgeons to continue refining the indications for carpal tunnel biopsy and spreading awareness of carpal tunnel biopsy and amyloid testing, as much work is still needed.

Higher densities of T-lymphocytes in the subsynovial connective tissue of people with carpal tunnel syndrome

Symptoms in people with carpal tunnel syndrome (CTS) are traditionally attributed to neural tissue, but recent studies suggest that the subsynovial connective tissue (SSCT) may also play a role in CTS. The SSCT undergoes fibrotic thickening which is generally described as "non-inflammatory" based on basic histology. This study uses immunohistochemistry to determine the presence of macrophages and T-cells within SSCT and their relationship with symptoms in people with CTS. SSCT was collected from twenty people with CTS and eight controls undergoing wrist fracture surgery. Immunohistochemical quantification of CD3+ T-cells and CD68+ macrophage densities as well as CD4+/CD8+ T-cell subpopulations were compared between groups using independent t-tests. Spearman correlations were used to identify associations between immune cell densities and CTS symptom scores. The density of CD3+ T-cells was significantly higher in SSCT of people with CTS compared to controls (CTS mean 26.7 (SD 13.7); controls 6.78 (6.3), p = 0.0005) while the density of CD68+ macrophages was lower (CTS mean 9.5 (SD 6.0); controls 17.7 (8.2), p = 0.0058). Neither CD68+ nor CD3+ cell densities correlated with symptom scores. In contrast to previous assumptions, our data show that the SSCT in the carpal tunnel in both people with CTS and controls is not devoid of immune cells. Whereas the higher density of CD68+ macrophages in control participants may be associated with their early recruitment after acute fracture, CD3+ cells within the SSCT may play a role in chronic CTS.

Current Insights into Carpal Tunnel Syndrome: Clinical Strategies for Prevention and Treatment

BACKGROUND

Carpal tunnel syndrome (CTS) is a condition that is caused by medial nerve compression, resulting in symptoms such as numbness, tightness, or weakness in the hand.

OBJECTIVES

The aim of the study was to find out the genetic modulation, mechanism, available treatment, and recommendation for carpal tunnel syndrome at its specific stage.

METHODS

Almost 200 papers were searched for this review article, and 145 articles were selected. The literature was collected from different sources like Google scholar, PubMed, a directory of open-access journals, and science.gov by using keywords, such as treatment, risk factors, recommendation, and clinical features of carpal tunnel syndrome.

RESULTS

The most efficient non-surgical treatment is methylprednisolone acetate, which reduces inflammation by acting on the glucocorticoid receptor in conjunction with immunofilling. It has also been used successfully as a second-line drug for the treatment of patients with mild or moderate conditions in order to provide relief. New non-pharmacological options include laser therapy in acupuncture, transcutaneous electric nerve stimulation (TENS), and sham therapy. Modern treatments like TENS, laser therapy, splints, and injections of methylprednisolone acetate have been demonstrated to be helpful in sporadic situations. For patients with mild and moderate problems, more research should be conducted that includes the combination of these surgical and non-surgical treatments.

CONCLUSION

We propose a multifunctional panel construct and define standard data items for future research into carpal tunnel syndrome. A discussion on idiopathic carpal tunnel syndrome, risk factors, combination of therapies, using guidelines-based recommendations and treatment should be initiated.

High incidence of trigger finger after carpal tunnel release: a systematic review and meta-analysis

INTRODUCTION

Trigger finger (TF) often occurs after carpal tunnel release (CTR), but the mechanism and outcomes remain inconsistent. This study evaluated the incidence of TF after CTR and its related risk factors.

MATERIALS AND METHODS

​PubMed, Embase, and Scopus databases were searched up to 27 August 2022, with the following keywords: "carpal tunnel release" and "trigger finger". Studies with complete data on the incidence of TF after CTR and published full text. The primary outcome was the association between CTR and the subsequent occurrence of the TF and to calculate the pooled incidence of post-CTR TF. The secondary outcomes included the potential risk factors among patients with and without post-CTR TF as well as the prevalence of the post-CTR TF on the affected digits.

RESULTS

Ten studies with total 10,399 participants in 9 studies and 875 operated hands in one article were included for meta-analysis. CTR significantly increases the risk of following TF occurrence (odds ratio=2.67; 95% CI 2.344-3.043; P <0.001). The pooled incidence of TF development after CTR was 7.7%. Women were more likely to develop a TF after CTR surgery (odds ratio=2.02; 95% CI 1.054-3.873; P =0.034). Finally, the thumb was the most susceptible fingers, followed by middle and ring fingers.

CONCLUSIONS

High incidence of TF comes after CTR, and women were more susceptible than man. Clinicians were suggested to notice the potential risk of TF after CTR in clinical practice.

LEVEL OF EVIDENCE

Level III, meta-analysis.

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.

Clinical Characteristics and Treatment of Adult Idiopathic Carpal Tunnel Syndrome Accompanied with Trigger Digit

Purpose

To investigate the clinical characteristics and treatment of adult idiopathic carpal tunnel syndrome (CTS) accompanied with trigger digit.

Materials and Methods

A retrospective analysis was performed on a total of 74 patients with adult idiopathic CTS accompanied with trigger digit admitted to and treated at the Hand Surgery Department of Ningbo No. 6 Hospital from January 1, 2017 to December 31, 2019. Data on patients' gender, age, occupation, course of the disease, menstruation, surgeries, examination-related information, complications, treatment methods, and prognoses during follow-up were recorded and subsequently used to analyze the pathogeneses, clinical characteristics, and treatment.

Results

A total of 74 patients (72 females and 2 males) were included. Among female patients, 51 were postmenopausal and 18 were non-postmenopausal. There were 101 fingers with trigger digit, including 14 patients with trigger digit in both hands, and 115 wrists affected by the CTS. The average course of CTS was 34.5 ± 49.3 months, and that of trigger digit was 10.5 ± 22.4 months. Seventy had both trigger digit and CTS in one hand, while among patients with both hands involved, only 4 had trigger digit or CTS in one hand. Eighty-nine fingers underwent A1 pulley release, and 104 hands underwent carpal tunnel surgery, with steroids being injected under the adventitia of the median nerve during the surgery. All patients who underwent surgeries had I/A-healed incisions, and 14 of them had obvious synovial hyperplasia observed in the carpal tunnel and flexor tendon sheath during surgeries. Follow-up visits, which lasted 3 to 35 months, had an average duration of 1.34 years and included 72 patients. In 63 patients (63/72), the syndrome of tenosynovitis and numbness disappeared and normal hand functions were restored; in 6 patients, the numbness in hands greatly improved and normal hand functions were almost completely restored, while no improvement in numbness of hands and limited hand functions were still observed in 3 patients.

Conclusion

CTS accompanied with trigger digit was more common in postmenopausal females, and the course of CTS was longer than that of trigger digit. CTS and trigger digit were more likely to simultaneously occur in the same hand, while some patients might not have obvious synovial hyperplasia in the carpal tunnel. Surgeries were effective in severe cases.

A Comparison of Histologic and Intraoperative Visual Assessments of Transverse Carpal Ligament During Revision Carpal Tunnel Release

PURPOSE

We sought to determine surgeon-pathologist agreement with respect to distinguishing between a previously undivided transverse carpal ligament (TCL) and scar during revision carpal tunnel release (CTR). Additionally, we aimed to describe the histologic findings of the TCL and flexor tenosynovium during revision CTR.

METHODS

All patients undergoing revision CTR for persistent or recurrent CTS by a single surgeon between 2013 and 2019 were included. An intraoperative assessment was made as to the presence of scar versus a previously undivided TCL by the surgeon. Two pathology specimens (1 consisting of flexor retinaculum and 1 consisting of tenosynovium) were sent for histopathological analysis with hematoxylin-eosin staining. The pathologist's assessment of the flexor retinaculum specimen was categorized as either "ligamentous" if a previously undivided TCL was identified or "nonligamentous" if scar or any other tissue was identified. The surgeon's intraoperative assessment served as the reference standard when comparing the histologic assessment.

RESULTS

A total of 40 patients underwent 46 revision CTRs. The histologic assessment agreed with the surgeon's intraoperative assessment of a previously undivided TCL versus a scar in 30 of 46 (65%) cases. In 12 of 46 (26%) revision cases, the surgeon determined that there was a previously undivided TCL. In these 12 cases, the pathologist identified a ligament 17% of the time.

CONCLUSIONS

Surgeon-pathologist agreement is low with respect to determining previously undivided TCLs versus nonligamentous tissue in the setting of revision CTR. The results of this investigation suggest that pathologists (with limited clinical information) have difficulty confirming the clinical diagnosis of persistent CTS with previously unreleased TCL when using routine hematoxylin-eosin staining. Routine biopsy of the TCL during revision CTR may be of limited clinical utility, as it does not alter the diagnosis or management in these cases.

TYPE OF STUDY/LEVEL OF EVIDENCE

Diagnostic III.

Carpal Tunnel Syndrome: Pathophysiology and Comprehensive Guidelines for Clinical Evaluation and Treatment

In carpal tunnel syndrome (CTS), the median nerve is compressed at the level of the carpal tunnel in the wrist. This entrapment manifests as unpleasant symptoms, such as burning, tingling, or numbness in the palm that extends to the fingers. As the disease progresses, afflicted individuals also report decreased grip strength accompanied by hand weakness and restricted movement. The first half of this review elaborates on CTS pathology by providing readers with a comprehensive understanding of the etiology, relevant anatomy, and disease mechanism.

CTS is considered the most common entrapment neuropathy, affecting around 3-6% of the adult population. Further, CTS prevalence has seen a dramatic increase in the last few decades paralleling the growth of everyday technology usage. Despite how common it is to have CTS, it can be quite challenging for physicians to make a definite diagnosis due to differentials that present with overlapping symptoms. Even more difficult can be deciding on a course of treatment that is the most effective and considerate of patient needs. Thus arises the need for clear clinical direction, and hence we end with a discussion around such guidelines that serve as a starting point toward effective diagnoses and patient treatment.

Evaluation of the Transverse Carpal Ligament in Carpal Tunnel Syndrome by Shear Wave Elastography: A Non-Invasive Approach of Diagnosis and Management

Objectives

The goal of this work is to determine the clinical value of the transverse carpal ligament (TCL) in carpal tunnel syndrome (CTS) for guiding subsequent treatment.

Methods

This study analyzed patients who underwent median nerve (MN) ultrasound (US) examination of the wrist from April 2020 to April 2021. The cross-sectional area and anteroposterior diameter of the MN, as well as the TCL thickness and stiffness, were measured from images. The intra-group and intra-patient subgroup differences were compared using a t-test and a rank test. We also utilized receiver operating characteristic (ROC) curves to diagnose CTS and evaluate the severity.

Results

The final cohort consisted of 120 wrists (bilateral) from 60 samples, evenly balanced across the patient and control groups according to their CTS diagnosis. In the unilateral positive patient subgroup, the MN and TCL of the positive hand were significantly thicker and stiffer than the negative counterparts (both, p &lt; 0.05). The values from the right were also thicker and stiffer than the left (both, p &lt; 0.05) in patients with bilateral CTS. The MN and TCL of the patient group were also significantly thicker and stiffer than those of the control group (both, p &lt; 0.001). For diagnosing CTS, the area under the curve (AUC) of TCL thickness and stiffness at the distal carpal tunnel (DCT) ranged between 0.925 and 0.967. For evaluating CTS severity, we found that the optimal TCL stiffness is sufficient for diagnosing mild and non-mild patient cases (AUC: Emean = 0.757, Emax = 0.779).

Conclusions

Shear wave elastography is therefore an effective method for CTS diagnosis and management.

Prevalence and Subtypes of Tenosynovial Amyloid in Patients Undergoing Carpal Tunnel Release

PURPOSE

The purpose of this study was to determine the prevalence and subtypes of amyloid in tenosynovial biopsies of patients undergoing carpal tunnel release (CTR).

METHODS

A retrospective review was performed involving patients who underwent CTR from June 2020 to July 2021. Prior to this period, a protocol had been established to obtain routine intraoperative tenosynovial biopsies. Tenosynovium was preserved in formalin and stained with Congo red for amyloid. Positive specimens were sent to an external laboratory for confirmation and subtyping by mass spectrometry. Men 50 years or older and women 60 or older were included for analysis. Acute, traumatic, and revision cases were excluded.

RESULTS

Of 185 patients who underwent CTR with tenosynovial biopsy, 54 (29%) demonstrated positive Congo red stain, confirmed by the external laboratory. A subtype analysis revealed wild-type transthyretin (TTR) in 44 patients (80%), mixed wild-type TTR with κ light chains in 1 patient, and hereditary TTR in 1 patient. Patients with positive specimens were significantly older than those who tested negative (77 vs 68 years, respectively), and positivity increased by decade for both sexes. Male sex, atrial fibrillation, and spinal stenosis were significantly more prevalent among positive cases. There were no complications from the biopsies.

CONCLUSIONS

We confirmed evidence of amyloidosis in the tenosynovium of 29% of men 50 years or older and women 60 or older who underwent CTR. The majority demonstrated wild-type TTR. As these patients are at risk of developing cardiomyopathy, there is an opportunity for early detection, monitoring, and interventions known to improve outcomes. Considering the low cost of Congo red staining and the potential value of subtyping with regard to treatment of cardiomyopathy, our findings support routine tenosynovial biopsy during CTR in patients who meet the age criteria.

TYPE OF STUDY/LEVEL OF EVIDENCE

Differential diagnosis or symptom prevalence study II.

T2-weighted MRI defines critical compression in the distal carpal tunnel that is relieved after decompressive surgery

Introduction

Despite Carpal Tunnel Syndrome (CTS) being the most common entrapment neuropathy, its pathophysiology remains debated. Sub-synovial connective tissues (SSCT) within the carpal tunnel are thought to play a role but are poorly characterised. MRI analysis offers potentially novel insights into SSCT characteristics.

Methods

A pilot study of T2-weighted MRI was performed in healthy controls (n=7), and in CTS patients (n=16) pre- and 6 months post-surgical decompression. Image analysis was performed to quantify SSCT cross-sectional area, SSCT signal intensity ratio, and wrist index (depth/width) at distal, middle and proximal wrist landmarks.

Results

Median SSCT signal intensity was lower in the distal carpal tunnel of CTS patients pre-operatively (0.96) compared to controls (1.13; P = 0.008) and normalised post-operatively (1.13, P = 0.001). Median wrist index was also lower in CTS patients pre-operatively (0.60) compared to controls (0.67, P = 0.022), and again normalised post-operatively (0.74, P =0.001). This was attributed to changes in carpal depth in the antero-posterior axis with decompression surgery.

Conclusion

This pilot study successfully demonstrated MRI assessment of SSCT in patients with CTS. The decreased SSCT signal intensities suggest predominant changes at the distal tunnel, potentially indicating reduced SSCT perfusion pre-surgery which normalised post-surgery. Our preliminary findings merit further investigation in a larger cohort.

Plasmin activity promotes amyloid deposition in a transgenic model of human transthyretin amyloidosis

Cardiac ATTR amyloidosis, a serious but much under-diagnosed form of cardiomyopathy, is caused by deposition of amyloid fibrils derived from the plasma protein transthyretin (TTR), but its pathogenesis is poorly understood and informative in vivo models have proved elusive. Here we report the generation of a mouse model of cardiac ATTR amyloidosis with transgenic expression of human TTR^S52P. The model is characterised by substantial ATTR amyloid deposits in the heart and tongue. The amyloid fibrils contain both full-length human TTR protomers and the residue 49-127 cleavage fragment which are present in ATTR amyloidosis patients. Urokinase-type plasminogen activator (uPA) and plasmin are abundant within the cardiac and lingual amyloid deposits, which contain marked serine protease activity; knockout of α₂-antiplasmin, the physiological inhibitor of plasmin, enhances amyloid formation. Together, these findings indicate that cardiac ATTR amyloid deposition involves local uPA-mediated generation of plasmin and cleavage of TTR, consistent with the previously described mechano-enzymatic hypothesis for cardiac ATTR amyloid formation. This experimental model of ATTR cardiomyopathy has potential to allow further investigations of the factors that influence human ATTR amyloid deposition and the development of new treatments.

ATTR amyloidosis causes heart failure through the accumulation of misfolded transthyretin in cardiac muscle. Here the authors report a mouse model of ATTR amyloidosis and demonstrate the involvement of protease activity in ATTR amyloid deposition.

Flexor tenosynovectomy in carpal tunnel syndrome as a screening tool for early diagnosis of amyloidosis

INTRODUCTION

Amyloidosis is a heterogeneous group of diseases that most often presents with advanced cardiac pathology. Another presentation of the disease can include symptoms consistent with carpal tunnel syndrome; however, the true incidence of amyloidosis in patients with carpal tunnel syndrome remains unclear.

METHODS

We performed a retrospective chart review on all patients who underwent an open carpal tunnel release, with tenosynovium biopsy by a single surgeon between 01/2000 and 12/2018. Samples were stored in formalin following hematoxylin-eosin or congo red staining. A total of 199 patients were excluded for incomplete records, and carpal tunnel release performed for traumatic or infectious etiologies. Histologic findings of the attending pathologist were examined and categorized as follows: amyloidosis, fibrous tissue, tenosynovitis/inflammation edematous, benign tenosynovium, and gout.

RESULTS

Exactly 898 open carpal tunnel releases were performed, and 699 patients were included for final analysis. In all patients, biopsies for histology with hematoxylin-eosin (HE) staining were taken; in those HE stains where amylogenic proteins were suspected (73 or 10.4%), a subsequent congo red staining was additionally performed which confirmed the diagnosis of amyloidosis in 10 patients (1.4% of the carpal tunnel procedures). Overall, 10 patients were identified and constituted 1.4% of all HE stains (n = 10/699) and 13.7% of all congo red stains (n = 10/73).

CONCLUSION

Our results suggest that the incidence of amyloidosis in the general CTS patient population may be as high as 1.4% with routine screening by synovial biopsy and the diagnosis should be considered as a potential cause. Level of Evidence: III, retrospective study.

Association between carpal tunnel syndrome and trigger finger: a clinical and electrophysiological study

Background

Carpal tunnel syndrome is a prevalent mononeuropathy. Trigger finger is a flexor stenosing tenosynovitis. The aim of the study was to assess the concomitant occurrence of carpal tunnel syndrome and trigger finger in the same hand among patients presented with idiopathic carpal tunnel syndrome or idiopathic trigger finger. The study included 110 hands (75 patients) presented with carpal tunnel syndrome or trigger finger and 60 asymptomatic hands (46 apparently healthy individuals). Clinical assessment and neurophysiological evaluation were done.

Results

Regarding the presenting clinical complaints, there were 76 hands (69.1%) from 48 patients (64.0%) presented with idiopathic carpal tunnel syndrome. There 34 hands (30.9%) from 27 patients (36.0%) presented with idiopathic trigger finger. Classification of the patients into three groups depending on the final diagnosis: (I) carpal tunnel syndrome group, 57 hands (51.8%) with only carpal tunnel syndrome from 36 patients (48.0%); (II) trigger finger group, 25 hands (22.7%) with only trigger finger from 22 patients (29.3%); and (III) carpal tunnel syndrome with trigger finger group, 28 hands (25.5%) with both conditions from 24 patients (32.0%); and among them, seven patients had contralateral hand carpal tunnel syndrome only. The duration of complaints among the carpal tunnel syndrome with trigger finger group was significantly shorter than that in the other two groups. There were statistically significantly higher values of patient global assessment of hand symptoms and effect of hand symptoms on function and quality of life among the carpal tunnel syndrome with trigger finger group versus the other two groups. There was no statistically significant difference between the carpal tunnel syndrome with trigger finger group versus the carpal tunnel syndrome group regarding different classes of the Padua neurophysiological classification scale. The most common digit to have trigger finger was the middle finger in 19 hands (35.8%).

Conclusions

The concurrent presentation of idiopathic carpal tunnel syndrome and idiopathic trigger finger in the same hand is common. Each of them could be associated with the other one. The symptoms of one of them usually predominate the patient’s complaints. The identification of this association is essential for proper diagnosis and comprehensive management of patients presented with these conditions.

Molecular and Clinical Elucidation of the Mechanism of Action of Steroids in Idiopathic Carpal Tunnel Syndrome

BACKGROUND

Carpal tunnel steroid injection is a nonoperative intervention for the treatment for idiopathic carpal tunnel syndrome (CTS). The antifibrotic, anti-inflammatory, and antiedematous properties of steroids account for their therapeutic effects in the context of CTS; however, their relative contribution has not been clarified.

METHODS

Fibroblasts from subsynovial connective tissues (SSCT) were intraoperatively collected from patients with idiopathic CTS and were incubated with or without the steroid triamcinolone acetonide (TA) for 1, 3, and 7 days; the expression of fibrosis-related genes and inflammatory cytokines was evaluated using quantitative reverse transcription-polymerase chain reaction. A clinical prospective study was conducted with patients who received carpal tunnel TA injections. We performed clinical and electrophysiological evaluations before and 1, 3, and 5 months after TA injection; and we compared the median nerve, flexor tendon, and SSCT areas and the median nerve flattening ratio before and 1 month after TA injection using 3-T magnetic resonance imaging (MRI).

RESULTS

TA induced downregulation of the fibrosis-related genes Col1A1 (collagen type I alpha 1 chain), Col1A2, and Col3A1 but not the inflammation-related genes. The nerve flattening ratio did not change after TA injection according to the MRI-based observation of the median nerve, flexor tendon, and SSCT areas.

CONCLUSIONS

The therapeutic effects of injected TA are apparently mediated by its antifibrotic rather than its anti-inflammatory and antiedematous properties. TA probably alters the properties but not the morphology of SSCT.

LEVEL OF EVIDENCE

Therapeutic Level II. See Instructions for Authors for a complete description of levels of evidence.

Carpal tunnel syndrome treatment and the subsequent alterations in tendon and connective tissue dynamics

BACKGROUND

Carpal tunnel syndrome patients demonstrate diminished motion of the median nerve and fibrotic changes in the subsynovial connective tissue within the carpal tunnel. Currently, there are few prognostic factors to help predict the outcome of commonly performed treatments including surgical carpal tunnel release and corticosteroid injections. This study aimed to non-invasively assess the changes in the dynamic response of the subsynovial tissue relative to tendon motion after the intervention and to correlate this with disease severity.

METHODS

A total of 145 patients with carpal tunnel syndrome were recruited into this study. Clinical and demographic data, electrophysiological severity and dynamic ultrasound images were collected before and after treatment, either by injection or surgery. The relative motion of the subsynovial tissue with the underlying middle finger flexor digitorum superficialis tendon was measured using a speckle tracking algorithm and was expressed as a shear index (SI). Baseline and follow-up data, the association between change in SI and severity, and the role of treatment modality were analyzed and statistically compared.

FINDINGS

Overall, there was a significant increase (more relative motion) after treatment in the mean shear index from 79.9% (±15.4% SD) to 82.9% (±14.8% SD) (p = 0.03). Secondary analyses showed that this change was mostly present in those with mild disease severity undergoing surgery (p = 0.01).

INTERPRETATION

This study shows that the relative subsynovial tissue movement increases in patients after intervention. The present study lays a foundation for future studies to non-invasively assess the role of carpal tunnel dynamics in response to treatment.

The Influence of Transverse Carpal Ligament Thickness on Treatment Decisions for Idiopathic Mild to Moderate Carpal Tunnel Syndrome

PURPOSE

The main cause of carpal tunnel syndrome (CTS) is pathological changes in the flexor synovium, which is a known cause of pressure elevation in the carpal tunnel. The importance of the transverse carpal ligament (TCL) in the pathogenesis of CTS has hitherto been overlooked. However, the TCL significantly affects carpal biomechanics; the TCL is known to affect the carpal bone to a greater extent when intra carpal tunnel pressure is high. In addition, the effect of TCL properties on the progression course of idiopathic CTS is unknown.Therefore, we hypothesized that TCL thickness, measured using ultrasonography, would influence the results of conservative treatment for CTS patients with mild to moderate symptoms. We aimed to investigate the relationship between the ultrasound-measured TCL thickness and idiopathic carpal tunnel conservative treatment surgery rate.

MATERIALS AND METHODS

We analyzed the wrists of 127 patients with mild to moderate symptoms of CTS. The patients were diagnosed on the basis of electrophysiological assessment outcomes, median nerve cross-sectional area in the carpal tunnel, and clinical symptoms. The Boston carpal tunnel questionnaire score was also measured. Patients with a TCL thinner than 1.5 mm were classified into group A (n = 62), and those with a TCL thicker than 1.5 mm were classified into group B (n = 65). Patients with severe symptoms or other diseases were excluded. The patients were initially treated with night splinting after diagnosis. If symptoms were not ameliorated, steroid injection and surgical treatment were performed consecutively. The procedures were determined by a single surgeon.

RESULTS

The mean TCL thickness was 1.51 mm: 0.98 mm in group A and 2.28 mm in group B. The percentages of patients who underwent surgery were 43.0% in group A and 67.7% in group B. Group B was 1.77 times more likely to have surgery, and the interval between diagnosis and surgery and/or steroid injection was shorter. The TCL thickness in group B was also related to cross-sectional area and symptom duration.

CONCLUSIONS

Transverse carpal ligament thickness affects disease progression and may affect treatment efficacy, depending on the treatment method. Transverse carpal ligament thickness may be a criterion for deciding between surgical and conservative treatments based on a thickness threshold of 1.5 mm.

Flexor Tenosynovectomy for Recurrent Carpal Tunnel Syndrome: A Retrospective Case Series of 108 Hands

Background: The etiology of recurrent carpal tunnel syndrome (CTS) is unclear, and outcomes following secondary surgery in this demographic have been poorer than primary surgery. Fibrosis and hypertrophy have been identified in the flexor tenosynovium in these patients. The authors use flexor tenosynovectomy (FTS) for recurrent CTS after primary carpal tunnel release and present a review of these patients. Methods: A retrospective chart review was performed of 108 cases of FTS for recurrent CTS from 1995 to 2015 by 4 attending surgeons at one institution. Demographic information, symptoms, and outcomes were among the data recorded. A phone survey was conducted on available patients where the shortened version of the Disabilities of the Arm, Shoulder and Hand Questionnaire (QuickDASH) and satisfaction were assessed. Results: Average office follow-up was 12 months. Average age was 57.5 years. A total of 104 (96%) reported symptom improvement and 48 (44%) reported complete symptom resolution. Forty patients were available for long-term follow-up at an average 6.75 years postoperatively via phone interview. Average QuickDASH score was 31.2 in these patients. Thirty-six (90%) of 40 patients were initially satisfied at last office visit, and 31 (78%) of 40 were satisfied at average 6.9 years, a maintenance of satisfaction of 86%. Satisfied patients were older (58 years) than unsatisfied patients (51 years). Conclusion: Both long-term satisfaction and QuickDASH scores in our cohort are consistent with or better than published results from nerve-shielding procedures. The authors believe a decrease in both carpal tunnel volume and potential adhesions of fibrotic or inflammatory synovium contributes to the benefits of this procedure. This remains our procedure of choice for recurrent CTS.

Delineation of a new fibrillino-2-pathy with evidence for a role of FBN2 in the pathogenesis of carpal tunnel syndrome

BACKGROUND

Although carpal tunnel syndrome (CTS) is the most common form of peripheral entrapment neuropathy, its pathogenesis remains largely unknown. An estimated heritability index of 0.46 and an increased familial occurrence indicate that genetic factors must play a role in the pathogenesis.

METHODS AND RESULTS

We report on a family in which CTS occurred in subsequent generations at an unusually young age. Additional clinical features included brachydactyly and short Achilles tendons resulting in toe walking in childhood. Using exome sequencing, we identified a heterozygous variant (c.5009T>G; p.Phe1670Cys) in the fibrillin-2 (FBN2) gene that co-segregated with the phenotype in the family. Functional assays showed that the missense variant impaired integrin-mediated cell adhesion and migration. Moreover, we observed an increased transforming growth factor-β signalling and fibrosis in the carpal tissues of affected individuals. A variant burden test in a large cohort of patients with CTS revealed a significantly increased frequency of rare (6.7% vs 2.5%-3.4%, p<0.001) and high-impact (6.9% vs 2.7%, p<0.001) FBN2 variants in patient alleles compared with controls.

CONCLUSION

The identification of a novel FBN2 variant (p.Phe1670Cys) in a unique family with early onset CTS, together with the observed increased frequency of rare and high-impact FBN2 variants in patients with sporadic CTS, strongly suggest a role of FBN2 in the pathogenesis of CTS.

Ultrasound-Guided Hydrodissection With Corticosteroid Injection in the Treatment of Carpal Tunnel Syndrome: A Pilot Study

OBJECTIVES

Corticosteroid injections can provide (temporary) relief in patients with mild to moderate carpal tunnel syndrome (CTS). Hydrodissection as part of an injection has been associated with positive clinical outcomes but data for CTS so far has been scarce. This study is designed to assess patient tolerance and secondarily provide pilot data on the added effect of hydrodissection.

METHODS

Twenty CTS patients were randomized to an ultrasound-guided betamethasone injection with hydrodissection (5 mL) or without (2 mL). Patient tolerance was assessed directly after intervention and patient-reported outcome after 4 and 24 weeks. Intra-group data were compared using Wilcoxon Signed Rank and inter-group with Wilcoxon rank-sum tests.

RESULTS

Tolerance and pain scores did not differ between the two groups. Symptom scores decreased in both groups, but to a lesser extent in the hydrodissection group with a mean difference of -0.8 versus -1.5 in the control group at 4 weeks (P = .02). At 6 months, this difference was no longer present (P = .81). No statistically significant differences were found between the hydrodissection and control groups in the function or pain scores at follow-up at either time point.

CONCLUSION

After injection, both symptomatic and functional scores improved, but the hydrodissected group did not show additional improvement. Data presented can be used to support larger studies to assess the value of hydrodissection in CTS management.

Genetic Risk of Trigger Finger: Results of a Genomewide Association Study

BACKGROUND

Trigger finger, or stenosing tenosynovitis, is one of the most common conditions affecting the hand, yet its pathophysiology remains poorly understood, and genetic association studies of trigger finger are lacking. The purpose of this study was to identify single-nucleotide polymorphisms associated with trigger finger through a genomewide approach.

METHODS

The authors performed a case-control genomewide association study in the Partners HealthCare Biobank. Single-nucleotide polymorphism- and gene-based association analyses were carried out after quality control, imputation, and filtering.

RESULTS

Among 942 trigger finger cases and 24,472 controls, the authors tested 7,846,471 single-nucleotide polymorphisms for association with trigger finger. In the single-nucleotide polymorphism-based analysis, a single locus on chromosome 13 corresponding to KLHL1 met the genomewide significance threshold (lead single-nucleotide polymorphism rs59988404; OR, 1.74; 95 percent CI, 1.47 to 2.07; p = 1.99 × 10). After mapping, gene-based analysis demonstrated a significant association with POLE2 (p = 7.53 × 10) on chromosome 14. Among trigger finger cases, rs59988404 genotype was significantly associated with the total number of trigger finger procedures performed (p = 0.026).

CONCLUSIONS

In the first reported genomewide association study of trigger finger, the authors report significant associations of KLHL1 and POLE2 with risk of trigger finger. The authors' results may help to elucidate the pathophysiology of trigger finger and facilitate an individualized, precision-medicine treatment approach.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Risk, III.

Mutations in COMP cause familial carpal tunnel syndrome

Carpal tunnel syndrome (CTS) is the most common peripheral nerve entrapment syndrome, affecting a large proportion of the general population. Genetic susceptibility has been implicated in CTS, but the causative genes remain elusive. Here, we report the identification of two mutations in cartilage oligomeric matrix protein (COMP) that segregate with CTS in two large families with or without multiple epiphyseal dysplasia (MED). Both mutations impair the secretion of COMP by tenocytes, but the mutation associated with MED also perturbs its secretion in chondrocytes. Further functional characterization of the CTS-specific mutation reveals similar histological and molecular changes of tendons/ligaments in patients’ biopsies and the mouse models. The mutant COMP fails to oligomerize properly and is trapped in the ER, resulting in ER stress-induced unfolded protein response and cell death, leading to inflammation, progressive fibrosis and cell composition change in tendons/ligaments. The extracellular matrix (ECM) organization is also altered. Our studies uncover a previously unrecognized mechanism in CTS pathogenesis.

Familial carpal tunnel syndrome (CTS) is common, but causal genes are not characterized. Here the authors report two CTS-related mutations in two large families that impair secretion of COMP in tenocytes, leading to ER stress-induced unfolded protein response, inflammation and fibrosis in patients and mouse models.

Assessing the Performance of Morphologic and Echogenic Features in Median Nerve Ultrasound for Carpal Tunnel Syndrome Diagnosis

OBJECTIVES

To assess the feasibility of using ultrasound (US) image features related to the median nerve echogenicity and shape for carpal tunnel syndrome (CTS) diagnosis.

METHODS

In 31 participants (21 healthy participants and 10 patients with CTS), US images were collected with a 30-MHz transducer from median nerves at the wrist crease in 2 configurations: a neutral position and with wrist extension. Various morphologic features, including the cross-sectional area (CSA), were calculated to assess the nerve shape. Carpal tunnel syndrome commonly results in loss of visualization of the nerve fascicular pattern on US images. To assess this phenomenon, we developed a nerve-tissue contrast index (NTI) method. The NTI is a ratio of average brightness levels of surrounding tissue and the median nerve, both calculated on the basis of a US image. The area under the curve (AUC) from a receiver operating characteristic curve analysis and t test were used to assess the usefulness of the features for differentiation of patients with CTS from control participants.

RESULTS

We obtained significant differences in the CSA and NTI parameters between the patients with CTS and control participants (P < .01), with the corresponding highest AUC values equal to 0.885 and 0.938, respectively. For the remaining investigated morphologic features, the AUC values were less than 0.685, and the differences in means between the patients and control participants were not statistically significant (P > .10). The wrist configuration had no impact on differences in average parameter values (P > .09).

CONCLUSIONS

Patients with CTS can be differentiated from healthy individuals on the basis of the median nerve CSA and echogenicity. Carpal tunnel syndrome is not manifested in a change of the median nerve shape that could be related to circularity or contour variability.

Subsynovial connective tissue development in the rabbit carpal tunnel

The carpal tunnel contains the digital flexor tendons and the median nerve, which are embedded in a unique network of fibrovascular interconnected subsynovial connective tissue (SSCT). Fibrous hypertrophy of the SSCT and subsequent adaptations in mechanical response are found in patients with carpal tunnel syndrome (CTS), but not much is known about the development of the SSCT. This observational study describes the morphological development of SSCT using histology and ultramicroscopy in an animal model at four time points between late‐term fetuses through adulthood. A transition is seen between 3 days and 6 weeks post‐partum from a dense solid SSCT matrix to a complex multilayered structure connected with collagenous fibrils. These preliminary data show a developmental pattern that matches an adaptive response of the SSCT to loading and motion. Understanding the anatomical development aids in recognizing the pathophysiology of CTS and supports research on new therapeutic approaches.

Shear wave elastography of the median nerve: A mechanical study

BACKGROUND

Shear wave elastography (SWE) shows promise in peripheral neuropathy evaluation but has potential limitations due to tissue size and heterogeneity. We tested SWE sensitivity to elasticity change and the effect of probe position in a median nerve cadaver model.

METHODS

Ten specimens were used to measure median nerve elasticity under increasing loads using SWE and indentation. Measurements were compared using repeated-measures analysis of variance.

RESULTS

Indentation and SWE-based longitudinal nerve elasticity increased with tensile loading (P < .01), showing a similar relationship. Acquisition in a transverse plane showed lower values compared with longitudinal measurements, mostly under higher loads (P = .03), as did postdissection elasticity (P = .02). Elasticity did not change when measured proximal to the carpal tunnel.

CONCLUSIONS

Longitudinal SWE is sensitive to changes in median nerve elasticity. Measuring elasticity of peripheral nerves noninvasively could elucidate intra-neural pathology related to compression neuropathies, and proof to be of added value as a diagnostic or prognostic tool.

Sonographic Findings Associated With Carpal Tunnel Syndrome

PURPOSE

The purpose of this study was to identify associations between the clinical manifestations of carpal tunnel syndrome (CTS) and the sonographic measurements of the median nerve in the carpal tunnel. We hypothesized that sonographic changes in the median nerve from proximal to distal along the carpal tunnel would be associated with symptom severity scores.

METHODS

We report on 38 patients with clinical signs and symptoms of CTS in a prospective investigation. Subjects underwent sonographic evaluation with measurement of median nerve cross-sectional area (CSA) at 3 locations: the level of the pronator quadratus, pisiform, and hamate. In addition, we measured dimensions of the carpal tunnel at the levels of the pisiform (inlet) and hamate (outlet). Finally, we recorded maximal thickness of the transverse carpal ligament (TCL). Patients underwent routine clinical evaluation and 31 patients had electrodiagnostic examination. Patients completed the Levine Katz Questionnaire (LKQ) to characterize severity of clinical symptoms. Each clinician was blinded to symptom severity scores. Pearson correlation coefficients were calculated to measure the relationship between LKQ score and sonographic measures.

RESULTS

Median nerve CSA decreased over the course of the carpal tunnel from proximal to distal in 30 of 38 wrists. A greater absolute change in CSA of the median nerve over the course of the carpal tunnel between the pisiform and the hamate as well as between the pronator quadratus and the hamate correlated with increased severity of clinical symptoms. Increased thickening of the TCL also correlated with greater symptom severity scores.

CONCLUSIONS

Changes in CSA of the median nerve as well as thickening of the TCL correlate with CTS severity.

TYPE OF STUDY/LEVEL OF EVIDENCE

Diagnostic II.

Hand Pain and Sensory Deficits: Carpal Tunnel Syndrome

The Academy of Orthopaedic Physical Therapy and the Academy of Hand and Upper Extremity Physical Therapy have an ongoing effort to create evidence-based clinical practice guidelines (CPGs) for orthopaedic and sports physical therapy management and prevention of musculoskeletal impairments described in the World Health Organization's International Classification of Functioning, Disability and Health (ICF). This particular guideline focuses on hand pain and sensory deficits in carpal tunnel syndrome. J Orthop Sports Phys Ther 2019;49(5):CPG1-CPG85. doi:10.2519/jospt.2019.0301.

A genome-wide association analysis identifies 16 novel susceptibility loci for carpal tunnel syndrome

Carpal tunnel syndrome (CTS) is a common and disabling condition of the hand caused by entrapment of the median nerve at the level of the wrist. It is the commonest entrapment neuropathy, with estimates of prevalence ranging between 5-10%. Here, we undertake a genome-wide association study (GWAS) of an entrapment neuropathy, using 12,312 CTS cases and 389,344 controls identified in UK Biobank. We discover 16 susceptibility loci for CTS with p < 5 × 10^-8. We identify likely causal genes in the pathogenesis of CTS, including ADAMTS17, ADAMTS10 and EFEMP1, and using RNA sequencing demonstrate expression of these genes in surgically resected tenosynovium from CTS patients. We perform Mendelian randomisation and demonstrate a causal relationship between short stature and higher risk of CTS. We suggest that variants within genes implicated in growth and extracellular matrix architecture contribute to the genetic predisposition to CTS by altering the environment through which the median nerve transits.

Expression of vitamin D receptor in the subsynovial connective tissue in women with carpal tunnel syndrome

Studies suggest that low vitamin D levels are associated with carpal tunnel syndrome. We aimed to evaluate whether level of vitamin D receptor expression in the endothelial cells of the subsynovial connective tissue is associated with clinical features of carpal tunnel syndrome. We obtained the subsynovial connective tissue from 52 women with carpal tunnel syndrome during surgery and performed immunohistochemical analysis of vitamin D receptors in the endothelial cells of the subsynovial connective tissue. We explored correlation of vitamin D receptor expression with clinical features of carpal tunnel syndrome, such as age, symptom duration, symptom severity and electrophysiological severity. Diverse range of vitamin D receptor expression was observed. Vitamin D receptor expression was independently associated with distal motor latency. This suggests that vitamin D receptor expression may be associated with disease progression, as prolonged distal motor latency reflects severity of the disease. Further studies are necessary to explore the role of vitamin D and vitamin D receptors in patients with carpal tunnel syndrome.

LEVEL OF EVIDENCE

IV.

Ultrasound elastography for carpal tunnel pressure measurement: A cadaveric validation study

Carpal tunnel pressure is a key factor in the etiology of carpal tunnel syndrome. Numerous approaches have been conducted to measure carpal tunnel pressure. However, most techniques are invasive and take time and effort. We have developed an innovative approach to noninvasively assess the tunnel pressure by using the ultrasound surface wave elastography (USWE) technique. In a previous study it was shown that the shear wave speed in a tendon increased linearly with increasing tunnel pressure enclosed the tendon in a simple tendon model. This study aimed to examine the relationship between the carpal tunnel pressure and the shear wave speeds inside and outside the carpal tunnel in a human cadaveric model. The result showed that the shear wave speed inside the carpal tunnel increased linearly with created carpal tunnel pressure, while the shear wave speed outside the carpal tunnel remained constant. These findings suggest that noninvasive measurement of carpal tunnel pressure is possible by measuring the shear wave speed in the tendon. After fully establishing this technology and being applicable in clinic, it would be useful in the diagnosis of carpal tunnel syndrome. For that reason, further validation with this technique in both healthy controls and patients with carpal tunnel syndrome is required. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:477-483, 2018.

The biomechanics of subsynovial connective tissue in health and its role in carpal tunnel syndrome

Carpal Tunnel Syndrome (CTS) is the most common surgically treated problem in the hand. Aside from the neuropathy itself, the most common findings are fibrosis of the subsynovial connective tissue (SSCT) and increased intra carpal tunnel pressure. Normally, the SSCT is a multilayer tissue interspersed among the carpal tendons and nerve. As the tendons move, successive SSCT layers are recruited, forming a gliding unit and providing a limit to differential movement. Exceeding this limit, damages the SSCT as has been shown in both cadavers and animal models. This damage leads to a non-inflammatory response with progressive fibrosis and nerve ischemia leaving the SSCT more susceptible to injury. Although the direct consequences for patients are not fully understood, ultrasound research shows that this fibrosis restricts median nerve displacement during tendon loading. This article aims to provide insights into the mechanical properties of SSCT described so far and place it in the context of CTS pathophysiology. A theoretical damage model concerning the SSCT is proposed showing a chain of events and vicious cycles that could lead to the nerve compression as it is found in CTS. Although not complete, this model could explain the pathophysiological pathway of idiopathic CTS.

Can flexor tenosynovectomy and microsurgical epineurectomy improve clinical outcomes following open carpal tunnel release?

INTRODUCTION

The purpose of this study was to comparatively evaluate the clinical outcomes of open carpal tunnel release with or without flexor tenosynovectomy and epineurectomy for the treatment of idiopathic carpal tunnel syndrome.

METHODS

In this prospective single-blinded study, 61 wrists of 47 patients randomized to open carpal tunnel release without (Group-1) or with (Group-2) flexor tenosynovectomy and microsurgical epineurectomy. Physical examination including Phalen and Tinel's signs, visible thenar atrophy, two-point discrimination, and grip strength measurement was performed. Visual Analogue Scale (VAS), Quick Disability of Arm Shoulder Hand (DASH) Questionnaire, Symptoms Severity Scale, Functional Status Scale, and electrophysiological study were assessed.

RESULTS

The increase in the grip strength and Quick Disability of Arm Shoulder Hand Questionnaire score were significantly better in flexor tenosynovectomy and microsurgical epineurectomy group. The average pre-operative two-point discrimination was 6.3 ± 2 mm in Group-1 and 5.8 ± 1.7 mm in Group-2. Post-operatively at the end of 12 months, the mean two-point discrimination was measured as 5.9 ± 1.6 mm in Group-1 and 5.6 ± 1.3 mm in Group-2. When we compare the two groups according to the changes in VAS, Quick-DASH, symptoms severity scale, and functional status scale, only Quick-DASH score improvement was significantly better in Group-2 (p < 0.05). Improvements in VAS, symptoms severity scale, and functional status scale did not differ significantly.

CONCLUSION

We do not recommend routine flexor tenosynovectomy and microsurgical epineurectomy during open carpal tunnel release in patients with idiopathic carpal tunnel syndrome.

Relaxin Modulates the Expression of MMPs and TIMPs in Fibroblasts of Patients with Carpal Tunnel Syndrome

PURPOSE

The aim of this study was to investigate the anti-fibrotic effect of relaxin in subsynovial fibroblasts activated by transforming growth factor beta (TGF-β).

MATERIALS AND METHODS

To test the anti-fibrotic effect of an adenovirus-relaxin construct (Ad-RLN) on subsynovial fibroblasts in vitro, cells from subsynovial connective tissue of patients with carpal tunnel syndrome were activated with TGF-β1 and exposed to Ad-RLN (as a therapeutic gene) or adenovirus-lacZ construct (as a marker gene) for four hours. Subsynovial fibroblast cultures without adenoviral exposure served as controls.

RESULTS

We observed induction of gene expressions of collagen I, III and IV, as well as the abatement of alpha-smooth muscle actin (a-SMA) synthesis, Smad2 phosphorylation, and fibronectin at the protein level, in comparison to controls. In addition, protein expressions of matrix metalloproteinase (MMP) I was significantly induced, whereas the protein expressions of tissue inhibitor of metalloproteinases (TIMP) I and IV were reduced due to relaxin expression.

CONCLUSION

RLN prevents excessive synthesis of extracellular matrix by reducing the expressions of its components, such as fibronectin, a-SMA, and phosphorylated Smad2, by increasing the expression of MMPs; and by decreasing the expression of TIMPs.

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.

Comparison of Median Nerve Cross-sectional Area on 3-T MRI in Patients With Carpal Tunnel Syndrome

This study correlated morphologic abnormalities of idiopathic carpal tunnel syndrome (CTS) with the severity of CTS using 3-T magnetic resonance imaging (MRI). The relationship of the severity of CTS and the cross-sectional area of the median nerve (CSA) was assessed at several levels. Seventy wrists of 35 patients (27 women and 8 men) with unilateral idiopathic CTS underwent nerve conduction study and 3-T MRI of the wrist. The CSA at 4 levels (distal radioulnar joint, body of scaphoid, tubercule of scaphoid, and hook of hamate) and the thickness of the transverse carpal ligament at 3 levels in both affected and unaffected hands were measured using 3-T MRI and correlated with the severity of CTS assessed with distal motor latency. The CSA in the affected hand at the scaphoid body level was significantly higher than in the unaffected hand. The CSA at the scaphoid body level was positively correlated with distal motor latency in the affected hand. The CSA in the affected hand at the scaphoid tubercule level was significantly lower than in the unaffected hand. The CSA had a negative correlation with distal motor latency at the scaphoid tubercule level. The CSA at the distal radioulnar joint and the hamate hook was not significantly different between the affected hand and the unaffected hand. The CSA at the distal radioulnar joint level and hook level were not correlated significantly with distal motor latency in the affected hand. The mean CSA of the affected hand at the scaphoid body level was highest in 4 levels. [Orthopedics. 2017; 40(1):e77-e81.].

Work Practices and Histopathological Changes in the Tenosynovium in Carpal Tunnel Syndrome in Men

The aim of this prospective study was to assess whether the fibrous thickening of the carpal tunnel tenosynovium is influenced by working practices. We did this by investigating 50 men (58 hands) with idiopathic carpal tunnel syndrome, who were undergoing carpal tunnel decompression.

Occupational history, including vibration tool exposure, and presence of callosities and/or ingrained dirt on hands was recorded at the time of surgery. The flexor tenosynovium was biopsied, and assessed histologically by an observer blinded to occupational history.

Occupational group, age, weight and smoking showed no significant association with fibrous tenosynovial thickening. There was also no significant association between fibrous tenosynovial thickening and the presence of hand callosities/in-grained dirt or regular use of vibration tools. Thus no association was found between heavy occupational hand usage and the development of fibrous tenosynovial thickening around tendons within the carpal tunnel.

Assessment of Median Nerve Mobility by Ultrasound Dynamic Imaging for Diagnosing Carpal Tunnel Syndrome

Carpal tunnel syndrome (CTS) is the most common peripheral neuropathy and is characterized by median nerve entrapment at the wrist and the resulting median nerve dysfunction. CTS is diagnosed clinically as the gold standard and confirmed with nerve conduction studies (NCS). Complementing NCS, ultrasound imaging could provide additional anatomical information on pathological and motion changes of the median nerve. The purpose of this study was to estimate the transverse sliding patterns of the median nerve during finger movements by analyzing ultrasound dynamic images to distinguish between normal subjects and CTS patients. Transverse ultrasound images were acquired, and a speckle-tracking algorithm was used to determine the lateral displacements of the median nerve in radial-ulnar plane in B-mode images utilizing the multilevel block-sum pyramid algorithm and averaging. All of the averaged lateral displacements at separate acquisition times within a single flexion–extension cycle were accumulated to obtain the cumulative lateral displacements, which were curve-fitted with a second-order polynomial function. The fitted curve was regarded as the transverse sliding pattern of the median nerve. The R² value, curvature, and amplitude of the fitted curves were computed to evaluate the goodness, variation and maximum value of the fit, respectively. Box plots, the receiver operating characteristic (ROC) curve, and a fuzzy c-means clustering algorithm were utilized for statistical analysis. The transverse sliding of the median nerve during finger movements was greater and had a steeper fitted curve in the normal subjects than in the patients with mild or severe CTS. The temporal changes in transverse sliding of the median nerve within the carpal tunnel were found to be correlated with the presence of CTS and its severity. The representative transverse sliding patterns of the median nerve during finger movements were demonstrated to be useful for quantitatively estimating median nerve dysfunction in CTS patients.

Comparison of the histopathological findings of patients with diabetic and idiopathic carpal tunnel syndrome

PURPOSE

This study is aimed to investigate whether there are any histopathological differences between diabetic and idiopathic carpal tunnel syndromes.

METHODS

The biopsy specimens were taken from transverse carpal ligament (TCL), tenosynovium adjacent to median nerve and epineurium of median nerve and evaluated in 47 patients (21 diabetic and 26 idiopathic) who were diagnosed with carpal tunnel syndrome (CTS) and treated surgically with open carpal tunnel release. Fibroblast proliferation, fibrosis, perivascular inflammation, oedema, vascular proliferation and vascular wall thickness were determined and scored in all specimens.

RESULTS

There weren't any histopathological abnormalities in TCL specimens of both groups. Synovial hyperplasia, fibrosis and perivascular inflammation were not observed in tenosynovial analysis of both groups. Diabetic CTS patients, when compared with idiopathic CTS patients, had higher rates of synovial edema (idiopathic CTS 57 %, diabetic CTS 87 %), vascular proliferation (idiopathic CTS 30.8 %, diabetic CTS 90.5 %) and increased vascular wall thickness (idiopathic CTS 11.5 %, diabetic CTS 90.5 %). There was no oedema, fibrosis and perivascular inflammation of the epineurium in specimens of either group. But increases in vascular proliferation (idiopathic CTS 7.7 %, diabetic CTS 71.4 %) and vascular wall thickness (idiopathic CTS 3.8 %, diabetic CTS 71.4 %) was seen in the epineurium of diabetic patients and these differences were statistically significant (p < 0.05).

CONCLUSION

Because of the severe synovial and epineurial histopathological abnormalities and inadequate neural regeneration capacity, surgical open carpal tunnel decompression should be planned earlier in diabetic CTS patients. Further studies should be considered to evaluate the histopathological features of diabetic CTS patients early in the course of the disease.

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.

The role of ultrasound in the diagnosis and management of carpal tunnel syndrome: a new paradigm

Carpal tunnel syndrome (CTS) is the most common entrapment neuropathy, affecting 9% of women, and it is responsible for significant morbidity and occupational absence. Clinical assessment is used for initial diagnosis and nerve conduction (NC) studies are currently the principal test used to confirm the diagnosis. Sensitivity of NC studies is >85% and specificity is >95%. There is now good evidence that US can be used as an alternative to NC studies to diagnose CTS. US can assess the anatomy of the median nerve and also identify pathology of the surrounding structures that may compress the nerve. Median nerve enlargement (cross-sectional area ≥10 mm(2) at the level of the pisiform bone or tunnel inlet) is the most commonly used parameter to diagnose CTS on US, and sensitivity has been reported to be as high as 97.9% using this parameter. US may also be used to guide therapeutic corticosteroid injection into the carpal tunnel--thus avoiding median nerve injury--and to objectively monitor the response to treatment. There is now sufficient evidence to propose a new paradigm for the diagnosis of CTS that incorporates US. US is proposed as the initial diagnostic test in CTS based on similar sensitivity and specificity to NC studies but higher patient acceptability, lower cost and additional capability to assess carpal tunnel anatomy and guide injection.

Comparative study on the stiffness of transverse carpal ligament between normal subjects and carpal tunnel syndrome patients

The purpose of this study was to compare the stiffness of the transverse carpal ligament (TCL) between healthy volunteers and carpal tunnel syndrome (CTS) patients using sonoelastography. We studied 17 healthy volunteers (four men, 13 women; range 37-84 years) and 18 hands of 13 patients with CTS (three men, ten women; range 41-79 years). Thickness and elasticity of the TCL were evaluated by sonoelastography. Elasticity was estimated by strain ratio of an acoustic coupler, which has a standardized elasticity as a reference medium, to the TCL (AC/T strain ratio). The AC/T strain ratios of the healthy volunteers and the CTS patients were 6.0 and 8.1, respectively (p = 0.030). The AC/T strain ratio showed a positive correlation with the duration of symptoms in the CTS patients (p = 0.035, r = 0.50). We concluded that increased stiffness of the TCL could be one of the causes for CTS.

A comparison between ultrasonographic, surgical and histological assessment of tenosynovits in a cohort of idiopathic carpal tunnel syndrome patients

Carpal tunnel syndrome (CTS) may be caused by subclinical tenosynovitis which may be detected by ultrasonography (US). The objective of this study is to investigate whether ultrasonography has a place in the workup of idiopathic CTS patients. Therefore, we investigated the prevalence of tenosynovitis and its association with the clinical outcome of surgery. A cohort of 31 consecutive idiopathic CTS patients (33 wrists) who were a candidate for carpal tunnel release (CTR) surgery was assessed using greyscale ultrasonography (GSUS) and power Doppler ultrasonography (PDUS). Peroperatively, tenosynovitis was evaluated macroscopically by the surgeon. Tissue samples from areas macroscopically suspected for tenosynovitis were taken for histological evaluation. The clinical outcome of the operation was assessed after 6 months and if applicable alternative diagnoses for the CTS were proposed. US tenosynovitis (OMERACT) was detected preoperatively in 58 % of the wrists. Peroperatively, macroscopic tenosynovitis was detected visually in 88 % of the wrists. Histological evaluation demonstrated a limited influx of lymphocytes indicative of a mild chronic inflammatory response in 19 %. Non-specific reactive changes were observed in 78 % of the cases. Ultrasonographically defined tenosynovitis was associated with an OR of 2.81 (95 % CI 0.61-13) for responding well to surgery. Most cases of ultrasonographic and peroperatively defined tenosynovitis were classified by histology as reactive changes. The presence of ultrasonographic tenosynovitis might be associated with a better clinical outcome of surgery.

The incidence of trigger digit after carpal tunnel release in diabetic and nondiabetic patients

PURPOSE

To determine whether patients with diabetes mellitus (DM) are at greater risk for developing postoperative trigger digits (TD) after carpal tunnel release (CTR) compared with patients without diabetes.

METHODS

A retrospective review of our electronic medical records identified all patients who had undergone CTR by a single hand fellowship-trained surgeon from September 2007 through May 2012. For patients with DM, additional information regarding method of disease control and hemoglobin A1c (HbA1c) level was recorded. We recorded HbA1c levels 3 months before and 3 months after CTR. The location and time to development of postoperative, new-onset TD were recorded for each case. Statistical testing included chi-square or Student t test and multivariate logistic regression analysis.

RESULTS

Of the 1,217 CTRs, 214 had DM. Of the 1,003 CTRs in cases without DM, 3% developed TD within 6 months of CTR and 4% within 1 year of CTR, compared with 8% and 10%, respectively, for diabetic cases. A multivariate regression analysis revealed DM as a significant risk factor for developing TD after CTR at 6 and 12 months. We found no significant association between HbA1c level at the time of CTR and the likelihood of developing TD.

CONCLUSIONS

The incidence of TD after CTR was higher in the diabetic population compared with a nondiabetic cohort. The presence of DM rather than its severity was the most important factor for developing TD. Preoperative counseling for patients with DM undergoing CTR may alert them to the possibility of developing TD.

TYPE OF STUDY/LEVEL OF EVIDENCE

Prognostic IV.