Relationship of relaxin hormone and thumb carpometacarpal joint arthritis

Relaxin as a treatment for musculoskeletal fibrosis: What we know and future directions

Fibrotic changes in musculoskeletal diseases arise from the abnormal buildup of fibrotic tissue around the joints, leading to limited mobility, compromised joint function, and diminished quality of life. Relaxin (RLX) attenuates fibrosis by accelerating collagen degradation and inhibiting excessive extracellular matrix (ECM) production. Further, RLX disrupts myofibroblast activation by modulating the TGF-β/Smads signaling pathways, which reduces connective tissue fibrosis. However, the mechanisms and effects of RLX in musculoskeletal pathologies are emerging as increasing research focuses on relaxin's impact on skin, ligaments, tendons, cartilage, joint capsules, connective tissues, and muscles. This review delineates the actions of relaxin within the musculoskeletal system and the challenges to its clinical application. Relaxin shows significant potential in both in vivo and in vitro studies for broadly managing musculoskeletal fibrosis; however, challenges such as short biological half-life and sex-specific responses may pose hurdles for clinical use.

Significance of plasma relaxin-2 levels in patients with primary hypertension and type 2 diabetes mellitus

BACKGROUND

This study aimed to evaluate plasma relaxin‑2 (RLN-2) levels in patients with arterial hypertension (AH) and their relationships with clinical and laboratory parameters.

METHODS

The study involved 106 hypertensive patients, including 55 with type 2 diabetes mellitus (T2DM), and 30 control subjects. Plasma RLN-2 levels were measured using an enzyme-linked immunosorbent assay kit.

RESULTS

RLN-2 levels were reduced in patients with AH compared to healthy volunteers (p < 0.001), and hypertensive patients with T2DM had lower RLN-2 levels than those without impaired glucose metabolism (p < 0.001). RLN‑2 was negatively correlated with systolic blood pressure (SBP) (p < 0.001) and anthropometric parameters such as body mass index (BMI; p = 0.027), neck (p = 0.045) and waist (p = 0.003) circumferences, and waist-to-hip ratio (p = 0.011). RLN‑2 also had inverse associations with uric acid levels (p = 0.019) and lipid profile parameters, particularly triglycerides (p < 0.001) and non-HDL-C/HDL‑C (p < 0.001), and a positive relationship with HDL‑C (p < 0.001). RLN‑2 was negatively associated with glucose (p < 0.001), insulin (p = 0.043), HbA1c (p < 0.001), and HOMA-IR index (p < 0.001). Univariate binary logistic regression identified RLN‑2 as a significant predictor of impaired glucose metabolism (p < 0.001).

CONCLUSIONS

Decreased RLN-2 levels in patients with AH and T2DM and established relationships of RLN‑2 with SBP and parameters of glucose metabolism and lipid profile suggest a diagnostic role of RLN‑2 as a biomarker for AH with T2DM.

Knee Laxities Changes with Sex-steroids throughout the Menstrual Cycle Phases in Athlete and Non-athlete Females

Objective:  Our study investigated changes of knee laxities in athletes and non-athletes females and relationship between knee laxity and sex-steroid at menstrual cycle phases. Methods:  Forty six healthy females, twenty four athletes and twenty two non-athletes not on hormone contraceptive pills, had no previous knee injuries and with regular menstrual cycles for 3 consecutive months, participated in the study. Medial and lateral knee laxities were determined by varus-valgus tests at follicular, ovulatory and luteal phases. Serum level of relaxin, estrogen, progesterone and testosterone were determined by ELISA and radioimmunoassay. Results:  Knee laxities in athletes and non-athletes at 0° and 20° flexion were the highest in luteal phase with non-athletes possess greater laxity than athletes. Positive correlation between progesterone and relaxin levels with knee laxities were observed. Meanwhile, the levels of both hormones were highest in the luteal phase. Conclusion:  Increased medial and lateral knee laxities in athletes and non-athletes associated with high serum progesterone and relaxin levels in luteal phase may contribute toward increased risk of non-contact knee injury. However, lower knee laxity in athletes than non-athletes suggest that exercise could be a protective factor.

Minimally Invasive Treatment of Trapeziometacarpal Osteoarthritis: Results of a Blinded Randomized Controlled Trial

BACKGROUND

Surgical therapy for widespread first carpometacarpal (CMC1) arthritis permanently alters the physiologic anatomy of the hand. The injection of autologous substances into the thumb saddle joint could achieve temporary pain relief and delay surgical indications. This trial aimed to compare the pain-reducing effects of autologous fat and/or platelet-rich plasma (PRP) with saline 0.9% in the infiltration therapy of carpometacarpal arthritis of the thumb (CMC1 arthritis).

METHODS

A blinded, randomized controlled trial was conducted. Ninety-five patients with CMC1 arthritis were included in the study. The mean follow-up period was 2 years. Participants were injected with 1.5 mL of autologous fat, PRP, autologous fat and PRP, or 0.9% saline solution into the CMC1 joint, depending on the group allocation. The primary outcome of this study was the evaluation of pain reduction in each treatment group.

RESULTS

The combination of fat and PRP was the only treatment that resulted in a significantly greater reduction in pain compared with 0.9% saline ( P = 0.003). Similarly, fat and PRP in combination was the only therapy group to achieve clinically relevant Quick Disabilities of Arm, Shoulder, and Hand score reduction, and the only group that showed a significantly better Medical Outcomes Study 36-Item Short-Form Health Survey score than 0.9% saline ( P = 0.016). No major complications were noted.

CONCLUSIONS

In addition to pain reduction, the combination of autologous fat and PRP yields a relevant improvement in hand function and a corresponding improvement in quality of life. This treatment seems to be a viable and safe alternative to short-acting glucocorticoids.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, II.

The role of relaxin in anterior cruciate ligament injuries: a systematic review

OBJECTIVE

Anterior cruciate ligament (ACL) tears are exceedingly common among the athletic population and are seen with higher incidence in females. Observational studies have noted peak ACL tear rates in the luteal phase of the menstrual cycle, a time in which the hormone relaxin peaks in serum concentration.

METHODS

A systematic review of the literature was performed. Inclusion criteria specified all prospective and retrospective studies which included the role of relaxin in the pathogenesis of ACL tears.

RESULTS

Six studies met inclusion criteria yielding 189 subjects from clinical studies and 51 in vitro samples. Included studies found that ACL samples exhibit selective relaxin binding. When pre-treated with estrogen prior to relaxin exposure, female ACL tissue samples exhibit increased expression of collagen degrading receptors.

CONCLUSION

Relaxin displays binding specificity to the female ACL and increased serum concentrations are correlated with increased ACL tear rates in female athletes. Further research is needed in this area.

LEVEL OF EVIDENCE

V.

Selective Denervation for the Thumb Carpometacarpal Joint: Clinical Outcome and Comparison Based on Eaton Stage

PURPOSE

Various operative treatment options for advanced thumb carpometacarpal (CMC) joint arthritis have been presented without a definite surgical guideline. Selective denervation is a less invasive method for thumb CMC arthritis. However, it is unclear whether the clinical outcome varies with the stage of thumb CMC arthritis. This study aimed to evaluate the effectiveness of selective denervation on CMC arthritis for pain relief and functional outcome and to determine whether selective denervation depends on the stage of thumb CMC arthritis.

METHODS

We evaluated 29 thumbs of 28 patients with thumb CMC arthritis treated with selective denervation. The disease stage was determined with the classification system described by Eaton. The denervation was performed in the articular branches of the palmar cutaneous branch of the median nerve, lateral antebrachial cutaneous nerve, and superficial branch of radial nerve. The clinical outcomes were evaluated using the visual analog scale (VAS) and Disabilities of the Arm, Shoulder, and Hand (DASH) scores, along with evaluation of the improvement in both postoperative range of motion and strength recovery.

RESULTS

The mean duration of follow-up was 24 months (range, 18-48 months). The average VAS and DASH scores decreased from 6.1 to 1.3 and from 54.3 to 24.1, respectively. The range of motion during palmar abduction and opposition of the metacarpophalangeal joint improved with an increase in mean value from 44.1 to 53.7 degrees, and the Kapandji score increased from 7.2 to 9.2, respectively. The grip and key pinch strengths increased from mean preoperative values of 14.3 and 3.1 kg to 27.1 and 6.2 kg, respectively, as measured at the 12-month follow-up. The rate of change in the VAS and DASH scores was significantly higher in stages I to III than in stage IV ( P = 0.01, P < 0.01, respectively).

CONCLUSION

The selective denervation for thumb CMC arthritis was effective in pain relief and functional recovery with several advantages, including less invasive procedure, quick recovery time, and regaining of strength. The clinical outcomes were more effective in the early-stage group (Eaton stages I and II) compared with the advance-stage group (Eaton stages III and IV).

Radiological Influencing Factors in the Diagnosis of Painful Habitual Instability of the Thumb Basal Joint as a Precursor of Carpometacarpal Arthritis of the Thumb-A Retrospective Study

BACKGROUND

Painful habitual instability of the thumb basal joint (PHIT) is a rarely diagnosed condition that can severely impair hand function. Furthermore, it can increase the risk of developing carpometacarpal arthritis of the thumb (CMAOT). Clinical examination and radiographic imaging provide the foundation for a correct diagnosis, but early detection is still challenging. We investigated two objective, radiographically obtainable parameters as potential risk factors for PHIT.

METHODS

Clinical data and radiographic images of 33 patients suffering from PHIT were collected and compared to those of 35 people serving as the control group. The two main objectives, the slope angle and the bony offset of the thumb joint, were gathered from the X-rays and statistically analyzed.

RESULTS

The analysis showed no differences between the study and the control group concerning the slope angle. Gender and the bony offset, on the other hand, had a significant influence. Female sex and higher offset values were associated with an increased risk of PHIT.

CONCLUSIONS

The results of this study prove a connection between a high bony offset and PHIT. We believe this information can be valuable in early detection and will allow more efficient treatment of this condition in the future.

Dynamic stabilization home exercise program for treatment of thumb carpometacarpal osteoarthritis: A prospective randomized control trial

STUDY DESIGN

Randomized control trial.

INTRODUCTION

Thumb carpometacarpal (CMC) osteoarthritis (OA) is a common cause of hand pain and disability. Standard conservative therapy (SCT) for thumb CMC OA includes an orthosis and instruction in joint protection, adaptive equipment, and pain relieving modalities. The dynamic stability home exercise (HE) program is complementary conservative therapy designed to strengthen the stabilizing muscles of the thumb CMC.

PURPOSE OF THE STUDY

To investigate whether the addition of HE to SCT (SCT+HE) was more effective at reducing pain and disability in thumb CMC OA compared to SCT alone.

METHODS

The study compared 2 groups: SCT and SCT+HE. The SCT group received SCT with in-home pain management instructions, joint protection strategies with adaptive equipment, and a hand-based thumb-spica orthosis. The SCT+HE group received HE program instructions for adductor stretching and opponens and first dorsal interosseous strengthening in addition to SCT. Our primary outcome measure was the numerical rating scale (NRS) with secondary outcome measures of QuickDASH (shortened Disabilities of the Arm, Shoulder and Hand questionnaire), range of motion, grip strength, and pinch strength. Outcome measurements were assessed at first visit, 6 weeks, and 6 months.

RESULTS

There was no statistical difference between the 2 groups for NRS and QuickDASH at 6 weeks (P = .28 and P = .36, respectively) or 6 months (P = .52 and P = .97, respectively). However, there was a statistically significant decrease in NRS and QuickDASH scores at 6 weeks and 6 months within both groups.

CONCLUSIONS

Both SCT and SCT+HE are effective at reducing pain and disability in OA of the thumb CMC joint. Neither therapy program was superior to the other at improving NRS or QuickDASH scores at 6-week or 6-month follow-up.

Indications for Ligament Reconstruction and Suspensionplasty in Carpometacarpal Arthroplasty

The trapeziometacarpal joint is the site that most commonly develops arthritis in the hand. Although optimal treatment requires careful consideration of history, physical examination, radiographs, and functional goals, many patients ultimately undergo surgical intervention. Several described techniques and approaches are highlighted in this article, especially pertaining to carpometacarpal arthroplasty with ligament reconstruction and tendon interposition. The rationale, benefit, and evidence for each approach are discussed and the author's preferred technique is described.

Anatomy and Biomechanics of the Thumb Carpometacarpal Joint

This review discusses the anatomy and biomechanics of the thumb carpometacarpal (CMC) joint. This articulation between the trapezium and first metacarpal is integral for opposition and other complex movements necessary for pinch and grasp maneuvers. Fortunately, this joint is well equipped to handle the extreme forces imposed by these movements, as it is stabilized by an elaborate arrangement of ligaments and muscles. Without this stability, thumb subluxation would occur with loading during pinch and grasp, and human prehension would be impossible. Understanding the interactions occurring within this joint is essential for adequately treating pathology arising in this crucial joint.

Immunoexpression of Relaxin and Its Receptors in Stifle Joints of Dogs with Cranial Cruciate Ligament Disease

Simple Summary

Spontaneous cranial cruciate ligament rupture is one of the most frequently encountered joint diseases in dogs, often leading to disabling chronic progressive osteoarthritis. The cause of the progressive intra-articular collagen matrix degradation, leading to tear and mechanical failure, is unknown. A variety of contributing factors has been found, however, an initiating mediator triggering the collagen degrading cascade remains to be identified. Our finding of strong relaxin- and relaxin receptor expression on intra-articular target tissues, such as on ligament fibrocytes and synovial membranes, renders relaxin a candidate for pathogenetic involvement, for collagen lysis, and progressive ligament fiber disruption. If confirmed, this opens the way for medical treatment of the disease in its early stages. In addition, further proof of relaxin involvement in canine osteoarthritis and ligament rupture would constitute a useful spontaneous animal model for human disease.

Abstract

The etiology of spontaneous cranial cruciate ligament rupture in dogs is unknown despite being one of the most impacting orthopedic diseases in dogs. Numerous studies have contributed to the understanding of a multifactorial pathogenesis, this, however, without identifying a pivotal link to explain progressive collagen degeneration and osteoarthritic changes. In human medicine, recent reports have identified relaxin as a triggering factor in ligament ruptures in knee and metacarpal joints. We thus hypothesized that relaxin might also play a role in canine cruciate ligament rupture. Relaxin’s primarily known property is connective tissue remodeling through collagenolysis. We therefore investigated relaxin and its cognate receptors LGR7/LGR8 in 18 dogs with cranial cruciate ligament disease (CCLD) and compared them to a group of dogs with normal stifle joints. Applying immunohistochemistry (IHC), double immunofluorescence (dIF), and western blot analysis (WB), we found strong and significantly increased expression of both relaxin and its receptors in ruptured cruciate ligaments, and in synovial membranes. Pattern of immuno-staining on dIF strongly suggests relaxin binding to primed receptors and activation of signaling properties, which in turn may have affected collagen matrix metabolism. Thus, in canine cranial cruciate ligament disease, relaxin/receptor signaling may be a primary trigger for collagen fiber degradation and collagen lysis, eventually followed by ligament rupture.

Patient satisfaction with the CMC controller: A cohort study

STUDY DESIGN

Cohort study.

INTRODUCTION

The evidence specific to understanding patient satisfaction, preference and the effects on occupational performance using a CMC orthosis is sparse.

PURPOSE OF THE STUDY

The main purpose of this study was to determine patient satisfaction, aspects of the orthotic preference, and the effect on pain and function of the CMC Controller Plus neoprene orthotic device.

METHODS

This research was conducted at two outpatient clinics located in Pennsylvania and Florida during 2019. The subjects of this study included any individuals referred to one of two participating hand therapy facilities with either a primary or secondary diagnosis of thumb CMC joint arthritis or present with this diagnosis as a comorbidity. The CMC Controller Plus orthosis (Hely & Weber) was provided to each patient by the treating therapist at no cost to the patient after the patient agreed to take part in the study. None of the patients received hand therapy treatment for the CMC pain; the only intervention provided was the CMC Controller Plus.

RESULTS

The CMC Controller Plus orthosis improved the patients' functional status and reduced their pain. The effect size for the change in function was large (1.29) compared to the effect size for the reduction in pain which approached moderate at 0.49.

DISCUSSION

The CMC Controller Plus orthosis improved the patient's functional status by 52% and reduced their pain by 29%.

CONCLUSION

The results were both statistically and clinically significant.

Greater presence of receptors for relaxin in the ligamentum teres of female infants who undergo open reduction for developmental dysplasia of the hip

BACKGROUND

While many factors involved in the etiology of developmental dysplasia of the hip (DDH), one of which is the hormone relaxin. Relaxin concentrations in patients with DDH may lead to pathodynamic changes during hip development by altering the physiological nature of the ligament, as well as by long-term exposure to relaxin during pregnancy. Our objective in this study was to determine the number of relaxin receptors in the ligamentum teres and their role in causing DDH.

METHODS

We identified 26 infants between birth and 3 years of age who had undergone open reduction for DDH between 2010 and 2012. 12 hips of 12 miss abortus fetus between 20 to 35 weeks of gestation were used as control group. Specimens obtained from two groups were stained with Relaxin-2 antibody, and the amount of staining for relaxin receptors was determined using an ordinal H score.

RESULTS

The mean (SD) H scores of infants with DDH were significantly higher than those of controls: 215 (59) versus 52 (48); P = 0.00; 95% CI. Statistically significant difference between the two groups in terms of gender was not found.

CONCLUSION

As a result, increased number of relaxin receptors in the ligamentum teres could be a risk factor for DDH.

LEVEL OF EVIDENCE

Level 2, Prospective comparative study.

High body mass index is associated with increased risk for osteoarthritis of the first carpometacarpal joint during more than 30 years of follow-up

Introduction

Osteoarthritis (OA) of the first carpometacarpal (CMC-1) joint is a common hand disorder with symptoms including pain and weakness of the thumb. Previous studies have associated high BMI with OA of weight-bearing joints, whereas studies regarding non-weight-bearing joints have shown conflicting results. Thus, the aim of this study was to investigate the influence of overweight and obesity on incident OA of the CMC-1 joint.

Method

During 1974 to 1992, 33 346 participants aged 26–61 years were included in the population-based cohort Malmö Preventive Project. Endpoint data were retrieved from Swedish national registers until end of 2018. Sex-stratified Cox regression models adjusted for potential confounders were calculated using BMI as a continuous variable and stratified for normal weight, overweight and obesity.

Results

Median follow-up was 36 years for men and 32 years for women. A one-unit increment of BMI was independently associated with incident OA of the CMC-1 joint in men (HR 1.12; 95% CI 1.09 to 1.15, p<0.001) and women (HR 1.05; 95% CI 1.03 to 1.08, p<0.001). Stratifying for BMI groups, obesity was independently associated with OA of the CMC-1 joint in men (HR 3.57; 95% CI 2.68 to 4.77, p<0.001) and women (HR 1.98; 95% CI 1.44 to 2.73, p<0.001).

Conclusion

High BMI and obesity are major risk factors for OA of the CMC-1 joint. The association was stronger among men but could be demonstrated also among women. Future studies are warranted to clarify underlying pathophysiological mechanisms for this association, enabling identification of potential therapeutic targets related to obesity in order to prevent the development of OA of the CMC-1 joint.

Is Thumb Proprioception Decreased in Patients With Trapeziometacarpal Joint Osteoarthritis?

Proprioception is thought to be essential for normal joint homeostasis, and its decreased function has been associated with an increased risk of joint diseases. However, only a few studies have been performed on the association between proprioceptive function in the trapeziometacarpal joint (TMCJ) and osteoarthritis. The purpose of this study was to compare TMCJ proprioceptive function in elderly women with radiographic TMCJ osteoarthritis relative to age-matched control women without osteoarthritis. We enrolled 19 women (mean age, 66 years) with symptomatic, radiographic Eaton and Littler grade 2, 3, and 4 TMCJ osteoarthritis and 19 age-matched control women without osteoarthritis. We evaluated thumb proprioception by using a joint-position reproduction test and compared the reposition error (RE) between the groups. We carried out a multivariate analysis for factors potentially associated with increased RE, such as age, body mass index, hand dominance, the presence of diabetes, pain level, and the presence of osteoarthritis. Also, a logistic regression analysis was performed for factors associated with the occurrence of TMCJ osteoarthritis. Patients with TMCJ osteoarthritis had greater RE than did the control patients in the joint-position reproduction test at 20°, 30°, and 40° of thumb palmar abduction. The multivariate analysis indicated that increased RE was associated with the presence of osteoarthritis, but not with the other factors assessed. The occurrence of TMCJ osteoarthritis was associated with increased RE at 20°, 30°, and 40° of thumb palmar abduction. This study showed that decreased proprioceptive function was associated with the presence of osteoarthritis in the TMCJ, although the causality remains unknown. Further studies on the role of proprioception in the pathogenesis of TMCJ osteoarthritis and the potential role of its training for disease prevention or treatment are required.

Hybrid LPG-FBG Based High-Resolution Micro Bending Strain Sensor

Sensitivity and reliability are essential factors for the practical implementation of a wearable sensor. This study explores the possibility of using a hybrid high-resolution Bragg grating sensor for achieving a fast response to dynamic, continuous motion and Bragg signal pattern monitoring measurement. The wavelength shift pattern for real-time monitoring in picometer units was derived by using femtosecond laser Bragg grating processing on an optical wave path with long-period grating. The possibility of measuring the demodulation system's Bragg signal pattern on the reflection spectrum of the femtosecond laser precision Bragg process and the long-period grating was confirmed. By demonstrating a practical method of wearing the sensor, the application of wearables was also explored. It is possible to present the applicability of sophisticated micro transformation measurement applications in picometer units.

Autologous fat transplantation for the treatment of trapeziometacarpal joint osteoarthritis

Rhizarthrosis is a progressive and disabling pathology affecting the carpometacarpal joint. It’s very common in elderly patients and typically affects postmenopausal women. The diagnosis of rhizarthrosis is mainly made by using different physical examination tests and by evaluating the type of pain and it’s then confirmed by imaging. Over the last few years increasing attention has been devoted to the assessment of new treatment techniques for rhizarthrosis. In this context intra-articular injection of autologous fat grafting for cartilage regeneration has demonstrated promising results in experimental settings as an alternative to open surgery procedures. The aim of this study was therefore to sum up the evidences available so far on autologous fat grafting as an emerging treatment for patients affected by carpometacarpal rizarthrosis. An electronic literature research was carried out on Pubmed, Google Scholars and Cochrane Library using “fat grafting”, “fat graft”, “adipose”, “fat transfer” and “lipoaspirate” as search terms. Authors believe autologous fat grafting is an interesting technique, that hand surgeon should keep in mind especially in early stages of rhizarthrosis were pain has not been solved with non-surgical treatment.

Pregnancy-Related Ligamentous Laxity Mimicking Dynamic Scapholunate Instability: A Case Report

CASE

A 29-year-old woman presented with spontaneous, isolated, total palmar scaphoid subluxation in the left hand approximately 6 weeks postpartum. She had a positive Watson scaphoid shift test, with an easily subluxable and reducible scaphoid unilaterally. She was diagnosed with scapholunate ligamentous laxity with dynamic instability. Approximately 4 months after stopping lactation, she had complete resolution of the scapholunate subluxation; there was no recurrence of symptoms over the next 5 years of follow-up.

CONCLUSION

Women can have manifestations of pregnancy and lactation-related ligamentous laxity, including scapholunate instability, which may spontaneously resolve upon cessation of lactation.

Thumb Basal Joint Arthritis

The thumb basal joint is the second most common site of osteoarthritis in the hand, and osteoarthritis of this joint can contribute to painful movement and debilitating function. To achieve a high degree of prehensile and manipulative function, this highly mobile joint is constrained by both the saddle morphology of the trapezium and a stout complement of ligamentous constraints. The disease proceeds progressively with several wear patterns. Substantial new biomechanical and longitudinal clinical studies have changed some of the prevailing opinions on the process of serial degenerative changes. Diagnosis is made with a thorough clinical examination and radiographic staging, as described by Eaton and Littler. Thumb basal joint arthritis can be initially managed with medications, orthoses, and steroid injections; however, it frequently progresses despite these interventions. Surgical management commonly consists of trapeziectomy with or without interposition or suspension, arthroplasty with implant, volar ligament reconstruction, osteotomy, or arthrodesis; none of these techniques has been proved to be superior to the others.

Comparison of Computed Tomography Articular Surface Geometry of Male Versus Female Thumb Carpometacarpal Joints

BACKGROUND

Given the predilection of first carpometacarpal (CMC) joint osteoarthritis in women compared with men, we aim to determine the differences in first CMC joint surface geometry and congruence between young healthy males and females.

METHODS

Wrist computed tomographic scan data of 11 men and 11 women aged 20 to 35 years were imported into 3-dimensional software programs. The first metacarpal and the trapezium were aligned in a standardized position according to landmarks at key points on Gaussian and maximum curvature maps. Measurements of joint congruence and surface geometry were analyzed, including joint space volume, distance between the bones at the articular surface edges, area of the joint space, and radii of curvature in the radial-ulnar and volar-dorsal planes.

RESULTS

The mean thumb CMC articular space volume was 104.02 ± 30.96 mm³ for females and 138.63 ± 50.36 mm³ for males. The mean first metacarpal articular surface area was 144.9 ± 10.9 mm² for females and 175.4 ± 25.3 mm² for males. After normalizing for size, the mean thumb CMC articular space volume was 119.4 ± 24.6 mm³ for females and 117.86 ± 28.5 mm³ for males. There was also no significant difference for the articular space volume, articular surface distances, articular space, and mean radii of curvatures.

CONCLUSIONS

This study found that there are sex differences in the first CMC joint articular volume without normalizing for size; however, there are no sex differences in first CMC joint articular volume, curvature characteristics, or joint congruence of young, healthy patients after normalizing for joint size.

Weaker Functional Pinch Strength Is Associated With Early Thumb Carpometacarpal Osteoarthritis

BACKGROUND

The thumb carpometacarpal (CMC) joint orchestrates pinch in its various positions, and thumb CMC osteoarthritis (OA) is a major source of orthopaedic morbidity. Self-reported pain, weakness, and physical examination may not correspond to radiographic findings when diagnosing early thumb CMC OA. Weakness is a prominent feature of the disease, but little evidence exists to quantify self-reported loss of strength with time, or to compare weakness with that of a nonarthritic population during early disease.

QUESTIONS/PURPOSES

We asked: (1) Is pinch strength in subjects with early thumb CMC OA less than that in asymptomatic control subjects; and (2) weakness in which pinch position (key, tripod, or tip pinch) has the strongest association with early OA diagnosis?

METHODS

For this case-control study, we recruited 23 subjects who were asymptomatic and 91 with early OA for comprehensive history, physical examination, strength measurements, pain surveys, and radiographic evaluation. We used multivariate logistic regression to quantify the association between declining pinch strength and early OA diagnosis after controlling for age, sex, and BMI. This analysis was performed for three different pinch positions (key, tripod, and tip pinch) to evaluate which measurement was most closely associated with diagnosis.

RESULTS

Pinch strength was less in patients with early thumb CMC OA. Key pinch had the most robust association with OA diagnosis, in which a 20% decrease in key pinch strength from the control subjects' baseline was associated with a 10% increase in the OA diagnosis (95% CI, 3%-16%; p = 0.004). This had a stronger association with OA diagnosis than tip pinch, in which a 20% decrease in strength was associated with a 6% increase in early CMC OA (95% CI, 1.0%-11%; p = 0.031). Tripod pinch also was associated to a lesser extent; a 20% reduction in tripod pinch led to a 5% increase in OA (95% CI, 1.3%-9%; p = 0.048).

CONCLUSIONS

Decreasing pinch strength, especially key pinch, is associated with early CMC arthritis before the development of extensive radiographic disease.

CLINICAL RELEVANCE

Weakness in pinch strength, especially key pinch, is an important feature in the pathogenesis of early CMC OA and may appear before radiographic disease is present or advanced. These findings suggest a role for intervention in early disease for promoting nonoperative joint protection and strengthening, and designing surgical procedures aimed to delay or prevent clinical and radiographic progression.

Thumb carpometacarpal joint congruence during functional tasks and thumb range-of-motion activities

Joint incongruity is often cited as a possible etiological factor for the high incidence of thumb carpometacarpal (CMC) joint osteoarthritis (OA) in older women. There is evidence suggesting that biomechanics plays a role in CMC OA progression, but little is known about how CMC joint congruence, specifically, differs among different cohorts. The purpose of this in vivo study was to determine if CMC joint congruence differs with sex, age, and early stage OA for different thumb positions. Using CT data from 155 subjects and a congruence metric that is based on both articular morphology and joint posture, we did not find any differences in CMC joint congruence with sex or age group, but found that patients in the early stages of OA exhibit lower congruence than healthy subjects of the same age group.

Evaluation of Radiographic Instability of the Trapeziometacarpal Joint in Women With Carpal Tunnel Syndrome

PURPOSE

To determine whether median nerve dysfunction measured by electrophysiologic studies in carpal tunnel syndrome (CTS) is associated with thumb trapeziometacarpal (TMC) joint instability.

METHODS

We evaluated 71 women with CTS and 31 asymptomatic control women. Patients with generalized laxity or TMC joint osteoarthritis were excluded. We classified the electrophysiologic severity of CTS based on nerve conduction time and amplitude and assessed radiographic instability of the TMC joint based on TMC joint stress radiographs. We compared subluxation ratio between patients with CTS and controls and performed correlation analysis of the relationship between the electrophysiologic grade and subluxation ratio.

RESULTS

Thirty-one patients were categorized into the mild CTS subgroup and 41 into the severe CTS subgroup. There was no significant difference in subluxation ratio between the control group and CTS patients or between the control group and CTS subgroup patients. Furthermore, there was no significant correlation between electrophysiologic grade and subluxation ratio.

CONCLUSIONS

This study demonstrated that patients with CTS did not have greater radiographic TMC joint instability compared with controls, and suggests that TMC joint stability is not affected by impaired median nerve function. Further studies could investigate how to better evaluate proprioceptive function of TMC joint and whether other nerves have effects on TMC joint motor/proprioceptive function, to elucidate the relationship between neuromuscular control of the TMC joint, its stability, and its progression to osteoarthritis.

TYPE OF STUDY/LEVEL OF EVIDENCE

Diagnostic II.

Male and female differences in musculoskeletal disease

Gender differences exist in the presentation of musculoskeletal disease, and recognition of the differences between men and women's burden of disease and response to treatment is key in optimizing care of orthopaedic patients. The role of structural anatomy differences, hormones, and genetics are factors to consider in the analysis of differential injury and arthritic patterns between genders.

In vivo recruitment patterns in the anterior oblique and dorsoradial ligaments of the first carpometacarpal joint

The anterior oblique ligament (AOL) and the dorsoradial ligament (DRL) are both regarded as mechanical stabilizers of the thumb carpometacarpal (CMC) joint, which in older women is often affected by osteoarthritis. Inferences on the potential relationship of these ligaments to joint pathomechanics are based on clinical experience and studies of cadaveric tissue, but their functions has been studied sparsely in vivo. The purpose of this study was to gain insight into the functions of the AOL and DRL using in vivo joint kinematics data. The thumbs of 44 healthy subjects were imaged with a clinical computed tomography scanner in functional-task and thumb range-of-motion positions. The origins and insertion sites of the AOL and the DRL were identified on the three-dimensional bone models and each ligament was modeled as a set of three fibers whose lengths were the minimum distances between insertion sites. Ligament recruitment, which represented ligament length as a percentage of the maximum length across the scanned positions, was computed for each position and related to joint posture. Mean AOL recruitment was lower than 91% across the CMC range of motion, whereas mean DRL recruitment was generally higher than 91% in abduction and flexion. Under the assumption that ligaments do not strain by more than 10% physiologically, our findings of mean ligament recruitments across the CMC range of motion indicate that the AOL is likely slack during most physiological positions, whereas the DRL may be taut and therefore support the joint in positions of CMC joint abduction and flexion.

Detection of relaxin receptor in the dorsoradial ligament, synovium, and articular cartilage of the trapeziometacarpal joint

Basilar thumb osteoarthritis (OA) is postulated to occur due to ligament attenuation of the trapeziometacarpal (TM) joint. Relaxin is a peptide hormone, which loosens ligaments before childbirth, through remodeling of the extracellular matrix via upregulation of matrix metalloproteases (MMPs). We postulated that relaxin family peptide receptor 1 (RXFP-1), the receptor for circulating relaxin, was present in tissues of the TM joint. Ligaments and synovium were sampled from 15 patients during surgery for TM arthritis. We obtained trapezial cartilage from two autopsy donors and four patients. Tissues were fixed, paraffin embedded, and sectioned at 5 µm, then were immunostained for RXFP-1, as well as MMP-1, and MMP-13, using rabbit anti-human polyclonal antibodies. Eight DRL samples showed positive immunostaining for relaxin receptor, with 14/15 positively stained in synovium. Greater staining was seen in specimens obtained from women with more severe TM arthritis. Trapezial cartilage demonstrated receptor staining within chondrocytes in the middle and deep zones. Immunostaining for MMPs co-localized with relaxin receptor staining. Relaxin receptors are present at the ligament, cartilage, and synovium of the TM joint, indicating that it is a potential target for relaxin. This suggests that circulating relaxin may impact joint stability. The role of relaxin in cartilage and synovium may be related to its role in collagen regulation as a possible tissue response to OA.

Development of a biomimetic hand exotendon device (BiomHED) for restoration of functional hand movement post-stroke

Significant functional impairment of the hand is common among stroke survivors and restoration of hand function should be prioritized during post-stroke rehabilitation. The goal of this study was to develop a novel biomimetic device to assist patients in producing complex hand movements with a limited number of actuators. The Biomimetic Hand Exoskeleton Device (BiomHED) is actuated by exotendons that mimic the geometry of the major tendons of the hand. Ten unimpaired subjects and four chronic stroke survivors participated in experiments that tested the efficacy of the system. The exotendons reproduced distinct spatial joint coordination patterns similar to their target muscle-tendon units for both subject groups. In stroke survivors, the exotendon-produced joint angular displacements were smaller, but not significantly different, than those of unimpaired subjects [Formula: see text]. Even with limited use of the BiomHED, the kinematic workspace of the index finger increased by 63%-1014% in stroke survivors. The device improved the kinematics of the tip-pinch task in stroke survivors and resulted in a significant reduction in the fingertip-thumb tip distance ( 17.9 ±15.3 mm). This device is expected to enable effective "task-oriented" training of the hand post-stroke.