The morphology of the thumb carpometacarpal joint does not differ between men and women, but changes with aging and early osteoarthritis

What is the most important mechanical factor involved in trapeziometacarpal osteoarthritis development? A sensitivity analysis based on biomechanical modelling

Few studies consider the variability of the model parameters. This study aimed to perform a sensitivity analysis of a trapeziometacarpal joint model, by performing 675 finite element simulations built from the combination of different morphologies, joint passive stiffness, and grip strategies to estimate the joint pressure. Pressure variability was significantly more affected by morphology than grip strategy and joint passive stiffness. The effect of morphology and grip strategy on joint pressure was significant. A significant correlation between the trapezium dorso-volar curvature and the joint pressure was found. Morphology seems more important than the other parameters to estimate joint contact pressure correctly.

Morphology of the scaphotrapeziotrapezoid joint: A multi-domain statistical shape modeling approach

The scaphotrapeziotrapezoid (STT) joint is involved in load transmission between the wrist and thumb. A quantitative description of baseline STT joint morphometrics is needed to capture the variation of normal anatomy as well as to guide staging of osteoarthritis. Statistical shape modeling (SSM) techniques quantify variations in three-dimensional shapes and relative positions. The objectives of this study are to describe the morphology of the STT joint using a multi-domain SSM. We asked: (1) What are the dominant modes of variation that impact bone and articulation morphology at the STT joint, and (2) what are the morphometrics of SSM-generated STT joints? Thirty adult participants were recruited to a computed tomography study of normal wrist imaging and biomechanics. Segmentations of the carpus were converted to three-dimensional triangular surface meshes. A multi-domain, particle-based entropy system SSM was used to quantify variation in carpal bone shape and position as well as articulation morphology. Articular surface areas and interosseous proximity distributions were calculated between mesh vertex pairs on adjacent bones within distance (2.0 mm) and surface-normal angular (35°) thresholds. In the SSM, the first five modes of variation captured 76.2% of shape variation and contributed to factors such as bone scale, articular geometries, and carpal tilt. Median interosseous proximities-a proxy for joint space-were 1.39 mm (scaphotrapezium), 1.42 mm (scaphotrapezoid), and 0.61 mm (trapeziotrapezoid). This study quantifies morphological and articular variations at the STT joint, presenting a range of normative anatomy. The range of estimated interosseous proximities may guide interpretation of imaging-derived STT joint space.

The Female Thumb Carpometacarpal Joint: Motion and Force Changes Due to Arthritis and Surgical Intervention

Thumb carpometacarpal (CMC) osteoarthritis (OA) has been one of the most common locations of hand OA. CMC OA disproportionately occurs in females over males. In severe cases, surgical intervention may be needed. However, to determine the effects of surgical treatment, normative, pre-, and postsurgery function must be understood. The goals of this work were to compare the thumb motion and force abilities of older healthy (OH) females without CMC OA to those of females with CMC OA and who received ligament reconstruction with tendon interposition (LRTI) surgery at time points presurgery, 3- and 6-months postsurgery. On average, CMC OA participants 3- and 6-months postsurgery showed 35.6% and 32.9% less overall metacarpal motion compared to presurgery, 31.9% and 29.1% less than OH, and exhibited altered motion. Metacarpal flexion/extension and abduction/adduction ranges were 51.9 deg and 43.4 deg for OH, 52.9 deg and 40.3 deg presurgery, 39.9 deg and 33.5 deg at 3-months, and 42.6 deg and 32.7 deg at 6-months postsurgery. On average, participants had increased force generation at 6-months postsurgery compared to presurgery, and 20% of participants returned to the level of OH females. These data sets highlight changes in thumb metacarpal movement and thumb force generation due to disease and surgical intervention. This work has the ability to support both surgeons and patients through improved outcome assessments as well as additional data to inform the decision process on intervention.

Radiomics signature of osteoarthritis: Current status and perspective

Osteoarthritis (OA) is one of the fast-growing disability-related diseases worldwide, which has significantly affected the quality of patients' lives and brings about substantial socioeconomic burdens in medical expenditure. There is currently no cure for OA once the bone damage is established. Unfortunately, the existing radiological examination is limited to grading the disease's severity and is insufficient to precisely diagnose OA, detect early OA or predict OA progression. Therefore, there is a pressing need to develop novel approaches in medical image analysis to detect subtle changes for identifying early OA development and rapid progressors. Recently, radiomics has emerged as a unique approach to extracting high-dimensional imaging features that quantitatively characterise visible or hidden information from routine medical images. Radiomics data mining via machine learning has empowered precise diagnoses and prognoses of disease, mainly in oncology. Mounting evidence has shown its great potential in aiding the diagnosis and contributing to the study of musculoskeletal diseases. This paper will summarise the current development of radiomics at the crossroads between engineering and medicine and discuss the application and perspectives of radiomics analysis for OA diagnosis and prognosis.

The translational potential of this article

Radiomics is a novel approach used in oncology, and it may also play an essential role in the diagnosis and prognosis of OA. By transforming medical images from qualitative interpretation to quantitative data, radiomics could be the solution for precise early OA detection, progression tracking, and treatment efficacy prediction. Since the application of radiomics in OA is still in the early stages and primarily focuses on fundamental studies, this review may inspire more explorations and bring more promising diagnoses, prognoses, and management results of OA.

Estimation of radiographic joint space of the trapeziometacarpal joint with computed tomographic validation

Purpose

Joint space width (JSW) is a common metric used to evaluate joint structure on plain radiographs. For the hand, quantitative techniques are available for evaluation of the JSW of finger joints; however, such techniques have been difficult to establish for the trapeziometacarpal (TMC) joint. This study aimed to develop a validated method for measuring the radiographic joint space of the healthy TMC joint.

Approach

Computed tomographic scans were taken of 15 cadaveric hands. The location of a JSW analysis region on the articular surface of the first metacarpal was established in 3D space and standardized in a 2D projection. The standardized region was applied to simulated radiographic images. A correction factor was defined as the ratio of the CT-based and radiograph-based joint space measurements. Leave-one-out validation was used to correct the radiograph-based measurements. A t-test was used to evaluate the difference between CT-based and corrected radiograph-based measurements (α = 0.05 ).

Results

The CT-based and radiograph-based measurements of JSW were 3.61 ± 0.72    mm and 2.18 ± 0.40    mm , respectively. The correction factor for radiograph-based joint space was 1.69 ± 0.41 . Before correction, the difference between the CT-based and radiograph-based joint space was 1.43 mm [95% CI: 0.99 - 1.86    mm ; p < 0.001 ]. After correction, the difference was - 0.11    mm [95% CI: - 0.63 - 0.41    mm ; p = 0.669 ].

Conclusions

Corrected measurements of radiographic TMC JSW agreed well with CT-measured JSW. With in-vivo validation, the developed methodology has potential for automated and accurate radiographic measurement of TMC JSW.

Basal osteotomy of the first metacarpal using patient-specific guides and instrumentation: biomechanical and 3D CT-based analysis

INTRODUCTION

The aim of this study was to investigate the radiological outcomes of proximal closing metacarpal extension osteotomies using patient-specific guides and instruments (PSI) in early-stage trapeziometacarpal osteoarthritis to gain further insight into the joint loading surface and the benefits of the procedure.

METHODS

In a prospective observational study, nine patients were included between 11/2020 and 12/2021, undergoing a total of ten proximal metacarpal extension osteotomies for basal thumb osteoarthritis. Computer-assisted surgical planning was performed using computed tomography (CT) and three-dimensional (3D) segmentation, allowing the fabrication of 3D-printed PSIs for surgical treatment. Inclusion criteria were a 1-year follow-up by CT to assess postoperative correction of the positional shift of the first metacarpal (MC1) and the location of peak loads compared with the preoperative situation.

RESULTS

Radiographic analysis of the peak loading zone revealed a mean displacement on the articular surface of the trapezius of 0.4 mm ± 1.4 mm to radial and 0.1 mm ± 1.2 mm to palmar, and on the articular surface of the MC1 of 0.4 mm ± 1.4 mm to radial and 0.1 mm ± 1.2 mm to dorsal.

CONCLUSION

There were trends indicating that a flatter pressure distribution and a dorsal shift of the peak loading zone may contribute to an improvement in subjective pain and patient satisfaction associated with this surgical procedure. The non-significant radiological results and the minor dorsal-radial shifts in our small study group limit a firm conclusion.

LEVEL OF EVIDENCE

III.

Rhizarthrosis Part I: A Literature Review

Rhizarthrosis (RA), or trapeziometacarpal osteoarthritis, is an arthritic degenerative process that affects the first joint of the thumb. The objective of this work is to provide therapists with an overview of the fundamental issues related to the therapeutic management of trapeziometacarpal joint instability. Prevalent in females, especially post-menopause, and linked to age, RA involves ligament and muscle structures, with causes ranging from hormonal influences to mechanical factors. Understanding the biomechanics, stability, and factors contributing to RA is crucial for effective intervention. This study explores the role of ligaments, muscles, and anatomical variants in thumb joint degeneration, emphasizing the importance of stability and congruence. RA manifests as pain at the base of the thumb, limiting grip strength and hindering everyday tasks. Pain initially occurs during specific movements but can progress to constant discomfort, affecting sleep. Chronic RA leads to joint stiffness, deformities like the "Z thumb," and muscle atrophy, impacting daily functions. Clinical evaluation involves pain assessment, joint mobility examination, and palpation. Diagnostic tests like the grind test and lever test aid in confirming RA. Radiographic examination reveals joint space degeneration and osteophytes and helps classify RA stages using the Eaton-Littler classification. Conservative treatment aims to alleviate pain, reduce joint stress, and enhance function. Orthoses help stabilize the joint. Therapeutic exercises, emphasizing muscle strength and dynamic stability, prove beneficial. Manual therapies like neurodynamic, Kaltenborn, Mulligan, and Maitland techniques target pain reduction and improve joint mechanics. The studies on conservative approaches provide evidence that a multimodal intervention consisting of joint mobilization, neural mobilization, and exercise is beneficial in reducing pain in patients with RA. When conservative therapy fails, surgical intervention is indicated.

Is increased trapezial slope a cause of early trapeziometacarpal osteoarthritis?

OBJECTIVES

Thumb carpometacarpal joint osteoarthritis is one of the most common forms of osteoarthritis in the hand. The underlying causes are multifactorial. We investigated whether increased trapezial slope could be a causal factor.

MATERIAL AND METHODS

We measured trapezial slope and 1st metacarpal slope in 37 patients with early thumb carpometacarpal joint osteoarthritis and compared results with 41 patients without osteoarthritis, using computer-supported 3D-analysis based on CT scans.

RESULTS

There was a significant intergroup difference in trapezial slope (111° in patients with osteoarthritis, and 107° in patients without) and in 1st metacarpal slope (17° versus 14°).

CONCLUSION

Steeper trapezial slope seemed to be a risk factor for thumb carpometacarpal joint osteoarthritis. Therefore, correction of trapezial slope by trapezium osteotomy could be a valuable surgical approach in early thumb carpometacarpal joint osteoarthritis.

Relationship between trapeziometacarpal joint morphological parameters and joint contact pressure: a possible factor of osteoarthritis development

The trapeziometacarpal (TMC) joint is the one of the hand joints that is most affected by osteoarthritis (OA). The objective of this study was to determine if specific morphological parameters could be related to the amount of pressure endured by the joint which is one of the factors contributing to the development of this pathology. We developed 15 individualized 3D computer aided design (CAD) models of the TMC joint, each generated from the CT scan of a different participant. For each participant, we measured several crucial morphological parameters: the width and length of the trapezium bone and dorso-volar and ulno-radial curvature, of the trapezium and the metacarpal bone. Each CAD model was converted into a finite element model, of both bones and the cartilage located in between. The joint forces applied during pinch grip and power grip tasks were then applied in order to estimate the contact pressures on joint cartilage for each model. Correlations between joint contact pressures and morphology of the trapezium and the metacarpal bone were then analysed. Important variations of TMC joint pressures were observed. For both pinch and power grip tasks, the strongest correlation with joint contact pressure was with the dorso-volar curvature of the trapezium bone. Our findings indicate that dorso-volar curvature of the trapezium bone has a significant impact on mechanical loadings on the TMC joint. This contributes to understanding the prevalence of OA in certain patients.

Bone morphological changes of the trapezium and first metacarpal with early thumb osteoarthritis progression

BACKGROUND

Thumb carpometacarpal osteoarthritis is characterized by osteophyte growth and changes in the curvature of the articular surfaces of the trapezium and first metacarpal. The aim of this longitudinal study was to quantify in-vivo bone morphology changes with osteoarthritis progression.

METHODS

The study analyzed an observational dataset of 86 subjects with early thumb osteoarthritis and 22 age-matched asymptomatic controls. CT scans of subjects' affected hands were acquired at enrollment (year 0), and at 1.5, 3, 4.5, and 6-year follow-up visits. Osteoarthritic subjects were classified into stable and progressive groups, as defined by osteophyte volume and the rate of osteophyte growth. Trapezium height, width, and volar facet recession, along with first metacarpal volar beak recession and recession angle, were quantified.

FINDINGS

Mean trapezium width increased 12% over six years in the progressive osteoarthritis group. Trapezium volar recession of the progressive osteoarthritis group was significantly greater than stable at enrollment (P < 0.0001) and year 6 (P < 0.0001). The first metacarpal volar beak of the progressive osteoarthritis group recessed significantly faster than stable (P = 0.0004) and control (P = 0.0003). In year 6, volar beak surfaces in subjects with progressive osteoarthritis were flatter with reduced curvature, measuring -8.7 ± 4.0 degrees, compared to the stable osteoarthritis (P < 0.0001) and control groups (P = 0.0003), which maintained nominal curvatures, measuring 0.7 ± 2.5 and 0.2 ± 3.2 degrees, respectively.

INTERPRETATION

Our results demonstrate significant recession and reduction in the angle of the first metacarpal volar beak in progressive osteoarthritis. Flattening of the first metacarpal volar beak may have important associations with carpometacarpal joint contact and loading migrations, further propagating osteophyte formation and bony remodeling. This work highlights the volar beak of the first metacarpal as a region of morphology change with disease.

Reproducibility and repeatability of a semi-automated pipeline to quantify trapeziometacarpal joint angles using dynamic computed tomography

Background

The trapeziometacarpal (TMC) joint is a mechanically complex joint and is commonly affected by musculoskeletal diseases such as osteoarthritis. Quantifying in vivo TMC joint biomechanics, such as joint angles, with traditional reflective marker-based methods can be difficult due to the joint’s location in the hand. Dynamic computed tomography (CT) can facilitate the quantification of TMC joint motion by continuously capturing three-dimensional volumes over time. However, post-processing of dynamic CT datasets can be time intensive and automated methods are needed to reduce processing times to allow for application to larger clinical studies. The purpose of this work is to introduce a fast, semi-automated pipeline to quantify joint angles from dynamic CT scans of the TMC joint and evaluate the associated error in joint angle and translation computation by means of a reproducibility and repeatability study.

Methods

Ten cadaveric hands were scanned with dynamic CT using a passive motion device to move thumbs in a radial abduction–adduction motion. Static CT scans and high-resolution peripheral quantitative CT scans were also acquired to generate high-resolution bone meshes. Abduction–adduction, flexion–extension, and axial rotation angles were computed using a joint coordinate system. Reproducibility and repeatability were assessed using intraclass correlation coefficients, Bland–Altman analysis, and root mean square errors. Target registration errors were computed to evaluate errors associated with image registration.

Results

We found good repeatability for flexion–extension, abduction–adduction, and axial rotation angles. Reproducibility was moderate for all three angles. Joint translations exhibited greater repeatability than reproducibility. Specimens with greater joint degeneration had lower repeatability and reproducibility. We found that the difference in resulting joint angles and translations were likely due to differences in segment coordinate system definition between multiple raters, rather than due to registration errors.

Conclusions

The proposed semi-automatic processing pipeline was fast, repeatable, and moderately reproducible when quantifying TMC joint angles and translations. This work provides a range of errors for TMC joint angles from dynamic CT scans using manually selected anatomical landmarks.

The Efficacy and Safety of Chinese Herbal Medicine in the Treatment of Knee Osteoarthritis: An Updated Systematic Review and Meta-Analysis of 56 Randomized Controlled Trials

Objective

This systematic review and meta-analysis were performed to investigate the efficacy and safety of Chinese herbal medicine (CHM) in the treatment of knee osteoarthritis (KOA).

Methods

An electronic search was conducted in eight databases (PubMed, EMBASE, Web of Science, Cochrane Library, Chinese National Knowledge Infrastructure, Chinese Biomedical Literature Database, Chinese VIP Database, and Wanfang Database) from inception until December 2019. The risk of bias assessment of the included RCTs was evaluated by Cochrane collaboration's tool. The inclusion criteria were RCTs that investigated the efficacy and safety of CHM in the treatment of KOA, with no restrictions on publication status or language. The exclusion criteria included nonrandomized or quasi-RCTs, no clear KOA diagnostic approach, combined Chinese medicinal herbs with other traditional Chinese medicine treatment modalities, and published using repeated data and missing data. We computed the relative risk (RR) and the standard mean difference (SMD) for dichotomous outcomes and continuous outcomes, respectively. When heterogeneity was detected or there was significant statistical heterogeneity (P < 0.05 or I² > 50%), a random-effects model was employed, followed by further subgroup analysis and metaregression estimations to ascertain the origins of heterogeneity. Otherwise, we used a fixed-effects model (P ≥ 0.05 or I² ≤ 50%). The primary outcome measures were visual analog score (VAS), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), Lysholm score, and Lequesne index. Secondary outcome measures were the total clinical effective rate and adverse events. The meta-analysis was performed using the Stata 14.0 software.

Results

A total of 56 RCTs comprising 5350 patients met the inclusion criteria. This meta-analysis showed that application of CHM as adjuvant therapy or monotherapy for KOA can significantly decrease VAS, WOMAC, and the Lequesne index and improve the Lysholm score as well as the total effective rate. In addition, this treatment has fewer adverse effects, suggesting that CHM is generally safe and well tolerated among patients with KOA.

Conclusion

Our study offers supportive evidence that CHM, either adjuvant therapy or monotherapy, reduces the VAS, WOMAC, and Lequesne index and improves the Lysholm score and overall effective rate in patients with KOA. Additionally, CHM was well tolerated and safe in KOA patients. We found frequently used CHMs that might contribute to the formulation of a herbal formula that could be considered for further clinical use. However, given the heterogeneity and limited sample size in this study, larger multicenter and high-quality RCTs are needed to validate the benefits of CHM in the treatment of KOA.

The Association of AUSCAN and PRWHE Patient-reported Outcome Measures With Radiographic Progression of Early Thumb Carpometacarpal Arthritis at 36-Month Follow-up Is Limited to Subtle Changes in the Pain Subscale

BACKGROUND

There is a paucity of literature that examines how patient-reported outcomes correspond to early radiographic progression of thumb carpometacarpal (CMC) osteoarthritis (OA). This study examines how Australian/Canadian Osteoarthritis Hand Index (AUSCAN) and Patient-Rated Hand and Wrist Evaluation (PRWHE) scores change over 36 months in subjects with early CMC OA.

METHODS

Ninety-one subjects with symptomatic early thumb CMC OA were enrolled. Differences in AUSCAN and PRWHE scores were measured between subjects at baseline and at 18-month follow-up, and between the subjects at baseline and at 36-month follow-up. Radiographic progression was defined as an increase in modified Eaton Stage. Differences in AUSCAN and PRWHE scores were compared between these 2 groups in order to determine if radiographic progression was associated with a greater change in AUSCAN and PRWHE at 18- and 36-month follow-up.

RESULTS

At 18- and 36-month follow-up visits, there were no significant differences in AUSCAN or PRWHE compared to baseline. Multivariable logistic regression analysis did not reveal any significant differences between subjects with radiographic progression to subjects without radiographic progression at 18-month follow-up. At 36-month follow-up, this analysis did demonstrate that subjects with evidence of radiographic progression had a significant increase in the PRWHE pain subscale.

CONCLUSION

AUSCAN and PRWHE scores were not found to significantly progress at 18-month and 36-month follow-up. However, when comparing the subset of subjects with and without radiographic OA, subjects with early CMC OA who had 1 stage of radiographic progression were found to have a significantly higher intensity of pain on the PRWHE pain subscale at 36-month follow-up.

Small molecule natural compound targets the NF-κB signaling and ameliorates the development of osteoarthritis

Osteoarthritis (OA) is a multifactorial and chronic disease describing the destruction of cartilage that can lead to defects in the elderly. There is currently no practical strategy that can reverse the OA process. Here, we describe nepetin, a small natural compound with extracellular matrix (ECM) and inflammation regulating functions. In this study, we investigated the therapeutic effects of nepetin on interleukin-1β (IL-1β)-induced inflammation in mice chondrocyte and OA model. In chondrocytes, treatment with nepetin inhibited the overexpression of pro-inflammatory cytokines and mediators induced by IL-1β. Moreover, pretreatment or posttreatment with nepetin also reduced the ECM catabolism and enhanced the ECM anabolism. Mechanistically, nepetin suppressed NF-κB signaling pathway in IL-1β stimulated chondrocyte. Meanwhile, our molecular docking studies indicated nepetin had a powerful binding capacity to p65. Furthermore, nepetin showed a protective and therapeutic effect on the mouse OA model. To sum up, this study indicated nepetin had a new potential therapeutic option in OA.

Thumb Carpometacarpal Joint Pathoanatomy-A Computed Tomography-Based Study

Background  Thumb carpometacarpal joint (CMCJ) osteoarthritis is common and can lead to significant morbidity making it a condition frequently treated by hand surgeons when initial conservative measures fail. The surrounding ligamentous structures are complex and important to maintain thumb CMCJ stability. Objectives  The aim of this study was to review the normal and arthritic anatomy of the thumb CMCJ, focusing on morphology and position of osteophytes and the gap between metacarpal bases, and the effect of these on intermetacarpal ligament integrity. This may be the sole ligament suspending the first metacarpal following trapeziectomy and could determine the need for further stabilization during surgery, avoiding potential future failures. Methods  Computed tomography (CT) scans of a normal cohort and those with arthritic changes who had undergone trapeziectomy following the scan were identified. The three-dimensional reconstructions were examined for osteophyte position on the saddle and the intermetacarpal distance. Results  A total of 55 patients, 30 normal and 25 arthritic, were identified and studied. The most common anatomic position for osteophytes was the intermetacarpal ulnar aspect of the trapezium. The intermetacarpal distance increased by an average of 2.1 mm in the presence of the arthritic process. Conclusions  The findings point to an increase in the intermetacarpal distance, and hence lengthening of the ligament with potential damage, possibly secondary to osteophyte formation and wear. Further prospective research is required to determine whether using preoperative CT scanning to define osteophyte position and measure the intermetacarpal distance would predict probable damage to the ligament, hence providing an indication for stabilization and reconstruction in trapeziectomy surgery. Level of Evidence  This is a Level III, retrospective cohort study.

Anatomy and biomechanics of healthy and arthritic trapeziometacarpal joints

Understanding the biomechanics of the trapeziometacarpal (TMC) or first carpometacarpal (CMC1) joint, the pathophysiology of basal thumb arthritis, the design and performance of surgical procedures require a solid anatomical basis. This review of literature summarizes the most recent data on the descriptive, functional, and comparative anatomy of healthy and arthritic TMC joints.

The effect of orthoses on the kinematics of the trapeziometacarpal, scaphotrapeziotrapezoidal, and radioscaphoid joints

The in vivo effect of four different types of thumb and thumb-wrist orthoses on the three-dimensional kinematics of the trapeziometacarpal (TMC), scaphotrapeziotrapezoidal (STT) and radioscaphoid joints was quantified using computed tomography (CT). Eighteen healthy female volunteers were recruited. The dominant hand of each subject was scanned in four thumb and wrist positions, each in three conditions: without orthosis, with a thumb orthosis (Push Ortho and immediate fitting, IMF) and with a thumb-wrist orthosis (Ligaflex Manu and IMF). CT images were analyzed and rotations relative to the more proximal bone were expressed in a joint-specific coordinate system. Without orthosis, the largest STT rotations were observed during radioulnar deviation of the wrist and the STT range of motion (ROM) was significantly lower during wrist flexion-extension. All tested orthoses caused a significant reduction of the ROM at each joint compared to free motion. Significant differences in movement reduction were observed between prefabricated and IMF orthoses.The IMF thumb-wrist outperformed the Ligaflex Manu in terms of immobilization of the radioscaphoid joint. In addition, the IMF thumb orthosis immobilized the TMC joint significantly better during thumb abduction and adduction than the Push Ortho. We found that different types of thumb and thumb-wrist orthotics are effective in reducing joint mobility. While this reduction tends to be higher using IMF compared to prefabricated orthoses, this effect is only significant for the radioscaphoid and TMC joint. The finding that thumb movements do not induce large STT rotations suggests that the thumb does not need to be immobilized in case of isolated STT osteoarthritis.

Osteophyte volume calculation using dissimilarity-excluding Procrustes registration of archived bone models from healthy volunteers

Osteophytes are associated with later stage osteoarthritis and are most commonly described using semiquantitative radiographic grading systems. A detailed understanding of osteophyte formation is, in part, limited by the ability to quantify bone pathology. Osteophytes can be quantified relative to pre-osteoarthritic bone, or to the contralateral bone if it is healthy; however, in many cases, neither are available as references. We present a method for computing three-dimensional (3D) osteophyte models using a library of healthy control bones. An existing data set containing the computed tomography scans of 90 patients with first carpometacarpal osteoarthritis (OA) and 46 healthy subjects were utilized. A healthy bone that best fit each OA subject's bone was determined using a dissimilarity-excluding Procrustes registration technique (DEP) that minimized the influence of dissimilar features (ie, osteophytes). The osteophyte model was then computed through Boolean subtraction of the reference bone model from the OA bone model. DEP reference bones conformed significantly better to the OA bones (P < .0001) than by finite difference iterative closest point registration (root mean squared distances, 0.33 ± 0.05 and 0.41 ± 0.16 mm, respectively). The effect of library size on dissimilarity measure was investigated by leave-k-out cross-validation randomly reducing k from 46 to 1. A library of n ≥ 31 resulted in less than 10% difference from the theoretical minimum value. The proposed method enables quantification of osteophytes when the disease-free bone or the healthy contralateral bone is not available for any 3D data set. Quantifying osteophyte formation and growth may aid in understating the associated mechanisms in OA.

Statistical shape modelling of the first carpometacarpal joint reveals high variation in morphology

The first carpometacarpal (CMC) joint, located at the base of the thumb and formed by the junction between the first metacarpal and trapezium, is a common site for osteoarthritis of the hand. The shape of both the first metacarpal and trapezium contributes to the intrinsic bony stability of the joint, and variability in the morphology of both these bones can affect the joint’s function. The objectives of this study were to quantify the morphological variation in the complete metacarpal and trapezium and determine any correlation between anatomical features of these two components of the first CMC joint. A multi-object statistical shape modelling pipeline, consisting of scaling, hierarchical rigid registration, non-rigid registration and projection pursuit principal component analysis, was implemented. Four anatomical measures were quantified from the shape model, namely the first metacarpal articular tilt and torsion angles and the trapezium length and width. Variations in the first metacarpal articular tilt angle (− 6.3° < θ < 12.3°) and trapezium width (10.28 mm < \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\fancyscript{w}}$$\end{document}w < 11.13 mm) were identified in the first principal component. In the second principal component, variations in the first metacarpal torsion angle (0.2° < α < 14.2°), first metacarpal articular tilt angle (1.0° < θ < 6.4°) and trapezium length (12.25 mm < \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\text{ }\ell$$\end{document}ℓ < 17.33 mm) were determined. Due to their implications for joint stability, the first metacarpal articular tilt angle and trapezium width may be important anatomical features which could be used to advance early detection and treatment of first CMC joint osteoarthritis.

Hand osteoarthritis: clinical phenotypes, molecular mechanisms and disease management

Osteoarthritis (OA) is a highly prevalent condition, and the hand is the most commonly affected site. Patients with hand OA frequently report symptoms of pain, functional limitations and frustration in undertaking everyday activities. The condition presents clinically with changes to the bone, ligaments, cartilage and synovial tissue, which can be observed using radiography, ultrasonography or MRI. Hand OA is a heterogeneous disorder and is considered to be multifactorial in aetiology. This Review provides an overview of the epidemiology, presentation and burden of hand OA, including an update on hand OA imaging (including the development of novel techniques), disease mechanisms and management. In particular, areas for which new evidence has substantially changed the way we understand, consider and treat hand OA are highlighted. For example, genetic studies, clinical trials and careful prospective imaging studies from the past 5 years are beginning to provide insights into the pathogenesis of hand OA that might uncover new therapeutic targets in the disease.

Automatic segmentation of the thumb trapeziometacarpal joint using parametric statistical shape modelling and random forest regression voting

We propose an automatic pipeline for creating shape modelling suitable parametric meshes of the trapeziometacarpal (TMC) joint from clinical CT images for the purpose of batch processing and analysis. The method uses 3D random forest regression voting (RFRV) with statistical shape model (SSM) segmentation. The method was demonstrated in a validation experiment involving 65 CT images, 15 of which were randomly selected to be excluded from the training set for testing. With mean root mean squared (RMS) errors of 1.066 mm and 0.632 mm for the first metacarpal and trapezial bones respectively, and a segmentation time of ~2 minutes per CT image, the preliminary results showed promise for providing accurate 3D meshes of TMC joint bones for batch processing.

Trapeziometacarpal stabilization through dorsoradial ligament reconstruction: An early post-surgery in vivo biomechanical analyses

Ligament reconstruction can provide pain relief in patients with a painful, unstable, pre-arthritic trapeziometacarpal (TMC) joint. Imbrication of the dorsoradial ligament (DRL) has been proposed as a minimal invasive stabilization technique. It requires less invasive surgery than an Eaton-Littler technique and shows promising long-term clinical outcome. We used dynamic CT to objectively review the effects of the imbrication. Four patients with pain and laxity at the TMC joint, but without radiographic signs of osteoarthritis, were recruited. Dynamic CT scans were made during active thumb abduction-adduction, flexion-extension, and two functional grip tasks using a radiolucent jig. Scans of the patients were acquired before and 3 to 6 months after DRL reconstruction. Motion of each bone in the articular chain of the thumb was quantified. In addition, we mapped changes in the contact patterns between the articular facets during the entire thumb motion. After DRL imbrication, we found no overall decrease in MC1 movement in three out of four patients. Furthermore, no increase in TMC joint congruency, defined as proximity area size, was found for three out of four patients. Pre- and post-operative differences in congruency across different tasks were patient-dependent and relatively small. We demonstrated that, from a biomechanical perspective, there is high variability in post-operative outcome between patients that undergo identical surgical procedures performed by the same surgeon. A post-operative decrease in range of motion, increase in joint congruency or decrease in proximity area shift during thumb motion is not omnipresent. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:2851-2864, 2018.

Early morphologic changes in trapeziometacarpal joint bones with osteoarthritis

OBJECTIVE

Characterising the morphological differences between healthy and early osteoarthritic (EOA) trapeziometacarpal (TMC) joints is important for understanding osteoarthritis onset, and early detection is important for treatment and disease management. This study has two aims: first, to characterise morphological differences between healthy and EOA TMC bones. The second aim was to determine the efficacy of using a statistical shape model (SSM) to detect early signs of osteoarthritis (OA).

METHODS

CT image data of TMC bones from 22 asymptomatic volunteers and 47 patients with EOA were obtained from an ongoing study and used to generate a SSM. A linear discriminant analysis (LDA) classifier was trained on the principal component (PC) weights to characterise features of each group. Multivariable statistical analysis was performed on the PC to investigate morphologic differences. Leave-one-out classification was performed to evaluate the classifiers performance.

RESULTS

We found that TMC bones of EOA subjects exhibited a lower aspect ratio (P = 0.042) compared with healthy subjects. The LDA classifier predicted that protrusions (up to 1.5 mm) at the volar beak of the first metacarpal were characteristic of EOA subjects. This was accompanied with widening of the articular surface, deepening of the articular surface, and protruding bone growths along the concave margin. These characteristics resulted in a leave-one-out classification accuracy of 73.9% (95% CI [61.9%, 83.8%]), sensitivity of 89.4%, specificity of 40.9%, and precision of 75.9%.

CONCLUSION

Our findings indicate that morphological degeneration is well underway in the EOA TMC joint, and shows promise for a clinical tool that can detect these features automatically.

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.

The protective effect of phloretin in osteoarthritis: an in vitro and in vivo study

Osteoarthritis (OA) is a degenerative joint disease characterized by the degradation and inflammation of cartilage. Phloretin, a type of dihydrochalcone mainly found in apples and apple-derived products, has been reported to possess various potent biological effects such as antioxidant, anticancer, anti-inflammatory, and immunomodulatory. However, the anti-inflammatory effects of phloretin on OA have not been reported. This study was aimed at assessing the effects of phloretin on human OA chondrocytes. Human OA chondrocytes were pretreated with phloretin (10, 30, and 100 μM) for 2 h and subsequently stimulated with IL-1β for 24 h. The production of NO, PGE2, TNF-α, and IL-6 was determined using the Griess reagent and ELISAs. The mRNA expression of COX-2, iNOS, MMP-3, MMP-13, and ADAMTS-5 was measured by real-time PCR. Changes in the protein expression of COX-2, iNOS, MMPs, ADAMTS, aggrecan, collagen-II, NF-κB, and the PI3K/Akt signaling pathway were detected by western blotting. In this study, we found that phloretin significantly inhibited the IL-1β-induced production of NO, PGE2, TNF-α, and IL-6, the expression of COX-2, iNOS, MMP-3, MMP-13, and ADAMTS-5, and the degradation of aggrecan and collagen-II in human OA chondrocytes. Furthermore, phloretin dramatically suppressed the IL-1β-stimulated phosphorylation of PI3K/Akt and activation of NF-κB in human OA chondrocytes. In addition, treatment with phloretin not only prevented the destruction of cartilage and the thickening of subchondral bone but also relieved synovitis in a mouse model of OA. Moreover, immunohistochemical results showed that phloretin significantly decreased the expression of MMP-13 and increased the expression of collagen-II in OA in mice. In conclusion, these results suggest that phloretin may be a potential agent for the treatment of OA.

The Teleology of the Thumb: On Purpose and Design

The Andrew J. Weiland Medal is presented by the American Society for Surgery of the Hand to a midcareer researcher dedicated to advancing patient care in the field of hand surgery. The Weiland Medal for 2017 was presented to the author at the annual meeting of the American Society for Surgery of the Hand. The purpose of this article is to present current evidence on how biomechanics and morphology influence the pathophysiology of thumb carpometacarpal joint osteoarthritis.

Changes in Local Bone Density in Early Thumb Carpometacarpal Joint Osteoarthritis

PURPOSE

Thumb carpometacarpal (CMC) osteoarthritis (OA) represents a major source of functional morbidity. The effects of early CMC OA on loading and use patterns potentially lead to changes in local bone density and microarchitecture. Hounsfield units (HU), a quantitative attenuation coefficient obtained from computed tomography (CT) scans, have been shown to be a reliable marker of bone density. We hypothesized that early CMC OA is associated with lower local bone density about the CMC joint as assessed by HU.

METHODS

We examined HU units from CT scans in 23 asymptomatic subjects and 91 patients with early CMC OA. The HU measurements were obtained within cancellous portions of the trapezium, capitate, first and third metacarpal bases, and distal radius. Linear regression models, with age and sex included as covariates, were used to assess the relationship between CMC OA and HU values at each anatomical site.

RESULTS

Early OA patients had significantly lower HU than asymptomatic subjects within the trapezium (mean, 377 HU vs 436 HU) and first metacarpal bases (265 HU vs 324 HU). No significant group differences were noted at the capitate, third metacarpal, or distal radius. Male sex and younger age were associated with significantly higher HU at all the anatomical sites, except the first metacarpal base, where age had no significant effect.

CONCLUSIONS

Subjects presenting with early CMC OA had significantly lower bone density as assessed with HU at the thumb CMC joint (trapezium and first metacarpal base). Early thumb CMC OA and discomfort may lead to diminished loading across the basal joint, producing focal disuse osteopenia. These findings in symptomatic early arthritis suggest a relationship between symptoms, functional use of the CMC joint, and local bone density.

TYPE OF STUDY/LEVEL OF EVIDENCE

Diagnostic II.

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.

WRIST: A WRist Image Segmentation Toolkit for carpal bone delineation from MRI

Segmentation of the carpal bones from 3D imaging modalities, such as magnetic resonance imaging (MRI), is commonly performed for in vivo analysis of wrist morphology, kinematics, and biomechanics. This crucial task is typically carried out manually and is labor intensive, time consuming, subject to high inter- and intra-observer variability, and may result in topologically incorrect surfaces. We present a method, WRist Image Segmentation Toolkit (WRIST), for 3D semi-automated, rapid segmentation of the carpal bones of the wrist from MRI. In our method, the boundary of the bones were iteratively found using prior known anatomical constraints and a shape-detection level set. The parameters of the method were optimized using a training dataset of 48 manually segmented carpal bones and evaluated on 112 carpal bones which included both healthy participants without known wrist conditions and participants with thumb basilar osteoarthritis (OA). Manual segmentation by two expert human observers was considered as a reference. On the healthy subject dataset we obtained a Dice overlap of 93.0 ± 3.8, Jaccard Index of 87.3 ± 6.2, and a Hausdorff distance of 2.7 ± 3.4 mm, while on the OA dataset we obtained a Dice overlap of 90.7 ± 8.6, Jaccard Index of 83.0 ± 10.6, and a Hausdorff distance of 4.0 ± 4.4 mm. The short computational time of 20.8 s per bone (or 5.1 s per bone in the parallelized version) and the high agreement with the expert observers gives WRIST the potential to be utilized in musculoskeletal research.

Trapeziometacarpal joint contact varies between men and women during three isometric functional tasks

Trapeziometacarpal (TMC) joint osteoarthritis (OA) affects women two to six times more than men, and is influenced by stresses and strains in the cartilage. The purpose of this study was to characterise sex and age differences in contact area and peak stress location of the healthy TMC joint during three isometric tasks including pinch, grasp and jar twist. CT images of the hand from 50 healthy adult men and women were used to create a statistical shape model that was used to create finite element models for each subject and task. Force-driven simulations were performed to evaluate cartilage contact area and peak stress location. We tested for sex and age differences using Principal Component Analysis, linear regression, and Linear Discriminant Analysis. We observed sex differences in peak stress location during pinch (p = .0206), grasp (p = .0264), and jar twist (p = .0484). The greatest sex differences were observed during jar twist, where 94% of peak stresses in men were located in the centre compared with 50% in the central-volar region in women. These findings show that peak stress locations are more variable in women during grasp and jar twist than men, and suggest that women may employ different strategies to perform these tasks.

In vivo biomechanical behavior of the trapeziometacarpal joint in healthy and osteoarthritic subjects

BACKGROUND

The contact biomechanics of the trapeziometacarpal joint have been investigated in several studies. However, these led to conflicting results and were mostly performed in vitro. The purpose of this study was to provide further insight on the contact biomechanics of the trapeziometacarpal joint by in vivo assessment of healthy and osteoarthritic subjects.

METHODS

The hands of 16 healthy women and 6 women with trapeziometacarpal osteoarthritis were scanned in positions of maximal thumb extension, flexion, abduction and adduction during three isometric tasks (lateral key pinch, power grasp and jar twist) and in thumb rest posture (relaxed neutral). Three-dimensional surface models of the trapezium and first metacarpal were created for each thumb configuration. The articular surface of each bone was measured in the neutral posture. A computed tomography-based proximity mapping algorithm was developed to calculate the distance between opposing joint surfaces, which was used as a surrogate for intra-articular stress.

FINDINGS

Distinct proximity patterns were observed across tasks with a recurrent pattern reported on the volar aspect of the first metacarpal. The comparison between healthy and arthritic subjects showed a significantly larger articular area, in parallel with a significant joint space narrowing and an increase in proximity area in arthritic subjects. We also observed severe articular deformations in subjects with late stage osteoarthritis.

INTERPRETATION

This study has increased our insight in the contact biomechanics of the trapeziometacarpal joint during tasks and positions of daily life in healthy and arthritic subjects, which might contribute to a better understanding of the occurrence mechanisms of degenerative diseases such as osteoarthritis.

Silibinin protects against osteoarthritis through inhibiting the inflammatory response and cartilage matrix degradation in vitro and in vivo

Osteoarthritis (OA) is a degenerative joint disease characterized by cartilage degradation and inflammation. Silibinin, a polyphenolic flavonoid derived from fruits and seeds of Silybum marianum, has been reported to possess various potent beneficial biological effects, such as antioxidant, anti-cancer, hepatoprotective and anti-inflammatory activities. However, the anti-inflammatory effects of silibinin on OA have not been reported. This study aimed to assess the effects of silibinin on OA both in vitro and in vivo. In this study, we found that silibinin significantly inhibited the nterleukin-1β (IL-1β)-induced production of nitric oxide (NO), prostaglandin E2 (PGE2), tumor necrosis factor-α (TNF-α) and IL-6, expression of cyclooxygenase2 (COX-2), inducible nitric oxide synthase (iNOS), matrix metalloproteinase-1 (MMP-1), MMP-3, MMP-13, a disintegrin and metalloproteinase with thrombospondin motifs-4 (ADAMTS-4) and ADAMTS-5, degradation of aggrecan and collagen-II in human OA chondrocytes. Furthermore, silibinin dramatically suppressed IL-1β-stimulated phosphatidylinositol 3 kinase/ protein kinase B (PI3K/Akt) phosphorylation and nuclear factor-kappa B (NF-kB) activation in human OA chondrocytes. In addition, treatment of silibinin not only prevented the destruction of cartilage and the thickening of subchondral bone but also relieved synovitis in mice OA models. Also, the immunohistochemistry results showed that silibinin significantly decreased the expression of MMP-13 and ADAMTS-5 and increased the expression of collagen-II and aggrecan in mice OA. Taken together, these results suggest that silibinin may be a potential agent in the treatment of OA.

Evidence-Based Medicine: Thumb Basal Joint Arthritis

LEARNING OBJECTIVES

After studying this article, the participant should be able to: 1. Assess the patient's history, clinical examination, and radiographic findings to diagnose and stage basilar joint arthritis. 2. Recall the cause and epidemiology of the condition. 3. Formulate a management plan including nonoperative management, and evaluate the candidacy for surgical treatment. 4. Understand the rationale for the various surgical options available (including rehabilitation), their potential complications, and the evidence related to outcomes.

SUMMARY

This article has been prepared to accompany practice-based assessment with ongoing surgical education for the Maintenance of Certification for the American Board of Plastic Surgery. It is designed for clinicians to analyze and structure their care of a patient with arthritis of the trapeziometacarpal joint.

Reduction in Cylindrical Grasp Strength Is Associated With Early Thumb Carpometacarpal Osteoarthritis

BACKGROUND

Advanced thumb carpometacarpal (CMC) osteoarthritis (OA) can cause substantial impairment in hand function, from grasping heavy objects to fine manipulation of implements and tools. In the clinical setting, we commonly measure the grip strength of gross grasp with a hand dynamometer in patients with CMC OA. Cylindrical grasp, which requires more thumb contribution than gross grasp, is an alternative method of measuring grip strength and one that may provide insight into thumb-related conditions. Because gross grasp and cylindrical grasp use the thumb in different planes, measurement of gross grasp alone might underestimate impairment. Therefore, it is important to evaluate cylindrical grasp as well. To our knowledge this tool has yet to be examined in a population with early thumb CMC OA.

QUESTIONS/PURPOSES

(1) Is cylindrical grasp and gross grasp strength reduced in subjects with early thumb CMC OA compared with asymptomatic control subjects? (2) What is the association of cylindrical and gross grasp to thumb CMC OA after adjusting for age, sex, and hand dominance?

METHODS

We recruited 90 subjects with early symptomatic and radiographic thumb CMC OA and 38 asymptomatic healthy control subjects for this multisite controlled study. Demographic information, hand examination, comprehensive histories, plain film radiographs, and cylindrical and gross grasp strength data were collected on all 128 subjects. Mean grasp strength was calculated for cylindrical and gross grasp in the population with early CMC OA and the control population. A t-test was performed on cylindrical and gross grasp to evaluate the difference between the mean in the control and early CMC OA populations. We used separate linear regression models for the two types of grasp to further quantify the association of grasp with a diagnosis of early thumb CMC OA controlling for age, sex, and whether the subject used their dominant or nondominant hand in the study.

RESULTS

Cylindrical grasp was weaker in the population with thumb CMC OA compared with healthy control subjects (6.3 ± 2.7 kg versus 8.4 ± 2.5 kg; mean difference, 2.1; 95% CI, 1.1-3.1; p < 0.001), but there was no difference in gross grasp force (29.6 ± 11.6 kg versus 31.4 ± 10.1 kg; mean difference, 1.7; 95% CI, -2.5 to 6.0; p = 0.425). When adjusting for age, sex, and handedness, cylindrical grasp reduction was related to CMC OA (β = -2.3; standard error [SE], 0.46; p < 0.001) (Y-intercept = 8.2; SE, 1.8; R² = 0.29), whereas gross grasp was not reduced in early thumb CMC OA (β = -2.8; SE, 1.6; p = 0.072) (Y-intercept = 34.3; SE, 6.3; R² = 0.48).

CONCLUSIONS

A reduction in cylindrical grasp is associated with early symptomatic and radiographic CMC OA, whereas gross grasp is not associated with early thumb CMC OA, suggesting that cylindrical grasp may be a better tool to detect changes in thumb and hand function seen during early disease stages.

CLINICAL RELEVANCE

Cylindrical grasp may serve as a more-sensitive measure for detecting early changes in early CMC OA. The associated decline in hand function also might provide an opportunity for measuring the effectiveness of treatment and intervention.

Echinocystic Acid Inhibits IL-1β-Induced COX-2 and iNOS Expression in Human Osteoarthritis Chondrocytes

Echinocystic acid (EA), a pentacyclic triterpene isolated from the fruits of Gleditsia sinensis Lam, displays a range of pharmacological activities including anti-inflammatory and antioxidant effects. However, the effect of EA on IL-1β-stimulated osteoarthritis chondrocyte has not been reported. The purpose of this study was to assess the effects of EA on IL-1β-stimulated human osteoarthritis chondrocyte. Chondrocytes were stimulated with IL-1β in the absence or presence of EA. NO and PGE2 production were measured by Griess reagent and ELISA. The expression of COX-2, iNOS, nuclear factor-κB (NF-κB), inhibitory kappa B (IκBα), c-Jun N-terminal kinase (JNK), p38, and extracellular signal-regulated kinase (ERK) were detected by Western blot analysis. The results showed that EA suppressed IL-1β-induced collagenase-3 (MMP-13), NO, and PGE2 production in a dose-dependent manner. IL-1β up-regulated the expression of COX-2 and iNOS, and the increase was inhibited by EA. Furthermore, IL-1β-induced NF-κB and mitogen-activated protein kinase (MAPK) activation were inhibited by EA. In conclusion, EA effectively attenuated IL-1β-induced inflammatory response in osteoarthritis chondrocyte which suggesting that EA may be a potential agent in the treatment of osteoarthritis.

Subject-specific thumb muscle activity during functional tasks of daily life

BACKGROUND

The trapeziometacarpal joint is subjected to high compressive forces during powerful pinch and grasp tasks due to muscle loading. In addition, muscle contraction is important for stability of the joint. The aim of the present study is to explore if different muscle activation patterns can be found between three functional tasks.

METHODS

Isometric forces and fine-wire electromyographic (fEMG) activity produced by three intrinsic and four extrinsic thumb muscles were measured in 10 healthy female volunteers. The participants performed isometric contractions in a lateral key pinch, a power grasp and a jar twist task. The tasks were executed with and without EMG recording to verify if electrode placement influenced force production.

RESULTS

A subject-specific muscle recruitment was found which remained largely unchanged across tasks. Extrinsic thumb muscles were significantly more active than intrinsic muscles in all tasks. Insertion of the fEMG electrodes decreased force production significantly in all tasks.

CONCLUSION

The thumb muscles display a high variability in muscle activity during functional tasks of daily life. The results of this study suggest that to produce a substantial amount of force, a well-integrated, but subject-specific, co-contraction between the intrinsic and extrinsic thumb muscles is necessary.

The Envelope of Physiological Motion of the First Carpometacarpal Joint

Much of the hand's functional capacity is due to the versatility of the motions at the thumb carpometacarpal (CMC) joint, which are presently incompletely defined. The aim of this study was to develop a mathematical model to completely describe the envelope of physiological motion of the thumb CMC joint and then to examine if there were differences in the kinematic envelope between women and men. In vivo kinematics of the first metacarpal with respect to the trapezium were computed from computed tomography (CT) volume images of 44 subjects (20M, 24F, 40.3 ± 17.7 yr) with no signs of CMC joint pathology. Kinematics of the first metacarpal were described with respect to the trapezium using helical axis of motion (HAM) variables and then modeled with discrete Fourier analysis. Each HAM variable was fit in a cyclic domain as a function of screw axis orientation in the trapezial articular plane; the RMSE of the fits was 14.5 deg, 1.4 mm, and 0.8 mm for the elevation, location, and translation, respectively. After normalizing for the larger bone size in men, no differences in the kinematic variables between sexes could be identified. Analysis of the kinematic data also revealed notable coupling of the primary rotations of the thumb with translation and internal and external rotations. This study advances our basic understanding of thumb CMC joint function and provides a complete description of the CMC joint for incorporation into future models of hand function. From a clinical perspective, our findings provide a basis for evaluating CMC pathology, especially the mechanically mediated aspects of osteoarthritis (OA), and should be used to inform artificial joint design, where accurate replication of kinematics is essential for long-term success.

Postoperative Therapy for Chronic Thumb Carpometacarpal (CMC) Joint Dislocation

Surgical arthroplasty of thumb carpometacarpal (CMC) joint osteoarthritis is commonly performed. Postoperative therapeutic protocols aim to improve range of motion and function of the revised thumb. We describe a case in which the thumb CMC joint had been chronically dislocated before surgery, with shortening of the soft-tissue dynamic and static stabilizers of the joint. The postoperative protocol addressed the soft tissues using splinting and exercises aimed at lengthening and strengthening these structures, with good results. It may be beneficial to evaluate soft-tissue tension and the pattern of thumb use after surgery for thumb CMC joint osteoarthritis to improve postoperative functional results.

Registration-Based Morphometry for Shape Analysis of the Bones of the Human Wrist

We present a method that quantifies point-wise changes in surface morphology of the bones of the human wrist. The proposed method, referred to as Registration-based Bone Morphometry (RBM), consists of two steps: an atlas selection step and an atlas warping step. The atlas for individual wrist bones was selected based on the shortest ℓ2 distance to the ensemble of wrist bones from a database of a healthy population of subjects. The selected atlas was then warped to the corresponding bones of individuals in the population using a non-linear registration method based on regularized ℓ2 distance minimization. The displacement field thus calculated showed local differences in bone shape that then were used for the analysis of group differences. Our results indicate that RBM has potential to provide a standardized approach to shape analysis of bones of the human wrist. We demonstrate the performance of RBM for examining group differences in wrist bone shapes based on sex and between those of the right and left wrists in healthy individuals. We also present data to show the application of RBM for tracking bone erosion status in rheumatoid arthritis.

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.

Early osteoarthritis of the trapeziometacarpal joint is not associated with joint instability during typical isometric loading

The saddle-shaped trapeziometacarpal (TMC) joint contributes importantly to the function of the human thumb. A balance between mobility and stability is essential in this joint, which experiences high loads and is prone to osteoarthritis (OA). Since instability is considered a risk factor for TMC OA, we assessed TMC joint instability during the execution of three isometric functional tasks (key pinch, jar grasp, and jar twist) in 76 patients with early TMC OA and 44 asymptomatic controls. Computed tomography images were acquired while subjects held their hands relaxed and while they applied 80% of their maximum effort for each task. Six degree-of-freedom rigid body kinematics of the metacarpal with respect to the trapezium from the unloaded to the loaded task positions were computed in terms of a TMC joint coordinate system. Joint instability was expressed as a function of the metacarpal translation and the applied force. We found that the TMC joint was more unstable during a key pinch task than during a jar grasp or a jar twist task. Sex, age, and early OA did not have an effect on TMC joint instability, suggesting that instability during these three tasks is not a predisposing factor in TMC OA.

Older asymptomatic women exhibit patterns of thumb carpometacarpal joint space narrowing that precede changes associated with early osteoarthritis

In small joints, where cartilage is difficult to image and quantify directly, three-dimensional joint space measures can be used to gain insight into potential joint pathomechanics. Since the female sex and older age are risk factors for carpometacarpal (CMC) joint osteoarthritis (OA), the purpose of this in vivo computed tomography (CT) study was to determine if there are any differences with sex, age, and early OA in the CMC joint space. The thumbs of 66 healthy subjects and 81 patients with early stage CMC OA were scanned in four range-of-motion, three functional-task, and one neutral positions. Subchondral bone-to-bone distances across the trapezial and metacarpal articular surfaces were computed for all the positions. The joint space area, defined as the articular surface that is less than 1.5mm from the mating bone, was used to assess joint space. A larger joint space area typically corresponds to closer articular surfaces, and therefore a narrower joint space. We found that the joint space areas are not significantly different between healthy young men and women. Trends indicated that patients with early stage OA have larger CMC joint space areas than healthy subjects of the same age group and that older healthy women have larger joint space areas than younger healthy women. This study suggests that aging in women may lead to joint space narrowing patterns that precede early OA, which is a compelling new insight into the pathological processes that make CMC OA endemic to women.

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.

Men and women have similarly shaped carpometacarpal joint bones

Characterizing the morphology of the carpometacarpal (CMC) joint bones and how they vary across the population is important for understanding the functional anatomy and pathology of the thumb. The purpose of this paper was to develop a statistical shape model of the trapezium and first metacarpal bones to characterize the size and shape of the whole bones across a cohort of 50. We used this shape model to investigate the effects of sex and age on the size and shape of the CMC joint bones and the articulating surface area of the CMC joint. We hypothesized that women have similar shape trapezium and first metacarpal bones compared to men, following scaling for overall size. We also hypothesized that age would be a significant predictor variable for CMC joint bone changes. CT image data and segmented point clouds of 50 CMC bones from healthy adult men and women were obtained from an ongoing study and used to generate two statistical shape models. Statistical analysis of the principal component weights of both models was performed to investigate morphological sex and age differences. We observed sex differences, but were unable to detect any age differences. Between men and women the only difference in morphology of the trapezia and first metacarpal bones was size. These findings confirm our first hypothesis, and suggest that the women have similarly shaped trapezium and first metacarpal bones compared to men. Furthermore, our results reject our second hypothesis, indicating that age is a poor predictor of CMC joint morphology.

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.

In Vivo kinematics of the trapeziometacarpal joint during thumb extension-flexion and abduction-adduction

PURPOSE

The primary aim of this study was to determine whether the in vivo kinematics of the trapeziometacarpal (TMC) joint differ as a function of age and sex during thumb extension-flexion (Ex-Fl) and abduction-adduction (Ab-Ad) motions.

METHODS

The hands and wrists of 44 subjects (10 men and 11 women with ages 18-35 y and 10 men and 13 women with ages 40-75 y) with no symptoms or signs of TMC joint pathology were imaged with computed tomography during thumb extension, flexion, abduction, and adduction. The kinematics of the TMC joint were computed and compared across direction, age, and sex.

RESULTS

We found no significant effects of age or sex, after normalizing for size, in any of the kinematic parameters. The Ex-Fl and Ab-Ad rotation axes did not intersect, and both were oriented obliquely to the saddle-shaped anatomy of the TMC articulation. The Ex-Fl axis was located in the trapezium and the Ab-Ad axis was located in the metacarpal. Metacarpal translation and internal rotation occurred primarily during Ex-Fl.

CONCLUSIONS

Our findings indicate that normal TMC joint kinematics are similar in males and females, regardless of age, and that the primary rotation axes are nonorthogonal and nonintersecting. In contrast to previous studies, we found Ex-Fl and Ab-Ad to be coupled with internal-external rotation and translation. Specifically, internal rotation and ulnar translation were coupled with flexion, indicating a potential stabilizing screw-home mechanism.

CLINICAL RELEVANCE

The treatment of TMC pathology and arthroplasty design require a detailed and accurate understanding of TMC function. This study confirms the complexity of TMC kinematics and describes metacarpal translation coupled with internal rotation during Ex-Fl, which may explain some of the limitations of current treatment strategies and should help improve implant designs.