Trapeziometacarpal joint stability: the evolving importance of the dorsal ligaments

Internal brace augmentation improves the biomechanical properties of trapeziometacarpal joint dorsoradial ligament repair

This study investigated whether dorsoradial ligament repair with internal brace augmentation provided more immediate stability in the trapeziometacarpal joint than dorsoradial ligament repair alone. Seven matched pairs of cadaveric hands were used. One specimen from each pair was assigned to the repair-only group and the other to the repair + internal brace augmentation group. Trapeziometacarpal joint range of motion and translation were quantified under different conditions for both groups: (1) intact, (2) transected dorsoradial ligament, and (3) repaired dorsoradial ligament or repaired dorsoradial ligament plus internal brace augmentation. Load-to-failure tests were performed after repair. Range of motion and translation were increased by dorsoradial ligament transection and were decreased by dorsoradial ligament repair; however, compared to the intact condition, the repair-only group demonstrated greater flexion/extension range, while the repair + internal brace group showed no significant difference in range of motion. Mean loads at 2- and 3-mm displacements were greater in the repair + internal brace group than in the repair-only group (18.0 ± 1.8 N vs. 10.8 ± 1.3 N for 2 mm displacement and 35.3 ± 3.7 N vs. 23.1 ± 2.9 N for 3 mm displacement, respectively). Internal brace augmentation improved the load-to-failure characteristics of dorsoradial ligament repair without compromising range of motion. LEVEL OF EVIDENCE: IV.

Ligament reconstruction in thumb carpometacarpal joint instability: A systematic review

In thumb carpometacarpal (CMC) instability, laxity of the ligaments surrounding the joint leads to pain and weakness in grip and pinch strength, which predisposes the patient to developing CMC joint arthritis. Recent advancements in joint anatomy and kinematics have led to the development of various surgical reconstructive procedures. This systematic review outlines the available ligament reconstruction techniques and their efficacy in treating nontraumatic and nonarthritic CMC instability. Additionally, we aimed to provide evidence which specific ligament reconstruction technique demonstrates the best results. Four databases (Embase, MEDLINE, Web of Science, and Cochrane Central) were searched for studies that reported on surgical techniques and their clinical outcomes in patients with nontraumatic and nonarthritic CMC instability. Twelve studies were analyzed for qualitative review, including nine different surgical ligament reconstruction techniques involving two hundred and thirty thumbs. All but one of the reported techniques improved postoperative pain scores and showed substantial improvement in pinch and grip strength. Complication rates varied between 0% and 25%. The included studies showed that ligament reconstruction effectively alleviated the patients' complaints regarding pain and instability, resulting in overall high patient satisfaction. Nevertheless, drawing definitive conclusions regarding the superiority of any ligament reconstruction technique remains challenging owing to the limited availability of homogeneous data in the current literature.

Does the Number of Preoperative Corticosteroid Injections Affect Clinical and Radiographic Outcomes of Trapeziectomy and Suspensionplasty?

PURPOSE

This study aimed to determine whether an increasing number of preoperative corticosteroid injections is associated with greater radiographic subsidence of the thumb metacarpal at long-term follow-up after abductor pollicis longus suspensionplasty, secondary to steroid-induced pathologic weakening of capsuloligamentous restraints surrounding the thumb carpometacarpophalangeal joint and greater extension of the lunate, but neither affect patient-reported outcomes nor revision rates.

METHODS

A retrospective chart review was performed of patients who underwent primary trapeziectomy and abductor pollicis longus suspensionplasty by a single surgeon over a 10-year period. The number of preoperative corticosteroid injections in the trapeziometacarpal joint was documented, and patients were separated into 4 subgroups: 0, 1, 2, or 3 or more injections. Preoperative and final radiographs were evaluated for a change in the distance between the base of the thumb metacarpal and the distal pole of the scaphoid as a measure of thumb metacarpal subsidence and radiolunate angle as a measure of nondissociative carpal instability, which has been reported as a complication after basal joint arthroplasty. Additionally, the final patient-reported outcomes (Quick Disabilities of the Arm, Shoulder, and Hand and Patient-Rated Wrist Evaluation) and revision rates were also assessed.

RESULTS

Of a total of 60 patients with an average age of 64 years that were included in the study, 16 (26.7%) received 0, 19 (31.7%) received 1, 12 (20%) received 2, and 13 (21.7%) received 3+ preoperative injections. The median postoperative follow-up was 92 months. The mean distance between the base of the thumb metacarpal and the distal pole of the scaphoid decreased by 2 mm, and the mean radiolunate angle increased by 4° across the entire cohort. When comparing subgroups, no differences were observed in either parameter or the final Patient-Rated Wrist Evaluation and Quick Disabilities of the Arm, Shoulder, and Hand scores.

CONCLUSIONS

This study demonstrates no apparent detrimental effect of an increased number of preoperative corticosteroid injections on radiographic thumb metacarpal subsidence, increase in extension of radiolunate angle (nondissociative carpal instability), patient-reported outcomes, or revision rates at an average of almost 8 years after trapeziectomy and abductor pollicis longus suspensionplasty.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic IV.

Rhizarthrosis Part II: A New Approach of Manual Therapy and Therapeutic Exercise

Rhizarthrosis (RA), also known as trapezium-metacarpal osteoarthritis, is a degenerative condition affecting the thumb's first joint, leading to functional impairment and pain. Conservative treatment options are preferred for mild to moderate cases (Eaton-Littler grades I and II) and typically encompass a range of therapeutic modalities, including manual therapy. However, for the existing manual therapy techniques, there is a lack of comparative studies for efficacy, and therapeutic exercises are often generic and non-specific to RA. This study proposes a novel treatment protocol that combines manual therapy with specific therapeutic exercises grounded in the biomechanical analysis of the trapeziometacarpal joint. The focus is on enhancing joint stability, reducing pain, and improving function. The manual therapy component includes three phases. A passive phase, during which joint distractions are applied to alleviate discomfort and improve joint mobility. An active phase that addresses joint mobility on the adduction-abduction plane, the first plane of movement to suffer limitation: the therapist facilitates the isometric adduction of the thumb, followed by an assisted abduction. A second active phase is where Mulligan's Mobilization With Movement concept is applied. This technique involves passive pain-free joint mobilization with simultaneous active finger movements, to provide additional therapeutic benefits. The therapeutic exercises component focuses on strengthening the first dorsal interosseous muscle as an abductor to reduce thumb adductor muscle activation and joint stress. Patients are encouraged to perform finger spreading exercises using a rubber band between the first and fifth fingers, emphasizing first dorsal interosseous activation and stability of the thumb. This type of muscle strengthening does not involve movement of the trapeziometacarpal joint. It is recommended to start performing 5-10 repetitions or 5 seconds of isometric contraction, repeat throughout the day, and progressively increase the load by adding a turn to the rubber band or changing it, increasing the number of repetitions bringing it to 15 and/or increase the isometric contraction time to 10/15 seconds. The proposed therapeutic rationale, informed by biomechanical insights, lays a promising foundation for further investigation. Nevertheless, empirical validation through rigorous clinical trials remains essential to substantiate its clinical utility and advance the management of RA.

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.

The Role of the Flexor Carpi Radialis Groove in Trapeziometacarpal Osteoarthritis

BACKGROUND

Thumb carpometacarpal (CMC) osteoarthritis (OA) is a common condition. The contribution of surrounding ligaments and tendons to the stability of the CMC joint is likely altered in OA. The flexor carpi radialis (FCR) tendon runs in the trapezial FCR groove and is often noted to be frayed during CMC arthroplasty. We hypothesized that decreased integrity of the FCR tendon is related to FCR groove morphology and is associated with increased severity of CMC OA.

METHODS

We examined 3-dimensional surface models based on computed tomography (CT) scans of explanted trapezia from patients who underwent thumb CMC arthroplasty. Fraying of the FCR tendon was rated intraoperatively. Measurements were taken of the FCR groove to evaluate its morphology. Preoperative thumb CMC radiographs for each patient were scored using the modified Eaton classification system and the Thumb Osteoarthritis Index. Differences in the tendon groups were examined, and multivariable linear regression models were used to test the association between tendon group and FCR groove measurement.

RESULTS

There were 136 patients who were categorized into 4 tendon groups: intact, minor fraying, fraying, and ruptured. There were no differences between the tendon groups on any measures.

CONCLUSIONS

Our findings do not demonstrate a significant influence of FCR groove morphology on FCR tendon fraying in CMC arthroplasty patients. We also did not find a significant association between the FCR tendon state and degree of radiographic CMC OA. Further studies should investigate the in vivo FCR tendon to evaluate its tearing and inflammation in relation to basilar thumb pain.

Targeted partial arthroscopic trapeziectomy with temporary distraction: a retrospective study with 5-year follow-up

Targeted partial arthroscopic trapeziectomy with temporary distraction is a minimally invasive treatment for trapeziometacarpal osteoarthritis. We performed a retrospective single centre study from March 2011 to May 2022 and included patients with at least 5 years of follow-up. A failure was defined as a patient requiring a second procedure. Of the 28 patients with at least 5 years of follow-up, 23 were reviewed. Five of the 23 patients underwent revision surgery with a 5-year survival rate of 78%. There was a significant improvement in pain and the Quick Disabilities of the Arm, Shoulder and Hand (Q-DASH) score. There were three postoperative complications, one with complex regional pain syndrome, and two with hyperesthesia in the distribution of the sensory branch of the radial nerve. Targeted partial arthroscopic trapeziectomy with temporary distraction is a feasible temporary solution for early stage trapeziometacarpal joint osteoarthritis. However, there remains a 20% risk of failure.Level of evidence: IV.

The trapeziometacarpal screw home torque mechanism as a clinical indicator of the posterior joint ligament complex integrity: A cadaveric investigation

BACKGROUND

To date, no clinical test provides specific objective information on the integrity of key ligamentous support of the trapeziometacarpal (TMC) joint.

PURPOSE

To examine the potential of the TMC joint screw home torque mechanism (SHTM) in estimating the integrity of the posterior ligament complex in older adult population. STUDY DESIGN: Cross-sectional laboratory-based study.

METHODS

Twenty cadaver hands presenting with various degrees of TMC joint degradation ranging from none to severe osteoarthritis (OA) were radiographed in multiple positions to establish their degeneration status, joint mobility, and amount of dorsal subluxation at rest and with the application of the SHTM. Comparisons and correlations between degeneration status, joint mobility, subluxation reduction and ligament status obtained from dissection were calculated.

RESULTS

No significant statistical correlation was demonstrated with the subluxation reduction ratio of the SHTM and the combined ligament complex value however, a moderate negative correlation was found with dorsal central ligament injury at 21 Nm (τb = -0.46, p < 0.05) and 34 Nm (τb = -0.45, p < 0.05). A statistically significant reduction of radial subluxation of the TMC joint was observed between the subluxation at rest (M = 5.2, SD = 1.9) and subluxation with SHTM of 21 Nm (M = 4.4, SD = 2.4), t (19) = 3.2, p = 0.01, 95% CI [0.3, 1.4] and subluxation with SHTM of 34 Nm (M = 4.3, SD = 2.6), t (19) = 2.6, p = 0.02, 95% CI [0.2, 1.5].

CONCLUSION

Our results did not support the SHTM as indicator of the TMC posterior ligament complex integrity however, it demonstrated 100% stabilization effect with non-arthritic TMC population.

Dorsoradial Ligament Reconstruction in Trapeziometacarpal Joint Arthritis

BACKGROUND

The main purpose of the study is to present the alternative novel surgical technique in treating patients with trapeziometacarpal (TMC) joint arthritis using dorsoradial ligament (DRL) reconstruction technique and report the clinical outcomes.

METHODS

Patients who were diagnosed with TMC joint arthritis and underwent DRL reconstruction were evaluated. Visual analog pain score; Quick Disabilities of the Arm, Shoulder, and Hand (QuickDASH) score; grip, tip pinch, tripod pinch, and key pinch strengths along with range of motion of the thumb; and Kapandji score were recorded in the preoperative period and at follow-up. Stress examination was also performed under a fluoroscope.

RESULTS

Eleven patients were included in the study. Median follow-up time was 13 months. At follow-up, postoperative visual analog scale and QuickDASH score improved in all patients. Grip, tip pinch, tripod pinch, and key pinch strengths also improved. The range of motion and Kapandji score were slightly improved compared with the preoperative period except for the thumb metacarpophalangeal flexion. Two patients had numbness at the thumb and spontaneously recovered after 3 months.

CONCLUSIONS

According to recent evidence which proposed the importance of DRL in TMC joint stability, our DRL reconstruction technique may be an alternative treatment in treating patients presented with TMC joint arthritis. Further study with a longer follow-up period is needed.

Trapeziectomy, Partial Trapezoidectomy, and Abductor Pollicis Longus Dual Loop Ligament Reconstruction for Advanced Basal Joint Arthritis: Long-Term Outcome of 150 Cases

BACKGROUND

Although hand surgeons usually concur that arthroplasty is indicated for disabling basal joint arthritis, controversy persists regarding the preferred surgical methods. This article describes a novel technique of trapezial excisional arthroplasty with partial trapezoidectomy and abductor pollicis longus (APL) dual ligament reconstruction, and reports the long-term results of 150 cases. Based on this experience, we hypothesize that this technique is a reliably effective and durable surgical option for basal joint arthritis.

METHODS

This study evaluated consecutive patients with Eaton and Littler advanced stage III/IV basal joint arthritis, treated by this procedure, and followed for a minimum of 10 years. Outcome assessment included grip and pinch strength, thumb mobility, radiographic parameters, pain relief, and patient-reported outcomes as measured with the Disabilities of the Arm, Shoulder, and Hand (DASH) scoring system.

RESULTS

A total of 150 thumbs in 124 patients with an average follow-up of 13.5 years (range, 10-22 years) were studied. Alleviation of pain and patient satisfaction were constant outcomes, and the mean DASH score was a normative 8.7. Grip and pinch strength were significantly improved (P < .001), carpometacarpal joint malalignment and adduction deformities were consistently corrected, complications were few, and revision surgery was unnecessary.

CONCLUSIONS

These results support the premise that trapeziectomy and partial trapezoidectomy with APL dual ligament stabilization is a reliable and durable arthroplasty for basal joint arthritis with distinct advantages and equally favorable outcomes when compared with other frequently employed methods.

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.

Chronic Dislocation of the Thumb Carpometacarpal Joint: A Case Report

Dislocation of the thumb carpometacarpal (CMC) joint is a rare injury; chronic CMC dislocation can lead to significant disability. Traditionally, surgical intervention has focused on the reconstruction of the anterior oblique ligament, though more recently there has been more focus on the dorsoradial ligament. Consideration of both ligaments during CMC joint reconstruction is important to optimize functional outcomes. A 59-year-old male presented with a subacute/chronically dislocated CMC joint of the thumb. Open reduction with pin fixation and dorsoradial ligament repair and augmentation was chosen to restore the stability of the joint. Joint reduction without subluxation was successfully maintained. By 12 weeks postoperatively, there were no remaining major restrictions to activity. Repair of the dorsoradial ligament with augmentation and pinning is a viable approach for surgical management of subacute/chronic dislocation of the thumb CMC joint.

Trapeziometarpal joint arthritis in the young patient

Initial management of symptomatic trapeziometacarpal joint arthritis is generally non-operative. Though the aetiology of trapeziometacarpal arthritis remains controversial, unrecognized joint incongruity in early-stage arthritis (Eaton stage 1 or 2) is likely to lead to progression of joint degeneration. In established arthritis, salvage procedures can successfully alleviate symptoms and return of function; however the long-term outcome of these procedures has not been determined, and this is of particular concern in the younger patient. Recognition of the joint incongruity in these patients with early-stage disease can lead to measures which may prevent or delay the progression of joint degeneration.Level of evidence: V.

Outcomes of First Metacarpal Extension Osteotomy for Base of Thumb Arthritis

BACKGROUND

First metacarpal extension osteotomy (FMEO) aims to correct the adduction deformity associated with thumb arthritis, as well as improve the congruity at the first carpometacarpal (FCMC) joint. However, the benefits of this procedure are currently unclear. The purpose of this study is to investigate the outcomes of FMEO in the treatment of FCMC joint arthritis.

METHODS

Electronic databases were searched systematically for original data studies in the English language reporting outcomes following FMEO for base of thumb arthritis. Data were extracted from the text, tables, and figures of publications and meta-analyzed where possible.

RESULTS

Ten publications comprising 211 thumbs were included. FMEO was associated with an improvement in pain relief and patient-reported functional outcomes, however meta-analysis showed no significant long-term improvement in grip strength or lateral pinch grip. Although there was disease progression in one third of patients after FMEO, most did not require further procedures. Outcomes following secondary procedures was not analyzed in the literature. FMEO produced a range of minor complications, however, major complications were rare.

CONCLUSIONS

The available evidence suggests FMEO does not improve grip or pinch strength. However, it may have a role in analgesia and improvement in functional outcomes. Further studies should compare outcomes of FMEO to continued nonoperative treatment, or other surgical options including arthroscopy or ligamentous reconstruction.

Using a finite element model of the thumb to study Trapeziometacarpal joint contact during lateral pinch

BACKGROUND

Finite element (FE) analysis is widely used in different fields of orthopaedic surgery, however, its application to the trapeziometacarpal joint has been limited due to the small size, complex biconcave-convex joint geometry, and complex musculature. The goal of this study was to improve upon existing models by creating a muscle-driven FE thumb model and use the model to simulate the biomechanical effect of hand therapy exercises and ligament reconstructive surgeries.

METHODS

Bone and cartilage geometry were based on a CT dataset of a subject performing a static lateral pinch task. A previously validated musculoskeletal model was utilized to extract electromyography (EMG)-driven muscle forces. Five ligaments with biomechanical significance were modeled as springs using literature values and attached according to their anatomical landmarks.

FINDINGS

The biomechanical consequence of various interventions was proxied as a change in the maximum cartilage stress. The result shows tightening the dorsal ligament complex (dorsal radial ligament, dorsal central ligament, posterior oblique ligament) is the most effective, achieving a stress reduction of 4.8%. Five exercises used in hand therapies were modeled, among which thenar eminence strengthening showed the most prominent stress reduction of 4.0%. Four ligament reconstructive surgeries were modeled, with Eaton-Littler reconstruction showed the most significant stress reduction of 25.0%.

INTERPRETATION

Among the routinely utilized treatment options for early thumb osteoarthritis, we found that three methods: dorsal ligament imbrication, thenar eminence exercise, and the Eaton-Littler method may confer biomechanical advantages cartilage loading. These advantages align with the clinically observed favorable outcomes.

Anatomical 3 Ligaments Reconstruction for Symptomatic Thumb Carpometacarpal Joint Instability

Thumb carpometacarpal (CMC) joint instability is thought to be a debilitating disorder and, if left untreated, develops joint persistent synovitis and osteoarthritis. In this study, we report a novel surgical technique reconstructing the anterior oblique ligament, the dorsoradial ligament, and the intermetacarpal ligament simultaneously using both the transverse carpal ligament, and the palmaris longus tendon. Six patients with a mean age of 44 years showing no osteoarthritic changes by the radiographical examination underwent our anatomical three ligaments reconstruction for persistent painful thumb CMC joint instability. Clinical results with the mean follow-up of 20 months demonstrated that the pain was subjectively improved in all patients, both the grip and the pinch strength were increased significantly and good functional motion of the thumb could be observed after the operation. These findings indicated that our surgical procedure could be one option of treatment of the symptomatic CMC joint instability in early-stage arthritis.

Ultrasound of Thumb Muscles and Grasp Strength in Early Thumb Carpometacarpal Osteoarthritis

PURPOSE

The pathophysiology of thumb carpometacarpal (CMC) osteoarthritis (OA) involves complex interactions between the ligaments and muscles supporting the joint. Factors such as muscle volume and strength may be more relevant in early disease. We used ultrasound as a noninvasive method to explore differences in the intrinsic hand muscles of patients with early CMC OA, as determined using physical exam and radiographs, and healthy controls. We also assessed differences in grip strength.

METHODS

A convenience sample of postmenopausal women with early CMC OA diagnosed using a physical examination or radiographs was recruited from an orthopedic clinic specializing in hand surgery. Healthy controls who were matched for age and hand dominance were recruited from the same clinic. We used ultrasound to determine the length of the first metacarpal and the muscle thickness of the abductor pollicis brevis, opponens pollicis (OPP), and first dorsal interosseous. Grip strength measurements were taken using a standard Jamar dynamometer and 2 custom-designed tools for cylindrical grasp and pinch strength.

RESULTS

Twenty-three subjects were enrolled, with a total of 32 thumbs measured: 15 thumbs with arthritis and 17 healthy thumbs. Multivariable logistic regression models indicated that thumbs with thicker OPP had 0.85 lower odds (95% CI = 0.71-0.97) of early OA, adjusting for hand dominance and the first metacarpal length. Linear regression models indicated no association between early OA and grip strength.

CONCLUSIONS

The size of OPP may have a weak association with the diagnosis of early OA.

CLINICAL RELEVANCE

This study supports further exploration of the role of OPP in stabilizing the CMC joint, particularly with regard to minimizing joint subluxation. This may be clinically relevant to providers who treat patients with CMC OA early in the course of the disease, when nonsurgical treatment is the most relevant.

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.

Management of Acute and Chronic Thumb CMC Joint Dislocations

Isolated dislocations of thumb CMC joints are rare injuries with serious functional implications. Patients suffering these injuries will have decreased pinch and grip strength. A high-energy, axially directed force on a flexed thumb typically causes dislocation. Chronically dislocated thumb CMC joints may be due to untreated remote trauma, hypermobility, or connective tissue disorders. Roberts and CMC stress view radiographs help identify joint dislocations. Treatment of these injuries includes closed reduction and immobilization, percutaneous pinning, open reduction with direct repair, and ligament reconstruction. Timely identification, timely treatment, and proper hand therapy often lead to adequate joint stability with minimal residual pain.

Effect of first dorsal interosseous strengthening on clinical outcomes in patients with thumb osteoarthritis: a study protocol for a randomized controlled clinical trial

BACKGROUND

Thumb carpometacarpal osteoarthritis (CMC OA) is characterized by chronic progressive degeneration of the joint cartilage, with high prevalence. Patients present with pain at the base of the thumb, morning stiffness, and muscle weakness, symptoms that affect hand function and therefore interfere in activities and social participation. Movements that involve grip or lateral pinch are the most affected and directly impact independence, self-care, and leisure activities. In the literature consulted, several protocols with exercises for these patients were found. However, most do not compare the same intervention modality and only provide basic methodological information, with no consistent information on training load and load progression. In addition, most protocols only address the strengthening of the abductor and extensor thumb muscles and pinching or grasping exercises. However, some biomechanical and electromyographic studies have demonstrated the important role of the first dorsal interosseous muscles as stabilizers of the thumb carpometacarpal joint.

METHODS

This is a randomized, controlled, double-blind, and parallel clinical trial that will include 56 participants, over 40 years old, with radiographic evidence of thumb base osteoarthritis. Participants will be randomly allocated into two groups: control and intervention. The following evaluations will be conducted: the Australian/Canadian Hand Osteoarthritis Index, Canadian Occupational Performance Measure, Nine-Hole Peg Test, grip and pinch strength associated with muscle activation assessment, and Bilateral Upper Limb Function Test at four different times: baseline, session 13, session 18, and follow-up. Treatment will take place over 6 weeks, with reassessments in the fourth and sixth weeks and 3 months after the end of the intervention (follow-up). Qualitative variables will be expressed as frequency and percentage, and quantitative variables as mean and standard deviation. Intergroup comparison of the intervention will be performed by repeated measures ANOVA, considering the effect of the two groups and four assessments, and interactions between them.

DISCUSSION

This study will demonstrate whether the specific strengthening of the first dorsal interosseous muscle has a superior and positive effect on the clinical picture of patients with CMC OA. Additionally, if specific strengthening of the muscle is not superior to the traditional protocol in the literature, it will also be determined whether the two protocols are equivalent in terms of the best clinical picture.

TRIAL REGISTRATION

Brazilian Registry of Clinical Trials (ReBEC) RBR-8kgqk4 . Prospectively registered on 15 January 2020.

Thumb Carpometacarpal Instability

The basal joint complex of the thumb provides the framework necessary for function of the human hand. Although its unique saddle articulation allows for a wide range of motion necessary for routine function of the hand, it is rendered inherently unstable because of poor bony congruency and reliance on its capsuloligamentous support. Painful instability of this joint can stem from several causes including traumatic dislocation, various hypermobility conditions, and chronic overuse and microtrauma. A thorough history and examination as well adequate imaging is necessary for proper evaluation of instability. Treatment options range from nonoperative modalities to surgery, which entails closed, percutaneous, or open reduction with numerous ligament repair and reconstruction techniques. Arthroscopy can also serve to be a useful adjunct for assessment of the joint and stabilization of the critical capsuloligamentous structures. This review outlines the critical osseous and soft-tissue anatomy surrounding the thumb carpometacarpal joint, the key points in evaluating patients presenting with acute traumatic and chronic thumb carpometacarpal instability without fracture or arthritis, and reviews both nonoperative and operative treatments of this injury.

Ligamentous constraint of the first carpometacarpal joint

To examine the role of the ligaments in maintaining stability of the first carpometacarpal (CMC) joint, a sequential ligament sectioning study of sixteen specimens was performed. While a small compressive force was maintained, loads were applied to displace each specimen in four directions - volar, dorsal, radial, and ulnar. Translations of the specimen in both dorsal-volar and radial-ulnar axes were measured. Initially, the tests were conducted with the specimen intact. These tests were then repeated following sectioning of the CMC anterior oblique ligament (AOL), ulnar collateral ligament (UCL), intermetacarpal ligament (IML) and dorsal radial ligament (DRL). The first CMC joint translation was increased in the absence of IML and DRL (p < 0.05). Both IML and DRL were important in constraining the first CMC joint translation against external applied loads. Potential applications of these findings include the treatment of joint hypermobility and the reduction or delay of onset or progression of first CMC joint osteoarthritis.

Joint position sense impairments in older adults with carpometacarpal osteoarthritis: A descriptive comparative study

STUDY DESIGN

This study has a descriptive-comparative, cross-sectional design.

INTRODUCTION

Sensorimotor (SM) impairments have been observed after common wrist and hand injuries such as distal radius fractures. However, there is a lack of research regarding SM impairments in patients with carpometacarpal (CMC) osteoarthritis (OA).

PURPOSE OF THE STUDY

This study sought to quantify proprioception deficits in older adults with CMC OA as compared with healthy adults using the joint position sense (JPS) test.

METHODS

The active JPS test was used to measure proprioception function in 29 thumbs with CMC OA and their 29 matched-control healthy counterparts. For comparison, participants with unilateral CMC OA were matched against themselves, whereas those with lateral CMC OA were age matched with a healthy participant. Data analysis was performed to compute the mean error of JPS; an unpaired t test was used to compare the mean error of the non-CMC OA group with the healthy control group.

RESULTS

The mean positional error measured from subjects with CMC OA was 9.53° compared with 1.32° for the age-matched healthy subjects. The effect size for the difference in means was D = 1.96.

CONCLUSIONS

Thumb SM impairments were found to be greater in subjects with CMC OA than in their healthy counterparts when using the JPS test to assess proprioception.

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.

Efficacy of Surgical Interventions for Trapeziometacarpal (Thumb Base) Osteoarthritis: A Systematic Review

Purpose

Methods

Results

Conclusions

Type of study/level of evidence

Snapping Extensor Pollicis Longus Tendon Subluxation Secondary to Trapeziometacarpal Instability: Case Report and Technique

CASE

A 20-year-old woman presented with painful, snapping extensor pollicis longus (EPL) tendon subluxation and trapeziometacarpal (TMC) joint instability. Hemi-extensor carpi radialis longus (ECRL) tendon autograft stabilized the TMC joint, reconstructing the 1-2 intermetacarpal ligament. The subluxed EPL tendon was centralized over the dorsal first metacarpal by tightening the metacarpophalangeal radial sagittal band and creating a dorsal first metacarpal "neosheath" pulley using ECRL graft remnant. Postoperative rehabilitation included Spica bracing and immediate thumb interphalangeal joint exercises.

CONCLUSION

The patient's pain due to EPL tendon subluxation and TMC joint instability completely resolved. Postoperative thumb range of motion and function were equivalent to the nonaffected side.

First Carpometacarpal Joint Instability: Dorsal Ligament Reconstruction

The first carpometacarpal (CMC-I) joint has an elaborate ligamentous support. Recent evidence has demonstrated that the dorsal ligament group is imperative for joint stability and that CMC-I joint instability may occur as a consequence of trauma and ligamentous laxity, and other conditions, with possible CMC-I subluxation and the development of osteoarthritis. Although various surgical techniques have been introduced for the treatment of ligamentous CMC-I instability, the Eaton-Littler reconstruction has been regarded as the gold standard. It is widely accepted that impaired hand function may still be present following the reconstruction of the CMC-I joint ligaments, demonstrating the existing limitations of current surgical techniques. In this paper, a novel extra-articular technique relating to CMC-I joint instability and focusing on the dorsal ligament group is described. A graft taken from the abductor pollicis longus tendon is utilized to reconstruct the dorsal radial ligament and posterior oblique ligament. This technique may provide a less invasive alternative than the gold standard procedure and the hypothesis is that it will lead to a better outcome.

Radiological measurement of trapezial dysplasia - variation of trapezial tilt and trapezial inclination

Trapeziometacarpal instability is a well-known condition that could lead to trapeziometacarpal osteoarthritis. With the focus in the literature being on ligament insufficiency, bony deformity has received much less attention. Although trapezial tilt is currently used to measure trapezial dysplasia, we believe trapezial inclination is a more reliable measurement. The purpose of this study is to compare these two methods for evaluating trapezial dysplasia and to define the most reproducible measurement. Fifty patients were identified who had three consecutive radiographs of the trapeziometacarpal joint. Eaton views with little to no signs of osteoarthritis (Eaton stage I or II) were used. Both trapezial tilt and trapezial inclination were measured by two independent observers on three radiographs for every patient. Intra-observer variation, absolute agreement and consistency, and intra-observer variation and consistency were assessed for both measurements. Mean trapezial tilt was 135° and mean trapezial inclination was 10°. For both observers, intra-observer variation of trapezial inclination was significantly less than for trapezial tilt. Our study shows that mean trapezial inclination in a middle-aged adult population is approximately 10°. This measurement is more reproducible than the more frequently used trapezial tilt and may be a better parameter to define trapezial dysplasia and to guide its treatment.

Subtraction hemiarthroplasty in basal joint arthritis: A case report

BACKGROUND

Basal joint arthritis is a common disease which is especially present in post-menopausal women. A variety of procedures have been described once conservative treatment has failed. The purpose of our study is to present a novel surgical technique based on a clinical case with three-year follow-up which is highly effective, even after failure of previous procedures.

CASE SUMMARY

We present a case of a 39 year-old-woman who suffered from recurring, persistent, sharp left thumb pain for several years. After two operative procedures, she presented again with intolerable, sharp pain over the trapeziometacarpal joint, and wished to proceed with a pain relieving procedure or arthroplasty. Intraoperatively, the articular surfaces appeared well, without any bare areas of bone or eburnation, resulting in the decision to perform a “subtraction hemiarthroplasty”. A shortening osteotomy of the os trapezium was performed by removing a slice of 8-9 mm bone, without damaging the joint cartilages. The osteotomy was stabilized using two screws, the ligament and capsular tissue was suture imbricated, and a cut down on the translation and a dorsal radial ligament reconstruction were performed. Three years after the final procedure, a long-term follow-up demonstrates excellent results, pain free with full range-of-motion.

CONCLUSION

Subtraction hemiarthroplasty with ligament tightening imbrication and reconstruction of the radial ligament led to excellent results in motion and pain.

Radial subluxation in relation to hand strength and radiographic severity in trapeziometacarpal osteoarthritis

OBJECTIVE

Greater joint laxity and radial subluxation of the thumb metacarpal base have been shown to be risk factors for the development of trapeziometacarpal osteoarthritis in an asymptomatic and radiographically normal joint. Despite this, it is unknown whether joint laxity changes with disease progression from mild to severe osteoarthritis. This study aimed to investigate the relationship between joint laxity and osteoarthritis severity, using the trapeziometacarpal subluxation ratio as an indicator of joint laxity.

METHOD

Baseline data were used from the first 100 participants included in the COMBO (Efficacy of combined conservative therapies on clinical outcomes in base of thumb OA) trial. All participants had bilateral posteroanterior (PA) and Eaton stress view hand radiographs, as well as grip and tip-pinch strength measurements. The PA view was used to assess Kellgren-Lawrence and Eaton grades, and the Eaton stress view was used to assess the trapeziometacarpal joint subluxation ratios. Generalised estimating equations were utilized to account for the fact that hand data are paired, and within-person measurements are therefore not independent.

RESULTS

Lower radial subluxation ratios were associated with higher Kellgren-Lawrence grades (B-coefficient -0.302; p-value 0.027), and lower grip strength scores (B-coefficient 2.06; p-value 0.006).

CONCLUSIONS

Radial subluxation ratios decreased with increasing disease severity, contrary to the progression from a normal joint to one with mild osteoarthritis, wherein higher joint laxity is a risk factor for disease. This may be explained by the mechanical stabilization provided by osteophytes and capsular changes in worsening osteoarthritis, as has been shown to be the case in the knee.

TRIAL REGISTRATION NUMBER

ACTRN 12616000353493.

LEVEL OF EVIDENCE

III.

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 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.

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.

Evidence-Based Medicine: Management of Metacarpal Fractures

LEARNING OBJECTIVES

After reading this article, the participant should be able to: 1. Understand metacarpal anatomy and its role in fracture pathology. 2. Determine when surgical intervention is needed for metacarpal fractures. 3. Understand the various treatment options for surgical fixation of metacarpal fractures. 4. Describe the role for external fixation in managing difficult metacarpal fractures.

BACKGROUND

Metacarpal fractures are common injuries that plastic surgeons should be able to evaluate and treat. The goal of this review is to highlight current evidence for managing metacarpal fractures. This Continuing Medical Education article consists of a literature review, illustrations, videos, and an online Continuing Medical Education examination.

METHODS

The authors reviewed the scientific literature from 2000 to 2015 regarding treatment of metacarpal fractures. Cadaver models were used for instructional videography demonstrating common surgical techniques. Multiple-choice questions were created to review pertinent topics. A discussion and references are provided.

RESULTS

Numerous treatment options have been described for metacarpal fractures, including splinting, percutaneous fixation, open reduction with internal fixation, and external fixation. All modalities are acceptable strategies for treating metacarpal fractures. The ultimate goal is to maximize hand function with minimal morbidity.

CONCLUSIONS

A thorough understanding of treatment modalities is helpful in evaluating and managing metacarpal fractures. Although the current literature supports a wide array of treatment strategies, high-level evidence to guide fracture management remains lacking.

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.

Therapy management of thumb carpometacarpal osteoarthritis: Exploring UK therapists’ perceptions of joint instability

Introduction

Carpometacarpal joint osteoarthritis is a common and painful condition associated with ligament laxity, subluxation and joint instability. Therapy management includes several interventions targeting the symptoms associated with instability and subluxation. This study aimed to explore the perceptions of experienced therapists, about their understanding of joint instability in carpometacarpal joint osteoarthritis and its relationship with laxity, subluxation and strength, and the perceived effectiveness of exercise interventions.

Methods

A qualitative research design, consisting of individual semi-structured interviews was conducted with nine therapists. Interviews were transcribed and analysed using a thematic analysis.

Results

Three themes were identified: (a) relationships between instability and laxity – the terms laxity and instability were often used interchangeably. Instability was associated with laxity, subluxation and disease progression, and was perceived to be a problem that includes the whole thumb column; (b) clinical reasoning by stage of disease – conflicting opinions were expressed regarding instability being present in pre-arthritic lax joints, early disease or all stages of disease; (c) the role of exercise in management – there was disagreement as to whether instability could be modified by developing muscle strength, or whether treatment should be focussed on compensating for instability.

Conclusion

Different perceptions of instability were reflected in wide-ranging opinions regarding the need to manage instability, and regarding the potential for altering instability. The impact of instability on function, and the concept of instability were not easily identified. A clearer definition of instability would facilitate the development and assessment of interventions for instability.

[Biomechanical evaluation of the first carpometacarpal joint stability by using different reconstruction methods]

Objective

To study the biomechanical differences of the first carpometacarpal joint stability by using different reconstruction methods so as to provide theoretical basis for the clinical choice of reconstruction method.

Methods

The upper limb specimens were selected from 12 fresh adult cadavers, which had no fracture, bone disease, dislocation of wrist joint, deformity, degeneration, or ligament injury on the anteroposterior and lateral X-ray films. The specimens were randomly divided into 5 groups: normal group, injury group, palmar carpometacarpal ligaments reconstruction group, dorsal carpometacarpal ligaments reconstruction group, and palmar and dorsal carpometacarpal ligaments reconstruction group. Three normal specimens were used as normal group, and then were made of the first carpometacarpal joint dislocation models (injury group); after the first carpometacarpal joint dislocation was established in the other 9 specimens; the volar ligament, dorsal ligament, and volar-dorsal ligaments were reconstructed with Eaton-Little method, Yin Weitian method, and the above two methods in 3 construction groups. The biomechanical test was done to obtain the load-displacement curve and to calculate the elastic modulus.

Results

During biomechanical test, ligament rupture and loosening of Kirschner wire occurred in 1 case of injury group and palmar carpometacarpal ligaments reconstruction group; no slipping was observed. The elastic modulus values were (11.61±0.20), (5.39±0.12), (6.33±0.10), (7.12±0.08), and (8.30±0.10) MPa in normal group, injury group, palmar carpometacarpal ligaments reconstruction group, dorsal carpometacarpal ligaments reconstruction group, and palmar and dorsal carpometacarpal ligaments reconstruction group respectively, showing significant differences among groups ( P<0.05).

Conclusion

Volar ligament reconstruction, dorsal ligament reconstruction, and volar-dorsal ligament reconstruction all can greatly improve the stability of the first carpometacarpal joint. And the effect of volar-dorsal ligament reconstruction is the best, but the stability can not restore to normal.

Surgical stabilization for symptomatic carpometacarpal hypermobility; a randomized comparison of a dorsal and a volar technique and a cohort of the volar technique

BACKGROUND

Hypermobility of the first carpometacarpal joint is mostly surgically treated with a volar approached stabilization by Eaton, but recent studies indicate the importance of the dorsoradial and intermetacarpal ligaments (DRL and IML) for carpometacarpal joint stability. The aim of this study was to compare a dorsal and volar technique for primary carpometacarpal hypermobility regarding pain and functional outcome.

METHODS

Patients with non-degenerative, painful carpometacarpal hypermobility were included and were randomly assigned to either the volar technique using the FCR, or a dorsal technique using the ECRL. After premature termination of the trial, we followed all patients treated with the volar approach. Pain, strength, and ADL function using DASH and Michigan Hand Questionnaires (MHQ) were measured at baseline and 3 and 12 months after surgery.

RESULTS

After including 16 patients, the randomized trial comparing the volar and dorsal technique was terminated because of significant increased pain in the dorsal group. Although none of the other outcome measures were significant in the underpowered comparison, in line with the pain scores, all variables showed a trend towards a worse outcome in the dorsal group. Between 2009 and 2012, 57 thumbs were surgically stabilized. We found significant better pain and MHQ scores, and after 1 year improved grip and key pinch strength. Patients returned to work within 8 (±7) weeks, of which 85 % in their original job.

CONCLUSIONS

Surgical stabilization of the thumb is an effective method for patients suffering from hypermobility regarding pain, daily function, and strength. We recommend a volar approach. Level of Evidence: Level I, therapeutic study.

Current review of trapeziometacarpal osteoarthritis (rhizarthrosis)

Trapeziometacarpal (TMC) joint is the secondly affected joint for osteoarthritis in the hand. TMC joint arthritis affects most commonly postmenopausal women after the fifth decade of life, due to hormonal and structural factors. Rhizarthrosis may lead to a clinical spectrum from subtle symptoms to advanced symptoms such as; severe pain, limitation of range of motion, muscular weakness, bony deformities, and end up ultimately with disability. Regardless of the etiopathogenesis; a variety of non-surgical and surgical methods have been used for the treatment of rhizarthrosis, depending on the age of the patient, symptomatology and the stage of the disease. The main goals of the treatments are as follows; relief of pain, conservation or restoration the stability and mobility of the TMC joint with the optimal preservation of the strength of surrounding musculature. In this article, the current methods, which have been used for the treatment of TMC joint osteoarthritis, will be mainly reviewed, together with concise up-to-date information on both its diagnosis and the anatomy of the TMC joint.

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.

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.