A biomechanical assessment of ligaments preventing dorsoradial subluxation of the trapeziometacarpal joint

Anatomic and Biomechanical Study of Thumb Carpometacarpal Dislocations: A Laboratory Study

BACKGROUND

No previous study recreating an isolated thumb carpometacarpal (CMC) dislocation with or without suture augmentation has been performed in the laboratory. This investigation aimed to evaluate the mechanism and ligamentous complex of isolated thumb CMC dislocations.

METHODS

Biomechanical analysis was performed in 10 cadaveric specimens. A posteriorly directed force or axial loading with hyperflexion through the CMC joint was applied. Load was applied at a rate of 1 mm/s until posterior CMC dislocation was achieved. Maximum load, displacement under nominal loading, stiffness, and mode of failure were recorded. The native ligament was repaired, augmented with high-tensile suture, and testing was repeated.

RESULTS

Posteriorly directed force produced posterior CMC dislocations, while axial loading and hyperflexion through the CMC joint caused fractures. Load-to-failure of the native CMC joint was 217.76 N (SD = 66.03). Stiffness of the ligamentous complex on average was 18.86 N/mm (SD = 8.83). Mean load-to-failure after repair with suture augmentation was 94.62 N (SD = 39.77), with average stiffness of 8.21 N/mm (SD = 3.06). The native ligament was noted to have greater stiffness (P = .002) and greater load-to-failure (P = .0001) than repair with suture augmentation. Maximum displacement-to-failure of the native ligament was 14.5 mm compared with repair with suture augmentation 11.9 mm (P = .068).

CONCLUSION

Isolated CMC dislocation was achieved with a posteriorly directed force rather than hyperflexion of the joint. Ultimate failure load of the repaired ligaments with suture augmentation was about half of that of the native ligaments. Further research into this technique is warranted.

Sonographic diagnosis of radiographically undetectable bennet fracture

Intra-articular fractures of the base of the first metacarpal (Bennet fractures) are prone to dislocation and require surgical reduction and fixation to prevent secondary degenerative joint disease and chronic dysfunction. Therefore, a prompt diagnosis is necessary, mostly achieved by conventional roentgenograms. We report the case of a 62-year-old man in whom a Bennet fracture was highly suspected on ultrasound (US) examination realized after a fall. Standard radiographs, obtained after US to confirm the diagnosis, were interpreted as normal. A computed tomography was then performed showing a typical Bennet fracture. This case report demonstrates that a careful assessment of bones must be an integral part of any routine musculo-skeletal US examination, particularly in post-traumatic patients. US can detect bone fractures where radiograph is not discriminating.

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.

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.

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.

Selective Thumb Carpometacarpal Joint Denervation Versus Trapeziectomy and Ligament Reconstruction With Tendon Interposition for Painful Arthritis: A Prospective Study With 2 Years of Follow-Up

PURPOSE

Thumb carpometacarpal (CMC) joint denervation is a relatively novel method for the management of osteoarthritis-associated pain by selective transection of articular nerve branches of the CMC joint. This study compared functional/patient-reported outcomes after CMC denervation with those after trapeziectomy and ligament reconstruction with tendon interposition (T + LRTI) over a 2-year follow-up period. We hypothesized that the outcomes of denervation and T + LRTI would be similar over the course of the study and at the final 2-year follow-up.

METHODS

Adults with Eaton stage 2-4 disease, no evidence of CMC subluxation, and no history of thumb injury/surgery were included. Pain scores, brief Michigan Hand Questionnaire (bMHQ), Kapandji score, 2-point discrimination, and grip/key/3-point pinch strength were measured at 3-, 6-, 12-, and 24-months after surgery. On average, T + LRTI patients underwent 7 weeks of splinting, with release to full activity at 3 months; denervation patients were placed in a soft postoperative dressing for 2 weeks, with release to full activity as tolerated at 3 weeks.

RESULTS

Thirty-three denervation and 20 T + LRTI patients were included. Preoperative characteristics were similar between both groups. Two denervation patients underwent secondary T + LRTI during the study period; one denervation patient underwent fat grafting to the CMC joint at an outside institution. Data prior to secondary surgeries were included in the analysis. The average tourniquet times (minutes) for denervation and T + LRTI were 43.5 ± 11.8 and 82.7 ± 14.2 minutes, respectively. For denervation and T + LRTI, the postoperative bMHQ scores were significantly higher than those at baseline at all time points. No significant differences were found between both groups for bMHQ, sensation, or strength measures.

CONCLUSIONS

Carpometacarpal denervation is well tolerated, with shorter tourniquet times and faster return to full activity than T + LRTI. For the study cohort, the conversion rate to T + LRTI at 2 years was 9%. Both procedures demonstrated durable improvement in bMHQ compared with the preoperative state with similar long-term outcomes over 2 years of follow-up.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic II.

Dorsoradial Capsulodesis for Stage I Trapeziometacarpal Joint Arthrosis

BACKGROUND

Thumb trapeziometacarpal (TM) joint arthrosis is a common cause of thumb pain, which adversely affects hand function. Early arthrosis is characterized by capsular laxity, painful pinch and grip, and physical findings of joint tenderness and laxity. Dorsoradial capsulodesis (DRC) is a surgical technique used to stabilize the TM joint and treat early-stage arthrosis. We aim to evaluate the clinical outcomes of DRC for treating trapeziometacarpal instability in early-stage disease.

METHODS

Between 2003 and 2019, 23 patients underwent DRC. Patients with stage I TM arthritis and more than 6-month postoperative follow-up were included. Pain and disability scores were calculated along with physical examination and radiographic evaluation at the final follow-up.

RESULTS

At mean postoperative follow-up of 43.5 months, 13 patients with a mean age of 39.1 years were examined. The mean Disabilities of the Arm, Shoulder, and Hand score was 5.7, and visual analog pain score was 0.5. Patients had no significant difference in strength or range of motion in the ipsilateral versus contralateral hand. Follow-up radiographs did not demonstrate arthritic changes.

CONCLUSIONS

Dorsoradial capsulodesis is a technically simple and reasonable option for stabilizing the TM joint in patients with early-stage arthrosis. This intervention showed no midterm progression to advanced arthritis in this cohort.

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.

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.

Association of Acute Trapeziometacarpal Joint Dislocation and Trapezium Fracture in a 14-Year-Old Boy: A Case Report

Fracture-dislocation of the trapeziometacarpal (TM) joint in adolescent patients is a rare injury, with only 3 cases reported in literature to our knowledge. Its low incidence, together with the complexity of the anatomy and biomechanics of TM joint, may represent a challenge for surgeons in choosing the best treating option. Here, we report a case of a TM fracture dislocation in a 14-year-old boy treated with percutaneous Kirschner wire pinning. The results we obtained endorsed our choice in patients for whom closed reduction is achievable.

Anatomical study for elucidating the stabilization mechanism in the trapeziometacarpal joint

To determine the pathogenesis of trapeziometacarpal (TMC) joint instability, which leads to osteoarthritis, we investigated the anatomical relationships among the surrounding ligaments, muscles (first dorsal interosseous [FDI] and opponens pollicis [OPP]), and joint capsule. We examined the bone morphology and cortical bone thickening in 25 cadaveric thumbs using micro-computed tomography and performed macroscopic and histological analyses. The dorsal trapezium had a tubercle with cortical bone thickening, corresponding to the attachment of the FDI aponeurosis intermingled with the joint capsule. Radially, the thin joint capsule was observed to underlie the muscular part of the OPP. Therefore, the dorsal ligaments, which have been previously considered static stabilizers, could be interpreted as parts of the capsuloaponeurotic complex consisting of the FDI aponeurosis and joint capsule. In the radial aspect, muscular OPP activation may be essential for TMC joint stabilization. Our findings may contribute to the appropriate management of TMC osteoarthritis.

Systematic Review of Ligament Reconstruction of Traumatic Isolated Thumb Carpometacarpal Joint Dislocation

INTRODUCTION

Thumb carpometacarpal (CMC) joint dislocations are rare with minimal agreement on surgical management. The dorsoradial ligament (DRL) is the primary joint stabilizer but has not historically been reconstructed. We hypothesize that the reported reconstruction of first CMC joint dislocations primarily uses the flexor carpi radialis (FCR) without collective agreement on a surgical technique.

METHODS

A systematic review of the PubMed database from 1996 to 2022 was done. Keywords were "thumb dislocation," "thumb carpometacarpal dislocation," and "carpometacarpal joint ligament repair." Inclusion criteria included isolated, unstable thumb CMC dislocations with reconstruction. The Preferred Reporting Items for Systematic Reviews and Meta Analyses guidelines were used.

RESULTS

Four hundred thirty-seven records were identified, and nine met inclusion criteria. Two articles were cohort studies, and seven were case reports. Thirty-seven patients were included, and 26 patients had reconstruction with tendonous autograft. Twenty-five (96.2%) used the FCR and 1 (3.9%) from the palmaris longus. Three patients had reconstruction with a suture anchor. Surgical techniques varied between studies.

DISCUSSION

The recommendation of the authors recreates the DRL during autograft repair. Current repair techniques that recreate the DRL use the FCR, but quantitative comparisons of tendonous autografts or suture anchors have not been done.

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.

Influence of differences in bone morphology on the distribution patterns of subchondral bone density across the trapeziometacarpal joint

We aimed to clarify the effects of morphological patterns of the trapezium and first metacarpal on the distribution of subchondral bone density across the articular surface of the trapeziometacarpal (TMC) joint using computed tomography osteoabsorptiometry. Thirty-three patients with normal TMC joints were evaluated. The percentages of the high-density areas in the radial-dorsal and ulnar-volar regions of the trapezium were significantly higher than that in the ulnar-dorsal region, and that of the ulnar-dorsal region of the first metacarpal was significantly lower than in the other three regions. The percentage of the high-density area of the radial-dorsal region of the trapezium and trapezial inclination (TI) showed a significant positive correlation, and the percentages of the high-density areas in the ulnar-dorsal and ulnar-volar regions had significant negative correlations with TI at the articular surface of the first metacarpal. These results indicate that bony morphologic differences in the trapezium affect the distribution pattern of subchondral bone density through the TMC joint.

Arthroscopic Partial Trapeziectomy for Thumb Carpometacarpal Joint Osteoarthritis: 5-Year Follow-up

Osteoarthritis of the thumb carpometacarpal (CMC) joint is the most common type of arthritis of the hand. The goal of the study was to evaluate clinical results and radiographic changes after arthroscopic partial trapeziectomy combined with ligament shrinkage and K-wire fixation to treat thumb CMC joint arthritis. From February 2013 to March 2014, 24 patients with thumb CMC joint arthritis received this arthroscopic procedure. We investigated the preoperative and postoperative Modified Mayo Wrist Score (MMWS); Disabilities of the Arm, Shoulder and Hand (DASH) score; radiographic changes; and associated complications. Sixteen patients completed 5 years of functional score and radiographic follow-up. Comparison of preoperative and postoperative MMWS and DASH scores showed significant improvement after the arthroscopic procedure. Pre-operative and postoperative evaluation of radiographic changes showed significant differences in the CMC joint distance, scaphoid-metacarpal distance, trapezium-metacarpal distance, and metacarpal prominence distance. This arthroscopic procedure is an effective and less invasive method for the treatment of CMC joint arthritis. This procedure can improve clinical function, preserve the mechanical height of the trapezium, and increase CMC joint space. We report our surgical technique and some pitfalls that required attention during the arthroscopic procedure. [Orthopedics. 2022;45(3):e140-e147.].

Anatomy and Biomechanics of the Thumb Carpometacarpal Joint

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

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.

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.

Management of thumb carpometacarpal joint dislocations: A systematic review

Although rare, thumb Carpometacarpal (CMC) joint dislocations can have significant complications which impact hand function. Optimal management is crucial in restoring pinch and grasp strength, but no agreement exists regarding treatment due to a paucity of literature on this subject. Systematic review was conducted involving non-operative and operative management of the CMC joint. 15 articles with a total of 60 thumbs were evaluated from published literature. 12/60 thumbs with isolated CMC joint dislocations were treated with closed reduction, with 4 cases needing additional ligament repair due to joint instability post-reduction. 51/60 of the isolated CMC joint dislocations had ligament reconstruction, with flexor carpi radialis tendon autograft (29/51) as the most popular option. 60/60 patients regained full function and stability of the CMC joint with significant pain relief. Although good surgical outcomes have been achieved, long term clinical outcome reporting is needed to develop a standardized approach to treatment.

Prevalence and distribution of MRI abnormalities in the articular cartilage and supporting ligaments in patients with early clinical stage first carpometacarpal joint osteoarthritis

OBJECTIVE

We used magnetic resonance imaging (MRI) to evaluate where articular degeneration begins and which ligaments are most often involved in the early clinical stage first carpometacarpal joint (CMCJ-1) osteoarthritis.

MATERIALS AND METHODS

We retrospectively analyzed the MRI findings of 26 patients with early clinical stage CMCJ-1 osteoarthritis and no radiologic abnormalities and 19 control patients without CMCJ-1 pain or osteoarthritis who underwent MRI for dorsal or ulnar wrist pain. Two observers blinded to group and clinical findings independently assessed the presence of chondral defects in four quadrants of the CMCJ-1: volar-ulnar (VU), volar-radial (VR), dorso-ulnar (DU), and dorso-radial (DR). The integrity of the four major ligaments of the CMCJ-1, i.e., the anterior oblique ligament (AOL), the intermetacarpal ligament (IML), the posterior oblique ligament (POL), and the dorsal radial ligament (DRL), was assessed. The observer reliability was analyzed using Cohen's kappa coefficient. The prevalence of cartilage lesions and ligament abnormalities in the osteoarthritic and control patients was compared using Fisher's exact test.

RESULTS

Cartilage lesions were significantly more common in the VU quadrant of the trapezium in the osteoarthritic patients than in the control patients (17/26 vs. 2/19; P = 0.002). AOL abnormalities were more common in the osteoarthritic patients than in the control patients (14/26 vs. 3/19; P = 0.009).

CONCLUSION

The MRI findings of early clinical stage CMCJ-1 osteoarthritis commonly demonstrated cartilage lesions in the VU quadrant of the trapezium and ligament abnormalities in the AOL.

The Effect of the Joint Capsule and Anterior Oblique Ligament on Dorsal Subluxation of the First Metacarpal During Key Pinch

Laxity of the anterior oblique ligament (AOL) and/or the dorsoradial ligament (DRL) are believed to contribute to the progression of osteoarthritis in the trapeziometacarpal joint through increased dorsal subluxation. Stress radiographs during functional tasks, such as key pinch, can be used to evaluate such joint instability. Cadaveric experiments can explore joint contact pressures as well as subluxation under varying conditions, to gain knowledge about joint mechanics. The disturbance of supporting tissues, such as the joint capsule, during experiments may affect the recorded stability of the joint. To evaluate potential effects of opening the joint capsule and severing the AOL, eleven cadaveric specimens were rigged to simulate key pinch. An anteroposterior (AP) radiograph of the hand was recorded for each specimen while intact, after partially opening the joint capsule and after sectioning the AOL. First metacarpal subluxation levels were compared between the intact joint, partially open joint capsule, and sectioned AOL. Neither opening the joint capsule nor cutting the AOL had a statistically significant effect on metacarpal subluxation. The results indicate that partially opening the joint capsule has a negligible effect on joint mechanics and support recent studies that postulate that the AOL plays a less substantial role in preventing subluxation.

[Anatomy of the trapeziometacarpal joint in the context of arthroplasty]

The thumb has a crucial role in the hand due to its position with regard to the fingers. The CMC-1 joint enables an extraordinary range of motion, since its geometry allows for opposition. The former joint may often succumb to osteoarthritis because a great range of motion in combination with large forces, small contact areas, and thorough usage are always present. Joint replacement is challenged by the great range of motion based on the necessary joint stability and the demand for sufficient pain reduction. This review highlights the anatomy of the CMC-1 joint with regard to joint preplacement solutions.

Suture Suspension Arthroplasty With Trapeziectomy for Thumb Carpometacarpal Arthritis Using a Wide-awake Approach

Despite the introduction of various techniques for ligament reconstruction in the treatment of thumb carpometacarpal (CMC) arthritis, complications, including proximal migration, dorsal subluxation of the first metacarpal base, hyperextension of the thumb metacarpophalangeal joint, and impingement between the first and second metacarpal bases, have been reported. Even suture button suspensionplasty with Arthrex Mini TightRope may be unable to correct the adduction contracture deformity and does not effectively tether the trapeziometacarpal toward the base of the index metacarpal, thus potentially leaving patients with persistent decreased first web space angle, proximal migration, and collapse deformity. Hence, suture suspension arthroplasty with abductor pollicis longus (APL)-flexor carpi radialis (FCR) tendon suture after trapeziectomy, a simpler technique, was applied. This simple surgical reconstruction abducts the first metacarpal bone. Abduction of the CMC joint improves metacarpophalangeal joint hyperextension. However, strong tension of the APL-FCR causes abduction contracture of the first CMC joint and difficulty of pinch motion of the thumb to the other fingers. Therefore, we have modified the arthroplasty with a wide-awake approach. The procedure is performed with the patient fully awake under local anesthesia, without a tourniquet to allow the patient to actively move and pinch the thumb, which allows the surgeon to confirm the tension of the APL-FCR suture. A fiber wire is connected to the APL-FCR with proper tension. The patient and surgeon can ensure pinch motion and thumb opposition with satisfaction during surgery.

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.

Chronic Carpometacarpal Dislocation of the Thumb: A Case Report and Review of the Literature

CASE

We report a case of a chronic, irreducible carpometacarpal (CMC) dislocation of the thumb, which was managed with a trapeziometacarpal arthrodesis.

CONCLUSION

This case demonstrates that arthrodesis is a suitable salvage procedure for chronic, irreducible CMC dislocations of the thumb.

Modified Eaton-Littler's Reconstruction for Traumatic Thumb Carpometacarpal Joint Instability: Operative Technique and Clinical Outcomes

Background  Injuries to thumb carpometacarpal joint ligaments lead to instability. Eaton-Littler's ligament reconstruction traditionally uses a strip of flexor carpi radialis to stabilize the CMC joint. Study Description  We have modified this technique to reproduce the direction of active action of the anterior oblique ligament by reconstructing both the volar and dorsoradial ligaments. In this prospective study, we evaluated patients with confirmed traumatic thumb CMC joint instability who underwent modified Eaton-Littler's reconstruction. Strength analysis, Michigan Hand Outcome Questionnaire, QuickDASH, and subjective outcome measures were collected pre- and postoperatively with minimum 3 years of follow-up. Eleven patients were included in the final analysis, with mean age of 29 years (range: 16-52) and average follow-up of 6.2 years (range: 3-11). There was a statistically significant improvement in all outcome measures. Clinical Relevance  Our modified technique helps to simultaneously address both volar and dorsal ligaments and yields satisfactory clinical outcomes at medium term follow-up. Level of Evidence  Level IV, case series.

An anatomical study on the effectiveness of Arthrex Mini TightRope® ligament reconstruction in an unstable trapeziometacarpal joint

INTRODUCTION

Laxity in the trapeziometacarpal (TMC) joint is a debilitating condition usually affecting a young population. It can be treated operatively with ligament reconstruction. The purpose of this study was to determine the effectiveness of the Arthrex Mini TightRope^® in reinforcing the stabilizing ligaments in an unstable TMC joint without decreasing the range of motion of the thumb. This method was compared with the "gold standard" published by Eaton and Littler in 1973.

MATERIALS AND METHODS

Six fresh frozen arms from five cadavers were included. TMC joint laxity was measured on stress view radiographs as the ratio of the radial subluxation (RS) of the first metacarpal in relation to the trapezium, by the first metacarpal articular width (AW) (as described by Wolf in 2009). Measurements of the pre- and post-operative range of motion (ROM) were performed and compared.

RESULTS

Both the Arthrex Mini TightRope^® and the Eaton-Littler stabilization improved the stability of the TMC joint. The pre-operative laxity value (ratio RS/AW) of 0.27 was significantly (P = 0.02) improved by each of the surgical interventions (Eaton-Littler RS/AW = 0.05 and Tightrope RS/AW = 0.09). The pre- and post-operative range of motion was not significantly different by each of the surgical interventions. There were no significant differences between the two stabilizing methods regarding laxity or range of motion.

CONCLUSION

The Arthrex Mini TightRope^® provided a good stabilization method for the TMC joint in this anatomical model without compromising the range of motion.

Trapezium Fracture Associated with Thumb Carpometacarpal Joint Dislocation: A Report of Three Cases and Literature Review

Isolated trapezium fracture in combination with thumb carpometacarpal (CMC) joint dislocation is extremely rare, and no treatment consensus exists. Herein, we report 3 successfully treated cases of isolated trapezium fracture with thumb CMC joint dislocation. While good short-term results have been reported in the literature, the possibility of substantial ligament injuries that can lead to future instability of the thumb CMC joint must be noted. In order to obtain an excellent long-term clinical result, we propose the consideration of the anatomical repair of the CMC joint in terms of both bony and ligamentous structures in cases where instability remains after fracture fixation.

In Vivo 3-Dimensional Kinematics of Thumb Carpometacarpal Joint During Thumb Opposition

PURPOSE

This study primarily aimed to demonstrate the screw-home rotation of the thumb carpometacarpal (CMC) joint and the function of surrounding ligaments during thumb oppositional motion.

METHODS

A 3-dimensional kinematic analysis of the thumb CMC joint was conducted using data derived from computed tomography of 9 healthy volunteers. Scans were obtained in the neutral forearm and wrist position and the thumb in maximum radial abduction, maximum palmar abduction, and maximum opposition. The movements of the first metacarpal and the palmar and dorsal bases on the trapezium during thumb oppositional motion from radial abduction through palmar abduction were quantified using a coordinate system originating on the trapezium. In addition to the kinematic analyses, the length of virtual ligaments, including the anterior oblique, ulnar collateral, dorsal radial, dorsal central (DCL), and posterior oblique ligament (POL), were calculated at each thumb position.

RESULTS

From radial abduction to opposition of the thumb through palmar abduction, the first metacarpal was abducted, internally rotated, and flexed on the trapezium. The palmar base of the first metacarpal moved in the palmar-ulnar direction, and the dorsal base moved in the palmar-distal direction along the concave surface of the trapezium. Although the DCL and POL lengthened, the lengths of other ligaments did not change significantly.

CONCLUSIONS

During thumb oppositional motion, internal rotation of the first metacarpal occurred, with the palmar base rotating primarily with respect to the dorsal base. The DCL and POL may be strained in thumb functional positions.

CLINICAL RELEVANCE

Kinematic variables indicated a screw-home rotation of the thumb CMC joint and the contribution of the dorsal ligaments to the stability of the rotation on the pivot point.

The Effect of Metacarpophalangeal Joint Hyperextension on Outcomes in the Surgical Treatment of Carpometacarpal Joint Arthritis

Purpose  In the surgical treatment of thumb carpometacarpal (CMC) joint arthritis, the effect of mild preoperative metacarpophalangeal (MCP) hyperextension on postoperative functional outcomes is unknown. We sought to examine outcomes after surgical treatment of CMC arthritis in patients with and without mild preexisting MCP deformity. Methods  A retrospective review was conducted to analyze the functional outcomes of patients treated for CMC arthritis at a single institution from March 1998 to May 2009. All patients were treated with one of two standard CMC arthroplasty procedures-either ligament reconstruction tendon interposition (LRTI) or a Weilby procedure-and none had additional procedures to address MCP hyperextension. Pre- and postoperative assessments included pinch and grip strength, degree of MCP hyperextension, and thumb radial and palmar abduction. A t -test was used to assume unequal variances. Results  A total of 203 patients were followed for an average of 27.3 months. Patients were divided into two groups: (1) patients without preoperative MCP hyperextension (167 patients) and (2) patients with mild but untreated preoperative MCP hyperextension (≤ 30 degrees; 36 patients). All patients underwent either a Weilby procedure (118 patients) or an LRTI; 85 patients). The main difference between techniques was the use of the abductor pollicis longus tendon as a post to secure the flexor carpi radialis (Weilby) or the use of a bone tunnel in the first metacarpal (LRTI). Analysis of the preoperative data showed no difference in the baseline parameters among both the groups, with the exception of MCP hyperextension. Postoperatively, neither the type of CMC procedure nor the presence of MCP hyperextension demonstrated any significant differences in key pinch, tip pinch, grip strength, and radial or palmar abduction of the thumb between the groups. Conclusion  There were no statistically significant differences in improvement of functional outcomes after surgery when comparing patients without preoperative MCP hyperextension to patients with untreated MCP hyperextension of less than 30 degrees. Level of Evidence  Level III, retrospective comparative study.

Assessment of normal trapeziometacarpal joint alignment

The purpose of this study was to determine the alignment of the normal trapeziometacarpal joint and any changes in its alignment with age. Radial, dorsal and dorsoradial subluxation were measured on computerized tomographic scans in 50 joints of 50 adults aged 18 to 62. There were statistically significant correlations between increasing age and dorsoradial subluxation but no significant correlation with dorsal and radial subluxation. Significant dorsoradial subluxation occurs after 46 years of age in the normal trapeziometacarpal joint. A mean dorsoradial subluxation of 21% (range 14%-30%) can be considered normal in this age group.

Sequential scapholunate and volar beak ligament reconstructions with flexor carpi radialis tendon grafts

The flexor carpi radialis tendon is considered by many the workhorse tendon in hand and wrist surgery. Some have expressed concerns about altering the mechanics of the wrist by sacrificing part or all of the flexor carpi radialis tendon. We present an interesting case of sequential scapholunate and volar beak ligament reconstructions using a flexor carpi radialis tendon autograft where a slip of tendon was harvested twice within three years, achieving a satisfactory clinical outcome at five years following the initial surgery.

[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.

Thumb Injuries in Athletes

Thumb injuries are common in athletes and present a challenging opportunity for upper extremity physicians. Common injuries include metacarpal base fractures (Bennett and Rolando types), ulnar and radial collateral ligament injuries, dislocation of the carpometacarpal and metacarpophalangeal joints, and phalanx fractures. This review, although not exhaustive, highlights some of the most common thumb injuries in athletes. The treating physician must balance pressure from athletes, parents, coaches, and executives to expedite return to play with the long-term well-being of the athlete. Operative treatment may expedite return to play; however, one must carefully weigh the added risks involved with surgical intervention.

Three-dimensional dynamic motion analysis of the first carpometacarpal ligaments

PURPOSE

The purpose of this study was to analyze the dynamic motion of the first carpometacarpal (CMC) ligaments on a three-dimensional (3-D) surface model and to examine the changes in the ligament lengths during the motion of the first CMC joint.

METHODS

Six fresh-frozen cadaver wrists were used to analyze the motion of the first CMC ligaments on a 3-D coordinate system using a digitizer. Four ligaments, namely, dorsoradial ligament (DRL), posterior oblique ligament (POL), superficial anterior oblique ligament (SAOL), and deep anterior oblique ligament (dAOL), were dissected and identified. Their attachments were digitized and represented on 3-D bone images. The distances between the ligament attachments of the first metacarpal and the trapezium, which were the ligament lengths, were measured during the extension-flexion and adduction-abduction of the first CMC joint.

RESULTS

Both the DRL and POL lengthened during flexion of the first CMC joint, and both the SAOL and dAOL lengthened during extension. Both the DRL and SAOL lengthened during adduction, and both the POL and dAOL lengthened during abduction. The DRL alone lengthened significantly at flexion and adduction when the first CMC joint was in dorsoradial dislocation.

CONCLUSIONS

The lengths of four ligaments changed significantly during first CMC joint motion. This study suggested that the DRL contributes substantial stability to the first CMC joint, preventing dorsoradial dislocation. This 3-D information improves the knowledge and understanding of the function of individual ligaments and their roles in the stability of the first CMC joint.

Efficacy of Dorsoradial Capsulodesis for Trapeziometacarpal Joint Instability: A Cadaver Study

PURPOSE

To test the biomechanical properties of the dorsoradial capsulodesis procedure.

METHODS

Six cadaveric hands were used. After exposing the trapeziometacarpal (TMC) joint, we placed Kirschner wires in the distal radius and thumb metacarpal. The rotation shear test was then performed to test the joint axial laxity, and angular measurements using Kirschner wires as reference points were documented. The dorsoradial (DR) ligament and capsule were released, followed by the intermetacarpal (IM) ligament; angular measurements were obtained. Finally, the DR capsulodesis procedure was performed, and final measurements were obtained. Comparisons were made among the various stages of ligament integrity to determine the amount of stability provided by DR capsulodesis.

RESULTS

All cadavers demonstrated axial laxity with transection of the DR ligament; an increase in stability was obtained after DR capsulodesis. Transection of the capsule and IM ligament caused increased laxity relative to the native joint (median, 24° and 35°, respectively, on rotational testing). After we performed DR capsulodesis, rotational stability improved by a median of 41° compared with DR ligament transection, 49° compared with DR and IM ligament transection, and 18° relative to the native joint.

CONCLUSIONS

Dorsoradial capsulodesis restores rotational stability for TMC joint after division of the DR and IM ligaments. The stability achieved was statistically significant compared with both an intact native TMC joint and induced laxity of the TMC joint.

CLINICAL RELEVANCE

The DR capsulodesis procedure may improve rotational stability to the TMC joint.

Trapeziometacarpal Ligaments Biomechanical Study: Implications in Arthroscopy

Purpose In the presence of early osteoarthritis, changes to the trapeziometacarpal joint (TMJ) often result in pain and is associated with joint instability and a tendency of dorsoradial subluxation. In these instances, arthroscopy may be indicated to: (1) assess the extent of cartilage disease and the laxity of ligaments and to (2) treat TMJ instability. The purpose of our study was to biomechanically analyze which ligaments are the primary stabilizers of the TMJ. Methods Overall, 11 fresh-frozen human cadaver specimens were dissected and attached to a testing device with the thumb positioned in neutral abduction, neutral flexion, and neutral opposition. The four extrinsic and five intrinsic muscle tendons acting on the TMJ were simultaneously loaded with weights proportional to their physiological cross-sectional area. The dorsal, volar, and ulnar groups of ligaments were dissected. A motion-tracking device, FasTrak (Polhemus Inc., Colchester, VT), was used to study the spatial position of the base of the first metacarpal bone (MC1), before and after random sectioning of each of the ligaments. Statistical analysis of the MC1 translation along the transverse XY plane was performed using one-way analysis of variance and a paired t-test, with a significance level of p < 0.05. Results After isolated sectioning of the volar or the ulnar ligaments, the MC1 moved dorsoradially with an average of 0.150 mm (standard deviation [SD]: 0.072) and 0.064 mm (SD: 0.301), respectively. By contrast, the destabilization of the MC1 after sectioning of the dorsal ligaments was substantially larger (0.523 mm; SD: 0.0512; p = 0.004). Conclusion Sectioning of the dorsal ligament group resulted in the greatest dorsoradial translation of the MC1. Consequently, the dorsal ligaments may be regarded as the primary TMJ stabilizers. Clinical Relevance This study suggests that stabilizing arthroscopic shrinkage of the TMJ should be targeted toward the dorsal TMJ ligaments.

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.

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.

Primary repair of capsuloligamentous structures of trapeziometacarpal joint: A preliminary study

BACKGROUND

Isolated trapezio-metacarpal joint dislocation is uncommon and challenging since controversy still exists regarding its management.

DESCRIPTION

We present a short case series in which direct repair of trapezio-metacarpal ligaments was done in three patients who had isolated, unstable dislocation of the thumb carpometacarpal joint. All of them were engaged in tasks where no compromise in hand functions and grip strength was affordable. The dislocation was addressed primarily by repair of volar oblique and dorsoradial ligaments with suture anchors. The joint was immobilised in a cast for 4 weeks followed by gradual mobilisation.

RESULTS

At an average follow up of 15 months, all the three patients have no restriction in the range of motion. There are no symptoms and signs of instability. In two patients, there is no pain at all; while one patient has occasional pain which is mild and does not interfere with the hand function. Radiographic examination showed normal joint alignment and no signs of subluxation or early osteoarthritis.

CONCLUSION

Repair of the capsuloligamentous complex with suture anchors may be considered as a treatment option in unstable trapezio-metacarpal joint dislocations in high demand patients.

Comparison of the anatomical dimensions and mechanical properties of the dorsoradial and anterior oblique ligaments of the trapeziometacarpal joint

PURPOSE

The respective roles of the dorsoradial (DRL) and anterior oblique (AOL) ligaments in stability of the highly mobile trapeziometacarpal (TMC) joint remain disputed. Earlier publications have pointed to the AOL as the key stabilizing structure; yet, more recent publications have challenged the stabilizing role of the AOL, favoring the DRL as the main TMC joint stabilizer. We executed an anatomical study of the ligaments, including detailed dissection to quantify the length, width, and thickness of the AOL and DRL and tested the material properties of these ligaments.

METHODS

Thirteen fresh frozen cadaveric thumbs from 9 specimens were used. Length, width, and thickness of the AOL and DRL were measured on magnetic resonance imaging and/or after dissection. Next, the first metacarpal and trapezium were isolated together with both ligaments, and both bones were cut sagittally to isolate a first metacarpal-AOL-trapezium and first metacarpal-DRL-trapezium complex from each thumb. These samples were subjected to cyclic loading in displacement-controlled tests. The obtained force-displacement curves were used to calculate stiffness and hysteresis of each sample.

RESULTS

Our results showed that the DRL is significantly shorter and thicker than the AOL, which is thin and ill-defined. Our results also indicate that the DRL has a higher stiffness than the AOL, making it a more likely candidate to provide joint stability.

CONCLUSIONS

Although the AOL has been asserted to be the primary restraint to dorsoradial subluxation, this view has been challenged over the past 10 years by several studies. These studies have shown the AOL to be relatively weak and compliant compared with the intermetacarpal and dorsoradial ligaments and have demonstrated that the DRL is the strongest and stiffest ligament of the TMC joint. Our studies confirm these findings.

CLINICAL RELEVANCE

This study indicates that the DRL is relatively stiff and thick, suggesting it should be repaired or reconstructed when disrupted to restore stability of the TMC joint.

Ultrastructure and innervation of thumb carpometacarpal ligaments in surgical patients with osteoarthritis

BACKGROUND

The complex configuration of the thumb carpometacarpal (CMC-1) joint relies on musculotendinous and ligamentous support for precise circumduction. Ligament innervation contributes to joint stability and proprioception. Evidence suggests abnormal ligament innervation is associated with osteoarthritis (OA) in large joints; however, little is known about CMC-1 ligament innervation characteristics in patients with OA. We studied the dorsal radial ligament (DRL) and the anterior oblique ligament (AOL), ligaments with a reported divergent presence of mechanoreceptors in nonosteoarthritic joints.

QUESTIONS/PURPOSES

This study's purposes were (1) to examine the ultrastructural architecture of CMC-1 ligaments in surgical patients with OA; (2) to describe innervation, specifically looking at mechanoreceptors, of these ligaments using immunohistochemical techniques and compare the AOL and DRL in terms of innervation; and (3) to determine whether there is a correlation between age and mechanoreceptor density.

METHODS

The AOL and DRL were harvested from 11 patients with OA during trapeziectomy (10 women, one man; mean age, 67 years). The 22 ligaments were sectioned in paraffin and analyzed using immunoflourescent triple staining microscopy.

RESULTS

In contrast to the organized collagen bundles of the DRL, the AOL appeared to be composed of disorganized connective tissue with few collagen fibers and little innervation. Mechanoreceptors were identified in CMC-1 ligaments of all patients with OA. The DRL was significantly more innervated than the AOL. There was no significant correlation between innervation of the DRL and AOL and patient age.

CONCLUSIONS

The dense collagen structure and rich innervation of the DRL in patients with OA suggest that the DRL has an important proprioceptive and stabilizing role.

CLINICAL RELEVANCE

Ligament innervation may correlate with proprioceptive and neuromuscular changes in OA pathophysiology and consequently support further investigation of innervation in disease prevention and treatment strategies.

Trapeziometacarpal joint stability: the evolving importance of the dorsal ligaments

BACKGROUND

Trapeziometacarpal (TMC) arthritis of the thumb is a common source of hand pain and disability. TMC ligamentous instability may play a role in TMC degeneration. However, the relative importance of the TMC ligaments in the etiology of degeneration and the use of surgery to treat instability in early-stage arthritis are unclear.

QUESTIONS/PURPOSES

In this review, we addressed several questions: (1) What are the primary ligamentous stabilizers of the thumb TMC joint? (2) What is the evidence for ligament reconstruction or ligament imbrication in the treatment of thumb TMC joint osteoarthritis? And (3) what is the evidence for thumb metacarpal osteotomy in the treatment of thumb TMC joint osteoarthritis?

METHODS

We performed a systematic review of the literature using PubMed (MEDLINE(®)) and Scopus(®) (EMBASE(®)) for peer-reviewed articles published until November 2012. Fifty-two studies fit the inclusion criteria. Twenty-four studies were anatomic, biomechanical, or histopathologic studies on TMC joint ligamentous anatomy, 16 studies were clinical studies concerning ligament reconstruction, and 12 studies were clinical studies on thumb metacarpal osteotomy.

RESULTS

Over the past two decades, increasing evidence suggests the dorsoradial ligament is the most important stabilizer of the TMC joint. Other ligaments consistently identified are the superficial anterior oblique, deep anterior oblique, intermetacarpal, ulnar collateral, and posterior oblique ligaments. Ligament reconstruction and metacarpal osteotomy relieve pain and improve grip strength based on Level IV studies.

CONCLUSIONS

The dorsal ligaments are the primary stabilizers of the TMC joint. Ligament reconstruction and metacarpal osteotomy ameliorate ligamentous laxity and relieve pain based on Level IV studies.

Carpometacarpal dislocation of the thumb associated with fracture of the trapezium

Carpometacarpal dislocation (CMC) of the thumb associated with fracture of trapezium is an extremely rare injury, with only 12 cases that sustained similar injuries reported in the literature. In this article, another patient with this rare injury was reported, and all previously published cases were extensively reviewed. The presented case and all previously published cases had a longitudinally oriented trapezium fracture, which is naturally unstable and almost always associated with dislocation of the CMC joint. In contrast to previous descriptions, we believe that CMC joint dislocation and trapezium fracture are not two distinct pathologies that occur simultaneously by chance but share cause and consequence.