Traumatic dislocations and instability of the trapeziometacarpal joint of the thumb

Trapeziometacarpal joint imaging: Normal high-resolution MRI, US and CT compared with cadaveric specimens and pathological imaging findings

INTRODUCTION

The trapeziometacarpal (TMC) joint is a complex joint, whose anatomy and function are different from the metacarpophalangeal joints of the long fingers. The stability of this joint is ensured at three levels by multiple structures: osteochondral, capsulo-ligamentous, and musculo-tendinous. The anatomical and biomechanical structures ensuring the stability of the TMC joint are perfectly evaluated on magnetic resonance imaging (MRI), with a high degree of confidence. All described ligaments are anatomically visible and perfectly assessed on MRI and ultrasound (US): the dorsoradial ligament, the posterior oblique ligament, the intermetacarpal ligament, the ulnar collateral ligament, the two bundles of the anterior oblique ligament (break ligament), as well as the superficial anterior oblique and deep anterior oblique ligaments.

METHODOLOGY

This educational review assesses the TMC joint anatomy using high-field MRI and US compared with cadaveric specimens as well the biomechanics of this joint. In addition, it highlights pathological patterns of traumatic (sprain, dislocation, and fractures) and degenerative diseases.

RESULTS AND CONCLUSION

Knowledge of TMC joint anatomy is crucial to the radiologists' understanding and assessment of various traumatic and degenerative pathologies, and thus helps clinicians and surgeons choose the appropriate treatment.

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.

Trapeziometacarpal Dislocations in Pediatric Age, Is There a Better Treatment? Series of Cases and a Systematic Review

(1) Background: Dislocations of the trapeziometacarpal joint (TMC) are uncommon in children and adolescents. Only a few isolated cases are reported in the literature. Therapeutic guidance is minimal and inconclusive. (2) Methods: The authors present four patients treated for this unusual lesion. We evaluated the evolution according to treatment, age, patient activity, and quickDASH. Despite the clear limitation of the small number of patients, it is relevant to try to better understand this lesion and its evolution. A systematic review of the literature was also conducted. (3) Results: This is the largest published series of TMC dislocations in children and adolescents. Patients included a 12-year-old girl treated conservatively with a poor quickDASH; a 9-year-old girl treated surgically with the Eaton-Littler technique for a new dislocation with a partially modified quickDASH; a 13-year-old boy with two necessary closed reductions for a new dislocation and a very good final quickDASH; and a 12-year-old boy treated with closed reduction and percutaneous fixation with excellent final results with quickDASH. (4) Conclusions: In the absence of scientific evidence, conservative treatment and ligament reconstruction did not provide good functionality. In contrast, closed reduction with percutaneous fixation provided excellent results. Therefore, the authors would recommend closed reduction and percutaneous needle fixation as an elective method to treat TMC dislocations in pediatric and adolescent patients.

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.

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.

Bilateral Bennett's fracture: A case report

Bennet's fracture represents one of the most common injuries of the hand district, involving the base of the thumb, and it is affects children and elderly patients the most. The fracture is caused by direct axial trauma to a partially flexed first metacarpal and it is always intra-articular: the fracture line separates the palmar ulnar aspect of the first metacarpal base from the remaining first metacarpal. The fracture pattern is such that the first metacarpal shaft moves dorsally, proximally, and radially due to the pull of the abductor pollicis longus, extensor pollicis longus, extensor pollicis brevis, and the adductor pollicis brevis, which remain attached to the fracture fragment. The surgical treatment consists of closed reduction with percutaneous pinning or open reduction with either pins or interfragmentary screws. The decision to treat these fractures with either open reduction or closed reduction is still a matter of debate. To the best of our knowledge, there are no cases of bilateral Bennett's fracture reported in literature. The aim of this paper is to present a rare case of bilateral Bennet's fracture, the decision of two different treatments, and the good clinical outcomes.

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.

Isolated Trapeziometacarpal Joint Dislocation With Five Years of Follow-up: A Case Report and Review of the Literature

Isolated trapezio-metacarpal joint dislocation is a rare injury. Despite being simple to reduce, there is not yet a consensus regarding how to secure the reduction, the type of immobilization, and the postoperative protocol. Herein, we present a rare case of pure trapezio-metacarpal joint dislocation without any associated fractures that was treated with closed reduction and intermetacarpal fixation, six weeks of immobilization, and an early rehabilitation protocol.

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.

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.

Patient satisfaction with the CMC controller: A cohort study

STUDY DESIGN

Cohort study.

INTRODUCTION

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

PURPOSE OF THE STUDY

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

METHODS

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

RESULTS

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

DISCUSSION

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

CONCLUSION

The results were both statistically and clinically significant.

Accuracy of fluoroscopic examination in the treatment of Bennett's fracture

Background

Restoration of joint congruity is an important factor for the prevention of subsequent arthritis in patients with Bennett’s fracture. Surgical treatment of Bennett’s fracture is thus generally recommended for displaced intra-articular fractures to the proximal aspect of the thumb metacarpal. Fluoroscopic examination is used to evaluate the adequacy of closed reduction after pinning of Bennett’s fracture. The purpose of this study was to determine the accuracy of fluoroscopy to determine the reduction of Bennett’s fractures.

Methods

A model was created, to mimic a Bennett’s fracture utilizing ten fresh-frozen cadaveric hands. An oblique cut was made in the proximal aspect of the thumb metacarpal using an oscillating saw. The small oblique fragment involved 1/4–1/3 of the joint surface was then shifted in position creating a step-off or gap at the fracture site. An anatomical reduction model, gap models (1 mm, 2 mm, 3 mm), and step-off models (1 mm, 2 mm, 3 mm) were created using percutaneous fixation with two 1.0 mm Kirschner wires for each cadaveric hand. Fluoroscopic assessment then took place and was reviewed by 2 attending hand surgeons blinded to the actual position. Their estimated fluoroscopic position was then compared to the actual displacement.

Results

The step-off and gap on fluoroscopic examination showed a significant difference compared to the step-off and gap from direct visualization. The frequency of underestimation for the 3 mm displacement models from the fluoroscopic examination was 60%. The frequency for overestimated was 9% for the models in which displacement was within 2 mm (0, 1, 2 mm).

Conclusions

The assessment of articular gap and step-off using PA (postero-anterior), AP (antero-posterior), and lateral view of fluoroscopic examination is not accurate as compared to the examination by direct visualization. Surgeons need to be aware that PA, AP and lateral view of fluoroscopic examination alone may not be sufficient to judge the final position of a reduced Bennett’s fracture. Other methods such as live fluoroscopy in multiple different planes, 3-dimensional fluoroscopy or arthroscopic examination should be considered.

Costal cartilage graft for an unstable post-traumatic trapeziometacarpal intra-articular malunion in a pediatric patient: A case report

Trapeziometacarpal dislocation is a rare traumatic lesion, especially in the pediatric population. Various treatments have been described for acute cases. We report the case of a 15-year-old boy who was admitted in the emergency department with chronic post-traumatic trapeziometacarpal dislocation due to an untreated first metacarpal base fracture (Bennett), with complete articular destruction. The patient was treated by open reduction, interposition of a costal cartilage graft, and intermetacarpal K-wire fixation. Follow-up at 2 years after the surgery showed excellent clinical and radiological results. This surgical technique had not been described previously in the pediatric population.

[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.

The effect of cup orientation on stability of trapeziometacarpal total joint arthroplasty: a biomechanical cadaver study

It has been suggested that the cup of a trapeziometacarpal total joint replacement should be positioned parallel with the proximal articular surface of the trapezium to align it with the centre of motion. This would diminish the chance of dislocation. The goal of this study was to test this idea biomechanically. A linked trapeziometacarpal prosthesis was implanted in seven cadaver hands and combined with three-dimensional printed trapezium cups in 17 different orientations. For every combination, stability of the prosthesis was assessed through its entire passive range of motion. Dorsal inclination of the cup relative to the proximal articular surface increased the risk of dislocation with thumb flexion and opposition. The risk of dislocation was also increased with lateral or medial inclination of the cup exceeding 20°. Our results demonstrate that cup orientation is an important factor in prosthetic joint stability. Cup placement parallel to the proximal articular surface is ideal.

Cartilage wear patterns in severe osteoarthritis of the trapeziometacarpal joint: a quantitative analysis

OBJECTIVE

The present quantitative study aimed to assess the three-dimensional (3-D) cartilage wear patterns of the first metacarpal and trapezium in the advanced stage of osteoarthritis (OA) and compare cartilage measurements with radiographic severity.

DESIGN

Using 19 cadaveric trapeziometacarpal (TMC) joints, 3-D cartilage surface models of the first metacarpal and trapezium were created with a laser scanner, and 3-D bone surface model counterparts were similarly created after dissolving the cartilage. These two models were superimposed, and the interval distance on the articular surface as the cartilage thickness was measured. All measurements were obtained in categorized anatomic regions on the articular surface of the respective bone, and we analyzed the 3-D wear patterns on the entire cartilage surface. Furthermore, we compared measurements of cartilage thickness with radiographic OA severity according to the Eaton grading system using Pearson correlation coefficients (r).

RESULTS

In the first metacarpal, the cartilage thickness declined volarly (the mean cartilage thickness of the volar region was 0.32 ± 0.16 mm, whereas that of the dorsal region was 0.53 ± 0.18 mm). Conversely, the cartilage evenly degenerated throughout the articular surface of the trapezium. Measurements of the categorized regions where cartilage thinning was remarkable exhibited statistical correlations with radiographic staging (r = -0.48 to -0.72).

CONCLUSIONS

Our findings indicate that cartilage wear patterns differ between the first metacarpal and trapezium in the late stage of OA. There is a need for further studies on cartilage degeneration leading to symptomatic OA in the TMC joint.

Bennett Fractures: A Biomechanical Model and Relevant Ligamentous Anatomy

PURPOSE

This study examined a palmar beak fracture model to determine which thumb carpometacarpal (CMC) joint ligament is the primary ligament relevant to the pattern of injury.

METHODS

Six fresh-frozen cadaveric wrists were used. The radius, ulna, and first metacarpal were secured and tested with a materials testing system, holding the wrist in 20° extension, 20° ulnar deviation, and 30° palmar abduction of the first metacarpal. Testing consisted of preconditioning cycles followed by compressive loading at 100 mm/s. We confirmed fractures with fluoroscopy and dissected the specimens to examine the CMC joint ligaments. The metacarpal was stressed through a range of motion to determine which maneuvers reduced or displaced the fractures.

RESULTS

Our model successfully created palmar beak fractures in all cadaveric specimens. All fractures were displaced and intra-articular. The anterior oblique ligament (AOL) was thin and partially attached to the palmar beak fracture fragment. The ulnar collateral ligament was attached in its entirety to the fracture fragment and represented a thicker, more robust ligament compared with the AOL. Radial abduction and pronation of the metacarpal reduced fracture displacement. Extension of the CMC joint or tensioning the AOL did not decrease fracture displacement.

CONCLUSIONS

This model successfully created a reproducible and clinically relevant palmar beak fracture in a biomechanical setting. The primary ligament attached to the palmar beak fracture fragment was the ulnar collateral ligament, and not the AOL as previously described. These findings suggest that the AOL may not be a substantial contributor to palmar beak fracture morphology.

CLINICAL RELEVANCE

A refined description of the ligamentous anatomy of the palmar break fracture enhances opportunities for improved reduction and treatment of this common hand injury.

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

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

Axial Rotation Test for Trapeziometacarpal Joint Hypermobility in the Normal Population

Background: The objective was to quantify joint laxity in healthy volunteers by measuring the passive axial rotation of the trapeziometacarpal joint using the axial rotation test.

Methods: Eighty volunteers (34 men and 46 women) were subjected to the axial rotation shear test and the degree of total rotational motion (TRM) was assessed. Volunteers were divided into Group I with a range of 18–50 years old and Group II for 51 years and older. Statistical analysis was performed.

Results: The average TRM in Group I was 32.3 mm for women, and 27.4 mm, for men (p = 0.04). The average TRM in women of Groups I and II, was 32.3 and 21.6 mm respectively, (p < 0.001). The average TRM in men of Groups I and II, was 27.4 and 19.4 mm (p < 0.001). In Group II the average TRM of women was 21.6 mm, and for men was 19.4 mm, which was not significantly different.

Conclusions: Young women have greater degree of rotational laxity in the TM joint compared to men of the same age group and to older women. The axial rotation test can quantify the degree of rotational laxity of the TM joint.

In vivo kinematics of the thumb during flexion and adduction motion: Evidence for a screw-home mechanism

The thumb plays a crucial role in basic hand function. However, the kinematics of its entire articular chain have not yet been quantified. Such investigation is essential to improve our understanding of thumb function and to develop better strategies to treat thumb joint pathologies. The primary objective of this study is to quantify the in vivo kinematics of the trapeziometacarpal (TMC) and scaphotrapezial (ST) joints during flexion and adduction of the thumb. In addition, we want to evaluate the potential coupling between the TMC and ST joints during these tasks. The hand of 16 asymptomatic women without signs of thumb osteoarthritis were CT scanned in positions of maximal thumb extension, flexion, abduction, and adduction. The CT images were segmented and three-dimensional surface models of the radius, scaphoid, trapezium, and the first metacarpal were created for each thumb motion. The corresponding rotations angles, translations, and helical axes were calculated for each sequence. The analysis shows that flexion and adduction of the thumb result in a three-dimensional rotation and translation of the entire articular chain, including the trapezium and scaphoid. A wider range of motion is observed for the first metacarpal, which displays a clear axial rotation. The coupling of axial rotation of the first metacarpal with flexion and abduction during thumb flexion supports the existence of a screw-home mechanism in the TMC joint. In addition, our results point to a potential motion coupling between the TMC and ST joints and underline the complexity of thumb kinematics. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:1556-1564, 2017.

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.

Development and implementation of a trapeziectomy rehabilitation protocol

Introduction

The purpose of this study was to evaluate a newly developed trapeziectomy rehabilitation protocol. Variability in trapeziectomy rehabilitation protocols and the arrival of new surgeons in our hospital required a uniform protocol.

Methods

Fifty hands in 44 patients (32 women/12 men) were immobilised for 4 weeks in a plaster cast after a trapeziectomy. A carpometacarpal splint immediately followed for 2 weeks, taken off for exercises and self-care. Patients were assessed preoperatively and at 3, 6 and 12 months using: a pain visual analogue scale (VAS), grip, tip pinch and lateral pinch strength, goniometry, the Modified Kapandji Index (MKI), the Quick Disabilities of the Arm, Shoulder and Hand questionnaire (Q-DASH, Dutch version) and the Short Form 36 (SF-36, Dutch version). At 3, 6 and 12 months, patient’s satisfaction with the operation was rated on a satisfaction VAS.

Results

The correlation between pain and patient satisfaction was significant ( ρ = −0.80). VAS pain improved from a median of 75 mm preoperatively to 20 mm at 12 months ( p < 0.01). The Q-DASH improved from a median of 48 preoperatively to 20 at 12 months ( p < 0.01). Median grip, tip pinch and lateral pinch strength increased at 12 months by 19%, 8% and 24%, respectively from the baseline measurement.

Conclusions

Patients participating in a standardised protocol after trapeziectomy with 4 weeks immobilisation demonstrated improvements in pain, Q-DASH, grip strength, tip pinch and lateral pinch grip. They were satisfied with the results. Further research into the optimal immobilisation time after trapeziectomy surgery is needed.

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.

The Envelope of Physiological Motion of the First Carpometacarpal Joint

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

Bennett fracture: Arthroscopically assisted percutaneous screw fixation versus open surgery: Functional and radiological outcomes

BACKGROUND

Arthroscopically assisted percutaneous screw fixation has been introduced to decrease the invasiveness of treatments for intra-articular fractures.

HYPOTHESIS

Arthroscopically assisted percutaneous screw fixation of Bennett fracture simplifies the postoperative course compared to open surgery.

MATERIAL AND METHODS

Twenty-one Bennett fractures detaching at least one-third of the joint surface were studied retrospectively. Among them, 11 were managed by percutaneous screw fixation and 10 by open surgery. Follow-up was at least 12 months. Clinical and radiological evaluations were performed to assess the development of complications, tourniquet time, immobilisation time, sick-leave time, QuickDASH score, Kapandji score, grip strength, pinch strength, return to work activities, intra-articular screw migration, inadequate reduction, non-union, and joint remodelling.

RESULTS

The percutaneous group had significantly shorter immobilisation (P<0.0001) and tourniquet (P=0.0068) times. The number of complications was 1 in the percutaneous group and 6 in the open-surgery group. Whereas no adverse radiographic outcomes were found in the percutaneous group, the open-surgery group had 2 cases of inadequate reduction, 3 cases of joint remodelling, and 4 cases of intra-articular screw migration. The number of patients unable to return to their previous work activities was 1 (9%) in the percutaneous group and 3 (30%) in the open-surgery group.

DISCUSSION

Arthroscopically assisted percutaneous screw fixation seems to ensure a simpler postoperative course, with fewer clinical and radiographic complications, as well as shorter tourniquet and immobilisation times.

LEVEL OF EVIDENCE

IV, retrospective comparative study.

Percutaneous fixation of first metacarpal base fractures using locked K-wires: a series of 14 cases

The treatment of choice for first metacarpal base fractures is surgical. Open fixation is stable but causes tendinous adhesions. Percutaneous fixation is minimally invasive but is often followed by secondary displacement. Herein, we describe an alternative approach that combines advantages of both techniques through increasing stability of the Iselin technique by externally connecting the K-wires. Our series included 13 men of mean age 28 years. There were 13 fractures, 6 of which were extra-articular; there were 7 Bennett fractures, 5 of which had a large fracture fragment. After reduction, two 18 mm K-wires were driven medially crossing the 3 cortices of the first and second metacarpals. After bending them at 90-degree angles, the K-wires were connected externally in a construction allowing adaptation of the gap between the K-wires. Gentle immediate mobilization was allowed and the K-wires were removed 6 weeks later in clinic. At 16-month follow-up, mean pain score was 0.2/10 and Quick DASH was 2.9/100. Pinch grip was 81.8% of the contralateral side and grip strength 91.2%. The first web space opening was 79.1%. There was 1 secondary displacement with a good final result and 2 malunions. No arthritis was noted, but the follow-up was short. Our results show that the Iselin technique using locked K-wires is minimally invasive, stable, allows immediate mobilization, and K-wire removal in the office. Its indications may be extended to all fractures of the base of the first metacarpal whether articular or extra-articular.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

CLINICAL RELEVANCE

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

Atypical Bennett's fracture-dislocation

We herein report an unusual case of a fracture-dislocation of the thumb metacarpal base. The injury consisted of features typical of Bennett's fracture-dislocation of the thumb trapeziometacarpal joint, with additional rotation of the proximal fragment, signifying a greater ligamentous injury. Radiographic features of this injury are discussed together with its pathomechanics. Surgical management was undertaken due to the inherent instability of this injury.

The 2014 ABJS Nicolas Andry Award: The puzzle of the thumb: mobility, stability, and demands in opposition

BACKGROUND

The paradoxical demands of stability and mobility reflect the purpose and function of the human thumb. Its functional importance is underscored when a thumb is congenitally absent, injured, or afflicted with degenerative arthritis. Prevailing literature and teaching implicate the unique shape of the thumb carpometacarpal (CMC) joint, as well as its ligament support, applied forces, and repetitive motion, as culprits causing osteoarthritis (OA). Sex, ethnicity, and occupation may predispose individuals to OA.

QUESTIONS/PURPOSES

What evidence links ligament structure, forces, and motion to progressive CMC disease? Specifically: (1) Do unique attributes of the bony and ligamentous anatomy contribute to OA? (2) Can discrete joint load patterns be established that contribute to OA? And (3) can thumb motion that characterizes OA be measured at the fine and gross level?

METHODS

We addressed the morphology, load, and movement of the human thumb, emphasizing the CMC joint in normal and arthritic states. We present comparative anatomy, gross dissections, microscopic analysis, multimodal imaging, and live-subject kinematic studies to support or challenge the current understanding of the thumb CMC joint and its predisposition to disease.

RESULTS

The current evidence suggests structural differences and loading characteristics predispose the thumb CMC to joint degeneration, especially related to volar or central wear. The patterns of degeneration, however, are not consistently identified, suggesting influences beyond inherent anatomy, repetitive load, and abnormal motion.

CONCLUSIONS

Additional studies to define patterns of normal use and wear will provide data to better characterize CMC OA and opportunities for tailored treatment, including prevention, delay of progression, and joint arthroplasty.

Current practice patterns in conservative thumb CMC joint care: survey results

STUDY DESIGN

Cross-sectional descriptive survey

INTRODUCTION

Best practice for conservative clinical care pathways is not well outlined in the literature for patients with thumb carpometacarpal joint (CMCJ) pain. This self-report survey investigated the current practice patterns of assessments and conservative interventions for the painful thumb CMCJ among hand therapists.

METHODS

An online survey was distributed to members of the American Society of Hand Therapists (ASHT). Questions were included about evaluation measures and intervention techniques used for this population. A descriptive analysis was completed of the results.

RESULTS

A total of 23.5% of the ASHT membership responded to the survey. Results were categorized using the International Classification of Functioning and Disability domains as a framework. The survey results report varying use of evaluation measures, therapeutic interventions, including orthotic fabrication, joint protection and patient education all therapeutic interventional techniques, and modalities.

CONCLUSION

Therapists use a comprehensive array of evaluation measures and interventions for body functions and structures in the care of thumb CMC pain. In contrast, more consistent use is needed of psychometrically-sound functional outcome measures that show change in activities and participation. This survey highlights areas to employ current evidence, as well as, future research should address environmental factors and personal factors for this population

LEVEL OF EVIDENCE

Not applicable.

Pediatric hand injuries: essentials you need to know

The hand is a common site of injury in children and adolescents. The most common mechanism of injury in younger children is crush injury resulting from the hand caught in a closing door while most fractures in teenagers result from recreational sports. Accurate diagnosis of hand fractures is a requisite for timely management of these injuries in order to restore normal function and achieve a satisfactory outcome since poorly treated injuries can have significant functional consequences. Metacarpal and phalangeal fractures can be difficult to diagnose at radiography due to their relatively small size leading to potential delays in treatment. Recognition of common fracture locations and patterns is essential in ensuring prompt and appropriate treatment.

The carpometacarpal joint of the thumb: MR appearance in asymptomatic volunteers

PURPOSE

To prospectively characterize the MR appearance of the carpometacarpal (CMC) joint of the thumb in asymptomatic volunteers.

MATERIALS AND METHODS

Thirty-four asymptomatic volunteers (17 women, 17 men, mean age, 33.9 ± 9.2 years) underwent MR imaging of the thumb after approval by the local ethical committee. Two musculoskeletal radiologists independently classified visibility and signal intensity (SI) characteristics of the anterior oblique (AOL/beak ligament), the posterior oblique (POL), the intermetacarpal (IML), and the dorsoradial ligaments (DRL) on a three-point Likert scale. The thickness of all ligaments, cartilage integrity, and presence of joint fluid were assessed. The alignment of the first metacarpal base with the trapezium was quantified on sagittal and coronal planes.

RESULTS

The ligaments of the CMC joint were constantly visible in all volunteers for the POL and IML, and in all but one for the AOL and DRL. On intermediate-weighted fat-saturated images the POL (65 %/74 % reader 1/reader 2) and DRL (58 %/64 %) were commonly of increased SI, while the IML had a striated appearance in 91 %/76 % of subjects. The AOL showed a variable SI (36 %/42 % low, 27 %/27 % increased, 36 %/30 % striated). The IML was the thickest ligament with a mean of 2.9 mm/3.1 mm and the DRL the thinnest (1.2 mm/1.4 mm). There was a mean dorsal subluxation of 1.8 mm/2.0 mm and radial subluxation of 2.8 mm/3.4 mm of the metacarpal base. The AOL was significantly thicker in men (1.7 mm) than in women (1.2 mm; p = 0.02). Radial subluxation was significantly larger in men (3.4 mm) than in women (2.2 mm; p = 0.02). No subluxation in palmar or ulnar direction was seen.

CONCLUSIONS

Radial and dorsal subluxation of the CMC joint can be a normal finding in a resting position at MR imaging. The CMC ligaments showed a considerable variability of signal intensity with a typically striated IML; thickness of the AOL is typically less than 2.2 mm, of the POL typically less than 2.9 mm.

Dorsoradial capsulodesis for trapeziometacarpal joint instability

We describe an alternative method for treating chronic trapeziometacarpal (TM) joint instability after acute injury or chronic repetitive use of the thumb by performing a dorsoradial capsulodesis procedure. The procedure is done by imbricating the redundant TM joint dorsoradial ligament and capsule after reducing the joint by pronating the thumb. The dorsoradial capsulodesis is a reasonable reconstructive option for chronic TM joint instability and subluxation.

Trapezium trabecular morphology in carpometacarpal arthritis

PURPOSE

In thumb carpometacarpal osteoarthritis, current evidence suggests that degenerative, bony remodeling primarily occurs within the trapezium. Nevertheless, the pathomechanics involved and the most common sites of wear remain controversial. Quantifying structural bone morphology characteristics with high-resolution computed tomography CT (micro-CT) infer regions of load transmission. Using micro-CT, we investigated whether predominant trabecular patterns exist in arthritic versus normal trapeziums.

METHODS

We performed micro-CT analysis on 13 normal cadaveric trapeziums and 16 Eaton stage III to IV trapeziums. We computationally divided each specimen into 4 quadrants: volar-ulnar, volar-radial, dorsal-radial, and dorsal-ulnar. Measurements of trabecular bone morphologic parameters included bone volume ratio, connectivity, trabecular number, and trabecular thickness. Using analysis of variance with post hoc Bonferroni/Dunn correction, we compared osteoarthritic and normal specimen quadrant measurements.

RESULTS

No significant difference existed in bone volume fraction between the osteoarthritic and normal specimens. Osteoarthritic trapeziums, however, demonstrated significantly higher trabecular number and connectivity than nonosteoarthritic trapeziums. Comparing the volar-ulnar quadrant of osteoarthritis and normal specimens collectively, this quadrant in both consistently possessed significantly higher bone volume fraction, trabecular number, and connectivity than the dorsal-radial and volar-radial quadrants.

CONCLUSIONS

The significantly greater trabecular bone volume, thickness, and connectivity in the volar-ulnar quadrant compared with the dorsal-radial and dorsal-ulnar quadrants provides evidence that the greatest compressive loads at the first carpometacarpal joint occur at the volar-ulnar quadrant of the trapezium, representing a consistently affected region of wear in both normal and arthritic states.

CLINICAL RELEVANCE

These findings suggest that trapezial trabecular morphology undergoes pathologic alteration. This provides indirect evidence that changes in load transmission occur with thumb carpometacarpal joint arthritis development.

Macroscopic and microscopic analysis of the thumb carpometacarpal ligaments: a cadaveric study of ligament anatomy and histology

BACKGROUND

Stability and mobility represent the paradoxical demands of the human thumb carpometacarpal joint, yet the structural origin of each functional demand is poorly defined. As many as sixteen and as few as four ligaments have been described as primary stabilizers, but controversy exists as to which ligaments are most important. We hypothesized that a comparative macroscopic and microscopic analysis of the ligaments of the thumb carpometacarpal joint would further define their role in joint stability.

METHODS

Thirty cadaveric hands (ten fresh-frozen and twenty embalmed) from nineteen cadavers (eight female and eleven male; average age at the time of death, seventy-six years) were dissected, and the supporting ligaments of the thumb carpometacarpal joint were identified. Ligament width, length, and thickness were recorded for morphometric analysis and were compared with use of the Student t test. The dorsal and volar ligaments were excised from the fresh-frozen specimens and were stained with use of a triple-staining immunofluorescent technique and underwent semiquantitative analysis of sensory innervation; half of these specimens were additionally analyzed for histomorphometric data. Mixed-effects linear regression was used to estimate differences between ligaments.

RESULTS

Seven principal ligaments of the thumb carpometacarpal joint were identified: three dorsal deltoid-shaped ligaments (dorsal radial, dorsal central, posterior oblique), two volar ligaments (anterior oblique and ulnar collateral), and two ulnar ligaments (dorsal trapeziometacarpal and intermetacarpal). The dorsal ligaments were significantly thicker (p < 0.001) than the volar ligaments, with a significantly greater cellularity and greater sensory innervation compared with the anterior oblique ligament (p < 0.001). The anterior oblique ligament was consistently a thin structure with a histologic appearance of capsular tissue with low cellularity.

CONCLUSIONS

The dorsal deltoid ligament complex is uniformly stout and robust; this ligament complex is the thickest morphometrically, has the highest cellularity histologically, and shows the greatest degree of sensory nerve endings. The hypocellular anterior oblique ligament is thin, is variable in its location, and is more structurally consistent with a capsular structure than a proper ligament.

High-resolution ultrasound evaluation of the trapeziometacarpal joint with emphasis on the anterior oblique ligament (beak ligament)

INTRODUCTION

The anterior oblique ligament is one of the main stabilizers of the trapeziometacarpal joint. Insufficiency of this ligament is closely linked to degenerative joint disease. High-resolution musculoskeletal ultrasound has advantages over magnetic resonance imaging (availability, dynamic nature, cost, patient comfort). This study evaluates the feasibility of ultrasound of the anterior oblique ligament.

MATERIAL AND METHODS

Ten cadaveric thumb specimens and 10 volunteers with normal trapeziometacarpal joints underwent imaging with high-frequency ultrasound. An ultrasound-guided, progressive dissection technique was used to confirm the ultrasound findings. Two radiologists reviewed the images in consensus. The detectability of the ligament was rated.

RESULTS

The anterior oblique ligament was identified and measured in 90% of the specimens and 100% of the volunteers. The ultrasound findings correlated well with the dissections. This ligament appeared as a thin hypoechogenic structure in the ulnar-most part of the trapeziometacarpal joint, with a thickness that varied from 1.0 to 2.0 mm. Detectability of this ligament was good in 66% of the specimens and 100% of the volunteers.

CONCLUSION

Ultrasound evaluation of the anterior oblique ligament of the trapeziometacarpal joint is feasible with state of the art equipment.

Current concepts of the anatomy of the thumb trapeziometacarpal joint

This review article describes the anatomy of the thumb trapeziometacarpal joint. In the final phase of opposition screw home torque rotation of the volar beak of the thumb metacarpal in the pivot area of the trapezium recess and tension on the dorsal ligament complex create stability for power pinch and power grip. The resulting compressive shear forces can lead over time to trapeziometacarpal joint osteoarthritis.

Median Nerve Injury following K-wire Fixation of Bennett's Fracture-Lessons Learned

Bennett's fracture is a relatively common injury. The fracture is unstable due to the displacing forces acting on the distal fragment and very commonly treated by stabilization with Kirschner wires. This would seem a relatively safe procedure, and injury to the median nerve has never been reported. We present this unusual complication following one such procedure with the evaluation of a safe approach utilizing the relevant surgical and radiological anatomy.

An unusual fracture-dislocation of the trapeziometacarpal joint of the thumb: a case report

Reports describing trapeziometacarpal joint fractures of the thumb have discussed Bennett's fracture or Rolando's fracture primarily. We report a patient with an unusual fracture which could not be classified as a Bennett's-type or Rolando's-type injury. The aetiology of the fracture pattern is proposed and treatment considerations are discussed.

Thumb trauma: Bennett fractures, Rolando fractures, and ulnar collateral ligament injuries

Injuries to the thumb are predominated by fractures of the proximal phalanx, ligamentous injuries about the metacarpophalangeal joint, and metacarpal base fractures. This article will attempt to summarize recent advancements within the realm of thumb trauma, with particular attention to Bennett fractures, Rolando fractures, and ulnar collateral ligament injuries.

Traumatic thumb carpometacarpal joint dislocations

Isolated traumatic dislocation of the thumb carpometacarpal joint, also called the trapeziometacarpal joint, is a rare injury. Controversy still exists concerning which ligaments are the true key stabilizers for the joint and therefore need to be damaged to result in dislocation, and optimal treatment strategies for thumb carpometacarpal joint dislocations are the subject of continuing debate. We give a review of the literature concerning traumatic dislocations of the carpometacarpal joint of the thumb and propose a treatment algorithm.