Kinematics of the trapeziometacarpal joint: a biomechanical analysis comparing tendon interposition arthroplasty and total-joint arthroplasty

Estimating the Thumb Rotation Angle by Using a Tablet Device With a Posture Estimation Artificial Intelligence Model

MediaPipe Hand (MediaPipe) is an artificial intelligence (AI)-based pose estimation library. In this study, MediaPipe was combined with four machine learning (ML) models to estimate the rotation angle of the thumb. Videos of the right hands of 15 healthy volunteers were recorded and processed into 9000 images. The rotation angle of the thumb (defined as angle θ from the palmar plane, which is defined as 0°) was measured using an angle measuring device, expressed in a radian system. Angle θ was then estimated by the ML model by using parameters calculated from the hand coordinates detected by MediaPipe. The linear regression model showed a root mean square error (RMSE) of 12.23, a mean absolute error (MAE) of 9.9, and a correlation coefficient of 0.91. The ElasticNet model showed an RMSE of 12.23, an MAE of 9.95, and a correlation coefficient of 0.91; the support vector machine (SVM) model showed an RMSE of 4.7, an MAE of 2.5, and a correlation coefficient of 0.99. The LightGBM model achieved high values: an RMSE of 4.58, an MAE of 2.62, and a correlation coefficient of 0.99. Based on these findings, we concluded that the thumb rotation angle can be estimated with high accuracy by combining MediaPipe and ML.

Scaphotrapeziotrapezoid joint loading during key pinch grip before and after trapeziometacarpal arthroplasty: a cadaver study

In a previous cadaver study, we directly measured the load acting on the trapeziometacarpal joint for increasingly greater key pinch forces. We noted that the joint load ranges from 2 kg to 4 kg during progressively greater key pinch from 0.5 kg to 1.5 kg. Using the same experimental approach, the aim of the current study was to measure and compare the load acting on the scaphotrapeziotrapezoid joint for the same levels of isometric key pinch force, and how it changes after trapeziometacarpal arthroplasty. We performed a cadaver study using 7 fresh-frozen, unembalmed adult forearms and hands (2 right and 5 left). Thumb pinch was simulated by loading the main actuator tendons involved in the key pinch grip (i.e., adductor pollicis, flexor pollicis longus, extensor pollicis longus, extensor pollicis brevis and abductor pollicis longus tendons). Measurements were made inside the joint using a force-sensing resistor sensor (Tekscan® FlexiForce™ force sensor). Before the trapeziometacarpal joint surgery, median load values recorded in the scaphotrapeziotrapezoid joint were 1.2 kg (IQR, 1.0-1.4), 1.6 kg (IQR, 1.6-2.5) and 2.4 kg (IQR, 2.3-3.4) during 0.5 kg, 1 kg and 1.5 kg key pinch, respectively. After the trapeziometacarpal arthroplasty, median joint contact forces did not change significantly relative to the original configuration. Our findings indicate that the loads measured in the scaphotrapeziotrapezoid joint during a simple key pinch are in fact lower than those measured inside the trapeziometacarpal joint. After trapeziometacarpal arthroplasty, the values are similar with no increase in load, suggesting that clinically asymptomatic scaphotrapeziotrapezoid radiographic involvement may not be a contraindication to arthroplasty.

Trapeziometacarpal joint loading during key pinch grip: A cadaver study

To our knowledge, no study has directly measured the loads in the trapeziometacarpal joint during an isometric key pinch. The aim of this study was to measure the load acting on the trapeziometacarpal joint for increasingly greater key pinch forces (0.5 kg-1.5 kg). We performed a cadaver study using 10 fresh-frozen, unembalmed adult forearms and hands (5 right and 5 left). Thumb pinch was simulated by loading the main actuator tendons involved in the key pinch grip (i.e., adductor pollicis, flexor pollicis longus, extensor pollicis longus, extensor pollicis brevis and abductor pollicis longus tendons). Measurements were made inside the joint using a force-sensing resistor sensor (Tekscan® FlexiForce™ force sensor). All specimens were tested twice in a row in the same condition. The median load values recorded in the trapeziometacarpal joint were 1.9 kg (IQR 2.2-1.5), 3 kg (IQR 3.4-2.7) and 4.1 kg (IQR 4.4-3.9) during 0.5 kg, 1 kg, and 1.5 kg key pinch, respectively. For each specimen, similar load values were observed during both loading trials. Our findings indicate that the loads measured directly in the trapeziometacarpal joint during a simple key pinch are materially lower than those estimated in biomechanical models of the thumb (generally greater than 10 kg for 1 kg of applied force) probably due to intersubject variability. This pilot study will serve as a basis for further studies, for example, comparing biomechanical thumb models and experimental measurements under the same set-up conditions.

Comparison of simulated key pinch after three surgical procedures for trapeziometacarpal osteoarthritis: a cadaver study

We performed a cadaver study using 18 fresh-frozen adult forearms and hands to compare the tendon loads required to generate progressively greater key pinch (0.5 kg to 2 kg) after three different surgical procedures to treat trapeziometacarpal osteoarthritis: isolated trapeziectomy, trapeziectomy followed by ligament reconstruction with tendon interposition and total joint arthroplasty using a Touch® implant. Thumb pinch was simulated by loading the main actuator tendons involved in the key pinch. Six specimens were randomly assigned to each of the three surgical procedure groups. Measurements were made before and after the joint surgery. Specimens that underwent trapeziectomy with or without ligament reconstruction with tendon interposition required significantly higher tendon loads than those with the implant to achieve the same pinch force. There was no significant difference between the isolated trapeziectomy and ligament reconstruction groups. Using the implant resulted in similar median tendon loads compared with those of the intact sample. Total joint arthroplasty with a Touch® prosthesis may yield a superior biomechanical profile in which the tendon loads needed to achieve a certain key pinch force are lower and better distributed between the actuator muscles compared with trapeziectomy with or without ligament reconstruction.

Paleobiological reconstructions of articular function require all six degrees of freedom

Paleobiologists typically exclude impossible joint poses from reconstructions of extinct animals by estimating the rotational range of motion (ROM) of fossil joints. However, this ubiquitous practice carries the assumption that osteological estimates of ROM consistently overestimate true joint mobility. Because studies founded on ROM-based exclusion have contributed substantially to our understanding of functional and locomotor evolution, it is critical that this assumption be tested. Here, we evaluate whether ROM-based exclusion is, as currently implemented, a reliable strategy. We measured the true mobilities of five intact cadaveric joints using marker-based X-ray Reconstruction of Moving Morphology and compared them to virtual osteological estimates of ROM made allowing (a) only all three rotational, (b) all three rotational and one translational, and (c) all three rotational and all three translational degrees of freedom. We found that allowing combinations of motions in all six degrees of freedom is necessary to ensure that true mobility is always successfully captured. In other words, failing to include joint translations in ROM analyses results in the erroneous exclusion of many joint poses that are possible in life. We therefore suggest that the functional and evolutionary conclusions of existing paleobiological reconstructions may be weakened or even overturned when all six degrees of freedom are considered. We offer an expanded methodological framework for virtual ROM estimation including joint translations and outline recommendations for future ROM-based exclusion studies.

Partial Trapeziotrapezoid Resection and Thumb Range of Movement After Trapeziometacarpal Joint Fusion-A Biomechanical Study

PURPOSE

Trapeziometacarpal (TMC) joint arthrodesis is an effective treatment for stage III osteoarthritis. Although this procedure alleviates thumb pain and restores grip power and pinch strength, persistent limitation of thumb movement is inevitable. This biomechanical study aimed to investigate the altered kinematics of thumb circumduction motion after TMC joint arthrodesis and subsequent excision of the trapeziotrapezoid (TT) and trapezio-second metacarpal (T-2MC) joint spaces.

METHODS

Eight cadaver upper extremities were mounted on a custom testing apparatus. The hand and carpal bones were fixed to the apparatus, except for the first metacarpal bone, trapezium, and trapezoid. A 50-g load was applied at the tip of the first metacarpal head to generate passive thumb circumduction. An electromagnetic tracking system measured the angular and rotational displacement of the first metacarpal. All specimens were tested in 4 conditions: intact, after simulated TMC joint fusion, after subsequent excision of 3 mm of bone at the TT joint space, and after additional 3 mm resection at the T-2MC joint space.

RESULTS

After simulated TMC arthrodesis, the range of angular motion of thumb circumduction decreased to 25% that of the intact thumb. Subsequent resections at the TT and T-2MC joint spaces increased circumduction ranges to 49% (TT joint) and 73% (TT plus T-2MC joints) that of the intact thumb. The range of thumb rotational motion showed a similar trend.

CONCLUSIONS

Trapeziometacarpal arthrodesis decreased the range of both angular and rotational motion during thumb circumduction. Subsequent resections at the paratrapezial space increased the range of thumb motion, suggesting that hypermobility of the paratrapezial joints increases thumb mobility after TMC joint fusion.

CLINICAL RELEVANCE

Patients with hypermobile paratrapezial joints may have larger thumb movement after TMC joint fusion. Additional resections of the TT and T-2MC joint spaces may further mobilize the thumb in patients who complain of stiffness after TMC fusion.

Partial trapeziectomy and pyrocarbon interpositional implant (Pyrodisk) for trapeziometacarpal osteoarthritis in the active working population: outcomes of a 10 years-experience

The treatment of trapeziometacarpal (TM) osteoarthritis is still debated, as many surgical options are available, and no technique has proven to be superior. Prosthetic treatment in this context has been described since the early 60s. Recently, the use of pyrolytic carbon-based prosthesis has revolutionized arthroplasty surgery in the hand. We performed a retrospective investigation of our surgical management of TM osteoarthritis since 2010 including the study only patients treated with partial trapeziectomy and Pyrodisk implant, with at least 5 years follow-up. After the application of inclusion criteria, 26 patients (6 males and 20 females) were retained. Despite the literature suggesting that implant TM surgery is well suited for older patients, in our experience, the procedure was mainly proposed to the young manual worker, with high demands in terms of thumb strength and stability (mean age of 53 years old, range 37-65). A statistically significant improvement in post-operative DASH, Kapandji and scores was observed. As well, strength measurements, particularly pinch strength and grip strength, increased significantly after the surgery. According to our findings, the Pyrodisk implant provides satisfactory results in terms of thumb strength and stability even in young and active patients and should therefore be considered as a valuable option in selected cases. Meticulous surgical procedure is mandatory in order to avoid complications and should therefore be executed by an expert surgeon. Abbreviation: IV: level of evidence.

Metacarpal Abduction Orthosis for Patients With the Thumb Carpometacarpal Osteoarthritis

Purpose

A specific orthosis to increase radial abduction of the metacarpal of the thumb rather than immobilize it was designed for patients with carpometacarpal (CMC) joint osteoarthritis. This orthosis was designed especially for musicians, who need a large abduction angle of the thumb CMC joint to maintain their hand span to perform music.

Methods

The thumb abduction orthosis was custom-made of flexible polypropylene, leaving the thumb metacarpophalangeal and wrist joints unrestricted and compressing the ulnar side of the thenar muscle to increase the radial abduction angle of the thumb metacarpal. Hand span and grip strength were measured, and clinical symptoms were assessed with the visual analog scale and Quick–Disabilities of the Arm, Shoulder, and Hand score. The Tubiana and Chamagne score was used to assess musical performance.

Results

A total of 23 thumbs of 19 professional musicians with CMC joint osteoarthritis were placed in an orthosis. The radial abduction angle of the thumb CMC joint, grip strength, and hand span were significantly increased or enlarged after bracing. Clinical symptoms evaluated by visual analog score, Quick–Disabilities of the Arm, Shoulder, and Hand score, and Tubiana and Chamagne score also improved.

Conclusions

Placement of a metacarpal abduction orthosis improved the hand span and improved patient-reported outcomes.

Type of study/level of evidence

Therapeutic IV.

The Effect of Surgical Treatments for Trapeziometacarpal Osteoarthritis on Wrist Biomechanics: A Cadaver Study

PURPOSE

Studies have shown the effects of surgical treatments for trapeziometacarpal osteoarthritis on thumb biomechanics; however, the biomechanical effects on the wrist have not been reported. This study aimed to quantify alterations in wrist muscle forces following trapeziectomy with or without ligament reconstruction and replacement.

METHODS

A validated physiological wrist simulator replicated cyclic wrist motions in cadaveric specimens by applying tensile loads to 6 muscles. Muscle forces required to move the intact wrist were compared with those required after performing trapeziectomy, suture suspension arthroplasty, prosthetic replacement, and ligament reconstruction with tendon interposition (LRTI).

RESULTS

Trapeziectomy required higher abductor pollicis longus forces in flexion and higher flexor carpi radialis forces coupled with lower extensor carpi ulnaris forces in radial deviation. Of the 3 surgical reconstructions tested post-trapeziectomy, wrist muscle forces following LRTI were closest to those observed in the intact case throughout the range of all simulated motions.

CONCLUSIONS

This study shows that wrist biomechanics were significantly altered following trapeziectomy, and of the reconstructions tested, LRTI most closely resembled the intact biomechanics in this cadaveric model.

CLINICAL RELEVANCE

Trapeziectomy, as a standalone procedure in the treatment of trapeziometacarpal osteoarthritis, may result in the formation of a potentially unfilled trapezial gap, leading to higher wrist muscle forces. This biomechanical alteration could be associated with clinically important outcomes, such as pain and/or joint instability.

Tendon versus Pyrocarbon Interpositional Arthroplasty in the Treatment of Trapeziometacarpal Osteoarthritis

Background

Trapeziometacarpal (TMC) arthritis is treated with surgery when nonsurgical treatment fails. The best surgical option for improving pain relief, functional outcomes, and postoperative complications remains controversial. The purpose of this study was to compare clinical and radiological outcomes and complications between trapezium excision with ligament reconstruction and tendon interposition (LRTI) and pyrolytic carbon interpositional arthroplasty.

Methods

From March 2009 to August 2014, 37 patients (39 wrists) with Eaton-Littler stage II or III TMC arthritis underwent complete trapezium excision with LRTI (Group L, n=19) or pyrolytic interpositional arthroplasty (Group P, n=20). Visual analog scale (VAS) pain scores; grip and pinch strength; Kapandji scores to quantify thumb opposition; and Disabilities of Arm, Shoulder, and Hand (DASH) scores were used to compare clinical outcomes between the two groups. Radiographic changes (metacarpal shortening, subluxation, and radiolucency) were evaluated on the radiographs of thumb basal joints.

Results

There were no differences in patient demographics, Eaton-Littler stage, preoperative outcome measures, or the duration of follow-up between the two groups. At the last follow-up, VAS pain scores, pinch and grip strengths, Kapandji scores, and DASH scores were significantly improved in both groups compared with preoperative scores. All follow-up measurements were similar between the two groups except pinch strength, which was 1.8 kg higher in Group P (p<0.001). Proximal metacarpal migration did not differ significantly between the groups. Periprosthetic lucency more than 1 mm was observed in 7 of 20 (35%) thumbs. Complication rates were similar between the two groups.

Conclusions

All subjective and objective outcomes were similar following LRTI and pyrolytic interpositional arthroplasty in patients with TMC arthritis, except pinch strength, which was more improved following pyrolytic interpositional arthroplasty. Longer follow-up is required to test adverse effects of high rates of periprosthetic lucency and prosthetic subluxation on clinical outcomes after PyroDisk interpositional arthroplasty.

Kinematic Accuracy in Tracking Total Wrist Arthroplasty with Biplane Videoradiography using a CT-generated Model

Total Wrist Arthroplasty (TWA) for improving the functionality of severe wrist joint pathology has not had the same success, in parameters such as motion restoration and implant survival, as hip, knee, and shoulder arthroplasty. These other arthroplasties have been studied extensively, including the use of biplane videoradiography (BVR) that has allowed investigators to study the in-vivo motion of the total joint replacement during dynamic activities. The wrist has not been a previous focus, and utilization of BVR for wrist arthroplasty presents unique challenges due to the design characteristics of TWAs. Accordingly, the aims of this study were 1) to develop a methodology for generating TWA component models for use in BVR, and 2) to evaluate the accuracy of model-image registration in a single cadaveric model. A model of the carpal component was constructed from a CT scan, and a model of the radial component was generated from a surface scanner. BVR was acquired for three anatomical tasks from a cadaver specimen. Optical motion capture was used as the gold standard. BVR's bias in flexion/extension, radial/ulnar deviation, and pronosupination was less than 0.3°, 0.5°, and 0.6°. Translation bias was less than 0.2 mm with a standard deviation of less than 0.4 mm. This BVR technique achieved a kinematic accuracy comparable to previous studies on other total joint replacements. BVR's application to the study of TWA function in patients could advance the understanding of TWA and thus the implant's success.

MAÏA Trapeziometacarpal Joint Arthroplasty: Clinical and Radiological Outcomes of 80 Patients With More than 6 Years of Follow-Up

PURPOSE

Trapeziometacarpal (TMC) total joint replacement is increasingly being performed in Europe. MAÏA TMC total joint arthroplasty is a modular uncemented ball-and-socket hydroxyapatite-coated implant. This study assessed the midterm clinical and radiological results of the MAÏA TMC prosthesis.

METHODS

This single-center retrospective study involved 80 patients who underwent 96 MAÏA TMC prosthesis implantations from February 2006 to April 2009, and who had a minimum of 5 years' follow-up. Indications for the procedure were painful TMC joint osteoarthritis affecting activities of daily living and a failure of at least 6 months of nonsurgical treatment. Pre- and postoperative clinical and radiographic data were reviewed.

RESULTS

The mean age at surgery was 68 years (range, 53-84 years) and the median follow-up was 76 months (range, 60-102 months). The mean Quick Disabilities of the Arm, Shoulder, and Hand score improved from 61.3 ± 17.1 to 17.5 ± 16. The mobility of the thumb was restored to a range of motion comparable with that of the contralateral thumb. Opposition, defined by the Kapandji score, was almost normal (9.2 of 10; range, 6-10), as was the final mean key pinch and grip strength, which improved by 26% and 43%, respectively. Among the 96 implants, 4 (4.2%) were surgically revised for trapezium loosening. One dislocation was treated with closed reduction; 3 (3.1%) posttraumatic trapezium fractures were immobilized for 8 weeks. Among the 26 preoperative reducible z-deformities, only 5 (19.2%) were not totally corrected after surgery. The procedure success, by survival analysis over 6 years, was 93% (95% confidence interval, 87-98).

CONCLUSIONS

MAÏA TMC total joint arthroplasty may be a reliable treatment option for TMC joint osteoarthritis, with very good results for pain relief, strength, mobility, and restoration of the thumb length, providing correction of most thumb z-deformities.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic IV.

Pyrolytic Carbon Arthroplasty versus Suspensionplasty for Trapezial-Metacarpal Arthritis

Purpose This study aims to compare outcomes after pyrolytic carbon implant hemiarthroplasty (PH) versus Thompson suspensionplasty (TS) for trapezial-metacarpal (TM) arthritis. Patients and Methods There were 87 arthritic TM joints in 71 patients treated with PH (n = 47 joints, 37 patients) or TS (n = 40 joints, 34 patients). Patients had significantly longer follow-up in the TS group (86.9 months, 25th-75th percentile = 55.6-103.8) versus the PH group (38.4 months, 25th-75th percentile = 23.2-65.8, p < 0.001). Results PH patients maintained higher final grip strength (p = 0.03) and apposition pinch strength (p = 0.01) compared with TS patients. Nelson scores were significantly higher among patients undergoing PH (mean = 50.4, standard deviation [SD] = 24.5) compared with TS (mean = 36.8, SD = 12.5, p < 0.01). There was a significantly higher proportion of complications (p < 0.01), reoperations (p < 0.01), and joint revision surgery (p < 0.01) in patients undergoing PH compared with TS. Controlling for age and sex, there was a 72.8% lower risk of complications (p = 0.02), 87.7% lower risk of reoperations (p = 0.01), and 87.2% lower risk of joint revision surgery (p < 0.01) among patients undergoing TS compared with PH. There was a shorter time to first complication (p < 0.01), reoperation (p < 0.02), and joint revision (p < 0.01) in those undergoing PH compared with TS. Conclusion Both cohorts exhibited functional range of motion and pinch and grip strengths postoperatively, and those undergoing PH began with and maintained higher grip and pinch strength at final follow-up. Those undergoing PH had significantly increased risk of complications, reoperations, and joint revision surgery. Most complications in patients undergoing PH were related to suspected development of scaphotrapezotrapezoidal (STT) arthritis postoperatively. We thus recommend careful evaluation of possible STT arthritis when considering PH arthroplasty. Level of Evidence Level III.

[Replacement of the thumb carpometacarpal joint : Current importance of endoprosthetics for operative treatment of rhizarthrosis]

The role of joint replacement in the treatment of osteoarthritis of the thumb carpometacarpal joint is a subject of considerable controversy in the current literature. In German-speaking countries this technique is used much less frequently than resection procedures. Aseptic loosening of the prosthesis is believed to be the major cause of the high failure rates reported for cemented and uncemented types of implants. In this study the different implant designs were evaluated on the basis of the results reported in the international literature. There are only a few studies that cover relatively long follow-up periods and provide convincing results for thumb carpometacarpal joint prostheses in terms of implant survival and function. Aseptic loosening is reported to be the major cause with failure rates of 50 % or more. Although a Norwegian study reported high 5 and 10-year survival rates for various thumb carpometacarpal joint prostheses according to the Norwegian arthroplasty registry, it did not recommend the widespread use of thumb carpometacarpal joint replacement at the present time. In our opinion, joint replacement may be considered as a possible treatment option for advanced osteoarthritis of the thumb carpometacarpal joint but it should not always be recommended because long-term results are inconsistent and similar functional outcomes have been reported for alternative surgical techniques, such as resection arthroplasty.

Mini Tightrope Fixation Versus Ligament Reconstruction - Tendon Interposition for Maintenance of Post-trapeziectomy Space Height: A Biomechanical Study

PURPOSE

To test the biomechanical stability of ligament reconstruction and tendon interposition (LRTI) compared with Mini TightRope fixation for thumb metacarpal subsidence after trapeziectomy.

METHODS

Fifteen fresh human cadaveric hands underwent trapeziectomy and were divided into 3 treatment groups: LRTI using a biotenodesis screw and single versus dual Mini TightRope fixation. The thumb and index fingers were removed distal to the metacarpal; the distal ends of the metacarpals and proximal radius were potted in urethane resin and mounted onto a servohydraulic testing machine. A cyclic axial load was applied to stress the trapezial cavity. We recorded displacement of the first metacarpal via the position of the actuator head and computed the size of the trapezial space as the difference of the initial size and first metacarpal displacement. Each specimen underwent cyclical loading until the first metacarpal had collapsed completely onto the scaphoid (failure of the repair) or until 6 hours of testing had been completed. The number of cycles to failure, change in the size of the trapezium cavity, and relative change in size of the trapezium cavity were determined.

RESULTS

The trapezial space had completely closed before 6 hours of testing were completed in all biotenodesis screw-augmented LRTI specimens and remained present in all single and dual Mini TightRope specimens. Absolute (and normalized) changes in the size of the trapezial cavity in the single and dual Mini TightRope specimens were 11 ± 2 and 10 ± 2 mm, respectively.

CONCLUSIONS

Dual Mini TightRope fixation provided superior load bearing and maintenance of trapezial space height compared with single Mini TightRope or LRTI biotenodesis screw procedures.

CLINICAL RELEVANCE

This study demonstrates that patients who undergo suture suspension arthroplasty may be able to move earlier because of the immediate stability the construct affords.

In vivo analysis of trapeziometacarpal joint kinematics during pinch tasks

This study investigated how the posture of the thumb while performing common pinch movements and the levels of pinch force applied by the thumb affect the arthrokinematics of the trapeziometacarpal joint in vivo. Fifteen subjects performed the pinch tasks at the distal phalange (DP), proximal interphalangeal (PIP) joint, and metacarpophalangeal (MP) joint of the index finger with 0%, 50%, and 80% of maximal pinch forces by a single-axis load cell. 3D images of the thumb were obtained using the computed tomography. The results show that the reference points moved from the central region to the dorsal-radial region when changing from pinching the DP to the MP joint without pinching force being applied. Pinching with 80% of the maximum pinching force resulted in reference points being the closest to the volar-ulnar direction. Significant differences were seen between 0% and 50% of maximum pinch force, as well as between 0% and 80%, when pinching the MP joint in the distal-proximal direction. The effects of posture of the thumb and applied pinch force on the arthrokinematics of the joint were investigated with a 3D model of the trapeziometacarpal joint. Pinching with more than 50% of maximum pinch force might subject this joint to extreme displacement.

A three-dimensional analysis of osteoarthritic changes in the thumb carpometacarpal joint

The purpose of this study is to gain a better understanding of the changes due to osteoarthritis (OA) occurring in the thumb carpometacarpal (CMC) joint by comparing quantitative geometrical measurements in computed tomography scans of healthy and pathological joints in various stages of OA. The measurements were (1) the subluxation of the metacarpal on the trapezium, (2) distance from the scaphoid centre to the metacarpal base, and (3) distance from the metacarpal base to the articulating surface of the trapezium. The three-dimensional position of three characteristic points on the metacarpal, trapezium, and scaphoid were detected in each of the 90 wrists we scanned. The distances between the points were compared by statistical analysis. With high accuracy, we have been able to confirm and quantify that subluxation occurs in the dorso-radial direction. A significant difference in trapezium height and joint space width was found between the OA and control groups. The results indicate how to restore the centre of rotation in surgical treatment of OA with total joint arthroplasty, but the clinical relevance of these findings has to be tested in further clinical studies.

Midterm results after modified Epping procedure for trapeziometacarpal osteoarthritis

BACKGROUND AND PURPOSE

Various surgical procedures have been proposed for the treatment of trapeziometacarpal joint (TMJ) osteoarthritis. Despite an overall satisfactory outcome in most cases, some patients complain about inadequate performance at work, due to instability of the TMJ. We present a cross-sectional study of patients with TMJ arthritis who underwent a modified Epping procedure for increased TMJ stability.

METHODS

71 patients underwent a modified Epping procedure with a flexor carpi radialis tendon sling stabilizer. 59 patients were followed up after a mean time of 38 months. Residual pain was evaluated by visual analog scale. Functional outcome was quantified by pinch and grip strength, static two-point discrimination test, as well as DASH outcome scoring. Quality of life measures included patients' perceived satisfaction, activities of daily living (ADL), grip/pinch force and manual performance at work.

RESULTS

85 % of the patients regained full or partial manual performance during labor. Strength and ADL improved or remained the same in 81 %. In cases of a unilateral treatment, no difference in grip between the operated and nonoperated hand was observed. Mean tip pinch strength was 2.8 kg for the operated and 3.6 kg for the nonoperated hand. Mean pain level during rest was 0.98, 0.95 during mild activity, and 3.70 during strenuous activity. Mean DASH score was 26.6.

CONCLUSION

The great majority of patients who underwent this novel procedure benefited from an unaffected or improved work performance, due to good TMJ stability combined with adequate motion for ADL. Less favorable results were seen in patients with accompanying hand pathologies.

Rehabilitation protocol after suspension arthroplasty of thumb carpometacarpal joint osteoarthritis

STUDY DESIGN

Retrospective case series.

INTRODUCTION

When conservative modalities and therapies fail to control symptoms of thumb carpometacarpal (CMC) joint osteoarthritis, surgery may be indicated.

PURPOSE OF THE STUDY

To present a rehabilitation protocol used in a series of patient cases after suspension arthroplasty and to evaluate outcomes.

METHODS

Twenty-seven patients with CMC osteoarthritis were treated by the same arthroplasty technique and the same rehabilitation program. Patients were evaluated before and 12th week after surgery, and at the last follow-up using a visual analog scale; the Disability of the Arm, Shoulder, and Hand questionnaire; strength measurements; range of motion evaluations; and radiographic assessment.

RESULTS

Average follow-up period was 31.5 months. There was a decreasing trend in both subjective scores during follow-ups (p=0.0001). Thirty-three percent and 30% improvements on radial and palmar abductions, respectively, and 29% improvement on pinch strengths were recorded at the final follow-up. Postoperative grip improvement was not preserved at the last follow-up.

CONCLUSIONS

The results demonstrate a high degree of patient satisfaction suggesting the efficacy of this surgical technique and postoperative rehabilitation protocol.

LEVEL OF EVIDENCE

Level 4.

Trapezium prosthetic arthroplasty (silicone, Artelon, metal, and pyrocarbon)

Trapezium prosthetic arthroplasty has been utilized to treat basal joint arthritis for nearly five decades in an attempt to mitigate some of the potential disadvantages of trapeziectomy while preserving range of motion. Implant arthroplasty seeks to preserve joint biomechanics, avoids metacarpal subsidence, and should provide immediate stability. These benefits may lead to improvements in strength, durability, and a decrease in metacarpophalangeal joint hyperextension which can occur subsequent to metacarpal shortening. First generation implants were primarily silicone trapezial spacers. While the use of these implants has been curtailed by their association with silicone synovitis, they still remain an option for low demand, rheumatoid patients. More recently developed synthetic spacers such as Artelon interposition arthroplasties have had results inferior to more established procedures including trapeziectomy. A variety of metal total joint prostheses have been developed and some of the more recent designs have shown good short-term outcomes. There are a number of different pyrocarbon implants that have become more recently available which range from trapezial substitution to non-anatomic hemiarthroplasty. Pyrocarbon arthroplasty offers a number theoretical advantages however early results have been mixed and further long term data is required.

Fixation of trapezial implants in a trapeziometacarpal total joint prosthesis tested in a model of porcine bone

High aseptic loosening rates have been reported in total joint prostheses of the carpometacarpal joint of the thumb, particularly in the trapezial component. The primary fixation of new implants may be tested in cadaver bones, but the anatomy of the pig is in many ways similar to that of the human, so we compared the central carpal bone from the forefoot of 6-month-old pigs, which has a saddle joint surface similar to the trapezium, to the trapezium in patients with carpometacarpal osteoarthritis. The mean (SD) bone mineral density of the 13 pig forefoot bones was 0.88 (0.12) g/cm(2) compared with 0.63 (0.16) g/cm(2) in the 31 human trapeziums. The measured size of the porcine bones was slightly larger than that of the human trapeziums. The similarity in form, size, and bone mineral density means that the central bone of the forefoot of 6-month-old pigs may be used for fixation tests in trapezial implants.

Ligament reconstruction of the Trapezial-metacarpal joint for early arthritis: a preliminary report

PURPOSE

To evaluate the results and determine the efficacy of an alternative ligament reconstruction technique in patients with a symptomatic trapezial-metacarpal joint associated with subluxation and early or limited chondral damage.

METHODS

This retrospective, nonrandomized study was composed of 6 patients, all women with ages between 31-46 years, treated by arthroscopic evaluation and reconstruction of the intermetacarpal and reverse anterior oblique ligament of the trapezial-metacarpal joint, using a strip of flexor carpi radialis tendon. Evaluation at an average follow-up of 18 months (range,12-28 mo) consisted of interview, examination, and computed tomography.

RESULTS

The visual analog pain score, preoperative rest pain, and activity pain improved significantly after surgery. Tip and lateral pinch strength measured 92% compared to the contralateral thumb, and computed tomography showed improved alignment of all joints.

CONCLUSIONS

Our results indicate that ligament reconstruction using the technique described reduced pain, increased strength, and improved the trapezial-metacarpal joint alignment in patients with early symptomatic trapezial-metacarpal joint osteoarthritis associated with joint subluxation.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic IV.

Implant arthroplasty of the carpometacarpal joint of the thumb

Resection arthroplasty with or without ligament reconstruction for thumb trapeziometacarpal arthritis can be complicated by thumb shortening and pinch-strength weakness. Implant arthroplasties have been developed to limit loss of thumb length, improve strength, and limit postoperative convalescence. The ideal thumb carpometacarpal implant should be strong and stable, provide full range of motion, and prevent loosening. Unfortunately, no current prosthesis accomplishes all of these goals. Until the ideal implant is developed, clinical acumen must be used to determine appropriate patients and implants.

Surface replacement trapeziometacarpal joint arthroplasty--early results

This study reviews the results of Surface Replacement Trapeziometacarpal (SR TMC, Avanta, San Diego, CA) total joint arthroplasty. Fifty patients (62 joints) were included in the study. Forty-three patients (54 joints) were seen at final follow up. Seven patients (eight joints) were interviewed over the phone. Seven patients were revised to trapeziectomy and ligament reconstruction with tendon interposition, five for aseptic loosening and two for dislocation. At final follow up, the mean Quick DASH score was 30.4 and the Sollerman Score was 77.3. Radiological review of the surviving 55 joints showed subsidence of four trapezial components in asymptomatic patients. Cumulative survival rate was 91% at 3 years. Eighty-five percent of the patients were satisfied with the outcome of their treatment.

Effects of age and gender on the movement workspace of the trapeziometacarpal joint

While researchers have suggested that joint mobility would probably be affected by age and gender, research findings often present discrepancies. Little research has been performed on the factors which effect mobility of the trapeziometacarpal (TMC) joint. The purpose of this study was to address the effects of age and gender on the ranges of motion of the normal TMC joint. Eighty normal subjects divided into four age groups participated in this study. The TMC joint motions were recorded using an electromagnetic tracking system. In order to achieve a maximal range of TMC joint motion which was defined as the maximal workspace, each subject was asked to perform actively maximal circumduction, flexion-extension, and abduction-adduction of the TMC joint. Numerical and statistical methods were used to compute the TMC workspace and to detect significant differences. A workspace-to-length ratio was determined as an index to examine the effects of the age and gender on the joint mobility. The results demonstrated that age and gender had significant influences on the TMC workspace among the groups studied. The understanding of TMC joint mobility under different age and gender conditions is achieved through this study. The findings can be used to report clinical measures in the determination of the extent of impairment of osteoarthritis as well as the outcomes between pre- and post-surgical (or non-surgical) interventions.

Treatment of advanced CMC joint disease: trapeziectomy and implant arthroplasty (silastic-metal-synthetic allograft)

Osteoarthritis of the basal joint of the thumb is a common and frequently debilitating condition, most often affecting middle-aged women. Nonoperative treatment with activity modification, splinting, oral anti-inflammatory medication, and intraarticular steroid injection frequently leads to acceptable control of symptoms. If nonoperative treatment fails, many surgical techniques have been described for management of symptomatic advanced degenerative joint changes. This article reviews the literature related to various arthroplasty options for advanced disease. Treatment decisions must clearly be tempered by the surgeon's experience, the patient's goals and expectations, and the extent of degenerative disease.

Basal joint arthritis of the thumb

The carpometacarpal joint of the thumb is the second most common site of arthritis in the hand. Patients in whom conservative treatment fails benefit from surgical intervention, although no consensus exists as to the best method to provide maximum pain relief and functional outcomes. The pathophysiology of carpometacarpal arthritis is loss of the integrity of the palmar oblique ligament, which allows for dorsal subluxation of the metacarpal on the trapezium. Most treatments revolve around resection or replacement of the arthritic carpometacarpal joint and restoration of the palmar oblique ligament. A critical appraisal of the current evidence-based research offers no guidance in treatment in the early stages of carpometacarpal arthritis; however, several evidence-based studies exist for more advanced stages. Although these studies exhibit limitations in regard to validated outcomes, power analysis, and blinded assessment, their conclusions question the clinical benefits of ligament reconstruction and tendon interposition. Further research is needed to delineate the best treatment of early stages of arthritis as well as the clinical significance of metacarpal subluxation and subsidence. Further, a standardized set of outcome tools is needed for the interpretation and comparison of data in regard to clinical outcomes.

Radial portal tendon harvest and interposition in arthroscopic treatment of thumb basilar joint osteoarthritis

This study describes an arthroscopic technique that uses the same radial arthroscopic access portal to harvest and to interpose tendon material into the trapeziometacarpal joint in the treatment of Eaton-Littler stage 2 and 3 osteoarthritis of the trapeziometacarpal joint. Clinical application of this technique has resolved pain and preserved motion at the trapeziometacarpal joint in this study experience.

Joint kinematics after thumb carpometacarpal joint reconstruction: an in vitro comparison of various constructs

PURPOSE

Osteoarthritis (OA) of the thumb carpometacarpal (CMC) joint causes pain and limits thumb motion. Different surgical procedures exist to treat thumb CMC OA; however, kinematic analyses of thumb reconstructions are limited. The purpose of this study was to evaluate kinematic changes of the thumb CMC joint as the result of different thumb reconstruction procedures.

METHODS

Fifteen cadaveric forearms were prepared and instrumented with an electromagnetic tracking device to measure the motion of the thumb metacarpal with respect to the trapezium (thumb trapeziometacarpal joint). Kinematics of the intact thumb and the thumb after trapeziectomy under passive motion were recorded. Specimens then had joint reconstruction consisting of either a ligament reconstruction with tendon interposition (LRTI), Weilby arthroplasty, or Thompson arthroplasty. The kinematic data collection analysis was repeated. The radius of joint motion and 3-dimensional (3D) work area were calculated for each surgery and were used for statistical analysis.

RESULTS

The type of surgical treatment significantly affected the joint radius of motion and the 3D work area. The Thompson and LRTI techniques produced a larger joint radius of motion than the other techniques (Weilby technique and total trapezial resection) and was similar to that of the intact joint. The Weilby and LRTI techniques produced a 3D work area similar to those of the intact joint and trapeziectomy and was also larger than that of the Thompson reconstruction.

CONCLUSIONS

Kinematic analysis of the thumb CMC joint is effective in differentiating surgical treatments used for end-stage of OA. Only the LRTI reconstruction produced a joint radius of motion and a 3D work area similar to the those of an intact thumb. Additional research is needed to define the optimal surgical techniques to treat the end-stage OA thumb CMC joint.

Biomechanic analysis of trapeziectomy, ligament reconstruction with tendon interposition, and tie-in trapezium implant arthroplasty for thumb carpometacarpal arthritis: a cadaver study

PURPOSE

Thumb carpometacarpal joint arthritis has been commonly treated with some combination of resection of the trapezium and interposition of a spacer using either a biologic or artificial material plus tenodesis to reconstruct the volar oblique ligament. The purpose of this study was to evaluate the biomechanic stability of the classic ligament reconstruction with tendon interposition (LRTI) or without tendon interposition compared with a newly developed 1-piece silicone trapezium implant.

METHODS

Twelve cadaver arm specimens had the following procedures: resection of the trapezium, tendon interposition, ligament reconstruction, LRTI, and the silicone implant. Biomechanic testing of joint stability was performed with a physiologic loading protocol before and after each procedure.

RESULTS

The implant significantly corrected the axial displacement after trapeziectomy and resulted in less radial displacement than LRTI. It significantly reduced angulation of the thumb metacarpal base but resulted in more rotation of the thumb during simulated pinch. There was no significant difference in stability measures between trapeziectomy and LRTI or ligament reconstruction without tendon interposition.

CONCLUSIONS

We found several biomechanic advantages to the implant compared with LRTI. Advantages include reduction in axial and radial displacement and maintenance of the trapezial space. We attribute these advantages to the effect of the implant as a spacer. The significant rotation with the implant, however, raises questions concerning implant design and fixation. We found no biomechanic advantage to LRTI or ligament reconstruction without tendon interposition over trapeziectomy alone.

Total joint arthroplasty in the treatment of advanced stages of thumb carpometacarpal joint osteoarthritis

PURPOSE

Osteoarthritis of the thumb basal joint is a very common and disabling condition that frequently affects middle-aged women. Many different surgical techniques have been proposed for extensive degenerative arthritis of the first carpometacarpal (CMC) joint. Joint replacement has been an effective treatment of this condition. The purpose of this article is to present the outcome of a total cemented trapeziometacarpal implant in the treatment of more advanced stages of this disease.

METHODS

Total joint arthroplasty of the trapeziometacarpal joint was performed on 26 thumbs in 25 patients to treat advanced osteoarthritis (Eaton and Littler stages III and IV) between 1998 and 2003. Indications for surgery after failure of conservative treatment were severe pain, loss of pinch strength, and diminished thumb motion that limited activities of daily living. A trapeziometacarpal joint prosthesis was the implant used in this series. The average follow-up time was 59 months.

RESULTS

At the final follow-up evaluation, thumb abduction averaged 60 degrees and thumb opposition to the base of the small finger was present. The average pinch strength was 5.5 kg (85% of nonaffected side). One patient had posttraumatic loosening, which was revised with satisfactory results. Radiographic studies at the final follow-up evaluations did not show signs of atraumatic implant loosening. One patient complained of minimal pain, and the remaining 24 patients were pain free.

CONCLUSIONS

In our series, total joint arthroplasty of the thumb CMC joint has proven to be efficacious with improved motion, strength, and pain relief. We currently recommend this technique for the treatment of stage III and early stage IV osteoarthritis of the CMC joint in older patients with low activity demands.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic IV.

Entire flexor carpi radialis tendon harvest for thumb carpometacarpal arthroplasty alters wrist kinetics

PURPOSE

To investigate the clinical outcome of thumb carpometacarpal arthroplasty with entire-thickness flexor carpi radialis (FCR) ligament reconstruction and tendon interposition and to investigate the isokinetic wrist flexion/extension torque and flexion fatigue strength of the surgically treated wrist compared with the nonsurgically treated wrist.

METHODS

Thirty-nine patients with osteoarthritis who had unilateral thumb carpometacarpal arthroplasty with the entire FCR tendon were studied prospectively with a minimum follow-up period of 24 months. Preoperative Disabilities of the Arm, Shoulder, and Hand (DASH) questionnaire score, grip, pinch, and postoperative DASH score, grip, pinch, and Biodex (Shirley, NY) isokinetic wrist flexion/extension torques were recorded. The nonsurgically treated extremity served as the control for each patient with unilateral ligament reconstruction and tendon interposition. Peak torque ratios and fatigue were measured for the control and surgically treated extremities with the Biodex.

RESULTS

Postoperative DASH scores were 12 +/- 4 and were improved significantly from preoperative scores of 43 +/- 4. The surgically treated extremity showed a significantly lower wrist flexion-to-extension peak torque ratio than the control extremity. The control extremity had 2.5 times greater wrist flexion fatigue resistance than the surgically treated side. After surgery the surgically treated extremity had significantly improved grip strength and thumb-index tip pinch compared with the preoperative status.

CONCLUSIONS

Our data show conclusively that wrist flexion extension torque ratio decreases and wrist flexion fatigue resistance decreases when the entire FCR tendon is harvested even though the final outcome is favorable and uniformly based on traditional DASH, grip, and pinch scores.

An in vitro analysis of ligament reconstruction or extension osteotomy on trapeziometacarpal joint stability and contact area

PURPOSE

Painful instability of the minimally osteoarthritic thumb carpometacarpal (CMC) joint can be treated successfully by either ligament reconstruction or metacarpal extension osteotomy. The purpose of this study was to measure the laxity of cadaveric thumb CMC joints and to determine the influence of ligament reconstruction and metacarpal osteotomy on joint laxity and contact area.

METHODS

The baseline laxity of CMC joints from 25 fresh-frozen human cadaveric specimens (average age, 42 y; range, 18-55 y) was measured in the position of lateral pinch on a custom-designed CMC joint laxity tester. Joint laxity was measured again after 2 surgical simulations consisting of either a metacarpal extension osteotomy (at 10 degrees and 15 degrees) or a simulated Eaton-Littler ligament reconstruction (including total, volar, and dorsal ligament reconstructions relative to the plane of the thumbnail). Contact area between the thumb metacarpal and trapezium during testing was determined using stereophotogrammetry.

RESULTS

The 15 degrees extension osteotomy significantly reduced CMC joint laxity in the radial-ulnar, dorsal-volar, pronation-supination, and distraction directions in the position of lateral pinch. The 10 degrees osteotomy reduced laxity only in the dorsal-volar direction. The total ligament reconstruction significantly reduced joint laxity in the radial-ulnar, dorsal-volar, and pronation-supination directions. The dorsal ligament reconstruction reduced laxity in the dorsal-volar direction only; the volar ligament reconstruction reduced laxity in both dorsovolar and radioulnar directions. The 10 degrees and 15 degrees osteotomies produced a dorsal shift of the weighted centroid of contact on the metacarpal and trapezium, whereas the ligament reconstruction did not produce such an effect.

CONCLUSIONS

In the position of lateral pinch the 15 degrees osteotomy and total ligament reconstruction significantly reduced laxity of the thumb CMC joint in all directions tested. The isolated dorsal or volar ligament reconstructions both reduced dorsal-volar laxity. Metacarpal extension osteotomy may stabilize the thumb CMC joint in lateral pinch to a degree similar to that of a standard ligament reconstruction.

Use of the de la Caffinière prosthesis in rheumatoid trapeziometacarpal destruction

This study evaluated the outcome of the de la Caffinière prosthesis in patients with an inflammatory arthropathy affecting the trapeziometacarpal joint. The procedure was performed in 57 thumbs for rheumatoid arthritis (41 cases), juvenile chronic arthritis (ten cases), psoriatic arthritis (four cases) and other inflammatory joint diseases (two cases). Survival analysis with a revision procedure or radiographic implant failure as end points was performed. Five loosened cups and two permanently dislocated prostheses underwent revision surgery. These were managed with a bone graft and tendon interposition technique. Radiographic follow-up yielded four additional implant failures (two loosened cups, one loosened metacarpal stem and one permanent dislocation). The implant survival rate based on revision operation was 87% (95% CI 73-94) at 10 years, and the total radiographic and implant failure rate based on radiographic findings was 15% (95% CI 7-29) at 10 years.

A kinematic method to calculate the workspace of the trapeziometacarpal joint

The specific aim of this study was to develop a quantitative method and a kinematic method to evaluate the maximal workspace of the trapeziometacarpal (TM) joint. Six fresh-frozen human cadaver hands were disarticulated 4 cm proximal to the wrist joint and used in this experiment. The three-dimensional motion data of the TM joint was collected by an electromagnetic tracking device at 30 Hz. The workspace was reconstructed according to a complete set of motion data included circumduction, flexion-extension and abduction-adduction. A spherical fitting technique was used to obtain a sphere encompassing all the motion trajectories and estimating the centre of the sphere. The surface area of the maximal TM workspace, located on the one part of the sphere surface, was calculated by surface integration. The interclass correlation coefficient values for the reliability estimation of the repeated measurements of the radius and surface area of all specimens were 0.91 and 0.98 respectively. The mean coefficients of variance of the measured radius and the surface area were 2.04 per cent and 3.65 per cent respectively. The results also showed that using a spherical model to calculate the maximal workspace as an index for assessing TM joint impairment is practical.

A quantitative method to measure maximal workspace of the trapeziometacarpal joint--normal model development

INTRODUCTION

A reliable and quantitative method for measuring motion of the thumb is lacking. In particular, review of the previous methods of motion analysis of the thumb joints shows that there is no objective method for clinicians to assess the impairment of the thumb trapeziometacarpal (TMC) joint. Based on the concept of the three-dimensional (3-D) space within which the first metacarpal can move relative to the trapezium (a concept of defining and measuring the workspace of the TMC motion), we present a quantitative method for measuring motion and impairment (loss of function) of the TMC joint.

METHODS

Twenty normal subjects were recruited in this study. An electromagnetic device was placed over the thumb metacarpal and long finger metacarpal, the 3-D relationship between them previously established. We measured the position and orientation of the TMC motion in space. Maximum movements of the thumb TMC joint in circumduction, flexion-extension and abduction-adduction were used to construct the 3-D maximal workspace of the TMC joint. Mathematical methods were used to verify the model and calculate the maximal workspace.

RESULTS

The results of this study demonstrate accurate and repeatable measurement of 3-D TMC motion with high statistical reliability and low variability of the maximal TMC workspace. A statistically significant linear correlation between the maximal surface area and the square of the first metacarpal length was obtained.

CONCLUSION

We conclude that a quantitatively comparative measurement of the range of motion of the TMC joint can be obtained with potential to measure motion in joints affected by arthritis or trauma and measured in both dynamic and static positions of the thumb.

[The Roseland prosthesis]

Total joint replacement of the trapezio-metacarpal (TMC) joint is one of the procedures available for the surgical treatment of degenerative osteoarthritis or rheumatoid arthritis of the first carpometacarpal joint. A four French Alpine surgeon group, (C. Lebrun, P. Massart, F. Moutet and C. Sartorius) have developed a new cementless total TMC joint prosthesis: the Roseland prosthesis. Such a device tries to improve the biomechanical conditions of the La Caffinière's implant, which was introduced in 1973. Clinical data of a 24 patients with a 38 month mean follow-up series are reported.

[Surgical treatment of carpometacarpal joint osteoarthritis of the thumb by trapeziectomy-interposition-ligamentoplasty]

INTRODUCTION

Osteoarthritis of the carpometacarpal joint of the thumb is a common pathology. Several surgical methods exist, including trapeziectomy, arthrodesis, cemented or cementless prosthesis. Therefore, one must question the legitimacy of non prosthetic surgery. The authors have tried to answer this question.

METHOD

Surgery consisted in trapeziectomy and ligament reconstruction with tendon interposition arthroplasty (LRTI). Authors reviewed 47 cases with five years follow-up. Patients were evaluated using a functional score, including pain, professional and domestic activities, and leisure involving the hand. Objective data were also assessed: thumb opposition, radiographic scaphometacarpal mobility, key and tip pinch, grasp strength.

RESULTS

Functional results ranged from good to excellent in 42 cases. Opposition was satisfactory in 46 cases. Scapho-metacarpal range of motion was 16 degrees. Pinch strength was 4.2 kg and grasp strength was 23 kg. There were no complications. Loss of pinch strength was 1 to 2 kg as compared to our reference group. Such a loss does not impair patients' daily life. Age and operated side do not influence results. Scores do not decrease with time. Radiographic staging seems to be linked with scoring. Reducing the trapezial space does not influence results. We had none of the complications described in other techniques: synovitis, ossifications, loosening and reflex sympathetic dystrophy.

DISCUSSION

This study, as well as literature, confirms that trapeziectomy and ligament reconstruction with tendon interposition arthroplasty gives satisfactory functional results which are stable with time and without complication. For all these reasons, the authors prefer this technique in degenerative osteoarthritis.

Biomechanical analysis of the trapeziometacarpal joint after surface replacement arthroplasty

A biomechanical analysis of the trapeziometacarpal joint was performed in 7 fresh-frozen normal human cadaveric hands to compare the kinematics of the trapeziometacarpal joint before and after surface total joint replacement. Using a 3-space magnetic Isotrak system (Polhemus, Colchester, VT), which provides a 3-dimensional analysis of motion of joints as well as translation, we found that kinematics and stability of the trapeziometacarpal joint could be duplicated by joint surface replacement arthroplasty provided that normal ligament tensions were present.

Does wrist fusion cause destruction of the first carpometacarpal joint in rheumatoid arthritis? 18 patients followed for 2-6 years

We evaluated radiographic destruction of the first carpometacarpal joint (CMC I) in 18 hands with wrist fusions and compared it with the unoperated contralateral hands preoperatively and after a follow-up of a mean of 4.4 (2-6) years. Patients were obtained from a prospective 20-year follow-up study of 103 patients with seropositive rheumatoid arthritis. The degree of destruction in the CMC I-joints was evaluated with Larsen grades. The mean value of Larsen indices for CMC I was 0.9 before wrist fusion and 2.5 (p < 0.001) at the follow-up, compared to 0.8 and 1.3 (p = 0.06) in the control hands, respectively. No preoperative difference was found between the hands to be fused and the control hands, but the difference was significant (p = 0.009) after the follow-up.