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Reasons for performing study We wished to add to the existing baseline data on impact loading of the distal limb as a precursor to assessing the potential role of impact in injury and joint disease. Objectives To examine the effect of 3 hoof-strike conditions (toe first, flat and heel first) and 2 specimen masses (with and without a ballast of ∼2% body mass) on impact deceleration and vibration frequencies and energies at the hoof, first phalanx and third metacarpal. Study design Biomechanical experiments in cadaver material. Methods Eight cadaver limbs were subjected to randomised, repeated controlled trials, in which the hoof was struck by a pendulum impact-testing machine (impact velocity, 3.55 m/s) in the 3 strike and 2 mass conditions. Data from triaxial accelerometers on the hoof, first phalanx and third metacarpal quantified, for all trials, the peak impact acceleration, frequencies in the first 6.4 ms following impact, the frequency with the most energy, 95% of the total energy and the frequency at 95% cumulative energy. The effects of the strike and mass conditions on each variable were statistically tested using repeated-measures ANOVA (α = 0.05). Results Signal energy reaching the third metacarpal was 6-31% of that at the hoof. A heel-first strike produced the largest peak accelerations and highest frequencies among all strike conditions, and changing the mass had no effect regardless of strike condition. Conclusions Large accelerations that occur upon impact of the hoof with the ground are attenuated by the distal structures of the equine limb, but still carry considerable energy within the signal that could be damaging to tissue and are dependent on hoof-strike condition but not ballast. Our results suggest that impact loading on the hoof could be a factor in contributing to bone injury and joint disease in the distal limb. [ABSTRACT FROM AUTHOR]

Fifty one anatomical specimens were dissected and the amplitudes of the trapeziometacarpal and metacacarpophalangeal joints of 33 were measured. These amplitudes were also measured on 26 animals asleep and many other animals were observed in relative freedom or in large aviaries. 419 skeletons of primates’ hands were measured and the measures converted in percentage with regard to the length of the 3rd metacarpal, in order to compare species in spite of their difference of size (collection of the Museum of Natural History in Paris). The morphological and functional differences of the trapeziometacarpal joint and the modes of pollicidigital prehension, help arranging primates in three categories.Among prosimians, the joint is concave/convex. The concavity follows a large vertical axis. Its articular surfaces are congruent. It works like a universal joint with two-degrees of freedom. Opposition with the two last fingers is only obtained with a maximum opening of the first commissure. Very long fingers are necessary to make a pinch. The 4th finger is the longest.Among platyrhinians, the joint is also concave/convex, but either slightly oblique or a little less congruent, or of condylar type (Callitrichinae). All fingers are long, especially the 3rd. The transversal intermetacarpal ligament of the first commissure hinders its opening. There is only pseudo-opposition in Cebidae and no opposition in Callitrichinae.In catarhinians, the joint has a 45 degrees tilt and its surfaces are not congruent. The attachment of the medial trapezométacarpal ligaments at the base of the metacarpal induces a rotation around its longitudinal axis. There are three degrees of freedom. Medial inclination is accompanied by pronation, which may be obtained with a very small displacement of the thumb. All the fingers are shorter than those of prosimians or platyrhinians. The thumb is particularly short. Only Macacus has a thumb almost as long as that of man. Two (sub-) families fall outside the rule. the Atelinae among the platyrhinians and the Colobinae among the catarhinians. Their first ray is atrophic and motionless; the thumb is almost buried in the thenar eminence.The metacarpophalangeal joint is condylar and unstable in almost all primates. This instability prohibits a powerfull and accurate grip. Only the human has a stable metacarpophalangeal joint. This stability is a critical factor during handling. The thumb is relatively long for a catarhinian. All these data on the pollical mobility are useful to understand the handling and the locomotion of the primates. These observations should help finding primitive characters of the hand of primates and to reconstitute a part of the evolution of the thumb toward its liberation.

In the human body there are many joints whose functions are very similar to revolute joints. To avoid the complexity of these joints, they are usually substituted by revolute joints in many humanoid robots. Revolute joints have purely rotational motion along their fixed axis, while real joints in the human body have Instantaneous Rotational Axis (IRA) due to their configuration. Substitution of this kind of human joints with revolute (hinge) joints in robots changes the kinematics of joints. Knowing the exact characteristics of the moving axis of rotation in human joints is a prerequisite for the kinematic study of a joint. Here the main geometrical difference between these kinds of joints in humans and their simplified (hinge-like) models in robots is described. Then, as a case study, the mechanism of the three joints of the index finger are compared with their hinge-like model using a multi-body code to understand when revolute joints can be substituted for anthropometric joints in hand exoskeletons and robotic hands. Furthermore, the position of IRA and its distance from the center of the condyle of the joint are presented. The concept and the results can be extended for other fingers and all similar joints, and can be used in humanoid robots, hand exoskeletons and robotic hands. [ABSTRACT FROM AUTHOR]

The purpose of this retrospective cohort study was to evaluate the outcomes of 18 primary pyrocarbon metacarpophalangeal joint replacements in 10 patients, performed for primary osteoarthritis. The mean age at operation was 66 years and mean follow-up was 58.6 months. The arc of motion improved from a mean of 30° to 40° and the mean QuickDASH score improved from 35 to 17. All except one patient were satisfied with their outcomes. Radiographically, there has been no evidence of dislocation or overt loosening, although there has been subsidence of some components up to 5 mm. One index finger implant was revised to a silastic implant for perceived alteration of precision pinch. Other complications included one intra-operative fracture that united and an asymptomatic stem fracture of one proximal phalangeal component. We continue to use the implant and aim to review our experience in a further 5 years. [ABSTRACT FROM PUBLISHER]

We report painful locking of the metacarpophalangeal joint in a man, his mother, and his sister, all of whom have brachymesophalangy. Surgical excision of loose osteocartilaginous fragments relieved their symptoms. The fragments appeared to be unfused ossicles of the metacarpal head, unique to patients with brachymesophalangy. [Copyright &y& Elsevier]

Purpose: To evaluate the clinical effectiveness of metacarpophalangeal (MCP) arthroplasty for nonrheumatic arthritis. We hypothesized that MCP arthroplasty would produce significant improvement in objective measures of hand function, pain relief, and overall patient satisfaction. Methods: This retrospective study evaluated 30 patients with 38 MCP arthroplasties for nonrheumatic arthritis over a 12-year period. Follow-up assessment was completed at an average of 56 months after surgery. Objective measures included range of motion; grip and pinch strength; Disabilities of the Arm, Shoulder, and Hand (DASH) score; and visual analog pain score. A subjective patient questionnaire was used to assess patient satisfaction. Results: There was marked improvement between preoperative and follow-up range of motion, DASH, and pain. Linear regression showed strong correlations between preoperative measurements and improvement at follow-up. No difference was detected for grip or pinch strength. Results of the questionnaire showed that 73% were very satisfied, 87% would definitely do it again, and 70% experienced rare or no pain. Follow-up x-rays showed 5° mean angulation and 2-mm mean subsidence compared with immediate postoperative x-rays. Four arthroplasties (11%) required revision. Conclusions: This study showed improved range of motion and DASH score, excellent pain relief, and excellent patient satisfaction in patients undergoing MCP arthroplasty for nonrheumatic arthritis. Patients with more severe range of motion limitation, DASH score, and pain score experienced a greater improvement of these measures at follow-up. Strength improvement was limited although it remained comparable to the nonoperated hand. Angulation, subsidence, and complications in the study population were consistent with those reported in the literature. Type of study/level of evidence: Therapeutic III. [Copyright &y& Elsevier]

We investigated the efficacy of axial traction of the fingers combined with magnetic resonance (MR) arthrography in assessing the metacarpophalangeal (MCP) joint cartilage in cadavers. Cartilage was imaged and graded before/after MR arthrography, with/without traction, then correlated with cadaveric sectioning. The application of traction with MR arthrography is a promising technique for improved visualization of the articular cartilage of the MCP joints compared with similar imaging without traction and/or without arthrography, but its true benefit requires further study. [ABSTRACT FROM AUTHOR]

Two hundred and thirty-two horses with lameness localized to the metacarpo(tarso)phalangeal (MCP/MTP) region without a radiographic diagnosis were evaluated. All horses had high-field magnetic resonance (MR) imaging of the MCP/MTP region performed for the lame limb and the contralateral limb for comparison. There were 46 horses that had bilateral abnormalities in the forelimbs; 27 of these horses were not lame in the contralateral limb at the time of examination. Bilateral hind limb abnormalities were observed in 37 horses; 22 horses were not lame in the contralateral limb. Soft tissue abnormalities alone were observed in 218 limbs (162 horses). Subchondral bone and articular cartilage abnormalities alone were observed in 43 limbs (34 horses). A combination of soft tissue, subchondral bone, and cartilage abnormalities were observed in 64 limbs (36 horses). The distribution of primary abnormalities was as follows; oblique distal sesamoidean ligament desmitis (73 limbs in 56 horses), straight distal sesamoidean ligament desmitis (44 limbs in 38 horses), chronic subchondral bone injuries (15 limbs in 12 horses), suspensory ligament branch desmitis (14 limbs in 12 horses), collateral ligament desmitis (12 limbs in 12 horses), tendonitis of the superficial and deep digital flexor tendons (10 limbs in 10 horses), osteochondral defects greater than 1 cm (nine limbs in six horses), osteochondral defects less than 1 cm (eight limbs in seven horses), bone marrow lesions (six limbs in five horses), intersesamoidean ligament desmitis (five limbs in four horses). MR imaging is useful in diagnosing bone and soft tissue injuries when radiographs and ultrasound fail to yield a diagnosis. [ABSTRACT FROM AUTHOR]

Abstract: The purpose of this study was to report the results of static triangular ligament reconstruction, in thumb metacarpophalangeal (MCP) joint chronic posttraumatic laxity using a tendon graft with a proximal apex in ten patients. The mean postoperative follow-up was 40.2 months. The mean postoperative thumb MCP joint stress testing was 43° less than before surgery, and 6.5° less than in the non-injured hand. The mean range of flexion was 10.5° lower in the operated thumb than in the contralateral one, and the mean range of extension was 8° lower. Minimal differences in the values of the Kapandji score, grip and key-pinch strength were found. The preoperative pain became an occasional discomfort after surgery. All patients had a subjective sense of stability until final follow-up. All patients returned to their work or daily activities. Level of evidence IV: For therapeutic studies investigating the results of treatment. [Copyright &y& Elsevier]

We compared the ability of 1.5 T magnetic resonance imaging (MRI), computed tomography (CT), and computed radiography (CR) to evaluate noncartilaginous structures of the equine metacarpophalangeal joint (MCP), and the association of imaging changes with gross cartilage damage in the context of osteoarthritis. Four CR projections, helical single-slice CT, and MRI (T1-weighted gradient recalled echo [GRE], T2*-weighted GRE with fast imaging employing steady-state acquisition [FIESTA], T2-weighted fast spin echo with fat saturation, and spoiled gradient recalled echo with fat saturation [SPGR-FS]) were performed on 20 racehorse cadaver forelimbs. Osteophytosis, synovial effusion, subchondral bone lysis and sclerosis, supracondylar lysis, joint fragments, bone marrow lesions, and collateral desmopathy were assessed with each modality. Interexaminer agreement was inferior to intraexaminer agreement and was generally moderate (i.e., 0.4<κ<0.6). Subchondral bone sclerosis scores using CT or MRI were correlated significantly with the reference quantitative CT technique used to assess bone mineral density ( P<0.0001). Scores for subchondral lysis and osteophytosis were higher with MRI or CT vs. CR ( P<0.0001). Although differences between modalities were noted, osteophytosis, subchondral sclerosis, and lysis as well as synovial effusion were all associated with the degree of cartilage damage and should be further evaluated as potential criteria to be included in a whole-organ scoring system. This study highlights the capacity of MRI to evaluate noncartilaginous changes in the osteoarthritic equine MCP joint. [ABSTRACT FROM AUTHOR]

Fracture–dislocations in the small joints of the fingers are challenging injuries. The surgeon must choose an appropriate treatment based on fracture pattern, joint stability, and injury chronicity. Fracture–dislocations of the proximal interphalangeal joint are notoriously unforgiving, with potential long-term sequelae of residual pain and stiffness. Similar injuries in the distal interphalangeal joint are more tolerant of fracture displacement and even joint subluxation. Dorsal dislocations of the metacarpophalangeal joint may be associated with shearing fractures of the metacarpal head but are most notable for the volar plate interposition that may block closed reduction. [Copyright &y& Elsevier]

Abstract: The purpose of this study was to compare subchondral bone density obtained using quantitative computed tomography with ash density values from intact equine joints, and to determine if there are measurable anatomic variations in mean subchondral bone density. Five adult equine metacarpophalangeal joints were scanned with computed tomography (CT), disarticulated, and four 1-cm3 regions of interest (ROI) cut from the distal third metacarpal bone. Bone cubes were ashed, and percent mineralization and ash density were recorded. Three-dimensional models were created of the distal third metacarpal bone from CT images. Four ROIs were measured on the distal aspect of the third metacarpal bone at axial and abaxial sites of the medial and lateral condyles for correlation with ash samples. Overall correlations of mean quantitative CT (QCT) density with ash density (r =0.82) and percent mineralization (r =0.93) were strong. There were significant differences between abaxial and axial ROIs for mean QCT density, percent bone mineralization and ash density (p <0.05). QCT appears to be a good measure of bone density in equine subchondral bone. Additionally, differences existed between axial and abaxial subchondral bone density in the equine distal third metacarpal bone. [Copyright &y& Elsevier]

Eleven fractured Sutter metacarpophalangeal prostheses were obtained from the hands of three patients. All of the implants had fractured at the junction of the distal stem and the hinge. After visual examination, the fracture faces were prepared and viewed using a scanning electron microscope. These images indicated that fracture was initiated by abrasion on the dorsal aspect of the distal stem of the prostheses, close to the hinge. Crack propagation was shown to be due to a fatigue process. Once a crack started, its direction of travel could be followed, using topographical features common to engineering fracture analyses. Propagation was from radial to ulnar and from dorsal to palmar. [ABSTRACT FROM AUTHOR]

A displaced complete radial collateral ligament avulsion with associated injury to the sagittal band of the metacarpophalangeal joint of the small finger, if left untreated, may result in chronic pain, instability, weakness, and deformity. A case of a displaced radial collateral ligament that ruptured through the radial sagittal band of the small finger, with resultant injury to the extensor mechanism, is described and discussed with a review of the literature. Proper identification of this injury by physical exam and imaging studies along with surgical repair is associated with good outcome. [ABSTRACT FROM AUTHOR]

Purpose: To review early outcomes of arthritic metacarpophalangeal (MCP) joints treated with nonconstrained pyrolytic carbon implants to evaluate efficacy, clinical outcomes, and durability. Methods: One hundred forty-two consecutive arthroplasties (61 patients) were retrospectively reviewed. Diagnoses included osteoarthritis (OA), traumatic arthritis, and inflammatory arthritis. One hundred thirty were primary joint replacements, and 12 were prior-silicone revisions. The average patient age was 55 years (range, 21–77 years); 36 patients were women and 25 were men. Average follow-up period was 17 months (range, 3–42 months), and 43 patients were followed up for a minimum of 1 year. Results: For OA patients, according to the analog pain scale used, pain decreased from 73.0 to 8.5 of 100, functionality increased from 20.1 to 86.6 of 100, and appearance improved from 62.7 to 93.6 of 100. The rheumatoid arthritis (RA) group showed decreased pain from 43.1 to 8.9 of 100, functional improvement from 26.7 to 83.3 of 100, and increased appearance from 25.2 to 77.1 of 100. At 1 year, satisfaction was greater than 90% for both groups. Arc of motion for OA patients improved from 44° to 58°. Oppositional pinch increased 126%, and grip strength improved 40%. Rheumatoid arthritis patients increased their MCP joint motion arc from 32° to 45°. Oppositional pinch increased 89%, but grip strength decreased. Radiographs at 1 year demonstrated stable prostheses in all of the OA joints. The RA group overall demonstrated evidence of axial subsidence (10.5% of joints) and periprosthetic erosions (16.4% of joints). In RA joints with greater than 1-year follow-up period, 55.0% had axial subsidence, 95.0% had an increased radiolucent seam, and 45.0% had periprosthetic erosions. The overall implant survivorship is 141 joints to date. The overall minor complication rate was 6%, and major complication rate was 9%. Conclusions: Preliminary results suggest that pyrolytic carbon MCP joint arthroplasty provides good pain relief, patient satisfaction, and functional improvement in managing OA and select cases of RA. Longer follow-up evaluation will help validate these promising early results. Type of study/level of evidence: Therapeutic IV. [Copyright &y& Elsevier]

Purpose: To evaluate retrospectively the functional and radiographic outcome of patients who had a thumb metacarpophalangeal joint arthrodesis with a single longitudinal K-wire. Methods: We performed a retrospective review of 27 patients who had a thumb metacarpophalangeal joint arthrodesis with a single longitudinal K-wire. Outcomes were assessed using self-reported measures (Patient-Rated Wrist/Hand Evaluation; AUSCAN Osteoarthritis Hand Index; Disabilities of the Arm, Shoulder and Hand questionnaire; Short Form-36 General Health questionnaire), measured physical impairments (range of motion, strength, manual dexterity), and radiographic review. Results: Patient-rated outcome scores indicated mild pain, difficulty with specific and usual tasks, and minimal concern with hand appearance. Most physical impairment measures were not significantly different from the side not surgically treated, and patient satisfaction was high. There was a slight decrease in tripod pinch strength, manual dexterity, interphalangeal joint flexion, handspan, and thumb opposition compared with the contralateral side. The overall complication rate was 11% (3 complications). Twenty-five patients (89%) were able to return to their previous occupations. There were no radiographic malunions or nonunions. Radiographic evidence of degenerative changes was present in 20% of patients at the carpometacarpal joint and 30% of patients at the interphalangeal joint. Conclusions: Our technique of performing a thumb metacarpophalangeal joint arthrodesis with a single longitudinal K-wire is effective, with high overall patient satisfaction and a relatively low complication rate, despite small losses of strength, manual dexterity, and motion. Type of study/level of evidence: Therapeutic IV. [Copyright &y& Elsevier]

Abstract: Various designs of two-piece finger prosthesis with conforming spherical surfaces have been proposed. These were compared by calculating the lubrication regime for the material combinations and operating conditions expected at the metacarpophalangeal joints of the fingers. Consideration was given to a range of loads from 2 to 50N, a range of entraining velocities from 0 to 30mm/s, and a range of prosthesis radii from 3 to 10mm. This theoretical lubrication analysis indicated that the optimum material combination of those available for two-piece metacarpophalangeal prostheses is in the order: ceramic-on-ceramic; metal-on-metal; pyrocarbon-on-pyrocarbon; and metal-on-polymer. However, it should be recognised that other factors may take precedence when choosing a material combination for a design of finger prosthesis. [Copyright &y& Elsevier]

Six metacarpophalangeal prostheses were each wear tested to five million cycles. Each prosthesis consisted of a metacarpal component with an approximately hemispherical shell on a titanium body, articulating against a titanium phalangeal component. Four prostheses had a shell made from ultra-high molecular weight polyethylene (UHMWPE) and two had a shell made from polyether ether ketone (PEEK). The tests were undertaken using a finger wear simulator. Despite pre-soaking and the use of control components, lubricant uptake by the metacarpal components was significant. Gravimetrically, the UHMWPE test components showed a greater weight gain than the UHMWPE control components. Therefore there was no apparent wear of any of the UHMWPE test metacarpal components. The original concentric machining marks of the UHMWPE components could still be seen after five million cycles of testing. For the metacarpal components with PEEK shells, gravimetric wear could be measured. Gravimetrically, all of the titanium phalangeal components showed little or no wear. Light scratches in the direction of sliding appeared on the articulating faces of all metacarpal and phalangeal test components, indicating slight abrasive wear. [ABSTRACT FROM AUTHOR]

Purpose: Previous studies have found that function and pain are the main factors that persuade physicians to recommend surgical reconstruction to patients with rheumatoid arthritis (RA). The factors that influence patients to choose surgical reconstruction, however, are not known fully. The purpose of this study was to determine how function, pain, and aesthetics rank in order of importance to RA patients who are considering metacarpophalangeal (MCP) joint arthroplasty for rheumatoid hand deformities. Methods: Study participants are part of a larger National Institutes of Health–sponsored study. Participants who are eligible to receive MCP joint arthroplasty are enrolled in our study using defined inclusion and exclusion criteria. All patients have RA and MCP joint extensor lag and/or ulnar deviation. Study participants choose whether they want to enroll in a surgical group to receive MCP joint arthroplasty or in a nonsurgical group. At enrollment all participants complete the Michigan Hand Outcomes Questionnaire. Function, pain, and aesthetic domains from the Michigan Hand Outcomes Questionnaire were used in a logistic regression model as predictors to determine the factors associated with patients choosing reconstruction for rheumatoid hand deformities. Results: Younger age and female gender were associated significantly with an increased likelihood for choosing MCP joint arthroplasty surgery. The age- and gender-adjusted odds ratios of choosing MCP joint arthroplasty were 0.50 for function, 1.47 for pain, and 0.83 for aesthetics. Patients with less function and greater pain were more likely to choose MCP joint arthroplasty. Aesthetic consideration was not a statistically significant predictor. Conclusions: Impaired function had the strongest association with patients choosing reconstruction and pain relief was the next most important factor. Although aesthetic consideration was less important, it may prove to be an important factor in determining patient satisfaction after surgery. Understanding which factors are associated with choosing rheumatoid hand reconstruction is an essential component of patient preoperative counseling. [Copyright &y& Elsevier]

Purpose: To determine the optimal tunnel placement positions for tendon graft reconstruction of chronic thumb metacarpophalangeal (MCP) ulnar collateral ligament injuries that would stabilize the joint while maintaining motion. Methods: Four commonly used tunnel placement methods were simulated on a cadaveric model using fresh-frozen thumbs and a suture/screw construct. The methods were as follows: (1) triangular configuration with apex proximal, (2) triangular configuration with apex distal, (3) cruciate configuration, and (4) parallel configuration. Stability was tested by valgus loading at 0° and 30°, and range of motion was tested by loading the thumb tendons. Statistical analysis was performed by 1-way analysis of variance testing. Results: Valgus load stability testing at 0° and 30° showed that all 4 reconstruction methods stabilized the MCP joint compared with the fully sectioned state. The amount of stability achieved was not significantly different between the 4 methods. Only the reconstruction method, however, with a triangular configuration with the apex proximal restored flexion/extension range of motion not significantly different from the intact state. The other 3 methods resulted in significantly decreased range of motion. Conclusions: The reconstruction tunnel positioning of triangular configuration with apex proximal stabilizes the thumb MCP joint while maintaining flexion/extension range of motion. We recommend this configuration for chronic MCP joint injuries in which the native ulnar collateral ligament is inadequate and tendon graft reconstruction is performed. [Copyright &y& Elsevier]

Abstract: Since the original description of wrist denervation, the principle of joint denervation in hand surgery has been extended to other joints like the first carpometacarpal, interphalangeal and metacarpophalangeal joints. At the wrist level as at the digital level, the results are comparable to those obtained with other surgical alternatives. In case of unsatisfactory results, a more traditional intervention remains always possible. [Copyright &y& Elsevier]

This paper describes the testing of three single-piece silicone NeuFlex metacarpophalangeal prostheses in a finger function simulator and describes the resulting modes of prosthesis failure. In all cases, failure was due to imminent fracture of the prosthesis across the pivot of the central hinge section. This result is in contrast with previous in-vitro and in-vivo experience with single-piece silicone Swanson and Sutter metacarpophalangeal prostheses, which both tend to fracture at the junction of the distal stem and the hinge. In comparison with earlier in-vitro simulator tests of the Sutter metacarpophalangeal prosthesis, the NeuFlex prostheses showed a greater longevity before fracture. To date, no other reports of fracture of the NeuFlex metacarpophalangeal prosthesis have been reported, either in vitro or in vivo. [ABSTRACT FROM AUTHOR]

Objective. To determine the mechanisms responsible for the recurrence of ulnar drift after metacarpophalangeal joint arthroplasty in the rheumatoid hand.Design. A three-dimensional biomechanical model of the index finger joints was used to predict the implant loads during several activities of daily living.Background. Post-operative clinical evaluation of Sutter metacarpophalangeal prostheses shows a high incidence of fracture and recurrent deformity.Methods. A six-component force transducer in conjunction with a six-camera motion analysis system were used to obtain kinematic and external loading data from eight patients with rheumatoid arthritis during several simulated activities. These data were used as input into a three-dimensional biomechanical model of the implant and interphalangeal joints of the index finger. Tendon lines of action and moment arms were obtained using a series of MRI scans and CAD modelling techniques.Results. Implant forces were oriented in a radial and dorsal direction to resist the ulnarpalmarly pull of tendons associated with the metacarpophalangeal joint.Conclusions. The recurrence of ulnar drift is attributable to fatigue failure of the prostheses. After fracture the implant is unable to support the repetitive loading patterns experienced during activities of daily living.Relevance Understanding the mechanisms responsible for the recurrence of ulnar drift and implant failure is a step towards improving the prosthesis design, surgical procedures and ultimately the patient''s prognosis. [Copyright &y& Elsevier]

This paper highlights the lack of an agreed testing standard for artificial finger joints. It reviews the anatomy, pathology and biomechanics of finger joints as well as the various designs of finger prostheses and the machines used to test them. While pre-implantation testing should be fundamental, increasing regulation of the biomedical engineering industry will further demand testing of prostheses to pre-agreed standards. Standards relating to the testing of other artificial joints are reviewed before possible parameters for testing finger prostheses are offered. [ABSTRACT FROM AUTHOR]

Low-profile flexible goniometers were used in an instrumented glove to monitor metacarpophalangeal (MCP) joint usage in patients with rheumatoid arthritis and control subjects over 3 days. Statistical analysis of the results provided descriptors of total joint motion per hour, the number of movements per hour and their duration, amplitude and angular velocity. The results show the patient group to have less overall joint usage than the control group, with movements being slower and smaller and with a restricted range. Yearly rates of joint usage were derived; these values are considerably higher than predicted in prosthetic joint testing protocols. [ABSTRACT FROM AUTHOR]

A protocol for analysing three-dimensional metacarpophalangeal (MCP) joint motion in vivo using two markers on the proximal phalanx is described. The analysis uses an assumption that the rotation of the phalanx about its own long axis is zero. In an experimental study 24 volunteers had surface markers applied to the dorsal surfaces of their hands and index and long finger proximal phalanges, with three-dimensional marker positions recorded in two hand and finger postures in an incomplete box design using a test-retest protocol. Kinematic parameters from the optoelectronic system were compared with those obtained from three-dimensional reconstruction of bone landmarks and of the marker positions identified on stereoradiographs. Pronation/supination angles obtained from bone landmarks showed high test-retest variability, reflecting the difficulty in obtaining reliable pronation/supination data in small bones without the use of implanted markers. Changes in MCP joint extension and deviation angles determined using two surface markers agree with those obtained from bone landmarks. The results indicate a reproducible protocol for tracking MCP joint motion using only two phalangeal markers, suggesting that the 'no-rotation assumption' can be applied without affecting measures of extension and deviation motion in the normal joint. [ABSTRACT FROM AUTHOR]

A dual-cycle finger wear simulator has been designed, manufactured and commissioned. The simulator interspersed dynamic flexion-extension motion under light load with a heavier static 'pinch' load to a test prosthesis immersed in a lubricant heated to 37 degrees C. A validation test was undertaken on a size 2 Swanson prosthesis, leading to prosthesis failure in less than 1 million cycles. A second test was carried out on a Durham metacarpophalangeal prosthesis. After 4.8 million cycles a total wear factor for the joint of 0.60 x 10(-6) mm3/N m was calculated, with no cracks or damage visible. Both test results compare well with earlier tests undertaken on the Stokoe finger wear simulator. [ABSTRACT FROM AUTHOR]

We present a case of simultaneous dislocation of the carpometacarpal and the metacarpophalangeal joints of the thumb (floating thumb metacarpal) in a 47-year-old motorcyclist. The treatment consisted of closed reduction of both joints with cast immobilization. After 24 months, the functional result was excellent. The mechanism of this rare injury and its therapeutic management are discussed. [ABSTRACT FROM AUTHOR]

Volar dislocations of the thumb metacarpophalangeal joint are uncommon and can be associated with rupture of the ulnar collateral ligament (UCL). We report a case where a volar thumb dislocation was successfully closed reduced, but instability required open repair of the UCL. Early motion protocol helped achieve favorable results. [ABSTRACT FROM AUTHOR]

Thumb metacarpophalangeal instability is commonly found in conjunction with trapeziometacarpal osteoarthritis. If not corrected, it can have detrimental effects on the outcome. The authors describe the two types of metacarpophalangeal deformities - hyperextension and valgus - their pathophysiology and the surgical repair techniques available to surgeons. An algorithm for treating this instability is presented., (Copyright © 2020. Published by Elsevier Masson SAS.)

The moment arm of a muscle's force represents the muscle's leverage or mechanical advantage in producing a joint moment. It is indicative of the muscle's potential to contribute to actuation of a joint in a particular joint motion direction and defines the role of the muscle, for example, as a joint flexor or abductor. The aims of this study were, firstly, to measure the moment arms of the flexor and extensor muscles of the metacarpophalangeal (MCP), proximal interphalangeal (PIP) and distal interphalangeal (DIP) joints, and the moment arms of the major abductor and adductor muscles of the metacarpophalangeal (MCP) joint of each finger in the hand; secondly, to assess the effect of change in joint angle on these moment arms; and thirdly, to determine if there are differences in a given flexor or extensor's muscle moment arms between the joints it spans on a given finger, and across its tendon slips to multiple fingers. The tendon-excursion method was used to measure instantaneous muscle moment arms in nine fresh-frozen entire forearm cadaver specimens. Joint flexion angle was found to have significant effects on the moment arms of the extensor muscles at the MCP and PIP joints (p < 0.05). In contrast, the digital flexor muscles maintained relatively constant moment arms through the range of joint flexion. The moment arms of the digital flexors and extensors spanning multiple joints in a finger were largest at the MCP joints and smallest at the DIP joints. The findings demonstrate greater torque generating capacity for tasks such as grasping at the proximal interphalangeal joints, and smaller torque capacity for finer movement control at the distal interphalangeal joints. The dataset generated in this study may be useful in the development and validation of computational models used in surgical planning, and rehabilitation. [ABSTRACT FROM AUTHOR]

Abstract: We report four cases of locked metacarpophalangeal joint. This is a rare and, sometimes, undiagnosed pathology. Locking of the joint is due to a conflict between the head of the metacarpal and one of the collateral ligaments. X-Rays may show an osteophyte or a malformation. Treatment varies from simple traction to surgery. Recurrence is rare. [Copyright &y& Elsevier]

Double dislocations of the finger interphalangeal and/or metacarpophalangeal joints are a rare entity. Sixty-four cases of distal and proximal interphalangeal joint double dislocations have been previously reported. Five cases of metacarpophalangeal and interphalangeal double dislocations of the thumb have also been reported. Only one case has been reported in the English literature regarding simultaneous dislocations of the distal interphalangeal and metacarpophalangeal joints in the nonthumb digit. The directions of the dislocation were the same; both were dorsal. We report, to our knowledge, the first ever case of a double dislocation a non-thumb digit in opposing directions—volar at the metacarpophalangeal joint and dorsal at the distal interphalangeal joint. [ABSTRACT FROM AUTHOR]

The aim of this study was to compare the outcome of patients who received rehabilitation to those who did not receive it after surgical treatment of acute and chronic tears of the ulnar collateral ligament (UCL) of the thumb. Forty-two patients with an acute UCL injury repaired with two soft mini-anchors to bone insertion sites, and 40 patients with a chronic UCL injury reconstructed with autografts were involved in this study. The patients were divided two subgroups depending on rehabilitation. Patient characteristics were not significantly different between the two groups and subgroups. Range of motion, grip strength and pinch strength were evaluated. There was no significant change in terms of grip and pinch strength in patients with acute UCL injury who received rehabilitation after surgical treatment. However, significantly better results were achieved in flexion, extension, ulnar and radial deviation. There was no significant change in pinch strength in patients with chronic UCL reconstructions, but significantly better results were achieved in grip strength, flexion, extension, ulnar and radial deviation. A rigid MCP splint in patients with acute and chronic UCL tears is effective in preventing early ligament insufficiency., (Copyright © 2020. Published by Elsevier Masson SAS.)

Infections in the joints of the hand and wrist carry the risk of significant morbidity. Common presenting symptoms include joint redness, swelling, and pseudoparalysis that occurs several days following a penetrating trauma. Diagnostic workup should be expedited, including a laboratory evaluation and arthrocentesis. Imaging, including radiographs, ultrasound, computed tomography, and/or MRI, are helpful tools in diagnosis. Once infection is identified, prompt surgical debridement and antibiotics are required. Once the infection has been managed, hand therapy is initiated to decrease the risk of stiffness. Stiffness is the most common complication following infection; additional reported complications include arthritis, ankylosis, and amputation.", (Copyright © 2020 Elsevier Inc. All rights reserved.)

A 12-year-old horse was brought to the clinic of Department of Veterinary Surgery and Radiology, CVAS, RAJUVAS, Bikaner with a history of lameness and swelling at fetlock region since one month. Clinical examination revealed appreciable swelling on the anterior aspect of metacarpophalangeal joint, short and choppy gait with lameness. Dorsopalmar and latera-medial radiographs of affected limb revealed mild new bone growth on lateral aspect of fetlock joint and sesamoiditis. Haematobiochemical examination revealed decreased serum calcium and increased ALP. On the basis of-all examinations, the case was diagnosed as "Osselets". Animal responded well to stall rest, heat therapy for about 4 to 6 weeks along with administration of NSAIDs and sodium salt of 4-dimethylamino-2 methylphenyl-phosphinic acid for 3 days. [ABSTRACT FROM AUTHOR]