Deviation Of Wrist Research Articles

Assessing the contribution of different upper limb degrees of freedom to an unconstrained shoulder proprioception task

For the purpose of testing shoulder joint proprioception while controlling for axioscapular muscle recruitment, a novel shoulder thoracohumeral (TH) rotation joint position sense (JPS) measurement device was designed. This device was intended to measure shoulder TH rotation, while also implicitly constraining other upper limb degrees of freedom (DOF) and minimizing cutaneous sensation. The purpose of this study was to determine whether joint motion aside from shoulder TH rotation is being captured by the shoulder JPS measurement device. Upper limb kinematics were collected from 32 participants during joint angle matching trials using the shoulder JPS measurement device. Step wise multiple regression revealed that shoulder TH rotation (β-Humeral Rotation = 0.409, p < 0.001), and wrist deviation (β-Wrist Deviation = 0.104, p = 0.008) both contributed a significant unique variance in the prediction of shoulder JPS measurement device rotation. Findings suggest that seated, unconstrained shoulder TH rotation JPS testing protocols in literature may be confounded by contributions from joints both proximal and distal to the shoulder. Researchers should be aware of the limitations of both constrained and unconstrained shoulder TH rotation JPS testing protocols.

Investigating the role connective tissue fibroblasts play in the altered muscle anatomy associated with the limb abnormality, Radial Dysplasia.

Radial dysplasia (RD) is a congenital upper limb birth defect that presents with changes to the upper limb anatomy, including a shortened or absent radius, bowed ulna, thumb malformations, a radially deviated hand and a range of muscle and tendon malformations, including absent or abnormally shaped muscle bundles. Current treatments to address wrist instability caused by a shortened or absent radius frequently require an initial soft tissue distraction intervention followed by a wrist stabilisation procedure. Following these surgical interventions, however, recurrence of the wrist deviation remains a common, long-term problem following treatment. The impact of the abnormal soft connective tissue (muscle and tendon) anatomy on the clinical presentation of RD and the complications following surgery are not understood. To address this, we have examined the muscle, fascia and the fascial irregular connective tissue (ICT) fibroblasts found within soft connective tissues, from RD patients. We show that ICT fibroblasts isolated from RD patients are functionally abnormal when compared to the same cells isolated from control patients and secrete a relatively disordered extracellular matrix (ECM). Furthermore, we show that ICT fibroblast dysfunction is a unifying feature found in RD patients, even when the RD clinical presentation is caused by distinct genetic syndromes.

Surgeon Upper Extremity Kinematics During Error and Error-Free Retropubic Trocar Passage.

Surgeon kinematics play a significant role in the prevention of patient injury. We hypothesized that elbow extension and ulnar wrist deviation are associated with bladder injury during simulated midurethral sling (MUS) procedures. We used motion capture technology to measure surgeons' flexion/extension, abduction/adduction, and internal/external rotation angular time series for shoulder, elbow, and wrist joints. Starting and ending angles, minimum and maximum angles, and range of motion (ROM) were extracted from each time series. We created anatomical multibody models and applied linear mixed modeling to compare kinematics between trials with versus without bladder penetration and attending versus resident surgeons. A total of 32 trials would provide 90% power to detect a difference. Out of 85 passes, 62 were posterior to the suprapubic bone and 20 penetrated the bladder. Trials with versus without bladder penetration were associated with more initial wrist dorsiflexion (-27.32 vs -9.03°, p = 0.01), less final elbow flexion (39.49 vs 60.81, p = 0.03), and greater ROM in both the wrist (27.48 vs 14.01, p = 0.02), and elbow (20.45 vs 12.87, p = 0.04). Wrist deviation and arm pronation were not associated with bladder penetration. Compared with attendings, residents had more ROM in elbow flexion (14.61 vs 8.35°, p < 0.01), but less ROM in wrist dorsiflexion (13.31 vs 20.33, p = 0.02) and arm pronation (4.75 vs 38.46, p < 0.01). Bladder penetration during MUS is associated with wrist dorsiflexion and elbow flexion but not internal wrist deviation and arm supination. Attending surgeons exerted control with the wrist and forearm, surgical trainees with the elbow. Our findings have direct implications for MUS teaching.

Use of a factor analysis to assess biomechanical factors of American Sign Language in native and non-native signers

Prior studies suggest that native (born to at least one deaf or signing parent) and non-native signers have different musculoskeletal health outcomes from signing, but the individual and combined biomechanical factors driving these differences are not fully understood. Such group differences in signing may be explained by the five biomechanical factors of American Sign Language that have been previously identified: ballistic signing, hand and wrist deviations, work envelope, muscle tension, and “micro” rests. Prior work used motion capture and surface electromyography to collect joint kinematics and muscle activations, respectively, from ten native and thirteen non-native signers as they signed for 7.5 min. Each factor was individually compared between groups. A factor analysis was used to determine the relative contributions of each biomechanical factor between signing groups. No significant differences were found between groups for ballistic signing, hand and wrist deviations, work envelope volume, excursions from recommended work envelope, muscle tension, or “micro” rests. Factor analysis revealed that “micro” rests had the strongest contribution for both groups, while hand and wrist deviations had the weakest contribution. Muscle tension and work envelope had stronger contributions for native compared to non-native signers, while ballistic signing had a stronger contribution for non-native compared to native signers. Using a factor analysis enabled discernment of relative contributions of biomechanical variables across native and non-native signers that could not be detected through isolated analysis of individual measures. Differences in the contributions of these factors may help explain the differences in signing across native and non-native signers.

Anconeus Muscle Transfer to Correct or Prevent Wrist Radial Deviation in Radial and Posterior Interosseous Nerve Injuries

Wrist radial deviation is a possible complication of tendon transfer for restoration of wrist extension in cases of radial nerve paralysis. In posterior interosseous nerve (PIN) injury, this is because of the imbalance caused by the intact extensor carpi radialis longus and paralysis of the extensor carpi ulnaris (ECU). This deformity may also occur following transfer of the pronator teres (PT) to the extensor carpi radialis brevis (ECRB) for radial nerve palsy. To address wrist radial deviation, we propose transferring the anconeus muscle, extended by the intermuscular septum between the ECU and the flexor carpi ulnaris (FCU), to the ECU tendon. Through an incision over the ulna, the intermuscular septum between the ECU and FCU is harvested at the level of the periosteum and left attached to the anconeus proximally. The anconeus muscle is then released from the ulna, and the intramuscular septum extension is sutured to the ECU tendon under maximal tension. Anconeus muscle transfer was performed on two patients to correct chronic wrist radial deviation following PT to ECRB tendon transfer for radial nerve injury, as well as on two patients with PIN paralysis. In four patients, transfer was performed in addition to standard tendon transfers for radial nerve paralysis to prevent radial wrist deviation deformity. Wrist radial deviation was corrected or prevented in all but one patient at an average follow-up of 10 months. Patients with PIN lesions and those who had anconeus transfer concomitantly with radial nerve tendon transfers were capable of active ulnar deviation. No patient experienced elbow extension weakness, pain, or instability. Anconeus muscle transfer extended by intermuscular septum presents a viable alternative for addressing radial deviation of the wrist in cases of PIN nerve lesions or following PT to ECRB tendon transfer in radial nerve paralysis. Therapeutic V.

Covariation between wrist bone morphology and maximal range of motion during ulnar deviation and supination in extant nonhuman primate taxa.

This study investigates the maximal range of motion (ROM) during wrist deviation and forearm rotation for five different primate genera and the possible correlation with the shape of the distal ulna, triquetrum, and hamate. A two-block phylogenetic partial least square analysis was done to test this covariation in a phylogenetic context, using shape coordinates and a matrix of maximal ROM data as input data. The results show that gibbons have the highest ROM for both ulnar deviation and supination, while Macaca exhibited the lowest ROM for supination, and Pan had the lowest ROM for ulnar deviation. These results can be attributed to differences in locomotor behaviour, as gibbons need a large wrist mobility in all directions for their highly arboreal lifestyle, while Macaca and Pan need a stable wrist during terrestrial locomotion. However, we found no correlation between distal ulna/triquetrum/hamate shape and maximal ROM during ulnar deviation and supination in the different primate taxa. A larger dataset in combination with behavioral and biomechanical studies, are needed establish form-function relationships of the primate hand which will aid the functional interpretation of primate fossil remains.

Ergonomic assessment of wheel hoe and design compliance for women farm worker

Weeding is carried out by women farm workers with hand tools and most of these tools are operated in squatting or bending posture. These tools are essentially designed for male farm workers. One of the common hand tool used for weeding is wheel hoe. Therefore, ergonomic assessments of an existing wheel hoe and design modification were done to make it compatible for women workers. The wheel hoe was ergonomically evaluated for physiological and postural parameters. Mismatches were observed between required energy and sustainable energy output and between tool dimensions and anthropometric measurements of female operators. Based on the ergonomic evaluation the hoe was modified with two blade sizes and three handle widths .The modified wheel hoes were re-evaluated. Working with an existing wheel hoe was categorized as “heavy work” with “higher” overall discomfort. Heart rate, oxygen consumption and energy expenditure were lowest for modified weeder (10%-440mm) and the work classification improved to “moderate category”. The resting period with the modified hoe reduced from 33.4 min to 20.7 min for one hour work cycle. With change in handle dimensions shoulder, elbow and wrist deviation were close to the natural range of motion. The body part discomfort score and overall discomfort score also reduced from 31 and 2.5 respectively to 18 and 1.5 for modified weeder (10%-440mm). Women workers found the modified hoe with 10% blade dimension and handle width 440mm, very comfortable to use. Modifications in the existing wheel hoe according to anthropometric parameters of female workers reduced energy consumption, body deviations and rest pause between work cycles and thus enhanced work output.

Passive wrist deviation to increase the ultrasound identified procedural safe zone in carpal tunnel syndrome: A retrospective cohort study.

Carpal tunnel syndrome (CTS) is the most common peripheral nerve entrapment syndrome. Although prior studies have explored the anatomic changes of the median nerve and carpal arch with different wrist deviations and positionings, the change in safe zone distance between the median nerve and ulnar artery with ulnar or radial wrist deviations has not been adequately investigated. To identify the optimal wrist positioning that increases the safe zone distance between the median nerve and ulnar artery using ultrasound in patients with CTS. Retrospective cohort study. Quaternary medical center multidisciplinary outpatient hand clinic. Twenty five patients (41 wrists) with clinical CTS who received an electrodiagnostic study (EDX) to evaluate CTS within 1 year prior to enrollment. Ultrasound-identified safe zone distance measurements were obtained in each patient between the ulnar aspect of the median nerve and the radial aspect of the ulnar artery with the wrist in neutral radial-ulnar deviation as well as in passive ulnar and radial deviation. The ultrasound-identified safe zone distance with the wrist in each of the three positions. The interstructural safe zone distance was significantly greater when measured in the ulnarly deviated position (1.08 cm) compared with either the neutral (0.61cm, p < .001) or radially deviated positions (0.52 cm, p < .001). Interstructural safe zone distance did not differ between those with normal, mild, moderate, or severe classifications of pathology, or between dominant and nondominant limbs. This study demonstrates that the ultrasound-measured interstructural safe zone distance was significantly greater in the ulnarly deviated position than in either the neutral position or radially deviated position. These findings may lead to improvement in the safety of ultrasound-guided injections.

Motion Analysis of the Extensor Carpi Ulnaris in Triangular Fibrocartilage Complex Injury Using Ultrasonography Images.

The subsheath of the extensor carpi ulnaris (ECU) tendon, a component of the triangular fibrocartilage complex (TFCC), is particularly important as it dynamically stabilizes the distal radioulnar joint. However, the relationship between TFCC injury and ECU dynamics remains unclear. This study aimed to analyze ECU movement and morphology using ultrasonography (US) images. Twenty wrists of patients with TFCC injury, who underwent TFCC repair, were included in the injury group, and 20 wrists of healthy volunteers were in the control group. For static image analysis, curvature and linearity ratios of the ECU in US long-axis images captured during radioulnar deviation were analyzed. For dynamic analysis of the ECU, the wrist was moved from radial deviation to ulnar deviation at a constant speed, and the velocity of the tendon was analyzed using particle image velocimetry. The static analysis showed that the ECU tendon was more curved in ulnar deviation in the injury group than in the control group, and the dynamic analysis showed that only vertical velocity toward the deep side during ulnar deviation was higher in the injury group. These results suggest that TFCC injury caused ECU curvature during ulnar deviation and increased the vertical velocity of the ECU during wrist deviation.

The effect of rigid tape on wrist postures during tree planting

Taping has been suggested to reduce the incidence of tendinopathy in tree planters. However, the ability of taping to reduce wrist postures during planting has not yet been formally evaluated. The primary aim was to test the effect of rigid taping on wrist postures during tree planting tasks. Eleven tree planters planted up to 50 trees in three conditions: no-tape (NT), tape-on-the-dorsum-of-the-hand (T1) and tape-on-the-thumb (T2) in a randomised cross-over, within-participant, repeat-measures design. Electrogoniometers (EG) recorded continuous wrist postures. Digital video recordings were used to segment EG traces of each planting cycle (one planted tree) into 4 kinematically distinct Phases. The tree and shovel wrist were analysed separately. Tree-wrist peak ulnar deviation and frequency of shovel-wrist awkward frontal plane postures were significantly reduced in the T2 condition. Taping may be effective at reducing non-neutral postures and should be researched further to determine its effectiveness in reducing tree planting injuries. Practitioner summary: The effect of rigid taping on wrist postures during tree planting has not yet been formally evaluated. A randomised cross-over, within-participant, repeat measures design was used to evaluate the effect of rigid taping on wrist postures during planting. Thumb rigid taping appeared to reduce wrist range of motion during planting. KEY POINTS Taping of the thumb reduced peak ulnar deviation of the tree wrist and frequency of awkward frontal plane postures of the shovel wrist. While taping of the dorsum of the hand appeared to be more restrictive, it did not significantly reduce wrist movement; this is likely because only its effect on sagittal plane posture was assessed which had a higher variance. Upon application, tape appeared to restrict voluntary movement patterns, decreased voluntary grip force exertion and physically restrain wrist movement. Overall, rigid tape was found to be an acceptable intervention for the tree planting occupation, with financial costs and perceived effort identified as the primary barriers to acceptability.

Evaluation of a New Simplified Inertial Sensor Method against Electrogoniometer for Measuring Wrist Motion in Occupational Studies.

Wrist velocity is an important risk factor for work-related musculoskeletal disorders in the elbow/hand, which is also difficult to assess by observation or self-reports. This study aimed to evaluate a new convenient and low-cost inertial measurement unit (IMU)-based method using gyroscope signals against an electrogoniometer for measuring wrist flexion velocity. Twelve participants performed standard wrist movements and simulated work tasks while equipped with both systems. Two computational algorithms for the IMU-based system, i.e., IMUnorm and IMUflex, were used. For wrist flexion/extension, the mean absolute errors (MAEs) of median wrist flexion velocity compared to the goniometer were <10.1°/s for IMUnorm and <4.1°/s for IMUflex. During wrist deviation and pronation/supination, all methods showed errors, where the IMUnorm method had the largest overestimations. For simulated work tasks, the IMUflex method had small bias and better accuracy than the IMUnorm method compared to the goniometer, with the MAEs of median wrist flexion velocity <5.8°/s. The results suggest that the IMU-based method can be considered as a convenient method to assess wrist motion for occupational studies or ergonomic evaluations for the design of workstations and tools by both researchers and practitioners, and the IMUflex method is preferred. Future studies need to examine algorithms to further improve the accuracy of the IMU-based method in tasks of larger variations, as well as easy calibration procedures.

Correlations between body postures and musculoskeletal pain in guitar players.

BackgroundThe guitar-playing community is the largest group at risk of developing playing related musculoskeletal disorders. A thorough investigation of the relationships between the various risk factors and players’ report on musculoskeletal pain using objective and accurate means of assessment has yet to be reported.Purpose(a) to explore the correlations between demographic characteristics, anthropometric measurements, playing habits, and personal habits of guitar player and their complaints of musculoskeletal pain, (b) explore the correlations between the upper body kinematics of guitar players during playing the guitar and their complaints of musculoskeletal pain, and (c) compare the upper body kinematics of guitar players during playing the guitar while sitting versus standing.MethodsTwenty-five guitar players (27.5±4.6 years old) filled out questionnaires regarding their guitar-playing habits, and the Standardized Nordic Questionnaires for the analysis of musculoskeletal symptoms. Kinematics of their torso and upper limbs were tracked while they played a tune twice, once while sitting and once while standing.ResultsWe found moderate correlations between the number of painful joints in the last year and factors, such as physical comfort while playing, years of playing, and position during playing. During standing, lower back pain severity correlated with the rotation range of the torso, while during sitting, it moderately correlated with the average radial-ulnar deviation of the right wrist. During sitting, we found higher anterior and right tilt of the torso, combined with greater abduction of the right shoulder, higher flexion in the left shoulder and higher radial deviation in the left wrist.ConclusionOur results point to several risk factors, related both to playing habits but also to playing posture, which should be considered by the guitar players in order to prevent playing-related musculoskeletal disorders.

A case of lunatomalacia

Lunatomalacia is a condition characterized by avascular necrosis of the lunate bone. It is also known as osteonecrosis, Kienbock´s disease, and aseptic or ischemic necrosis of the lunate. Although the mechanisms by which this disorder develops are not fully understood, compromise of the bone vasculature is the most commonly proposed cause. Both extraosseous and intraosseous blood vessels supply the lunate bone. Vessels that enter the lunate through the dorsal and volar poles of the bone make up the extraosseous blood supply. Pathomechanics where acute trauma or repetitive minor trauma leads to direct vessel break and ligament disruption causes blood supply interruption and bone necrosis. A 31-year-old male presented to the orthopedics outpatient department with pain and swelling over the right wrist since 1 year. Patient gave alleged history of trauma to wrist while lifting heavy object and Pain was sudden in onset, gradually progressive in nature and dull aching type which got aggravated by lifting weights and got relieved by taking rest and medication. On local examination, tenderness presented over radial styloid, ulna styloid and medial radio-ulnar joint. Wrist range of motion (ROM) range normal and terminally painful. Fovea sign - positive, suggest triangular fibrocartilage complex injury. Pain on ulnar deviation of wrist. The patient was managed with a form of splinting.

The Effects of Distal Pole Scaphoid Resection on Wrist Biomechanics.

Distal pole scaphoid resection (DPSR) is an effective way to manage chronic scaphoid non-union with limited degenerative arthritis. Studies have reported positive results in terms of pain relief, wrist range of motion and grip strength, and patient satisfaction. However, the biomechanical consequences of DPSR remain unclear. This study evaluates the effects of DPSR on carpal mechanics by assessing changes in radiographic parameters with varying quantities of scaphoid removal. Six fresh frozen cadaveric upper extremities were used. Resections of 25%, 50%, and 75% of the length of each scaphoid were performed under fluoroscopic image guidance. For the intact scaphoid and each resection level, the following radiographic parameters were assessed: radiolunate and capitolunate angles; carpal height and first metacarpal subsidence ratios, and ulnar carpal translation. Measurements were then repeated for grip and pinch as well as radial and ulnar wrist deviation positions. Radial styloid to trapezium distance in wrist radial deviation was also measured to assess for impingement. There was a statistically significant increase in the mean radiolunate angle with increasing scaphoid resection quantities. No statistically significant correlations were found between radial styloid clearance and increasing scaphoid resection percentages. Changes in the remaining variables did not reach statistical significance. Increasing levels of scaphoid resection is associated with progressive signs of carpal malalignment best depicted by increasing radiolunate angles. Diminishing radial styloid clearance was clinically evident as more scaphoid was resected. For this, prophylactic radial styloidectomy may be considered to avoid bony impingement.

Reliability and validity of expert assessments of hand-wrist physical exposures.

General population job-exposure matrices (JEMs) based on expert assessments of physical exposures may be valuable tools for studying occupation-related musculoskeletal disorders. Wrist-hand JEMs are few and the reliability and validity of expert assessments of wrist-hand exposures is uncertain. We examined intra- and inter-rater reliability of ratings of five experts of hand-wrist repetition, deviation, force, vibration, and computer work in 33 jobs selected to represent a large exposure variation. The validity of ratings of hand-wrist repetition was examined by comparison with electro-goniometer measurements of wrist angular velocity and mean power frequency (MPF), and the validity of hand-wrist deviation by comparison with goniometer measurements of range of motion (ROM). Intra-rater test-retest and inter-rater Spearman correlation coefficients controlling for rater effects, varied between 0.70 and 0.87. Corresponding kappa statistics of overall agreement showed similar high values, except for wrist deviation (kappa = 0.50). Regression analyses showed strong positive associations between expert assessments of repetition and goniometer measurements of wrist angular velocity (R2 = 0.56, p < 0.0001) and MPF (R2 = 0.37, p < 0.0003), while expert ratings of wrist deviation showed a weak statistically nonsignificant association with goniometer measurements of ROM (R2 = 0.032, p = 0.34). The reliability of expert assessments of wrist-hand physical exposures was high. Compared to goniometer measurements, the validity of assessments of wrist-hand repetition was also high, but it was low for assessments of wrist-hand deviation. The results are encouraging for establishing a hand-wrist JEM, but the results for wrist deviation emphasize that expert assessments should be validated against objective measurements.

Four-dimensional CT analysis of carpal kinematics: An explorative study on the effect of sex and hand-dominance

Wrist pathology is often diagnosed by using the contralateral wrist as a comparison of baseline motion and strength. However, recent range of motion studies suggest that females have different carpal motion patterns compared to males and that the dominant carpal bones have different motion patterns. The purpose of this study is to evaluate the effect of sex and hand dominance on in vivo kinematics of the scaphoid, lunate and capitate using four-dimensional computed tomography (4D-CT) analysis in healthy uninjured volunteers. In this prospective study, both wrist of 20 uninjured Caucasian volunteers (11 men and 9 women) were assessed using 4D-CT during active flexion–extension and radial-ulnar deviation. A linear mixed model was used to compare the carpal motion patterns. Sex had no influence on carpal kinematics. Hand-dominance in males did have a significant effect on carpal kinematics. During flexion–extension of the male wrist, more radial-ulnar deviation of the lunate, scaphoid and capitate of the non-dominant hand was seen. During radial-ulnar deviation of the male wrist, radial-ulnar deviation and pro-supination of the lunate was more in the dominant hand.This study provides a better understanding of carpal kinematics and the effect of sex and hand-dominance on the scaphoid, lunate and capitate in uninjured wrists.

Pronated Grip View With Wrist Deviation: A Pilot Study on the Effect on Ulnocarpal Relationships.

We hypothesize that different positions of the wrist in the coronal plane makes the carpus susceptible to ulnar impaction. We prospectively enrolled 10 adult volunteers and obtained fluoroscopic images of each wrist in 12 different positions using a standardized protocol. Distances from the ulna to the lunate (UL) and ulna to the triquetrum (UT) were digitally measured as was the portion of the lunate surface area that was uncovered (LUR) with wrist deviation. A wrist position of Pronation, Neutral Deviation, and Grip (P-ND-G) significantly shortened the ulnocarpal distance when compared to a position of Neutral Rotation, Neutral Deviation, and No Grip (NR-ND-NG). Radial deviation during pronation and gripping (Pronated, Radial Deviation, Gripping [P-RD-G]) resulted in the lowest mean UL distance (1.2 mm). UT distance was minimized by a position of ulnar deviation during a pronated grip (Pronated, Ulnar Deviation, Gripping [P-UD-G]) (3.1 mm). The lunate becomes more uncovered with radial deviation. Radial deviation minimizes the UL distance while ulnar deviation minimizes the UT distance during a wrist position of pronation and gripping. Further, there is more proximal lunate surface area uncoverage during all positions of radial deviation compared to ulnar deviation.

Effects of axial load on invivo scaphoid and lunate kinematics using four-dimensional computed tomography.

This in vivo study investigated the effect of axial load on lunate and scaphoid kinematics during flexion–extension and radial–ulnar deviation of the uninjured wrist using four-dimensional computed tomography. We found that applying axial load to the wrist results in a more flexed, radially deviated and pronated position of the lunate and scaphoid during flexion–extension of the wrist compared with when no load is applied. A larger pronation and supination range of the lunate and scaphoid was seen when the wrist was flexed and extended under axial load, whereas a larger flexion and extension range of the lunate and scaphoid occurred during radial–ulnar deviation of the wrist when axial load was applied.

Salvage of advanced carpal collapse: proximal row carpectomy with pyrocarbon resurfacing of the capitate versus four-corner arthrodesis.

In this retrospective study we report on two comparable groups of patients with advanced carpal arthritis treated with either proximal row carpectomy combined with a pyrocarbon resurfacing of the capitate (31 patients) or a four-corner arthrodesis and dorsal plating (26 patients). Follow-up time was 46 months (24-118). Except for a modestly higher radial wrist deviation in the patients treated with four-corner arthrodesis, there were no significant differences in outcomes between the groups. Asymptomatic progression of osteoarthritis in the lunate fossa was observed in four cases in both groups. Two cases were converted to a total wrist arthrodesis in the pyrocarbon group compared with one case in the four-corner arthrodesis group. Although four-corner arthrodesis remains the reference standard in the treatment of wrist osteoarthritis with involvement of the midcarpal joint, proximal row carpectomy combined with pyrocarbon resurfacing of the capitate is an alternative option. It can even be used in selected cases with erosion of the lunate fossa.Level of evidence: III.

Characterizing forearm muscle activity in university-aged males during dynamic radial-ulnar deviation of the wrist using a wrist robot

Functioning as wrist stabilizers, the wrist extensor muscles exhibit higher levels of muscle activity than the flexors in most distal upper-limb tasks. However, this finding has been derived mostly from isometric or wrist flexion-extension protocols, with little consideration for wrist dynamics or radial-ulnar wrist deviations. The purpose of this study was to assess forearm muscle activity during the execution of dynamic wrist radial-ulnar deviation in various forearm orientations (pronation/supination). In 12 healthy university-aged males, surface electromyography (EMG) was recorded from eight muscles of the dominant arm: flexor carpi radialis (FCR), flexor carpi ulnaris (FCU), flexor digitorum superficialis (FDS), extensor carpi radialis (ECR), extensor carpi ulnaris (ECU), extensor digitorum (ED), biceps brachii (BB) and triceps brachii (TB). While grasping a handle, participants performed dynamic radial-ulnar deviation using a three-degrees-of-freedom wrist manipulandum. The robotic device applied torque to the handle, in either a radial or ulnar direction, and in one of three forearm postures (30° supinated/neutral/30° pronated). Results indicated that forearm posture influenced the muscles acting upon the hand (FDS/ED), whereas movement phase (concentric-eccentric) and torque direction influenced nearly every muscle. The ECR demonstrated the greatest task-dependency of all forearm muscles, which is possibly reflective of forearm muscle lines of action. Co-contraction ratios were much higher in radial trials than ulnar (Radial: 1.20 ± 0.78, Ulnar: 0.28 ± 0.18, P < 0.05), suggesting greater FCU and ECU contribution to wrist joint stability in radial-ulnar movement. These findings highlight a greater complexity of wrist extensor function than has previously been reported in isometric work.