Wrist Research Articles

Charcot’s Arthropathy of the Wrist: A Case Report

Introduction: Charcot arthropathy is a myriad of osseous degenerative changes that can affect theoretically any joint of the body. The pathophysiology of this condition is based on microtrauma, leading to the deterioration of articular nerves. The most common cause in the upper extremity is syringomyelia. Case Report: A 64-year-old male patient presented with painless right wrist swelling and deformity. His radiographs showed degenerative changes in radiocarpal and intercarpal joints. Magnetic resonance imaging of the brain and cervical spine demonstrated Type II Chiari malformation and syringomyelia, and neurological evaluation revealed myelopathy. Conclusion: Charcot arthropathy of the wrist, an exceedingly rare condition, is a diagnosis of exclusion. The common causes of arthritis of the wrist such as Rheumatoid arthritis and tuberculosis must be ruled out. When a patient presents with wrist Charcot arthropathy thorough neurological examination must be done. Diabetes mellitus, tabes dorsalis, and leprosy are the other frequently cited causes that must be looked for. Keywords: Charcot arthropathy, wrist, syringomyelia.

Loss of Axin1 in limb mesenchymal cells leads to multiple synostoses syndrome-like phenotype in mice

<p>Multiple synostoses syndrome (SYNS) is a disease characterized by the fusion of multiple joints. Unfortunately, the underlying and critical signaling pathways of this disorder remain poorly understood. Given the pivotal role of Wnt/��-catenin signaling in skeletal development and the key regulatory effect of Axin1 and Axin2 in the ��-catenin pathway, limb mesenchymal stem cell (MSC) specific <i>Axin1</i> conditional KO (cKO) mice and <i>Axin1</i>/<i>Axin2</i> double KO (dKO) mice were generated to explore their involvement in joint formation. Abnormalities, such as developmental defects in joints and fusions in multiple joint tissues were observed in both <i>Axin1</i> cKO and <i>Axin1</i>/<i>Axin2</i> dKO mice, which resemble to the characteristics of human SYNS disease including synostoses of carpal and tarsal bones, as well as ankylosis of elbow joint and knee joint. Administration of ��-catenin or BMP inhibitor significantly reversed the joint fusion phenotype in <i>Axin1</i> cKO mice. Our findings suggest that Axin1 plays a key role in joint formation by inhibiting ��-catenin-BMP signaling and could potentially serve as a therapeutic target for SYNS.</p>

Hierarchical Optimization for Personalized Hand and Wrist Musculoskeletal Modeling and Motion Estimation.

Surface electromyography (sEMG) driven musculoskeletal models are promising to be applied in the field of human-computer interaction. However, due to the individual-specific physiological characteristics, generic models often fail to provide accurate motion estimation. This study optimized the general model to build a personalized model and improve the accuracy of motion estimation. Inspired by the coupling effect of wrist/hand movement, a hierarchical optimization approach for personalizing musculoskeletal models (HOPE-MM) is proposed, which aligns with the physiological characteristics of the human wrist and hand. To verify the effectiveness of personalized musculoskeletal model, single joint motions and simultaneous joint motions are estimated. In addition, Sobol sensitivity analysis is conducted to identify the key parameters of musculoskeletal model, providing guidance for model simplification. The mean pearson correlation coefficient between the predicted joint angles and the measured joint angles are 0.95 ± 0.03 and 0.93 ± 0.01 for simultaneous wrist and metacarpophalangeal (MCP) joint movements, respectively, which have a significant improvement compared with the stateof- the-art works. By optimizing only the key parameters including tendon slack length, maximal isometric force and optimal fiber length, the performances of simplified model are comparable to the full-parameter model. These results provide insights into the effects of muscletendon parameters on musculoskeletal model, and musculoskeletal models personalized using hierarchical optimization methods can improve the accuracy of motion estimates. These findings facilitate the clinical application of musculoskeletal models in rehabilitation and robotic control.

Novel Digital Biomarkers for Fine Motor Skills Assessment in Psoriatic Arthritis: The DaktylAct Touch-based Serious Game Approach.

Psoriatic Arthritis (PsA) is a chronic, inflammatory disease affecting joints, substantially impacting patients' quality of life, with European guidelines for managing PsA emphasizing the importance of assessing hand function. Here, we present a set of novel digital biomarkers (dBMs) derived from a touchscreen-based serious game approach, DaktylAct, intended as a proxy, gamified, objective assessment of hand impairment, with emphasis on fine motor skills, caused by PsA. This is achieved by its design, where the user controls a cannon to aim at and hit targets using two finger pinch-in/out and wrist rotation gestures. In-game metrics (targets hit and score) and statistical features (mean, standard deviation) of gameplay actions (duration of gestures, applied pressure, and wrist rotation angle) produced during gameplay serve as informative dBMs. DaktylAct was tested on a cohort comprising 16 clinically verified PsA patients and nine healthy controls (HC). Correlation analysis demonstrated a positive correlation between average pinch-in duration and disease activity (DA) and a negative correlation between standard deviation of applied pressure during wrist rotation and joint inflammation. Logistic regression models achieved 83% and 91% classification performance discriminating HC from PsA patients with low DA (LDA) and PsA patients with and without joint inflammation, respectively. Results presented here are promising and create a proof-of-concept, paving the way for further validation in larger cohorts.

An Assessment of Distraction Plating in the Management of Intra-Articular Comminuted Distal End Radius Fractures in the Elderly

Abstract Background: Distal radius fractures are one of the most common injuries, representing one-sixth of all fractures seen and treated in the emergency department. Distal radial fractures with extensive comminution involving the metaphyseal–diaphyseal junction present a major treatment dilemma, especially when it has an intra-articular involvement. This study evaluates the surgical and functional outcomes of intra-articular comminuted fracture of distal end radius treated with dorsal distraction plating. Materials and Methods: A prospective randomized controlled observational study was done with a sample size of 50 patients over a period of 3 years, each of whom was diagnosed to have an intra-articular fracture of distal end radius (AO classification type C). All patients were treated by distraction plating (radio-metacarpal). Minimum follow-up after treatment of upto 6 months was ensured, and a final assessment of the functional outcome was then decided. Results: The study showed that average union time was 8.65 ± 0.93 weeks, and average implant removal was done at 8.75 ± 0.85 weeks. All patients achieved full ROM at the wrist, maintaining articular congruity post-implant removal. In our study, we found two (6.67%) patients with superficial infections and two (6.67%) patients with complex regional pain syndrome. No patients were reported with the tendon (extensor pollicis longus) irritation, neuropraxia, stiffness of the wrist and inter-phalangeal joints, nonunion/malunion, or implant failure. Conclusion: The final results were evaluated and compared after making observations for age, sex, mode of trauma, dominancy of the affected hand, time interval between injury and admission, duration of hospital stay, duration of surgery, time to fracture union, and complications. The final outcome was measured by DASH SCORE. All patients had excellent or good results treated with distraction plating; six (20.00%) patients out of 30 studies were found to have excellent results, whereas the remaining 24 (80.00%) patients had good results.

Association of upper extremity anthropometry and subcutaneus adipose tissue with carpal tunnel syndrome

<p>Body mass index (BMI) is positively correlated with the frequency of carpal tunnel syndrome (CTS). However, there are different types of obesity, and the localization of adipose tissue differs between the genders. In this study, we purposed to investigate whether there was an association between the amount of local adipose tissue thickness and anthropometry in upper extremity with the presence and/or electrophysiological severity of CTS on both genders.</p>. <p>Our study included 150 patients who were diagnosed with CTS clinically and electrophysiologically and 165 healthy controls. The biceps and triceps skinfold thickness, the diameters of the wrist and metacarpal joints, and the upper arm circumferences over the belly of the biceps muscle were measured by using skinfold caliper and measuring cylinder. All data were analyzed by using the Statistics Open For All package (SofaStats) programme. To detect the role of anthropometric indexes, we used multivariable multinomial logistic regression models.&nbsp;</p>. <p>We revealed that BMI, biceps and triceps adipose tissue thicknesses were higher in females and also in patients with CTS. There was a positive correlation between electrophysiological grades of CTS and BMI with logistic regression analyzes. The mean Wrist circumference/Metacarpo&shy;ph&shy;arengeal Circumference ratio and biceps circumference were higher in moderate CTS groups. Metacarpofarengeal circumference was smaller in mild and moderate CTS cases compared to healthy ones.</p>. <p>We suggest that the differen&shy;ces between the anatomical bone structure and local adiposity between the genders may play an important role in the occurrence of CTS. Moreover, the structures of proximal muscle groups and distal metacarpal joints may contribute both to the development and severity of CTS.</p>.

Abnormal Wrist Sagittal Kinematics in Gymnasts With Dorsal Wrist Pain: A New Syndrome

Background: The pathology of dorsal wrist pain in gymnasts without abnormal radiographic findings remains unclear. Purpose/Hypothesis: The purpose of this study was to identify abnormal wrist sagittal kinematics in gymnasts with dorsal wrist pain. It was hypothesized that gymnasts with dorsal wrist pain would show abnormal sagittal kinematics with reversible hypermobility of the intercarpal joint. Study Design: Controlled laboratory study. Methods: Participants included 19 wrists in male gymnasts with dorsal wrist pain, 18 wrist in male gymnasts without wrist pain, and 20 adult men without a history of wrist pain. Magnetic resonance imaging (T2-weighted sagittal images) findings at 0°, 30°, 60°, and 90° of wrist extension were used in kinematic analysis. The angles and translations of the radiolunate, capitolunate, and third carpometacarpal joint were measured and compared between the 3 groups. Results: At 90° of wrist extension, gymnasts with dorsal wrist pain had a significantly lower radiolunate joint angle (28.70°± 6.28° vs 36.19°± 7.81°; P = .020) and a significantly higher capitolunate joint angle (57.99°± 6.15° vs 50.50°± 6.98°; P = .004) and distal translation (1.17 ± 0.50 mm vs 0.46 ± 0.62 mm; P = .002) than gymnasts without dorsal wrist pain. Conclusion: Gymnasts with dorsal wrist pain showed abnormal wrist sagittal kinematics. These novel findings may facilitate understanding of dorsal wrist pain, which can be recognized as a new syndrome termed “gymnast’s lunate dyskinesia.”

Validation of an established TW3 artificial intelligence bone age assessment system: a prospective, multicenter, confirmatory study.

In 2020, our center established a Tanner-Whitehouse 3 (TW3) artificial intelligence (AI) system using a convolutional neural network (CNN), which was built upon 9059 radiographs. However, the system, upon which our study is based, lacked a gold standard for comparison and had not undergone thorough evaluation in different working environments. To further verify the applicability of the AI system in clinical bone age assessment (BAA) and to enhance the accuracy and homogeneity of BAA, a prospective multi-center validation was conducted. This study utilized 744 left-hand radiographs of patients, ranging from 1 to 20 years of age, with 378 boys and 366 girls. These radiographs were obtained from nine different children's hospitals between August and December 2020. The BAAs were performed using the TW3 AI system and were also reviewed by experienced reviewers. Bone age accuracy within 1 year, root mean square error (RMSE), and mean absolute error (MAE) were statistically calculated to evaluate the accuracy. Kappa test and Bland-Altman (B-A) plot were conducted to measure the diagnostic consistency. The system exhibited a high level of performance, producing results that closely aligned with those of the reviewers. It achieved a RMSE of 0.52 years and an accuracy of 94.55% for the radius, ulna, and short bones series. When assessing the carpal series of bones, the system achieved a RMSE of 0.85 years and an accuracy of 80.38%. Overall, the system displayed satisfactory accuracy and RMSE, particularly in patients over 7 years old. The system excelled in evaluating the carpal bone age of patients aged 1-6. Both the Kappa test and B-A plot demonstrated substantial consistency between the system and the reviewers, although the model encountered challenges in consistently distinguishing specific bones, such as the capitate. Furthermore, the system's performance proved acceptable across different genders and age groups, as well as radiography instruments. In this multi-center validation, the system showcased its potential to enhance the efficiency and consistency of healthy delivery, ultimately resulting in improved patient outcomes and reduced healthcare costs.

Diagnosis and Management of Acute Scaphoid Fractures: A Narrative Review of Current Literature

Abstract Introduction: The scaphoid is the most common carpal bone to fracture in adults as well as children. The symptoms of acute scaphoid fractures, however, could be subtle and might be disregarded by patients initially. Conventional radiographs have limited reliability in ruling out these fractures, with 15%–25% of nondisplaced fractures remaining undetected. The resultant delay in diagnosis, along with the inherent tenuous vascularity and high mobility of the scaphoid, results in the high probability of complications such as nonunion, malunion, avascular necrosis, pseudoarthrosis, or scaphoid nonunion advanced collapse. The purpose of this review was to systematically present contemporary evidence on the diagnosis and management of acute scaphoid fractures. Methods: A literature search was conducted by the authors using the PubMed database and the following search terms: “[scaphoid (title/abstract)] AND [{fracture (title/abstract)} OR {fractures (title/abstract)}] AND [{management (title/abstract)} OR {treatment (title/abstract)} OR {diagnosis (title/abstract)} OR {evaluation (title/abstract)} OR {fixation (title/abstract)}].” Filters were applied to include human studies published between 2014 and 2023 in the English language. Results: Relevant research was identified and perused. Evidence was extracted from original research and systematic reviews. Conclusion: Data were charted manually, and the aggregated body of information was categorized, summarized, and presented systematically.

Pancarpal Arthrodesis Using Antibiotic–Impregnated Calcium Sulfate Beads in a Dog with Septic Arthritis and Osteomyelitis

AbstractA 6-year-old Lurcher dog was referred for evaluation and treatment of a septic carpal arthritis, associated osteomyelitis of the radius and radial carpal bone and antebrachiocarpal luxation following a previous articular surgery 14 weeks prior to presentation. A staged approached was elected and following removal of the original implants, a pancarpal arthrodesis was performed using autologous bone graft and gentamicin-impregnated bioabsorbable calcium sulfate beads. At 12 weeks postoperatively, lameness had resolved on the operated limb and complete joint fusion was confirmed on radiographic evaluation. The purpose of this case report is to describe the successful short- and long-term outcome of a pancarpal arthrodesis using antibiotic medication–impregnated calcium sulfate beads, providing details about the surgical technique used for management of a destructive septic arthritis and osteomyelitis.

Radiofrequency Ablation of Palmar Digital Branches of Ulnar Nerve in a Patient with Ulnar Neuropathy

Ulnar Tunnel Syndrome (UTS) is ulnar neuropathy at the wrist or hand typically caused by ganglion cysts, lipomas, wrist or hand compression, carpal bone fractures, carpal tunnel syndrome, or anything else that can impinge on the nerve. The symptoms of UTS can be uncomfortable and debilitating, with numbness and tingling of the 4th and 5th digits being the most common. Weakness of the ulnar portion of the hand can lead to decreased grip strength. UTS is typically managed with conservative treatment including anti-inflammatory oral medications, splinting, physical therapy, activity modification, acupuncture, and stretching. Second line treatment includes corticosteroid injections, although these have shown to have little efficacy. Surgery is also an option but may lead to iatrogenic ramifications. Radiofrequency ablation (RFA) is a treatment modality used for chronic pain, which utilizes heat to target nociceptive fibers. Traditionally, RFA is used in treating cervical and lumbar radiculopathy, but it is less studied in peripheral nerve areas. This case report examines a patient who had clinically significant pain relief after RFA to the palmar digital branches of the ulnar nerve. The patient was 63-year-old male who presented with left ulnar neuropathy that had been ongoing for 3 years. Despite conservative management, his symptoms of pain, paresthesia, and weakness persisted. The patient then elected to have a left cubital tunnel release at the elbow with anterior subcutaneous transposition. The surgery provided relief for three months but then led to worsening contractures and pain in the 4th and 5th digits of the left hand. Due to persistent symptoms after conservative management and surgical intervention, he was referred to interventional pain clinic. A decision was made to trial a digital nerve block of the left medial and lateral digital palmar nerves. Following the nerve block, the patient reported 100% improvement in pain and increased range of motion and function. Four weeks later, the patient returned for a radiofrequency ablation of the same nerves. In the week following the procedure, the patient reported that the pain in the little finger was entirely resolved. While radiofrequency ablation has become increasingly popular for the treatment of chronic back pain, its use in peripheral nerve pain has been limited to case reports and few randomized control trials. This case report highlights the successful use of radiofrequency ablation in the treatment of little finger pain and ulnar neuropathy by targeting the median and lateral branches of the palmar digital nerve.

Adaptação óssea ao exercício em cavalos árabes praticantes de enduro equestre de 120-160 km - análise quantitativa e funcional

ABSTRACT Seeking the improvement of equine sports medicine, the present work aimed to determine quantitative data from different bone structures. Therefore, the objective of this work was to quantify the thickness of the cortex in a comparative way to determine the bone densitometry and also the bone density of the bone trabeculae of the spongy substance of the radius, calcaneus, and metacarpal III bones of horses practicing equestrian enduro long-distance running tests. Six thoroughbred Arabian horses and long-distance competitors (120 and 160km) were evaluated for metacarpal III, calcaneus, and accessory carpal bone. Long bones have a different micro functional structure than short bones. The sites that received and dissipated energy varied in distal, proximal epiphysis, and diaphysis according to the bone. The calcaneus and accessory carpal bone had a lower transverse thickness of the compact substance and greater density of the same, this increase was related to the improvement of local resistance. The density of the spongy substance varied with different bones. Thus, it was concluded that stress directly influenced the quantity and quality of the compact and spongy substance.

Dexterity Assessment for Wrist Joints of Surgical Robots: A Statics-Based Evaluation Method

Dexterity Assessment for Wrist Joints of Surgical Robots: A Statics-Based Evaluation Method

Kinematic Sequence Differences Between Trained Baseball Players and Untrained Adolescent Individuals.

An overhead throwing motion is a common gross motor skill often taught in early childhood to improve physical activity participation. Yet, research investigating motor efficiency in overhead throws often focuses on improving performance in trained individuals. This project compares kinematic sequencing between trained and untrained youth. After a brief warm-up, untrained high school students (N = 9) and trained high school and college students (N = 10) threw a weighted tennis ball for accuracy (N = 10 throws). Upper extremity angular velocities were collected using 3-dimensional inertial sensor motion capture. Kinematic sequencing of joints and segments (pelvis, trunk, shoulder, elbow, and wrist) was assessed using Kruskal-Wallis test; Friedman and Wilcoxon tests identified group differences between sequences. Seven independent kinematic sequences were identified (N = 2 unique trained; N = 3 unique untrained; N = 2 shared). The rankings for the trained group maintained a mostly consistent pattern with only elbow and wrist joints producing similar rankings. The untrained group lacked that consistency with similar rankings of elbow versus wrist and shoulder versus elbow. Trained individuals threw with a more efficient proximal-to-distal sequencing pattern than the untrained participants, specifically at the trunk and shoulder. Continuous training of gross motor skills beyond initial skill development is necessary to maintain motor proficiency.

Incidence of pregnancy-related carpal tunnel syndrome with advancement of parity

Background: Pregnant women are at a risk of developing carpal tunnel syndrome (CTS). It is the most common mononeuropathy of the median nerve which is at risk of compression due to its location. The median nerve is present in the carpal tunnel at the wrist joint level. The median nerve gets compressed which leads to its hampered conduction, affecting the conduction velocity and latency of the nerve adversely as recorded by the electrodiagnostic technique. The chances of compression of the nerve are increased with the number of pregnancies a female goes through in the reproductive span of her life. Aims and Objectives: The aim of the study was to analyze any positive association between parity status and incidence of pregnancy-related CTS (PRCTS) in pregnant women. Materials and Methods: In this cross-sectional study, 75 pregnant females, recruited from the obstetrics ANC clinic JNMCH, AMU were screened for PRCTS through the electrodiagnostic technique in the neurophysiology laboratory, Department of Physiology, JNMCH, AMU. Out of these 75 pregnant females, 36 (48%) were found to be positive for PRCTS. Results: Among the 36 PRCTS-positive pregnant females, 26 were found to be multiparous, whereas 10 were primiparous. Conclusion: The study found a very strong association (statistically significant) of multiparous pregnant females with PRCTS.

EMG-based Simultaneous Estimations of Joint Angle and Torque during Hand Interactions with Environments.

It is necessary to control contact force through modulation of joint stiffness in addition to the position of our limb when manipulating an object. This is achieved by contracting the agonist muscles in an appropriate magnitude, as well as, balancing it with contraction of the antagonist muscles. Here we develop a decoding technique that estimates both the position and torque of a joint of the limb in interaction with an environment based on activities of the agonist-antagonistic muscle pairs using electromyography in real time. The long short-term memory (LSTM) network that is capable of learning time series of a longtime span with varying time lags is employed as the core processor of the proposed technique. We tested both the unidirectional LSTM network and bidirectional LSTM network. A validation was conducted on the wrist joint moving along a given trajectory under resistance generated by a robot. The decoding approach provided an agreement of greater than 93% in kinetics (i.e. torque) estimation and an agreement of greater than 83% in kinematics (i.e. angle) estimation, between the actual and estimated variables, during interactions with an environment. We found no significant differences in performance between the unidirectional LSTM and bidirectional LSTM as the learning device of the proposed decoding method.

Карпальды туннель синдромы мен стенозды лигаментиттің дамуы арасындағы байланыс: Әдеби шолу

Carpal tunnel syndrome and trigger finger disorder are both hand pathologies and the most common reasons for visiting a hand surgeon. Carpal tunnel syndrome is a compression of the median nerve by the flexor retinaculum ligament at the level of the wrist joint. Trigger finger disorder is a condition caused by compression of the digital flexor tendon by the A-1 annular ligament. During the development of hand surgery and new clinical studies, it was noticed that trigger finger often occurs after an operative treatment of carpal tunnel syndrome, less often - vice versa. There were also cases of simultaneous development of both pathologies. The authors of this review tried to find out the reason for this relationship between two different hand disorders by examining the currently available information, containing the results of genetic, histological, biochemical, and clinical studies on this topic. A search was made in the Web of Science, PubMed, Cochrane Library, and Google Scholar databases. The authors concluded that there is an unambiguous relationship between carpal tunnel syndrome and trigger finger disorder, manifested in similar risk factors, changes in the mechanism of movement of the flexor tendons after carpal tunnel release, similar biochemical and histological changes in the tissues of the hand in both pathologies, as well as the presence of the same genetic markers in such patients.

Continuous Prediction of Wrist Joint Kinematics Using Surface Electromyography from the Perspective of Muscle Anatomy and Muscle Synergy Feature Extraction.

Post-stroke upper limb dysfunction severely impacts patients' daily life quality. Utilizing sEMG signals to predict patients' motion intentions enables more effective rehabilitation by precisely adjusting the assistance level of rehabilitation robots. Employing the muscle synergy (MS) features can establish more accurate and robust mappings between sEMG and motion intentions. However, traditional matrix factorization algorithms based on blind source separation still exhibit certain limitations in extracting MS features. This paper proposes four deep learning models to extract MS features from four distinct perspectives: spatiotemporal convolutional kernels, compression and reconstruction of sEMG, graph topological structure, and the anatomy of target muscles. Among these models, the one based on 3DCNN predicts motion intentions from the muscle anatomy perspective for the first time. It reconstructs 1D sEMG samples collected at each time point into 2D sEMG frames based on the anatomical distribution of target muscles and sEMG electrode placement. These 2D frames are then stacked as video segments and input into 3DCNN for MS feature extraction. Experimental results on both our wrist motion dataset and public Ninapro DB2 dataset demonstrate that the proposed 3DCNN model outperforms other models in terms of prediction accuracy, robustness, training efficiency, and MS feature extraction for continuous prediction of wrist flexion/extension angles. Specifically, the average nRMSE and R2 values of 3DCNN on these two datasets are (0.14/0.93) and (0.04/0.95), respectively. Furthermore, compared to existing studies, the 3DCNN outperforms musculoskeletal models based on direct collocation optimization, physics-informed GANs, and CNN-LSTM-based deep Kalman filter models when evaluated on our dataset.

Design and Gesture Recognition of Wrist Joint Posture Sensor Based on Fiber Bragg Gratings

Design and Gesture Recognition of Wrist Joint Posture Sensor Based on Fiber Bragg Gratings

The efficacy of different torque profiles for weight compensation of the hand.

Orthotic wrist supports will be beneficial for people with muscular weakness to keep their hand in a neutral rest position and prevent potential wrist contractures. Compensating the weight of the hands is complex since the level of support depends on both wrist and forearm orientations. To explore simplified approaches, two different weight compensation strategies (constant and linear) were compared to the theoretical ideal sinusoidal profile and no compensation in eight healthy subjects using a mechanical wrist support system. All three compensation strategies showed a significant reduction of 47-53% surface electromyography activity in the anti-gravity m. extensor carpi radialis. However, for the higher palmar flexion region, a significant increase of 44-61% in the m. flexor carpi radialis was found for all compensation strategies. No significant differences were observed between the various compensation strategies. Two conclusions can be drawn: (1) a simplified torque profile (e.g., constant or linear) for weight compensation can be considered as equally effective as the theoretically ideal sinusoidal profile and (2) even the theoretically ideal profile provides no perfect support as other factors than weight, such as passive joint impedance, most likely influence the required compensation torque for the wrist joint.