Upper Limb Function in People With Upper and Lower Limb Loss 8 Years Postinjury: The Armed Services Trauma Outcome Study (ADVANCE) Cohort Study.

OBJECTIVE: Upper limb (UL) disability in people with UL amputation/s is well reported in the literature, less so for people with lower limb amputation/s. This study aimed to compare UL disability in injured (major trauma) and uninjured UK military personnel, with particular focus on people with upper and lower limb amputation/s. METHODS: A volunteer sample of injured (n = 579) and uninjured (n = 566) UK military personnel who served in a combat role in the Afghanistan war were frequency matched on age, sex, service, rank, regiment, role, and deployment period and recruited to the Armed Services Trauma Rehabilitation Outcome (ADVANCE) longitudinal cohort study. Participants completed the Disability of the Arm, Shoulder, and Hand (DASH) questionnaire, scored from 0 (no disability) to 100 (maximum disability) 8 years postinjury. Mann-Whitney U and Kruskal Wallis tests were used to compared DASH scores between groups. An ordinal model was used to assess the effect of injury and amputation on DASH scores. RESULTS: DASH scores were higher in the group with injuries compared to the group without injuries (3.33 vs 0.00) and higher in people with lower limb loss compared to the group without injuries (0.83 vs 0.00), although this was not statistically significant. In the adjusted ordinal model, the odds of having a higher DASH score was 1.70 (95% CI = 1.18-2.47) times higher for people with lower limb loss compared to the group without injuries. DASH score was not significantly different between people with major and partial UL loss (15.42 vs 12.92). The odds of having a higher DASH score was 8.30 (95% CI = 5.07-13.60) times higher for people with UL loss compared to the uninjured group. CONCLUSION: People with lower limb loss have increased odds of having more UL disability than the uninjured population 8 years postinjury. People with major and partial UL loss have similar UL disability. The ADVANCE study will continue to follow this population for the next 20 years. IMPACT: For the first time, potential for greater upper limb disability has been shown in people with lower limb loss long-term, likely resulting from daily biomechanical compensations such as weight-bearing, balance, and power generation. This population may benefit from prophylactic upper limb rehabilitation, strength, and technique.

A comparison of abductor hallucis muscle activation and medial longitudinal arch angle during nine different foot exercises.

BACKGROUND: Intrinsic foot muscles are known to support the medial longitudinal arch (MLA) and stabilize the foot, and they are activated with weight bearing and increased postural demand. Various types of intrinsic foot muscle training have been reported, but one of the most useful of these, the short foot exercise, is challenging to perform effectively and requires practice, making it difficult to implement in ordinary clinical settings. RESEARCH QUESTION: What are the differences in abductor hallucis longus (ABH) muscle activity and MLA angle during intrinsic foot muscle exercises that employ weight bearing and balancing conditions when they are performed with minimal practice? METHODS: Sixteen healthy volunteers performed nine different intrinsic foot muscle exercises, practiced once or twice. The exercises consisted of toe curl, short foot without pushing, short foot with pushing and toe spread exercises in sitting and standing positions, and single leg swing in a standing position. Each exercise was performed three times for five seconds. The activities of the ABH muscles were measured using surface electromyographic (EMG) sensors and the MLA angles during the exercises were captured using an optical motion tracking system. The integrals of the ABH EMG signals were calculated. RESULTS: Differences in the integral and maximum of the ABH EMG signal were found between the exercises (p < 0.001). Post-hoc pair-wise analysis revealed that the EMG activity was larger during the swing exercise than in exercises other than toe spread, both in sitting and standing positions, and short foot exercise with pushing while standing. The minimum MLA angle during each exercise was smaller for the toe spread exercise in a sitting position than other exercises (p < 0.023). SIGNIFICANCE: A single leg swing exercise may be effective for self-exercise of intrinsic foot muscles, particularly when intensive supervised physiotherapy is not possible.

Objective Methods of Monitoring Usage of Orthotic Devices for the Extremities: A Systematic Review.

Orthoses are commonly prescribed to relieve symptoms for musculoskeletal and neurological conditions; however, patients stop wearing orthoses as recommended for many reasons. When considering the effectiveness of orthoses, there needs to be an objective way to monitor whether participants wear the orthosis as instructed, because if this is not followed, the orthoses will not work as intended. This review aimed to identify, summarise, and compare objective methods used to measure compliance with orthoses applied to the extremities. Databases (Scopus, Web of Science, Embase, CINAHL, and MEDLINE) were searched for eligible studies. Twenty-three studies were accepted in the final review, including five studies that employed upper limb orthoses, two that employed hip orthoses, and fifteen that employed lower limb orthoses. To measure compliance objectively, studies utilised temperature sensors, pressure sensors, accelerometers, a step counter, or a combination of sensors. All sensor types have their own advantages and disadvantages and should be chosen based on study-specific parameters. Sensor-derived monitoring provides quantitative, objective data that are beneficial in both clinical and research settings. The ideal solution to monitoring compliance would consist of both objective and user-reported aspects that, in combination, would provide an all-encompassing picture of the orthotic treatment prescribed.

Epidemiological Characteristics of Foot and Ankle Injuries in 2 Professional Ballet Companies: A 3-Season Cohort Study of 588 Medical Attention Injuries and 255 Time-Loss Injuries.

Background: The foot and ankle are often reported as the most common sites of injury in professional ballet dancers; however, epidemiological research focusing on foot and ankle injuries in isolation and investigating specific diagnoses is limited. Purpose: To investigate the incidence rate, severity, burden, and mechanisms of foot and ankle injuries that (1) required visiting a medical team (medical attention foot and ankle injuries; MA-FAIs) and (2) prevented a dancer from fully participating in all dance-related activities for at least 24 hours after the injury (time-loss foot and ankle injuries; TL-FAIs) in 2 professional ballet companies. Study Design: Descriptive epidemiological study. Methods: Foot and ankle injury data across 3 seasons (2016-2017 to 2018-2019) were extracted from the medical databases of 2 professional ballet companies. Injury-incidence rate (per dancer-season), severity, and burden were calculated and reported with reference to the mechanism of injury. Results: A total of 588 MA-FAIs and 255 TL-FAIs were observed across 455 dancer-seasons. The incidence rates of MA-FAIs and TL-FAIs were significantly higher in women (1.20 MA-FAIs and 0.55 TL-FAIs per dancer-season) than in men (0.83 MA-FAIs and 0.35 TL-FAIs per dancer-season) (MA-FAIs, P = .002; TL-FAIs, P = .008). The highest incidence rates for any specific injury pathology were ankle impingement syndrome and synovitis for MA-FAIs (women 0.27 and men 0.25 MA-FAIs per dancer-season) and ankle sprain for TL-FAIs (women 0.15 and men 0.08 TL-FAIs per dancer-season). Pointe work and jumping actions in women and jumping actions in men were the most common mechanisms of injury. The primary mechanism of injury of ankle sprains was jumping activities, but the primary mechanisms of ankle synovitis and impingement in women were related to dancing en pointe. Conclusion: The results of this study highlight the importance of further investigation of injury prevention strategies targeting pointe work and jumping actions in ballet dancers. Further research for injury prevention and rehabilitation strategies targeting posterior ankle impingement syndromes and ankle sprains are warranted.

A Review of the Use of 3D Printing Technology in Treatment of Scaphoid Fractures.

Background: Three-dimensional (3D) printing technology is increasingly commercially viable for pre-surgical planning, intraoperative templating, jig creation and customised implant manufacture. The challenging nature of scaphoid fracture and nonunion surgery make it an obvious target. The aim of this review is to determine the use of 3D printed technologies in the treatment of scaphoid fractures. Methods: This is a review of the Medline, Embase and Cochrane Library databases examining studies aimed at therapeutic use of 3D printing, also known as rapid prototyping or additive technology, in the treatment of scaphoid fractures. All studies published up to and including November 2020 were included in the search. Relevant data extracted included modality of use (as template/model/guide/prosthesis), operative time, accuracy of reduction, radiation exposure, follow-up duration, time to union, complications and study quality. Results: A total of 649 articles were identified, of which 12 met the full inclusion criteria. Analysis of the articles showed that 3D printing techniques can be utilised in myriad ways to aid planning and delivery of scaphoid surgery. Percutaneous guides for Kirschner-wire (K-wire) fixation of non-displaced fractures can be created; custom guides can be printed to aid reduction of displaced or non-united fractures; patient-specific total prostheses may recreate near-normal carpal biomechanics and a simple model may help graft harvesting and positioning. Conclusions: This review found that the use of 3D printed patient-specific models and templates in scaphoid surgery can improve accuracy and speed, and reduce radiation exposure. 3D printed prostheses may also restore near-normal carpal biomechanics without burning bridges for potential future procedures. Level of Evidence: Level III (Therapeutic).

Biomechanical Comparison of 5 Different Fixation Constructs in a Trapeziometacarpal Joint Arthrodesis Model.

PURPOSE: Trapeziometacarpal joint (TMC) arthrodesis has a high rate of nonunion. This biomechanical analysis sought to determine the stiffness of 5 fixation methods in a TMC joint arthrodesis model. METHODS: Five fixation constructs were tested in a validated porcine model: crossed 1.1-mm K-wires, crossed 1.6-mm K-wires, crossed headless compression screws (HCSs), compression plating (CP), and locked compression plating (LCP). The cantilever bending stiffness was measured in abduction, adduction, flexion, and extension. Samples were loaded to failure in extension, and the mode of failure was examined. RESULTS: The crossed HCSs performed consistently well in all tests. Loading to failure resulted in screw pullout. In abduction and adduction, HCS and 1.6-mm K-wires were significantly stiffer than the other constructs. The mean load to failure in extension was similar in the HCS, CP, and LCP groups (304 N/mm, 311 N/mm, and 293 N/mm, respectively). There were no differences between CP and LCP in any biomechanical tests, and the mode of failure was through plate bending. The crossed 1.1-mm K-wires performed poorly in all tests. CONCLUSIONS: Crossed HCS displayed the greatest overall stability. Standard plating in compression mode and LCP had a similar biomechanical performance. CLINICAL RELEVANCE: The ideal construct stiffness required for the successful union after TMC joint arthrodesis is unknown, but HCS has the best overall biomechanical performance and, therefore, might be considered the best choice for this clinical setting.

Validation of two-dimensional video-based inference of finger kinematics with pose estimation.

Accurate capture finger of movements for biomechanical assessments has typically been achieved within laboratory environments through the use of physical markers attached to a participant's hands. However, such requirements can narrow the broader adoption of movement tracking for kinematic assessment outside these laboratory settings, such as in the home. Thus, there is the need for markerless hand motion capture techniques that are easy to use and accurate enough to evaluate the complex movements of the human hand. Several recent studies have validated lower-limb kinematics obtained with a marker-free technique, OpenPose. This investigation examines the accuracy of OpenPose, when applied to images from single RGB cameras, against a 'gold standard' marker-based optical motion capture system that is commonly used for hand kinematics estimation. Participants completed four single-handed activities with right and left hands, including hand abduction and adduction, radial walking, metacarpophalangeal (MCP) joint flexion, and thumb opposition. The accuracy of finger kinematics was assessed using the root mean square error. Mean total active flexion was compared using the Bland-Altman approach, and the coefficient of determination of linear regression. Results showed good agreement for abduction and adduction and thumb opposition activities. Lower agreement between the two methods was observed for radial walking (mean difference between the methods of 5.03°) and MCP flexion (mean difference of 6.82°) activities, due to occlusion. This investigation demonstrated that OpenPose, applied to videos captured with monocular cameras, can be used for markerless motion capture for finger tracking with an error below 11° and on the order of that which is accepted clinically.

HAILO: A Sensorised Hand Splint for the Exploration of Interface Forces.

This study presents the design and development of an instrumented splint for measuring the biomechanical effects of hand splinting and for assessing interface loading characteristics for people with arthritis. Sixteen multi-axial soft load-sensing nodes were mounted on the splint-skin interface of a custom 3D printed thumb splint. The splint was used to measure the interface forces between splint and hand in 12 healthy participants in 6 everyday tasks. Forces were compared between a baseline relaxed hand position and during states of active use. These data were used to generate a measure of sensor activity across the splint surface. Through direct comparison with a commercial splint, the 3D printed splint was deemed to provide similar levels of support. Observation of the activity across the 16 sensors showed that 'active' areas of the splint surface varied between tasks but were commonly focused at the base of the thumb. Our findings show promise in the ability to detect the changing forces imparted on the hand by the splint surface, objectively characterising their behaviour. This opens the opportunity for future study into the biomechanical effects of splints on arthritic thumbs to improve this important intervention and improve quality of life.

Do "Anatomic" Distal Ulna Plating Systems Fit the Distal Ulna Without Causing Soft Tissue Impingement?

Background: Distal ulna fracture fixation plates commonly cause irritation, necessitating removal, due to the narrow area between the ulna articular cartilage and the extensor carpi ulnaris. This study defines the safe zone for plate application and determines whether wrist position affects risk of impingement. Methods: Four different distal ulna anatomic plates (Acumed, Medartis, Skeletal Dynamics, and Synthes) were applied to 12 cadaveric specimens. Safe zone size was measured in circumferential distance and angular arc. Impingement was examined in flexion and extension in neutral, pronation, and supination. Results: The distal ulna safe zone has dimensions of a 92° arc and perimeter circumference of 15 mm. Cumulative extensor carpi ulnaris (ECU) impingement occurred in 0% of the 6 simulated wrist/forearm positions for the Acumed plate, 22% for the Synthes plate, 31% for the Skeletal Dynamics plate, and 68% for the Medartis plate. Impingement was most common in supination. Likelihood of ECU impingement significantly decreased in the following order; Medartis > Skeletal Dynamics > Synthes > Acumed. Conclusion: The ECU tendon's mobility can cause impingement on ulnarly placed distal ulna plates. Intra-operative testing should be performed in supination. Take home points regarding each plate from the 4 different manufacturers: contouring of Medartis plates, when placed ulnarly, is mandatory. The Acumed plate impinged the least but is not designed for far-distal fractures. The Synthes plate is least bulky but not suitable for proximal fractures. The Skeletal Dynamics plate appeared the most versatile with a reduced incidence of impingement compared to other ulnarly based plates.

An In Vitro Hand Simulator for Simultaneous Control of Hand and Wrist Movements.

A human hand is a complex biomechanical system, in which bones, ligaments, and musculotendon units dynamically interact to produce seemingly simple motions. A new physiological hand simulator has been developed, in which electromechanical actuators apply load to the tendons of extrinsic hand and wrist muscles to recreate movements in cadaveric specimens in a biofidelic way. This novel simulator simultaneously and independently controls the movements of the wrist (flexion/extension and radio-ulnar deviation) and flexion/extension of the fingers and thumb. Control of these four degrees of freedom (DOF) is made possible by actuating eleven extrinsic muscles of the hand. The coupled dynamics of the wrist, fingers, and thumb, and the over-actuated nature of the human musculoskeletal system make feedback control of hand movements challenging. Two control algorithms were developed and tested. The optimal controller relies on an optimization algorithm to calculate the required tendon tensions using the collective error in all DOFs, and the action-based controller loads the tendons solely based on their actions on the controlled DOFs (e.g., activating all flexors if a flexing moment is required). Both controllers resulted in hand movements with small errors from the reference trajectories ( ); however, the optimal controller achieved this with 16% lower total force. Owing to its simpler structure, the action-based controller was extended to enable feedback control of grip force. This simulator has been shown to be a highly repeatable tool (  N and variations in force and kinematics, respectively) for in vitro analyses of human hand biomechanics.

A study to compare strengths of cadaveric tendon repairs with round-bodied and cutting needles.

This human cadaver study investigated whether flexor tendon repairs performed with round-bodied needles had a higher risk of pull-out compared with those performed with cutting needles. Forty human cadaver tendons were repaired (20 with each type of needle), subjected to tensile traction testing and evaluated by failure load and mode of failure. The average failure load was 50 N (SD 13 N) for tendons repaired with round-bodied needles, compared with 49 N (SD 16 N) for tendons repaired with cutting needles. Round-bodied needles resulted in more suture pull-out (18 out of 20 tendons) than cutting needles (6 out of 20 tendons). We found no differences in failure load, but significant differences in the mode of failure between round-bodied and cutting needles when used for cadaveric flexor tendon repair.

Ligamentous constraint of the first carpometacarpal joint.

To examine the role of the ligaments in maintaining stability of the first carpometacarpal (CMC) joint, a sequential ligament sectioning study of sixteen specimens was performed. While a small compressive force was maintained, loads were applied to displace each specimen in four directions - volar, dorsal, radial, and ulnar. Translations of the specimen in both dorsal-volar and radial-ulnar axes were measured. Initially, the tests were conducted with the specimen intact. These tests were then repeated following sectioning of the CMC anterior oblique ligament (AOL), ulnar collateral ligament (UCL), intermetacarpal ligament (IML) and dorsal radial ligament (DRL). The first CMC joint translation was increased in the absence of IML and DRL (p < 0.05). Both IML and DRL were important in constraining the first CMC joint translation against external applied loads. Potential applications of these findings include the treatment of joint hypermobility and the reduction or delay of onset or progression of first CMC joint osteoarthritis.

The Influence of Cervical Spine Angulation on Symptoms Associated With Wearing a Rigid Neck Collar.

INTRODUCTION: Rigid cervical spine collars can be used to maintain the position of the cervical spine following injury or surgery. However, they have been associated with difficulty swallowing, pressure sores and pain, particularly in older patients. We aimed to investigate the relationship between cervical spine angulation, a rigid neck collar and neck pain in healthy young and older adults. METHODS: Twenty healthy young adults aged 25 ± 3 years and 17 healthy older adults aged 80 ± 8 years were tested. Magnetic resonance imaging scans of their cervical spines were taken before and after the rigid neck collar was worn for 1 hour. Measurement of vertebral angulation involved digitization of the scans and joint angle calculations using image processing software. Pain was quantified before and after the collar was worn, using a visual analogue scale. RESULTS: Pain scores increased in the young group after the collar was worn (p = 0.001). The older group showed no difference in pain score after the collar was worn. Statistical tests showed no significant correlations between the change in cervical angles and the change in pain scores after the collar was worn. DISCUSSION: The aging process may contribute to the changing distribution of subcutaneous tissue and increase risk of symptoms associated with wearing a collar. Oesophageal compression is not a result of collar use. CONCLUSION: There is no correlation between cervical spine vertebrae angulation and symptoms associated with wearing a neck collar. Generally, older individuals have greater cervical lordosis angles, and more straight and lordotic neck shapes. Older individuals may be more prone to skin-interface pressures from the neck collar than younger individuals.

Maximum dorsiflexion increases Achilles tendon force during exercise for midportion Achilles tendinopathy.

Rehabilitation is an important treatment for non-insertional Achilles tendinopathy. To date, eccentric loading exercises (ECC) have been the predominant choice; however, mechanical evidence underlying their use remains unclear. Other protocols, such as heavy slow resistance loading (HSR), have shown comparable outcomes, but with less training time. This study aims to identify the effect of external loading and other variables that influence Achilles tendon (AT) force in ECC and HSR. Ground reaction force and kinematic data during ECC and HSR were collected from 18 healthy participants for four loading conditions. The moment arms of the AT were estimated from MRIs of each participant. AT force then was calculated using the ankle torque obtained from inverse dynamics. In the eccentric phase, the AT force was not larger than in the concentric phase in both ECC and HSR. Under the same external load, the force through the AT was larger in ECC with the knee bent than in HSR with the knee straight due to increased dorsiflexion angle of the ankle. Multivariate regression analysis showed that external load and maximum dorsiflexion angle were significant predictors of peak AT force in both standing and seated positions. Therefore, to increase the effectiveness of loading the AT, exercises should apply adequate external load and reach maximum dorsiflexion during the movement. Peak dorsiflexion angle affected the AT force in a standing position at twice the rate of a seated position, suggesting standing could prove more effective for the same external loading and peak dorsiflexion angle.

Development of a clinically adoptable joint coordinate system for the wrist.

Kinematics play a vital role in answering both clinical and research questions regarding joint biomechanics. Standardisation of kinematic approaches is important; however, the method that is currently recommended for building the joint coordinate system (JCS) to measure kinematics of the wrist is difficult to implement in vivo. In this study, a series of JCSs were examined and compared to the International Society of Biomechanics (ISB) recommendations in terms of landmark digitisation repeatability, coordinate frame creation repeatability, and secondary rotations during planar motion. No differences were found between the ISB JCS and 338 of 408 of the JCSs proposed in the study, meaning that the proposed alternative can be used without affecting the measured joint angles or repeatability of the JCS. Forearm frames that used a vector between the epicondyles to define the YZ plane of the forearm were found to create JCSs that produced secondary rotations greater than that which would be clinically detectable and thus, they should be avoided when defining a JCS. The remaining 338 coordinate systems can be used interchangeably; consequently, should there be any clinical limitations that result in missing landmarks, alternative coordinate systems can be used. A joint coordinate system created using the radial styloid, ulnar styloid, medial epicondyle, lateral epicondyle, the heads of the second and fifth metacarpal, and the base of the third metacarpal is recommended for quantifying kinematics in vivo.

The effect of planar constraint on the definition of the wrist axes of rotation.

Instantaneous helical axes (IHAs) and screw displacement axes (SDAs) are commonly used to investigate joint functional axes of rotation. In the wrist, these have often been obtained through in vitro motion analysis. These definitions are then employed for in vivo applications, such as the design of implants or the development of musculoskeletal models. However, functional unguided joint motions are, by definition, affected by the activity of muscles. Previously published data has disagreed on the relative position and orientation of the two primary axes of rotation of the wrist, i.e. the radioulnar deviation (RUD) axis with respect to the flexion-extension (FE) axis. An in vivo study comparing the FE and RUD IHAs and SDAs of guided motions, to replicate in vitro conditions, and unguided motions of 23 healthy participants was conducted using optical motion capture. Guided motions were performed with the hand and forearm flush against a flat surface. The relative position and orientation of the RUD SDAs with respect to the FE SDAs differed (p = 0.019, p = 0.001) between unguided FE and guided RUD (0.1 ± 4.3 mm, 93.5 ± 16.0°) and guided FE and RUD (1.6 ± 4.0 mm, 107.8 ± 17.7°). This indicates that the use of different constraints, and not physiological differences, is the primary cause of differences in the relative positions and orientations of the FE and RUD axes in the literature. Thus, the practice of using in vitro definitions of the axes of rotation of the wrist for in vivo applications, especially involving FE, may be inappropriate and care must be taken to account for any constraint on wrist motion. It is recommended that investigators define the axes of rotation specifically for their study or refer to literature featuring the desired levels of constraint.

Identifying tasks to elicit maximum voluntary contraction in the muscles of the forearm.

Maximum voluntary contractions (MVCs) are often used for the normalisation of electromyography data to enable comparison of signal patterns within and between study participants. Recommendations regarding the types of tasks that are needed to collect MVCs for the muscles of the forearm have been made, specifically advocating the use of resisted moment tasks to get better estimates of forearm MVCs. However, a protocol detailing which specific tasks to employ has yet to be published. Furthermore, the effects of limb dominance on the collection of MVCs have not been considered previously. Muscle activity was monitored while 23 participants performed nine isometric, resisted tasks. The tasks that are likely to elicit MVC in the flexor carpi ulnaris, flexor carpi radialis, flexor digitorum superficialis, extensor carpi ulnaris, extensor carpi radialis, extensor digitorum communis, and pronator teres were identified. Thus, targeted protocols can be designed to mitigate against fatigue. Hand dominance had limited effect, with differences being found only in the finger flexors and extensors (p< 0.03). Thus, use of the contralateral flexor digitorum superficialis and extensor digitorum communis muscles to obtain baselines for activation levels and patterns may not be appropriate.

Reconstruction of the lower limb bones from digitised anatomical landmarks using statistical shape modelling.

BACKGROUND: Bone shapes strongly influence force and moment predictions of kinematic and musculoskeletal models used in motion analysis. The precise determination of joint reference frames is essential for accurate predictions. Since clinical motion analysis typically does not include medical imaging, from which bone shapes may be obtained, scaling methods using reference subjects to create subject-specific bone geometries are widely used. RESEARCH QUESTION: This study investigated if lower limb bone shape predictions from skin-based measurements, utilising an underlying statistical shape model (SSM) that corrects for soft tissue artefacts in digitisation, can be used to improve conventional linear scaling methods of bone geometries. METHODS: SSMs created from 35 healthy adult femurs and tibiae/fibulae were used to reconstruct bone shapes by minimising the distance between anatomical landmarks on the models and those digitised in the motion laboratory or on medical images. Soft tissue artefacts were quantified from magnetic resonance images and then used to predict distances between landmarks digitised on the skin surface and bone. Reconstruction results were compared to linearly scaled models by measuring root mean squared distances to segmented surfaces, calculating differences of commonly used anatomical measures and the errors in the prediction of the hip joint centre. RESULTS: SSM reconstructed surface predictions from varying landmark sets from skin and bone landmarks were more accurate compared to linear scaling methods (2.60-2.95 mm vs. 3.66-3.87 mm median error; p < 0.05). No significant differences were found between SSM reconstructions from bony landmarks and SSM reconstructions from digitised landmarks obtained in the motion lab and therefore reconstructions using skin landmarks are as accurate as reconstructions from landmarks obtained from medical images. SIGNIFICANCE: These results indicate that SSM reconstructions can be used to increase the accuracy in obtaining bone shapes from surface digitised experimental data acquired in motion lab environments.

Design and Evaluation of Magnetic Hall Effect Tactile Sensors for Use in Sensorized Splints.

Splinting techniques are widely used in medicine to inhibit the movement of arthritic joints. Studies into the effectiveness of splinting as a method of pain reduction have generally yielded positive results, however, no significant difference has been found in clinical outcomes between splinting types. Tactile sensing has shown great promise for the integration into splinting devices and may offer further information into applied forces to find the most effective methods of splinting. Hall effect-based tactile sensors are of particular interest in this application owing to their low-cost, small size, and high robustness. One complexity of the sensors is the relationship between the elastomer geometry and the measurement range. This paper investigates the design parameters of Hall effect tactile sensors for use in hand splinting. Finite element simulations are used to locate the areas in which sensitivity is high in order to optimise the deflection range of the sensor. Further simulations then investigate the mechanical response and force ranges of the elastomer layer under loading which are validated with experimental data. A 4 mm radius, 3 mm-thick sensor is identified as meeting defined sensing requirements for range and sensitivity. A prototype sensor is produced which exhibits a pressure range of 45 kPa normal and 6 kPa shear. A proof of principle prototype demonstrates how this can be integrated to form an instrumented splint with multi-axis sensing capability and has the potential to inform clinical practice for improved splinting.