Sex-Related Differences in Shoulder Complex Joint Dynamics Variability During Pediatric Manual Wheelchair Propulsion.

More than 80% of adult manual wheelchair users with spinal cord injuries will experience shoulder pain. Females and those with decreased shoulder dynamics variability are more likely to experience pain in adulthood. Sex-related differences in shoulder dynamics variability during pediatric manual wheelchair propulsion may influence the lifetime risk of pain. We evaluated the influence of sex on 3-dimensional shoulder complex joint dynamics variability in 25 (12 females and 13 males) pediatric manual wheelchair users with spinal cord injury. Within-subject variability was quantified using the coefficient of variation. Permutation tests evaluated sex-related differences in variability using an adjusted critical alpha of P = .001. No sex-related differences in sternoclavicular or acromioclavicular joint kinematics or glenohumeral joint dynamics variability were observed (all P ≥ .042). Variability in motion, forces, and moments are considered important components of healthy joint function, as reduced variability may increase the likelihood of repetitive strain injury and pain. While further work is needed to generalize our results to other manual wheelchair user populations across the life span, our findings suggest that sex does not influence joint dynamics variability in pediatric manual wheelchair users with spinal cord injury.

The Effect of Age and Fall History on Lower Extremity Neuromuscular Function During Descent of a Single Transition Step.

Despite the higher injury rate of falls on steps versus level ground, few studies have examined the influence of age and fall history on step descent. The purpose of this study was to determine the lead and trail limb neuromuscular function (peak joint moments and powers, electromyographic activity) differences between young females (n = 15) and older females with (n = 15) and without (n = 15) a fall history while descending a single step. Trail limb moments and powers did not differ between groups. Lead limb sagittal plane powers at the hip and knee were greater in the young adults. Electromyographic co-activation levels (knee and ankle) were not significantly different between groups. However, peroneal activation was greater in the older groups, which may have assisted in stabilizing the ankle joint in lieu of increased co-activation at the ankle. These results demonstrate consideration of step descent is important in working with older women at risk of falls.

Pain Characteristics and Symptom Management in Children with Hypermobile Ehlers-Danlos Syndrome and Hypermobility Spectrum Disorder.

AIMS: This study aims to investigate pediatric hypermobile Ehlers-Danlos syndrome (hEDS) and hypermobility spectrum disorder (HSD) pain features and management strategies. METHODS: This is a mixed-methods, cross-sectional study design using patient-reported outcomes in 21 children diagnosed with hEDS/HSD. Children who reported bothersome pain were interviewed for pain features. The Child Activity Limitation Interview-21, the Brief Pain Inventory pain interference items, and the Functional Disability Inventory were used to investigate pain interference. To evaluate psychological symptoms regarding pain, the pediatric version of the Survey of Pain Attitude and the child version of the Pain Catastrophizing Scale were used. RESULTS: Nineteen children had bothersome pain and of them, eight children reported constant pain. The most frequently reported regions of pain were at the ankle (mild pain) and the back (moderate-to-severe pain). Children reported mild-to-moderate pain interference and believed medications were beneficial for their pain management. Nineteen children sought treatment and of those 16 children used to exercise and acetaminophen and 13 visited physicians as a means of treatment. Parents were overall satisfied with their child's treatment (13 out of 19). CONCLUSIONS: Sufficient awareness of pain-related symptoms and understanding of the treatment strategies in early childhood is needed to prevent deleterious consequences in adulthood.

Reliability of 3D Depth Motion Sensors for Capturing Upper Body Motions and Assessing the Quality of Wheelchair Transfers.

Wheelchair users must use proper technique when performing sitting-pivot-transfers (SPTs) to prevent upper extremity pain and discomfort. Current methods to analyze the quality of SPTs include the TransKinect, a combination of machine learning (ML) models, and the Transfer Assessment Instrument (TAI), to automatically score the quality of a transfer using Microsoft Kinect V2. With the discontinuation of the V2, there is a necessity to determine the compatibility of other commercial sensors. The Intel RealSense D435 and the Microsoft Kinect Azure were compared against the V2 for inter- and intra-sensor reliability. A secondary analysis with the Azure was also performed to analyze its performance with the existing ML models used to predict transfer quality. The intra- and inter-sensor reliability was higher for the Azure and V2 (n = 7; ICC = 0.63 to 0.92) than the RealSense and V2 (n = 30; ICC = 0.13 to 0.7) for four key features. Additionally, the V2 and the Azure both showed high agreement with each other on the ML outcomes but not against a ground truth. Therefore, the ML models may need to be retrained ideally with the Azure, as it was found to be a more reliable and robust sensor for tracking wheelchair transfers in comparison to the V2.

Considering Propulsion Pattern in Therapeutic Outcomes for Children Who Use Manual Wheelchairs.

PURPOSE: Children who use manual wheelchairs encounter pain and injury risks to the upper body. Current literature does not describe how propulsion pattern and physiotherapeutic training methodologies impact response to treatment. METHODS: This study assesses the effect of community-based intensive physical and occupational therapy on functional outcomes over a 7-week period in pediatric manual wheelchair users. RESULTS: Key results include significant joint and musculotendon kinematic differences at the shoulder, improved speed and propulsion effectiveness, and changed propulsion pattern. CONCLUSIONS: Statistics also revealed that propulsion pattern was a predictor of response to therapy, as was weekly therapeutic duration, wheelchair-specific focus by the therapists, and stretching.

Motor unit number index examination in dominant and non-dominant hand muscles.

This study investigated the effect of handedness on motor unit number index (MUNIX). Maximal hand strength, compound muscle action potential (CMAP) and voluntary surface electromyography (EMG) signals were measured bilaterally for the first dorsal interosseous (FDI) and thenar muscles in 24 right-handed and 2 left-handed healthy subjects. Mean (±standard error) grip and pinch forces in the dominant hand were 43.99 ± 2.36 kg and 9.36 ± 0.52 kg respectively, significantly larger than those in the non-dominant hand (grip: 41.37 ± 2.29 kg, p < .001; pinch: 8.79 ± 0.46 kg, p < .01). Examination of myoelectric parameters did not show a significant difference among the CMAP area, the MUNIX or motor unit size index (MUSIX) between the two sides in the FDI and thenar muscles. In addition, there was a lack of correlation between the strength and myoelectric parameters in regression analysis. However, strong correlations were observed between dominant and non-dominant hand muscles in both strength and myoelectric measures. Our results indicate that the population of motor units or spinal motor neurons as estimated from MUNIX may not be associated with handedness. Such findings help understand and interpret the MUNIX during its application for clinical or laboratory investigations.

Quantitative Musculoskeletal Imaging of the Pediatric Shoulder.

ABSTRACT: Pediatric acquired and congenital conditions leading to shoulder pain and dysfunction are common. Objective, quantitative musculoskeletal imaging-based measures of shoulder health in children lag recent developments in adults. We review promising applications of quantitative imaging that tend to be available for common pediatric shoulder pathologies, especially brachial plexus birth palsy and recurrent shoulder instability, and imaging-related considerations of musculoskeletal growth and development of the shoulder. We highlight the status of quantitative imaging practices for the pediatric shoulder and highlight gaps where better care may be provided with advances in imaging technique and/or technology.

The association of pain with gait spatiotemporal parameters in children with hypermobile Ehlers-Danlos syndrome and hypermobility spectrum disorder.

BACKGROUND: Children with hypermobility spectrum disorder/hypermobile Ehlers-Danlos syndrome (HSD/hEDS) have a high prevalence of chronic pain, which may influence gait dynamics. However, little is known about pain outcomes and their association with gait spatiotemporal parameters in children with HSD/hEDS. RESEARCH QUESTION: Does pain correlate with gait spatiotemporal parameters in children with HSD/hEDS? METHODS: Eighteen children with HSD/hEDS and eighteen typically developing (TD) children participated in the study. The current level of pain (0-10 on the numeric rating scale), modified Brief Pain Inventory, and Pain Catastrophizing Scale-Child version were implemented to assess pain in children with HSD/hEDS. All children completed a gait analysis at a self-selected speed. Mean and variability (measured using the coefficient of variation) of gait spatiotemporal parameters were analyzed. Gait parameters included stride length, stride time, gait speed, percent stance time, and step width. A Mann-Whitney U-test was used to compare the gait parameters between children with HSD/hEDS and TD children. Spearman correlations were used to examine the relationships between pain and gait spatiotemporal parameters in children with HSD/hEDS. RESULTS: Children with HSD/hEDS had a longer percent stance time compared to TD children (p = 0.03). Lower pain interference in relationships with other people was significantly associated with faster gait speeds (ρ = -0.55, p = 0.03). Children with HSD/hEDS also had greater pain interference during mobility (ρ = 0.5, p = 0.05) and going to school (ρ = 0.65, p = 0.01), which were significantly correlated with greater stride length variability. Greater pain interference during enjoyment of life was significantly associated with greater percent stance time variability (ρ = 0.5, p = 0.05). Greater pain catastrophizing was correlated with decreased step width variability in children with HSD/hEDS (ρ = -0.49, p = 0.05). SIGNIFICANCE: Pain interference and catastrophe were significantly associated with gait spatiotemporal variability. Our findings suggest that assessing pain-associated gait alterations may help understand the clinical features and gait kinematics of children with HSD/hEDS.

Lower extremity inter-joint coupling angles and variability during gait in pediatric hypermobility spectrum disorder.

Complex musculoskeletal complications in children with hypermobility spectrum disorder (HSD) include pain, proprioception deficits, and joint instability, which may result in movement dysfunction during walking. However, no studies have explored the inter-joint coordination deficits in children with HSD. The purpose of this study was to determine the lower extremity inter-joint coupling angles, patterns, and variability during walking in children with HSD compared to children without HSD (non-HSD). Ankle, knee, and hip kinematics during the stance phase of walking in 18 children with HSD and 18 children without HSD were measured using three-dimensional motion analysis. Coupling angles, patterns, and variability of hip-knee, hip-ankle, and knee-ankle were quantified in the sagittal, frontal, and transverse planes using vector coding techniques. Statistical modeling of coupling angles on sine and cosine scales and bootstrapped standard errors were used to compare coupling angles between HSD and non-HSD groups. Permutational multivariate analysis of variance and statistical non-parametric mapping two-sample t-tests were used to compare the coupling patterns and variability between HSD and non-HSD groups, respectively. Our results indicated that coupling angles, patterns, and variability were not significantly different between the groups. These findings suggest that lower extremity inter-joint coordination and its variability during walking might not be a promising area for further research or intervention in children with HSD. Further research could use other biomechanical methods to investigate coordination deficits in pediatric patients with HSD, and how aging and disease progression are associated with coordination deficits in individuals with HSD.

TransKinect: a computer vision and machine learning clinical decision support system for automatic independent wheelchair transfer technique assessment.

BACKGROUND: Physical and occupational therapists provide routine care for manual wheelchair users and are responsible for training and assessing the quality of transfers. These transfers can produce large loads on the upper extremity joints if improper sitting-pivot-technique is used. Methods to assess quality of transfers include the Transfer Assessment Instrument, a clinically validated tool derived from quantitative biomechanical features; however, adoption of this tool is low due to the complex usage requirements and speed of typical transfers. OBJECTIVE: The objective of this study is to develop and validate a computer vison and machine learning solution to better implement the Transfer Assessment Instrument in clinical settings. METHODS: The prototype system, TransKinect, consists of an infrared depth sensor and a custom software application; usability testing was carried out with fifteen therapists who performed two transfer assessments with the TransKinect. Proficiency in using features, usability, acceptability and satisfaction were analysed with validated surveys and themes were extracted from the qualitative feedback. RESULTS: The therapists were able to successfully complete the transfer quality assessments with 86.7 ± 5.4% proficiency. Total scores for System Usability Scale (77.6 ± 14.7%) and Questionnaire for User Interface Satisfaction (83.5 ± 8.7%) indicated that the system was usable and satisfactory. Qualitative feedback indicated that TransKinect was user-friendly, easy to learn, and had high potential. DISCUSSION: The results support TransKinect as a potential clinical decision support system for therapists for the comprehensive assessment of independent transfer technique. Future research is needed to investigate the utility and acceptance of TransKinect in real clinical environments. Implications for RehabilitationMachine learning and computer vision can be used to analyze transfer techniqueTransKinect is a usable and user-friendly means for therapists to automate analysisSummary reports and videos of transfers show high potential for clinical useAdoption of TransKinect can increase quality of care for manual wheelchair users.

The influence of women's age and fall history on foot and lower limb kinematics during transition step descent.

Falls are a major public health concern, with older women being at the greatest risk to experience a fall. Step descent increases the likelihood of a fall injury, yet the influence of age and fall history on lower extremity kinematics have not been extensively studied. The purpose of this study was to examine lower extremity and foot kinematics of women with and without a fall history during single step descent. Hip, knee, and foot kinematics of young women (n = 15, age = 22.6 ± 3.2 years), older women with no recent falls (n = 15, age = 71.6 ± 4.4 years), and older women with a fall history (n = 15, age = 71.5 ± 5.0 years) as they descended a 17 cm step were examined. Differences in initial contact angles and ROM during landing were examined with between group MANOVA tests. Distal foot initial contact angles were not significant between groups. For range of motion, both older groups went through greater hip extension (p = 0.003, partial η2 = 0.25), but less hip adduction (p = 0.002, partial η2 = 0.27) and less lateral midfoot dorsiflexion (p = 0.001, partial η2 = 0.28) than the younger women. The older fall group had reduced knee flexion (p = 0.004, partial η2 = 0.23) than the younger group, and the older non-fallers slightly plantarflexed at the medial midfoot (p = 0.005, partial η2 = 0.23) while the young women dorsiflexed. Thelanding phase ROMdifferences exhibited by the older adult groupsmayincrease the likelihood of a misstep, which may result in a fall.

Handrim kinetics and quantitative ultrasound parameters for assessment of subacromial impingement in wheelchair users with pediatric-onset spinal cord injury.

BACKGROUND: Most manual wheelchair users with pediatric-onset spinal cord injury (SCI) will experience shoulder pain or pathology at some point in their life. However, guidelines for preservation of the upper limb in children with SCI are limited. RESEARCH QUESTION: What are the relationships between manual wheelchair handrim kinetics and quantitative ultrasound parameters related to subacromial impingement in individuals with pediatric-onset SCI? METHODS: Subacromial impingement risk factors including supraspinatus tendon thickness (SST), acromiohumeral distance (AHD), and occupation ratio (OR; SST/AHD) were measured with ultrasound in 11 manual wheelchair users with pediatric-onset SCI. Handrim kinetics were acquired during the stroke cycle, including peak resultant force (FR), peak rate of rise of resultant force (ROR) and fractional effective force (FEF). Variability of handrim kinetics was computed using the coefficient of variation and linear regression was performed to assess correlations between handrim metrics and quantitative ultrasound parameters. RESULTS: Peak resultant force significantly increased 1.4 % and variability of FEF significantly decreased 8.0 % for every 0.1 cm increase in AHD. FEF decreased 3.5 % for every 0.1 cm increase in SST. Variability of peak resultant force significantly increased 3.6 % and variability of peak ROR of resultant force significantly increased 7.3 % for every 0.1 cm increase in SST. FEF variability significantly decreased 11.6 % for every 0.1 cm increase in SST. Peak ROR significantly decreased 1.54 % with every 10 % increase in OR. FEF variability significantly decreased 1.5 % with every 10 % increase in OR. SIGNIFICANCE: This is the first study to investigate relationships among handrim kinetics and shoulder structure in manual wheelchair users with pediatric-onset SCI. Associations were identified between subacromial impingement risk factors and magnitude and variability of wheelchair handrim kinetics. These results indicate the critical need to further explore the relationships among wheelchair handrim kinetics, shoulder joint dynamics, and shoulder pathology in manual wheelchair users with pediatric-onset SCI.

Three-Dimensional Biomechanics of the Trunk and Upper Extremity During Overhead Throwing in Wheelchair Lacrosse Athletes With Spinal Cord Injury.

OBJECTIVE: Quantify differences in overhead throwing kinematics between wheelchair lacrosse athletes with spinal cord injury and able-bodied lacrosse athletes. DESIGN: This is a cross-sectional, prospective study. Motion analysis captured overhead throwing motions of five wheelchair lacrosse athletes with spinal cord injury and six able-bodied lacrosse athletes seated in a wheelchair and standing. Three-dimensional thorax and dominant arm sternoclavicular, acromioclavicular, glenohumeral, elbow, and wrist joint angles, ranges of motion, as well as angular velocities were computed using an inverse kinematics model. Nonparametric tests assessed group differences ( P < 0.05). RESULTS: Participants with spinal cord injury exhibited less peak thorax axial rotation, ranges of motion, and angular velocity, as well as greater wrist flexion than able-bodied participants seated. Participants with spinal cord injury exhibited less peak thorax axial rotation and lateral bending, ranges of motion, and three-dimensional angular velocities; less peak two-dimensional sternoclavicular joint motion, ranges of motion, and peak angular velocities; less peak acromioclavicular joint protraction angular velocity; less glenohumeral joint adduction-abduction and internal-external rotation motion, ranges of motion, and angular velocities; and greater wrist flexion than able-bodied participants standing. CONCLUSIONS: Kinematic differences were observed between groups, with athletes with spinal cord injury exhibiting less thorax and upper extremity joint motion and slower joint angular velocities than able-bodied athletes. This knowledge may provide insights for movement patterns and potential injury risk in wheelchair lacrosse.

BIOMECHANICAL EVALUATION OF PNEUMATIC SLEEVE ORTHOSIS FOR LOFSTRAND CRUTCHES.

Crutch walking, especially when using a swing-through gait pattern, is associated with high, repetitive joint forces, hyperextension/ulnar deviation of the wrist, and excessive palmar pressure that compresses the median nerve. To reduce these adverse effects, we designed a pneumatic sleeve orthosis that utilized a soft pneumatic actuator and secured to the crutch cuff for long-term Lofstrand crutch users. Eleven able-bodied young adult participants performed both swing-through and reciprocal crutch gait patterns with and without the custom orthosis for comparison. Wrist kinematics, crutch forces, and palmar pressures were analyzed. Significantly different wrist kinematics, crutch kinetics, and palmar pressure distribution were observed in swing-through gait trials with orthosis use (p<0.001, p=0.01, p=0.03, respectively). Reductions in peak and mean wrist extension (7%, 6%), wrist range of motion (23%), and peak and mean ulnar deviation (26%, 32%) indicate improved wrist posture. Significantly increased peak and mean crutch cuff forces suggest increased load sharing between the forearm and cuff. Reduced peak and mean palmar pressures (8%, 11%) and shifted peak palmar pressure location toward the adductor pollicis denote a redirection of pressure away from the median nerve. In reciprocal gait trials, non-significant but similar trends were observed in wrist kinematics and palmar pressure distribution, whereas a significant effect of load sharing was noticed (p=0.01). These results suggest that Lofstrand crutches modified with orthosis may improve wrist posture, reduce wrist and palmar load, redirect palmar pressure away from the median nerve, and thus may reduce or prevent the onset of wrist injuries.

Glenohumeral joint dynamics and shoulder muscle activity during geared manual wheelchair propulsion on carpeted floor in individuals with spinal cord injury.

This study investigated the effects of using geared wheels on glenohumeral joint dynamics and shoulder muscle activity during manual wheelchair propulsion. Seven veterans with spinal cord injury propelled their wheelchairs equipped with geared wheels over a carpeted floor in low gear (1.5:1) and standard gear (1:1) conditions. Hand-rim kinetics, glenohumeral joint dynamics, and muscle activity were measured using a custom instrumented geared wheel, motion analysis, and surface electromyography. Findings indicated that the propulsion speed and stroke distance decreased significantly during the low gear condition. The peak hand-rim resultant force and propulsive moment, as well as the peak glenohumeral inferior force and flexion moment, were significantly less during the low gear condition. The peak and integrated muscle activity of the anterior deltoid and pectoralis major decreased significantly, while the normalized integrated muscle activity (muscle activity per stroke distance) was not significantly different between the two conditions. Propulsion on carpeted floor in the low gear condition was accompanied by a reduced perception of effort. The notable decrease in the peak shoulder loading and muscle activity suggests that usage of geared wheels may be beneficial for wheelchair users to enhance independent mobility in their homes and communities while decreasing their shoulder demands.

The Influence of Age at Pediatric-Onset Spinal Cord Injury and Years of Wheelchair Use on Shoulder Complex Joint Dynamics During Manual Wheelchair Propulsion.

Objective: To assess the association of age at pediatric-onset spinal cord injury (SCI) and years of manual wheelchair use with shoulder dynamics. Design: Upper extremity kinematics and hand-rim kinetics were obtained during manual wheelchair propulsion. An inverse dynamics model computed three-dimensional acromioclavicular, sternoclavicular, and glenohumeral joint dynamics. Linear mixed effects models evaluated the association of age at injury onset and years of wheelchair use with shoulder dynamics. Setting: Motion laboratory within a children's hospital. Participants: Seventeen manual wheelchair users (N=17; 6 female, 11 male; mean age: 17.2 years, mean age at SCI onset: 11.5 years) with pediatric-onset SCI (levels: C4-T11) and International Standards for Neurological Classification of SCI grades: A (11), B (3), C (2), and N/A (2). Interventions: Not applicable. Main Outcome Measures: Acromioclavicular, sternoclavicular, and glenohumeral angles and ranges of motion, and glenohumeral forces and moments. Results: We observed a decrease in maximum acromioclavicular upward rotation (ß [95% confidence interval {CI}]=3.02 [0.15,5.89], P=.039) and an increase in acromioclavicular downward/upward rotation range of motion (ß [95% CI]=0.44 [0.08,0.80], P=.016) with increasing age at SCI onset. We found interactions between age at onset and years of use for maximum glenohumeral abduction (ß [95% CI]=0.16 [0.03,0.29], P=.017), acromioclavicular downward/upward rotation range of motion (ß [95% CI]=-0.05 [-0.09,-0.01], P=.008), minimum acromioclavicular upward rotation (ß [95% CI]=-0.34 [-0.64,-0.04], P=.026). A decrease in glenohumeral internal rotation moment (ß [95% CI]=-0.09 [-0.17,-0.009], P=.029) with increasing years of use was found. Conclusions: Age at injury and the years of wheelchair use are associated with shoulder complex biomechanics during wheelchair propulsion. These results are noteworthy, as both age at SCI onset and years of wheelchair use are considered important factors in the incidence of shoulder pain. These results suggest that investigations of biomechanical changes over the lifespan are critical.

Shoulder complex kinematics pre- and post- rotator cuff repair.

This study investigated shoulder complex joint kinematics and functional outcomes before and after full-thickness supraspinatus rotator cuff repair. Nine adults (mean age 63.4 ±â€¯6.2 years) participated in three test sessions: 0-12 weeks pre-operatively, 9-12 weeks, and 22-30 weeks post-operatively. Upper extremity kinematics of the surgical arm's glenohumeral, acromioclavicular, sternoclavicular and thoracohumeral joints over the duration of a hair combing task were quantified with motion analysis using inverse kinematics. The UCLA Shoulder Rating and Simple Shoulder Test shoulder health outcomes were administered at each session to determine patients' perceived function of their surgical shoulder. Results indicated multiple significant increases over time among the three joints comprising the shoulder complex in the coronal and transverse planes, despite no increases in thoracohumeral motion, and suggest that thoracohumeral motion alone does not provide a comprehensive assessment. Interestingly, more significant increases were observed at the 6-month evaluation than the 3-month evaluation, which is not aligned with the standard rehabilitation endpoint. Thus, our findings suggest that clinicians should evaluate all joints of the shoulder complex during longer-term rehabilitation assessment. Ultimately, knowledge of patients' pre-operative and post-operative shoulder complex kinematics may help to improve rehabilitation to promote improved patient outcomes.

Hand-rim biomechanics during geared manual wheelchair propulsion over different ground conditions in individuals with spinal cord injury.

Geared manual wheelchair wheels, a recently developed alternative propulsion mechanism, have the potential to alleviate the high upper extremity demands required for wheelchair propulsion and help decrease the risk of secondary injuries in manual wheelchair users. The objective of this study was to investigate the effects of using geared manual wheelchairs on hand-rim biomechanics of wheelchair propulsion in individuals with spinal cord injury (SCI). Seven manual wheelchair users with SCI propelled their wheelchairs equipped with geared wheels over tile, carpet, and up a ramp in low gear (gear ratio 1.5:1) and standard gear (gear ratio 1:1) conditions. Hand-rim kinetics and stroke cycle characteristics were measured using a custom instrumented geared wheel. Using the geared wheels in the low gear condition, propulsion speed (P = 0.013), peak resultant force (P = 0.005), peak propulsive moment (P < 0.006), and peak rate of rise of the resultant force (P = 0.035) decreased significantly in comparison with the standard gear condition. The significant increase in the number of stroke cycles when normalized to distance (P = 0.004) and decrease in the normalized integrated moment (P = 0.030) indicated that although a higher number of stroke cycles are required for travelling a given distance in the low gear than the standard gear condition, the low gear condition might be less demanding for the upper extremity. These results suggest that geared wheels could be a useful technology for manual wheelchair users to independently accomplish strenuous propulsion tasks including mobility on carpeted floors and ramp ascension, while reducing the risk factors contributing to the incidence of secondary upper extremity injuries.

Biomechanical analysis of wheelchair athletes with paraplegia during cross-training exercises.

CONTEXT: Extreme conditioning programs (ECPs), such as CrossFit®, are a relatively new method of fitness with rapid growth in individuals with paraplegia. However, it is unknown if wheelchair users are at an additional risk of musculoskeletal injury during these exercises. Biomechanical characterization is necessary to determine the safety and efficacy of ECPs as an exercise modality for wheelchair users with paraplegia. OBJECTIVE: To characterize the three-dimensional (3-D) thorax and upper extremity joint kinematics of paraplegic wheelchair athletes during exercises commonly prescribed as part of ECPs. DESIGN: Observational study. PARTICIPANTS: Three male wheelchair athletes, average age of 37.1 ± 4.6 years, with spinal cord injury levels of T8, L2, and T10, with varying exercise experience. METHODS: 3-D movement was acquired using motion capture during the performance of four exercises: battle ropes, sled pull, overhead press, and sledgehammer swing. A custom upper extremity inverse kinematics model was applied to compute 3-D joint angles. OUTCOME MEASURES: 3-D peak thorax, glenohumeral, elbow, and wrist joint angles and ranges of motion (ROM), Visual Analog Scale (VAS), and Borg Scale of Perceived Exertion. RESULTS: Large joint motions were required for the exercises, at times demanding extreme shoulder and/or wrist flexion and extension, abduction, and external rotation, which are concerning for injury risk in wheelchair users. Participants, however, were able to perform the exercises pain free. CONCLUSION: These quantitative findings highlight that wheelchair athletes may be exposed to potentially injurious positions during common ECP exercises. These findings provide insight that may lead to improved clinical guidelines for prescription and training of exercise regimens, particularly involving ECPs, for wheelchair users.

Effect of Rotation Sequence on Thoracohumeral Joint Kinematics during Various Shoulder Postures.

Current methods for selecting a rotation sequence to biomechanically model shoulder joint angles during motion assessment are challenging and controversial due to insufficient knowledge of their effect on the clinical interpretation of movement. Seven rotation sequences were examined by factors including incidences of gimbal lock and joint angle error in two healthy adults during 12 postures using right and left arms. This work was the first to explore the effects of each of the six Cardan angle sequences and the International Society of Biomechanics recommended YXY Euler sequence on the thoracohumeral joint in an array of postures. Results of this work show that there is not a "one size fits all" approach via rotation sequence selection for reliable and coherent expression of shoulder joint postures, particularly of the thoracohumeral joint. For best biomechanical modeling practice, it is recommended that researchers carefully consider the implications of a particular rotation sequence based on the posture or task of interest and resulting incidences of gimbal lock and joint angle error.Clinical Relevance- This work examines the effect of seven different mathematical computations for assessing shoulder joint angles in different postures for application of clinical movement analysis.