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.

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.

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.

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.

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.

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.

Biological Sex-Related Differences in Glenohumeral Dynamics Variability during Pediatric Manual Wheelchair Propulsion.

Shoulder pain and pathology are extremely common in adult manual wheelchair users with spinal cord injury (SCI). Within this population, biological sex and variability in shoulder joint dynamics have been shown to be important contributors to both shoulder pain and pathology. Sex-related differences in shoulder dynamics variability during pediatric manual wheelchair propulsion may influence a user's lifetime risk of shoulder pain and pathology. The purpose of this study was to assess the influence of biological sex on variability in three-dimensional (3-D) glenohumeral joint dynamics in pediatric manual wheelchair users with SCI. An inverse dynamics model computed 3-D glenohumeral joint angles, forces, and moments of 20 pediatric manual wheelchair users. Levene's tests assessed biological sex-related differences in variability. Females exhibited less variability in glenohumeral joint kinematics and forces, but greater variability in joint moments than males. Evaluation of glenohumeral joint dynamics with consideration for biological sex and variability strengthens our interpretation of the relationships among shoulder function, pain, and pathology in pediatric manual wheelchair users.Clinical Relevance- Female pediatric manual wheelchair users may be at an increased risk of shoulder repetitive strain injuries due to decreased glenohumeral joint motion and force variability during propulsion. This work establishes quantitative methods for determining the effects of biological sex on the variability of shoulder joint dynamics.

The Influence of Sex on Upper Extremity Joint Dynamics in Pediatric Manual Wheelchair Users With Spinal Cord Injury.

INTRODUCTION: Manual wheelchair propulsion is a physically demanding task associated with upper extremity pain and pathology. Shoulder pain is reported in over 25% of pediatric manual wheelchairs users, and this number rises over the lifespan. Upper extremity biomechanics in adults has been associated with shoulder pain and pathology; however, few studies have investigated upper extremity joint dynamics in children. Furthermore, sex may be a critical factor that is currently unexplored with regard to pediatric wheelchair mobility. OBJECTIVES: To investigate differences in upper extremity joint dynamics between pediatric male and female manual wheelchair users with spinal cord injury (SCI) during wheelchair propulsion. METHODS: Novel instrumented wheelchair hand-rims synchronized with optical motion capture were used to acquire upper extremity joint dynamics of 20 pediatric manual wheelchair users with SCI (11 males, 9 females). Thorax, sternoclavicular, acromioclavicular, glenohumeral, elbow, and wrist joint kinematics and kinetics were calculated during wheelchair propulsion. Linear mixed models were used to assess differences between sexes. RESULTS: Females exhibited significantly greater peak forearm pronation (p = .007), normalized wrist lateral force (p = .03), and normalized elbow posterior force (p = .04) than males. Males exhibited significantly greater peak sternoclavicular joint retraction (p < .001) than females. No significant differences between males and females were observed for the glenohumeral joint (p > .012). CONCLUSION: This study found significant differences in upper extremity joint dynamics between sexes during manual wheelchair propulsion. Our results underscore the importance of considering sex when evaluating pediatric wheelchair mobility and developing comprehensive wheelchair training interventions for early detection and prevention of upper extremity pain and pathology.

A comparison of glenohumeral joint kinematics and muscle activation during standard and geared manual wheelchair mobility.

The high prevalence of upper extremity joint injuries among manual wheelchair users is largely attributed to the high repetitive loading during propulsion. The purpose of this study was to evaluate the effects of using geared wheels for manual wheelchair mobility on shoulder joint biomechanics. Fourteen able-bodied participants performed overground propulsion and ramp ascension using standard and geared manual wheelchair wheels. Spatial temporal parameters, glenohumeral joint kinematics, and shoulder muscle activity were quantified. Findings indicated that regardless of the level of slope, the propulsion speed and stroke distance decreased significantly (p ≪ 0.001), and the stroke frequency increased significantly (p ≤ 0.025) during geared manual wheelchair propulsion. The glenohumeral joint ranges of motion in the coronal plane (p ≤ 0.005) and peak joint angles in the coronal (p ≤ 0.023) and transverse (p ≤ 0.012) planes were significantly different between standard and geared wheels usage. Shoulder muscle activity was substantially less using the geared wheels with significant findings in the pectoralis major (level floor, p ≤ 0.008) and infraspinatus (p ≤ 0.014) peak muscle activity, and the anterior deltoid (p ≤ 0.014) and pectoralis major (p ≤ 0.015) integrated muscle activity. However, the shoulder flexor normalized integrated muscle activity (muscle activity per stroke distance) was not different between the wheels.

Evaluation of shoulder joint kinematics and muscle activity during geared and standard manual wheelchair mobility.

Manual wheelchairs often lead to reduced independent function and an increase in shoulder pain and injuries. Geared manual wheelchairs may be a promising alternative that reduces the biomechanical demands of the shoulder needed for tasks such as propulsion on ramps and carpeted floors, while maximizing function and participation. To investigate the effects of geared manual wheelchair mobility during demanding tasks such as ramp ascent, six able-bodied subjects were evaluated in this study. Subjects were asked to propel both standard and geared manual wheelchairs on a tiled level floor and on a wheelchair ADA ramp. Shoulder muscle activity and glenohumeral joint kinematics were investigated. The results indicated that using geared manual wheelchair wheels did not alter the shoulder joint kinematics, but notably affected peak and integrated shoulder muscle activity. Muscle activity results normalized by stroke distance, indicated that using geared manual wheelchairs could decrease anterior deltoid, pectoralis major and infraspinatus muscle activity during ramp ascending, but on level floor infraspinatus muscle activity may increase. These results could have clinical implications for determining the types of functional mobility tasks for which geared manual wheelchairs are beneficial.

Biomechanical response to ladder slipping events: Effects of hand placement.

Ladder falling accidents are a significant, growing and severe occupational hazard. The factors that contribute to falls from ladders and specifically those that influence the motor response from ladder falls are not well understood. The aims of this research were to determine the effects of hand placement (rung versus rail) on muscle activation onset and peak activity timing in response to slipping on a ladder and to sequence the timing of events following slip initiation. Fifteen unexpected slips from 11 experienced ladder climbers were induced with a freely spinning rung under the foot, while subjects were randomly assigned to a rung versus rail hand grasping strategy. EMG onset time and peak activity time from five bilateral muscles (semitendinosis, vastus lateralis, triceps, biceps and anterior deltoid) were analyzed. Results indicated that significantly slower muscle activation onset and peak response times occurred during rail hand placement, suggesting that grasping ladder rungs may be preferable for improving the speed of the motor response. The triceps muscle activated and reached peak activity earlier in the slip indicating that subjects may initially extend their arms prior to generating hand forces. The study also revealed that slips tended to occur around the time that a foot and hand were in motion and there were just two points of contact (one hand and the slipping foot).

Biomechanics of Pediatric Manual Wheelchair Mobility.

Currently, there is limited research of the biomechanics of pediatric manual wheelchair mobility. Specifically, the biomechanics of functional tasks and their relationship to joint pain and health is not well understood. To contribute to this knowledge gap, a quantitative rehabilitation approach was applied for characterizing upper extremity biomechanics of manual wheelchair mobility in children and adolescents during propulsion, starting, and stopping tasks. A Vicon motion analysis system captured movement, while a SmartWheel simultaneously collected three-dimensional forces and moments occurring at the handrim. A custom pediatric inverse dynamics model was used to evaluate three-dimensional upper extremity joint motions, forces, and moments of 14 children with spinal cord injury (SCI) during the functional tasks. Additionally, pain and health-related quality of life outcomes were assessed. This research found that joint demands are significantly different amongst functional tasks, with greatest demands placed on the shoulder during the starting task. Propulsion was significantly different from starting and stopping at all joints. We identified multiple stroke patterns used by the children, some of which are not standard in adults. One subject reported average daily pain, which was minimal. Lower than normal physical health and higher than normal mental health was found in this population. It can be concluded that functional tasks should be considered in addition to propulsion for rehabilitation and SCI treatment planning. This research provides wheelchair users and clinicians with a comprehensive, biomechanical, mobility assessment approach for wheelchair prescription, training, and long-term care of children with SCI.

Evaluation of pediatric manual wheelchair mobility using advanced biomechanical methods.

There is minimal research of upper extremity joint dynamics during pediatric wheelchair mobility despite the large number of children using manual wheelchairs. Special concern arises with the pediatric population, particularly in regard to the longer duration of wheelchair use, joint integrity, participation and community integration, and transitional care into adulthood. This study seeks to provide evaluation methods for characterizing the biomechanics of wheelchair use by children with spinal cord injury (SCI). Twelve subjects with SCI underwent motion analysis while they propelled their wheelchair at a self-selected speed and propulsion pattern. Upper extremity joint kinematics, forces, and moments were computed using inverse dynamics methods with our custom model. The glenohumeral joint displayed the largest average range of motion (ROM) at 47.1° in the sagittal plane and the largest average superiorly and anteriorly directed joint forces of 6.1% BW and 6.5% BW, respectively. The largest joint moments were 1.4% body weight times height (BW × H) of elbow flexion and 1.2% BW × H of glenohumeral joint extension. Pediatric manual wheelchair users demonstrating these high joint demands may be at risk for pain and upper limb injuries. These evaluation methods may be a useful tool for clinicians and therapists for pediatric wheelchair prescription and training.

Upper extremity biomechanics of children with spinal cord injury during wheelchair mobility.

While much work is being done evaluating the upper extremity joint dynamics of adult manual wheelchair propulsion, limited work has examined the pediatric population of manual wheelchair users. Our group used a custom pediatric biomechanical model to characterize the upper extremity joint dynamics of 12 children and adolescents with spinal cord injury (SCI) during wheelchair propulsion. Results show that loading appears to agree with that of adult manual wheelchair users, with the highest loading primarily seen at the glenohumeral joint. This is concerning due to the increased time of wheelchair use in the pediatric population and the impact of this loading during developmental years. This research may assist clinicians with improved mobility assessment methods, wheelchair prescription, training, and long-term care of children with orthopaedic disabilities.

Biomechanical model for evaluation of pediatric upper extremity joint dynamics during wheelchair mobility.

Pediatric manual wheelchair users (MWU) require high joint demands on their upper extremity (UE) during wheelchair mobility, leading them to be at risk of developing pain and pathology. Studies have examined UE biomechanics during wheelchair mobility in the adult population; however, current methods for evaluating UE joint dynamics of pediatric MWU are limited. An inverse dynamics model is proposed to characterize three-dimensional UE joint kinematics and kinetics during pediatric wheelchair mobility using a SmartWheel instrumented handrim system. The bilateral model comprises thorax, clavicle, scapula, upper arm, forearm, and hand segments and includes the sternoclavicular, acromioclavicular, glenohumeral, elbow and wrist joints. A single 17 year-old male with a C7 spinal cord injury (SCI) was evaluated while propelling his wheelchair across a 15-meter walkway. The subject exhibited wrist extension angles up to 60°, large elbow ranges of motion and peak glenohumeral joint forces up to 10% body weight. Statistically significant asymmetry of the wrist, elbow, glenohumeral and acromioclavicular joints was detected by the model. As demonstrated, the custom bilateral UE pediatric model may provide considerable quantitative insight into UE joint dynamics to improve wheelchair prescription, training, rehabilitation and long-term care of children with orthopedic disabilities. Further research is warranted to evaluate pediatric wheelchair mobility in a larger population of children with SCI to investigate correlations to pain, function and transitional changes to adulthood.