Effect of shoulder pain on shoulder kinematics during weight-bearing tasks in persons with spinal cord injury

Nawoczenski DA, Riek LM, Greco L, Staiti K, Ludewig PM. Effect of shoulder pain on shoulder kinematics during weight-bearing tasks in persons with spinal cord injury.ObjectiveTo assess 3-dimensional scapulothoracic and glenohumeral kinematics between subjects with spinal cord injury and disease (SCI/D) with and without shoulder pain during a weight-relief raise and transfer task.DesignCase-control, repeated-measures analysis of variance.SettingMovement analysis laboratory.ParticipantsSubjects (N=43; 23 with clinical signs of impingement and 20 without) between 21 and 65 years of age, at least 1 year after SCI/D (range, 1–43y) resulting in American Spinal Injury Association Impairment Scale T2 motor neurologic level or below, and requiring the full-time use of a manual wheelchair.InterventionsWeight-relief raises and transfer tasks.Main Outcome MeasuresAn electromagnetic tracking system acquired 3-dimensional position and orientation of the thorax, scapula, and humerus. Dependent variables included angular values for scapular upward and downward rotation, posterior and anterior tilt, and internal and external rotation relative to the thorax, and glenohumeral internal and external rotation relative to the scapula. The mean of 3 trials was collected, and angular values were compared at 3 distinct phases of the weight-relief raise and transfer activity. Comparisons were also made between transfer direction (lead vs trail arm) and across groups.ResultsKey findings include significantly increased scapular upward rotation for the pain group during transfer (P=.03). Significant group differences were found for the trailing arm at the lift pivot (phase 2) of the transfer, with the pain group having greater anterior tilt (mean difference ± SE, 5.7°±2.8°). The direction of transfer also influenced kinematics at the different phases of the activity.ConclusionsPotentially detrimental magnitude and direction of scapular and glenohumeral kinematics during weight-bearing tasks may pose increased risk for shoulder pain or injury in persons with SCI/D. Consideration should be given to rehabilitation strategies that promote favorable scapular kinematics and glenohumeral external rotation.     

Three-dimensional shoulder kinematics during a pressure relief technique and wheelchair transfer

OBJECTIVE: To assess 3-dimensional scapulothoracic and glenohumeral kinematics in able-bodied subjects during a weight-relief raise and while transferring to and from a wheelchair. DESIGN: Repeated-measures analysis of variance. SETTING: Research laboratory. PARTICIPANTS: Twenty-five able-bodied subjects without spinal cord injury or shoulder symptoms (20 men, 5 women; age range, 20-37y). INTERVENTIONS: Completion of weight-relief raise and transfer tasks. Main Outcome Measures: An electromagnetic motion capture system tracked 3-dimensional position and orientation of the thorax, scapula, and humerus. Absolute angular values assessed included scapular downward and upward rotation, internal and external rotation, and posterior and anterior tipping all relative to the thorax, as well as humeral internal and external rotation relative to the scapula. Data were compared across 3 phases of the weight-relief raise and for transfer direction (leading arm, trailing arm). RESULTS: Key findings included significantly increased anterior tipping and internal rotation of the scapula and decreased scapular upward rotation and external rotation of the humerus during the weight-relief raise. The leading arm showed significantly greater scapular anterior tipping and internal rotation and less scapular upward rotation and humeral external rotation than the trailing arm during the final phase of the transfer. CONCLUSIONS: Both the weight-relief raise and transfer result in scapular and humeral positions and directions of motion that may negatively impact the available subacromial space. This may present increased risk for injury or progression of shoulder pain in persons who must routinely perform these tasks.     

The effect of a rotator cuff tear and its size on three-dimensional shoulder motion

BackgroundRotator cuff-disease is associated with changes in kinematics, but the effect of a rotator cuff-tear and its size on shoulder kinematics is still unknown in-vivo.MethodsIn this cross-sectional study, glenohumeral and scapulothoracic kinematics of the affected shoulder were evaluated using electromagnetic motion analysis in 109 patients with 1) subacromial pain syndrome (n = 34), 2) an isolated supraspinatus tear (n = 21), and 3) a massive rotator cuff tear involving the supraspinatus and infraspinatus (n = 54). Mixed models were applied for the comparisons of shoulder kinematics between the three groups during abduction and forward flexion.FindingsIn the massive rotator cuff-tear group, we found reduced glenohumeral elevation compared to the subacromial pain syndrome (16°, 95% CI [10.5, 21.2], p < 0.001) and the isolated supraspinatus tear group (10°, 95% CI [4.0, 16.7], p = 0.002) at 110° abduction. Reduced glenohumeral elevation in massive rotator cuff tears coincides with an increase in scapulothoracic lateral rotation compared to subacromial pain syndrome (11°, 95% CI [6.5, 15.2], p < 0.001) and supraspinatus tears (7°, 95% CI [1.8, 12.1], p = 0.012). Comparable differences were observed for forward flexion. No differences in glenohumeral elevation were found between the subacromial pain syndrome and isolated supraspinatus tear group during arm elevation.InterpretationThe massive posterosuperior rotator cuff-tear group had substantially less glenohumeral elevation and more scapulothoracic lateral rotation compared to the other groups. These observations suggest that the infraspinatus is essential to preserve glenohumeral elevation in the presence of a supraspinatus tear. Shoulder kinematics are associated with rotator cuff-tear size and may have diagnostic potential.     

Kinematics and muscle activation in subacromial pain syndrome patients and asymptomatic controls

BackgroundConflicting theories exist about the underlying cause of chronic subacromial pain in the middle-aged population. We aim to improve our understanding of kinematics and muscle activation in subacromial pain syndrome to provide insight in its pathophysiology.MethodsIn a cross-sectional comparison of 40 patients with subacromial pain syndrome and 30 asymptomatic controls, three-dimensional shoulder kinematics and electromyography-based co-contraction in 10 shoulder muscles were independently recorded. Glenohumeral and scapulothoracic kinematics were evaluated during abduction and forward flexion. Co-contraction was expressed as an activation ratio, specifying the relative agonistic and antagonistic muscle activity in each muscle.FindingsDuring abduction and forward flexion, the contribution of glenohumeral motion to elevation and glenohumeral external rotation was lower in subacromial pain syndrome (at 120⁰ abduction: −9°, 95% CI -14°- -3°; and − 8°, 95% CI -13°--3°, respectively), and was compensated by more scapulothoracic motion. The pectoralis major's activation ratio was significantly lower (Z-score: -2.657, P = 0.008) and teres major's activation ratio significantly higher (Z-score: -4.088, P < 0.001) in patients with subacromial pain syndrome compared to the control group.InterpretationReduced glenohumeral elevation and external rotation in subacromial pain syndrome coincided with less teres major antagonistic activity during elevation. These biomechanical findings provide a scientific basis for intervention studies directed at stretching exercises to reduce glenohumeral stiffness in the treatment of subacromial pain syndrome, and teres major strengthening to improve humeral head depressor function.     

Relationship of glenohumeral elevation and 3-dimensional scapular kinematics with disability in patients with shoulder disorders.

OBJECTIVE: To determine variables among glenohumeral elevation and 3-dimensional scapular rotations that are related to shoulder function as assessed by the Disability of the Arm, Shoulder and Hand-Disability/Symptom (DASH-D/S) scale. DESIGN: Prospective, cross-sectional study. PATIENTS: Eighty-eight patients with shoulder pain and limited range of motion were included. METHODS: Each patient performed 2 full active range of motion activities, forward flexion and abduction, and 2 activities of daily living, combing hair and simulating washing the back. Glenohumeral elevation and scapular rotations were measured by the Polhemus Fastrak electromagnetic system. RESULTS: On multiple regression analysis, glenohumeral elevation in combing hair and scapular lateral rotation in both abduction and simulating washing the back were the best predictors of shoulder function and explained 39.7% of the variance of the DASH-D/S score. CONCLUSION: These findings support the classical rehabilitation of the shoulder based on glenohumeral elevation and suggest the importance of attention paid to scapular lateral rotation.     

Patterns of motion loss in subjects with idiopathic loss of shoulder range of motion

BACKGROUND: Subjects with idiopathic loss of shoulder motion have difficulty sleeping, performing overhead activities, and completing activities of daily living. Treatment has been variable in approach and success. Cyriax's proposed shoulder capsular pattern was external rotation most limited followed by abduction followed by internal rotation. This investigation was performed to determine if a consistent pattern of motion loss was present in subjects with idiopathic loss of shoulder motion. METHODS: Repeated measurement of 25 (22 female) subjects' bilateral shoulder patterns of motion were compared. The three-dimensional position of the scapula and humerus throughout active shoulder abduction, external rotation, flexion, internal rotation, and scapular plane abduction was evaluated with an electromagnetic motion capture system. Patterns of motion loss were determined for both shoulders. The proportions of peak shoulder motion to mean maximum non-involved shoulders abduction, external, and internal rotation were utilized to determine the pattern of motion loss. FINDINGS: There was a significant difference in motion loss patterns between the involved and non-involved shoulders with the arm at the side. The internal rotation less than abduction less than external rotation pattern was demonstrated in 14 of 25 (56%) involved shoulders. No pattern was present in 14 of 21 (67%) non-involved shoulders. With the arm abducted, internal rotation was the most limited motion in 23 of 25 (92%) involved shoulders. INTERPRETATION: The results did not support Cyriax's proposed glenohumeral capsular pattern. Defining the pattern of motion loss in subjects with idiopathic loss of shoulder motion may assist in diagnosis and treatment.     

Analysis of rotation accompanying shoulder flexion

For effective rehabilitation of the shoulder, physical therapists must have correct knowledge of shoulder motion. Reports conflict on whether medial or lateral rotation of the humerus accompanies shoulder flexion. The purpose of this study was to determine the relationship between flexion and rotation at the glenohumeral joint. We determined rotation that accompanied active shoulder flexion by using a universal full-circle goniometer and an adjustable wooden bracket that served as a base for a gravity-activated angle finder. Therapists performed passive shoulder flexion with the humerus held allowing no rotation and then held in medial or lateral rotation. We used single-tailed t tests to determine analysis. We found significant differences (p less than .01) between the amount of shoulder rotation accompanying active shoulder flexion between men and women. Medial rotation of the shoulder accompanied active flexion in all subjects. Physical therapists should consider these results when the goal of treatment is to increase shoulder flexion.     

Kinematics of shoulder abduction in the scapular plane. On the influence of abduction velocity and external load

In this paper the kinematics of arm abduction in the scapular plane of 38 healthy experimental subjects is reported. The ratio of the glenohumoral and the scapulothoracic components of the motion were determined and the influence of the abduction speed and of the external load on it were investigated. The investigation of the effect of abduction speed involved all 38 subjects. Each of them performed one slow and one fast abduction. Statistical analysis showed that there were large differences between individuals, but that for any one individual the abduction process is essentially reproducible. For the one individual there is a strong, linear relationship between glenohumeral and scapulothoracic rotation. The slope of the regression of the glenohumeral component on total arm abduction varied from 0.75 to 0.5 with a sample mean of 0.66. It means that only two-thirds of arm abduction occurs in the glenohumeral joint, the remaining third taking place via scapular rotation. In slowly performed abductions the slope of the regression was significantly greater than in the high-speed movements, but differences were very small. In the investigation of the effect of external load, statistical analysis indicated that the slope of the intraindividual regression is largely independent of the load. The possibility of observer bias was analysed, too. It was found that the standard deviation of the abduction parameters determined by different observers was between 6 and 10% of that between different experimental subjects. RELEVANCE: A knowledge of the kinematics of the shoulder joint is necessary to understand subacromial pathology and in particular impingement problems. The scapulohumeral rhythm depends on the balanced and coordinated function of the muscles involved. The activation pattern of the abductor muscles, as reflected in shoulder kinematics, seems to be individual and stored as an engram.     

Characteristics of the scapula movement during shoulder elevation depend on posture

[Purpose] This study aimed to clarify the differences in scapular movement during flexion and abduction of the shoulder joint with different postures. [Participants and Methods] This study included 15 male participants. Their shoulder flexion and abduction and angles of the scapular upward rotation, scapular anterior tilt, scapular external rotation, and thoracic spine flexion were measured. Measurements were taken in three positions: the control, thoracic spine flexion, and thoracic spine extension positions using a three-dimensional motion capture system. [Results] In the shoulder flexion, the amount of change in the scapular external rotation was significantly greater in the thoracic flexion than in the thoracic extension. In shoulder abduction, the amount of change in the scapular anterior tilt and external rotation was significantly greater in the thoracic flexion than in the thoracic extension. A comparison of the scapular angles in shoulder flexion and abduction showed that the upward rotation, posterior tilt, and external rotation were significantly greater in abduction than flexion. [Conclusion] To avoid posture-induced incoordination of the scapula and thorax movement during shoulder elevation, postural adjustment of the thoracic spine based on the movements is necessary for the shoulder joint exercises.     

Stretching and strengthening exercises: their effect on three-dimensional scapular kinematics.

OBJECTIVE: To quantitatively evaluate the effects of commonly used shoulder exercises on shoulder kinematics and resting posture. STUDY DESIGN: A repeated-measures design was used with measurements performed before and after a 6-week exercise program. METHOD: Twenty asymptomatic subjects with forward shoulder posture were recruited. Stretching exercises for the pectoral muscles and resisted strengthening exercises for the scapular retractors and elevators and the glenohumeral abductors and external rotators were performed three times per week for 6 weeks. A three-dimensional electromechanical digitizer was used to measure thoracic inclination and scapular orientation and position. These measurements were taken with the arm (1) at the side, (2) abducted to 90 degrees, and (3) at maximal abduction. The isometric force of glenohumeral external and internal rotation and horizontal abduction and adduction were measured with a hand-held dynamometer. All subjects were tested before and after the 6-week exercise program. Hotelling's T2 and paired t tests were used for data analysis. RESULTS: The strength of horizontal abduction and internal and external rotation increased after exercise (p < .01). The anterior inclination of the thoracic spine decreased, and the glenohumeral contribution to arm elevation increased (p < .01). Resting scapular posture did not change. As the arm was abducted to 90 degrees, the scapula showed less upward rotation and less superior translation after the exercise program (p < .01). CONCLUSION: The exercise program improved muscle strength, produced a more erect upper trunk posture, increased scapular stability, and altered scapulohumeral rhythm.     

Scapular behavior in shoulder impingement syndrome.

OBJECTIVE: To quantify the contribution of each scapular rotation to the scapular total range of motion (ROM) in both shoulders of persons with a unilateral shoulder impingement syndrome (SIS), to compare 3-dimensional (3D) scapular attitudes of their symptomatic and asymptomatic shoulders in flexion and in abduction, and to characterize the scapular behavior of these subjects by classifying them into subgroups based on scapular tilting differences between their symptomatic and asymptomatic shoulders. DESIGN: Comparisons of 3D scapular attitudes, scapular total ROM, and percentage of contributions of each scapular rotation to the scapular total ROM. SETTING: A motricity laboratory. PARTICIPANTS: Fifty-one subjects, including 41 with a SIS (29 had an asymptomatic contralateral shoulder) and 10 healthy subjects. INTERVENTIONS: The 3D scapular attitudes were calculated with the subjects in a standardized seated position; with the arm at rest; or at 70 degrees, 90 degrees, and 110 degrees of shoulder flexion and abduction. Axial rotation angles were calculated using a fixed set of Cardanic angles. MAIN OUTCOME MEASURES: At 90 degrees of arm elevation, data from 10 shoulders of healthy subjects were used to set up normative values (99% confidence interval of mean 3D scapular attitudes) to compare with 3D scapular attitudes of symptomatic and asymptomatic shoulders of SIS subjects. We analyzed the scapula behavior of subjects with SIS and classified them into subgroups based on scapular anterior tilting asymmetry. RESULTS: In flexion, almost half of the scapular total ROM was provided by anterior tilting (48.2%-51.3%), whereas in abduction, external rotation (40.3%-42.4%) was the main contributor. Scapular total ROM was higher in abduction than in flexion in all arm positions for both shoulder groups (P <.01). Also, 3D scapular attitude patterns of both shoulders of SIS subjects were different from those of healthy subjects. At 90 degrees, scapular asymmetry in anterior tilting allowed us to classify SIS subjects with respect to more (lead) or less (lag) scapular tilting in the affected side (P <.0001) or no difference (P =.11) between the sides (symmetrical). No significant differences (P >.05), except for a small 2 degrees difference in transverse rotation during arm flexion at 110 degrees (P =.002), were observed in 3D scapular attitudes and scapular total ROM between both shoulders of SIS subjects. Patterns of 3D scapular attitudes and scapular total ROM were significantly different between flexion and abduction arm positions (P <.05). CONCLUSIONS: The contribution of rotations and scapular total ROM differed according to the plane of arm elevation in SIS subjects. Group analyses revealed no differences in 3D scapular attitudes between symptomatic and asymptomatic shoulders of subjects with unilateral SIS. This could be caused by the use, in SIS subjects, of inappropriate neuromuscular strategies affecting both shoulders. However, individual analyses revealed scapular asymmetry in the sagittal plane, which suggests that SIS subjects with less anterior tilting in the symptomatic shoulder, as compared with the asymptomatic contralateral one, may be at high risk of developing chronic SIS. This last finding provides scientific evidence to focus rehabilitation protocols toward a restoration of anterior tilting.     

Effect of motor control and strengthening exercises on shoulder function in persons with impingement syndrome: a single-subject study design

The aim of the study was to evaluate the effect of an intervention including shoulder control and strengthening exercises on function in persons with shoulder impingement. Eight subjects with shoulder impingement were evaluated weekly during the nine weeks of this single-subject design study. The study was divided into three phases (A(1)-B-A(2)) and involved repeated measures of shoulder pain and function (Shoulder Pain And Disability Index (SPADI) questionnaire), painful arc of motion, peak torque and 3-dimensional scapular attitudes. During the intervention phase, each subject participated in 12 exercise sessions supervised by a physiotherapist. Measures taken during the intervention and post-intervention phases were compared to pre-intervention values. All subjects showed significant improvement in the SPADI at the end of the study. A disappearance of a painful arc of motion in flexion and abduction (n=6), an increase in isometric peak torque in lateral rotation (n=3) and abduction (n=2), and changes in the scapular kinematics, mainly in the sagittal plane, were also observed. The present results provide preliminary evidence to support the use of shoulder control exercises to reduce pain and improve function of persons with shoulder impingement.     

Shoulder function and 3-dimensional scapular kinematics in people with and without shoulder impingement syndrome

BACKGROUND AND PURPOSE: Several factors such as posture, muscle force, range of motion, and scapular dysfunction are commonly believed to contribute to shoulder impingement. The purpose of this study was to compare 3-dimensional scapular kinematics, shoulder range of motion, shoulder muscle force, and posture in subjects with and without primary shoulder impingement syndrome. SUBJECTS: Forty-five subjects with impingement syndrome were recruited and compared with 45 subjects without known pathology or impairments matched by age, sex, and hand dominance. METHODS: Shoulder motion and thoracic spine posture were measured goniometrically, and force was measured with a dynamometer. An electromagnetic motion analysis system was used to capture shoulder kinematics during active elevation in both the sagittal and scapular planes as well as during external rotation with the arm at 90 degrees of elevation in the frontal plane. RESULTS: The impingement group demonstrated slightly greater scapular upward rotation and clavicular elevation during flexion and slightly greater scapular posterior tilt and clavicular retraction during scapular-plane elevation compared with the control group. The impingement group demonstrated less range of motion and force in all directions compared with the control group. There were no differences in resting posture between the groups. DISCUSSION AND CONCLUSION: The kinematic differences found in subjects with impingement may represent scapulothoracic compensatory strategies for glenohumeral weakness or motion loss. The decreased range of motion and force found in subjects with impingement support rehabilitation approaches that focus on strengthening and restoring flexibility.     

Documentation of medial rotation accompanying shoulder flexion. A case report

We dissected a fresh cadaver to determine which glenohumeral structures causes medial rotation of the humerus during flexion in the sagittal plane. All structures associated with both shoulders were dissected thoroughly. Both elbows were disarticulated to expose the distal end of each humerus to be used as measurement landmarks. We used a universal goniometer for measurements of shoulder flexion. To determine which structures cause passive medial rotation, the associated shoulder muscles, ligaments, and the capsule were individually reflected from the humerus. Passive shoulder flexion to the point where medial rotation started was measured after each structure was resected. The end passive glenohumeral flexion without rotation was 60 degrees after reflection of all musculature and other periarticular shoulder structures. Our results support Steindler's conclusion that during flexion of the humerus beyond the horizontal there is forced rotation caused by ligamentous tension. We also found that the bony configuration of the glenohumeral joints also plays an important role in medial rotation accompanying shoulder flexion.     

Arthrographic and clinical findings in patients with hemiplegic shoulder pain

OBJECTIVES: To identify the etiology of hemiplegic shoulder pain by arthrographic and clinical examinations and to determine the correlation between arthrographic measurements and clinical findings in patients with hemiplegic shoulder pain. DESIGN: Case series. SETTING: Medical center of a 1582-bed teaching institution in Taiwan. PARTICIPANTS: Thirty-two consecutive patients with hemiplegic shoulder pain within a 1-year period after first stroke were recruited. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Clinical examinations included Brunnstrom stage, muscle spasticity distribution, presence or absence of subluxation and shoulder-hand syndrome, and passive range of motion (PROM) of the shoulder joint. Arthrographic measurements included shoulder joint volume and capsular morphology. RESULTS: Most patients had onset of hemiplegic shoulder pain less than 2 months after stroke. Adhesive capsulitis was the main cause of shoulder pain, with 50% of patients having adhesive capsulitis, 44% having shoulder subluxation, 22% having rotator cuff tears, and 16% having shoulder-hand syndrome. Patients with adhesive capsulitis showed significant restriction of passive shoulder external rotation and abduction and a higher incidence of shoulder-hand syndrome (P=.017). Those with irregular capsular margins had significantly longer shoulder pain duration and more restricted passive shoulder flexion (P=.017) and abduction (P=.020). Patients with shoulder subluxation had significantly larger PROM (flexion, P=.007; external rotation, P<.001; abduction, P=.001; internal rotation, P=.027), lower muscle tone (P=.001), and lower Brunnstrom stages of the proximal upper extremity (P=.025) and of the distal upper extremity (P=.001). Muscle spasticity of the upper extremity was slightly negatively correlated with shoulder PROM. Shoulder joint volume was moderately positively correlated with shoulder PROM. CONCLUSIONS: After investigating the hemiplegic shoulder joint through clinical and arthrographic examinations, we found that the causes of hemiplegic shoulder pain are complicated. Adhesive capsulitis was the leading cause of shoulder pain, followed by shoulder subluxation. Greater PROM of the shoulder joint, associated with larger joint volume, decreased the occurrence of adhesive capsulitis. Proper physical therapy and cautious handling of stroke patients to preserve shoulder mobility and function during early rehabilitation are important for a good outcome.     

A comparison of symptomatic and asymptomatic office workers performing monotonous keyboard work--2: neck and shoulder kinematics

Prolonged static posture has been identified as a major risk factor for work-related neck and upper limb disorders (WRNULD) in computer users. Previous research has mainly examined working postures in healthy pain-free individuals. The present study examined whether symptomatic subjects exhibited the same kinematic patterns as asymptomatic controls during a prolonged computer task. In a Case-Control comparison, female office workers performed the same computer task using the same adjustable computer workstation for 1h. Three-dimensional (3D) kinematics were measured in the head-neck, thorax and shoulder (upper arm) segments. Case Group subjects (n=21) displayed trends for increased head-neck flexion angles and greater ranges of movements than the Control Group (n=17). There were also small but significant differences between groups in side flexion and rotation angles of the head-neck region. The shoulder joints displayed significantly greater flexion and abduction angles on the right in both groups, although no group differences were observed. The increased neck flexion angles were associated with significantly higher activity in the upper trapezius muscle and with neck and shoulder discomfort. The individual differences in postural habits appeared to be independent of the physical environment. These results suggest motor control changes are associated with the presence of WRNULD.     

Comparing supraspinatus to acromion proximity and kinematics of the shoulder and thorax between manual wheelchair propulsion styles: A pilot study

BackgroundRepetitive glenohumeral joint movement during manual wheelchair propulsion has been associated with shoulder pain in individuals with spinal cord injury. Clinical guidelines for shoulder health maintenance encourage semi-circular over arc propulsion to reduce loading frequency. This study aimed to determine the difference in estimated supraspinatus to acromion compression risk, and shoulder, thorax kinematics between (1) arc and semi-circular propulsion; and (2) self-selected and coached strategies.MethodsShoulder and thorax kinematics were captured during wheelchair propulsion, noting individually self-selected styles. Participants were then coached to perform the other style(s) of interest, arc and/or semi-circular. CT bone models of the humerus and scapula were animated using glenohumeral kinematics to estimate the minimum distance between the supraspinatus humeral attachment and the acromion. Compression risk was defined as the proportion of each propulsion phase where the minimum distance fell below 5 mm. Comparisons were made between conditions evaluating compression risk, minimum distances and kinematics at events throughout propulsion.FindingsTen individuals with spinal cord injury (9 male) participated. Arc and semi-circular propulsion did not significantly differ in compression risk or minimum distance across propulsion phases. Self-selected styles yielded lower compression risk and larger proximity values compared to coached styles. Glenohumeral horizontal abduction and thorax flexion differed between arc and semi-circular propulsion. Multiple glenohumeral and humerothoracic differences emerged between self-selected and coached conditions.InterpretationSupraspinatus compression was observed during both arc and semi-circular propulsion, suggesting risk may be unavoidable in this task. Self-selected styles yield less risk, likely related to coached style unfamiliarity.     

Subacromial pressure during diagnostic shoulder tests

The pressure in the subacromial bursa during passive provocation tests and during active motion was recorded in five healthy persons, and in seven patients with a subacromial pain syndrome. During the passive impingement test, the mean bursa pressure increased from 6 to 56 mmHg in healthy persons and from 8 to 45 mmHg in the patients. A passive test for anterior glenohumeral instability yielded bursa pressures below 0 mmHg in both groups. Active flexion of the arm at the shoulder produced a pressure increase up to 90° and a pressure decrease between 90 and 180° of flexion for both groups.     

Correlation of 3-dimensional shoulder kinematics to function in subjects with idiopathic loss of shoulder range of motion

BACKGROUND AND PURPOSE: People with idiopathic loss of shoulder range of motion (ROM) have difficulty completing activities of daily living. This investigation was performed to determine the association between active glenohumeral ROM and function and to develop a multiple regression equation to explain variation in function in people with idiopathic loss of shoulder motion. SUBJECTS AND METHODS: This was a comparative study of 21 subjects (18 female, 3 male), using measurements of shoulder kinematics and administration of the Shoulder Rating Questionnaire (SRQ). Electromagnetic tracking sensors monitored the 3-dimensional position of the scapula and humerus throughout active shoulder motions. Correlations were performed between the active ROMs of interest and various demographic factors and the SRQ. A multiple regression equation was generated. RESULTS: A multiple regression equation including scapular-plane abduction, external rotation at the side, external rotation at 90 degrees of abduction, and weight explained 69% of the variation in the SRQ scores. DISCUSSION AND CONCLUSION: The results suggest that active ROM can be used to predict function in people with idiopathic loss of shoulder ROM.