Effects of Low-Load Blood Flow Restriction Training on Rotator Cuff Strength and Hypertrophy: Case Series.

Background: The rotator cuff (RC) plays a pivotal role in the performance and health of the shoulder and upper extremity. Blood flow restriction training (BFRT) is a modality to improve strength and muscle hypertrophy with even low-load training in healthy and injured individuals. There is minimal evidence examining its effect proximal to the occluded area, and particularly on the RC. Hypothesis & Purpose: The purpose of this case series is to explore the effects of low-load BFRT on RC strength, hypertrophy, and tendon thickness in asymptomatic individuals. Study Design: Case series. Methods: Fourteen participants with asymptomatic, untrained shoulders were recruited to participate. They performed an eight-week low-load shoulder exercise regimen where BFR was applied to the dominant arm only during exercise. The dependent variables were maximal isometric strength of the shoulder external rotators(ER) and elevators (in the scapular plane in full can position) (FC) measured via handheld dynamometry, cross sectional area (CSA) of the supraspinatus and infraspinatus muscles, and supraspinatus tendon thickness measured via ultrasound imaging (US). Mean changes within and between arms were compared after training using paired t-tests. Cohen's d was used to determine effect sizes. Results: All participants were able to complete the BFRT regimen without adverse effects. Mean strength and CSA increased for all variables in both arms, however this increase was only significant (p\<0.01) for FC strength bilaterally and CSA for the supraspinatus and infraspinatus on the BFRT side. The effect sizes for increased supraspinatus and infraspinatus CSA on the BFRT side were 0.40 (9.8% increase) and 0.46 (11.7% increase) respectively. There were no significant differences when comparing the mean changes of the BFRT side to the non-BFRT side for strength or muscle CSA. There were no significant changes to supraspinatus tendon thickness. Conclusion: These results suggest variability in response of the RC musculature to low-load BFRT in asymptomatic individuals. The potential for a confounding systemic response in the study design makes determining whether low-load BFRT is more beneficial than low-load non-BFRT difficult. The hypertrophy seen on the BFRT side warrants further study. Level of Evidence: 4.

Defining substantial clinical benefit for patient-rated outcome tools for shoulder impingement syndrome.

OBJECTIVE: To define for 2 shoulder outcomes scales the substantial clinical benefit (SCB)-a metric that defines the change amount associated with patient perception of a large meaningful improvement and that can be used to interpret change over time in the outcome score. DESIGN: Cohort. SETTING: Clinic. PARTICIPANTS: Patients (N=74) with shoulder impingement syndrome. INTERVENTIONS: Standardized exercise and manual therapy for 6 weeks, and outcome measures completed at initial evaluation, discharge, and 6 to 8 weeks postdischarge. MAIN OUTCOME MEASURES: Disabilities of the Arm, Shoulder and Hand (DASH), Pennsylvania Shoulder Score (Penn), and a 13-point Global Rating of Change (GROC). Patients were classified as "substantially improved" when they reported "quite a bit better" (11) or greater on the GROC at discharge and again 6 to 8 weeks after discharge. Patients with GROC <11 at discharge or follow-up were classified as "nonsubstantially improved." The percentage and raw points change in the Penn and DASH that corresponded with patient-rated substantial improvement was determined with receiver operator characteristic (ROC) analyses. RESULTS: ROC analyses revealed the SCB for the DASH was 40% (area under the curve [AUC]=.79; confidence interval [CI], .69-.89) and 11 points (AUC=.63; CI, .50-.76); and for the Penn, 20% (AUC=.76; CI, .65-.87) and 21 points (AUC=.80; CI, .69-.90). CONCLUSIONS: The SCB of 40% for the DASH, and 20% and 21 points for the Penn represents substantial improvement over 6 weeks of care, which was sustained at 12 weeks. The SCB of 11 points for the DASH is not recommended for use because of poor discrimination. The SCB can be used to enable clinical decision-making and in future clinical trials. Alternative approaches such as the within- and between-group change values can produce different SCB values.

Experimental pain inhibits infraspinatus activation during isometric external rotation.

BACKGROUND: The effect of pain on muscle activation is poorly understood. This study examined the effects of acute experimental pain on rotator cuff muscle force and voluntary activation (VA). We hypothesized that acute subacromial pain would cause inhibition of infraspinatus VA with a corresponding decrease in external rotation force. MATERIALS AND METHODS: Seventeen healthy adults with no known shoulder pathology were tested. Isolated external rotation force was tested on a dynamometer. Participants performed 2 baseline maximum voluntary isometric contractions of external rotation, during which maximal electrical stimulation was used to assess VA. To elicit pain, 1.5 mL 5% hypertonic saline was injected into the subacromial space, and testing of maximum voluntary isometric contractions force and VA was repeated 3 times at 5-minute intervals. RESULTS: Mean ± standard deviation initial pain from the injection was 6.6 ± 1.3 points of 10 possible and produced a 32.8% decline in force and a 22.7% decline in VA (P < .05). Pain diminished over a 10-minute period. As pain resolved, force and VA improved (P < .0125). There was a strong relationship between force and VA (r(2) = 0.78, P < .05) and a moderate relationship between pain and VA (r(2) = 0.31, P < .05). CONCLUSIONS: Experimental subacromial pain elicits a decline in force and VA of the infraspinatus. Although this study only examines acute experimental pain, it supports the concept that pain affects rotator cuff muscle recruitment and function, which may contribute to abnormal shoulder mechanics in patients with rotator cuff pathology.

Measurement Properties of the Timed Functional Arm and Shoulder Test in Patients With Shoulder Problems.

OBJECTIVE: The purpose of this study was to determine the feasibility, reliability, validity, and responsiveness of the Timed Functional Arm and Shoulder Test (TFAST) in patients with shoulder problems. METHODS: This study was a repeated-measures clinical measurement observational cohort study. A total of 104 patients who were symptomatic participated in this study. The TFAST was collected as part of an patient's outpatient physical therapist care at 6 different sites. The test and data collection were performed at 3 time points: baseline (initial evaluation), follow-up at the patient's first return visit within 7 days of evaluation, and discharge at the patient's final visit for care. RESULTS: All participants were able to perform the TFAST at baseline, with 1 exception, and 67 participants completed data collection at all 3 time points. There were no adverse effects in any participant related to performing the TFAST. Intrarater intersession reliability, reported as ICC(2,1), was 0.91 (95% CI = 0.79-0.95). The mean difference in TFAST scores for the affected arm was 23.2 repetitions (77.4 at baseline to 100.6 at discharge). The Cohen d effect size was 1.02, and the standardized response mean was 0.95. The minimal clinically important difference was determined to be 21 repetitions. CONCLUSION: The TFAST seems to be feasible and appropriate for use in a wider population than other existing shoulder performance measures. The TFAST has demonstrated adequate reliability, validity, and responsiveness in patients with shoulder problems. Clinicians may consider using the TFAST to objectively assess patient performance. IMPACT: The TFAST may be used to expand measurement of objective shoulder performance in a wide population of patients with shoulder problems. This test may provide information beyond an patient's self-report and contribute to clinical decision-making.

Effects of scapular dyskinesis and scapular assistance test on subacromial space during static arm elevation.

BACKGROUND: Scapular dyskinesis is an abnormal scapular motion or position during active arm elevation. Dyskinesis is theorized to contribute to impingement syndrome by decreasing the subacromial space. A corrective maneuver of the scapular assistance test (SAT) proposes to increase scapular upward rotation and posterior tilt to increase the subacromial space. The purpose of this study is to determine the influence that 1) scapular dyskinesis and 2) passive manual correction with the SAT have on subacromial space and 3-dimensional (3-D) scapular kinematics. MATERIALS AND METHODS: Forty asymptomatic participants were classified with either obvious dyskinesis (n = 20) or normal motion (n = 20) using the scapular dyskinesis test. The anterior outlet of the subacromial space was measured via the acromiohumeral distance using ultrasound imaging and 3-D scapular orientation was assessed with electromagnetic motion analysis, with the arm at rest 45° and 90° of active elevation with and without the SAT, respectively. RESULTS: There were no differences in acromiohumeral distance or scapular kinematics with static active arm elevation between groups. The SAT increased scapular upward rotation, posterior tilt, and acromiohumeral distance in both groups. Participants with dyskinesis demonstrated greater scapular mobility in upward rotation with the SAT, but no additional increase in acromiohumeral distance. CONCLUSION: Scapular dyskinesis identified during active motion did not result in different 3-D scapular orientation or acromiohumeral distance during active arm elevation in static positions; however, the SAT altered scapular kinematics and increased acromiohumeral distance. The SAT may be helpful to identify individuals where subacromial compression is producing symptoms, regardless of dyskinesis.

Reliability and Concurrent Validity of Shoulder Tissue Irritability Classification.

OBJECTIVE: Rating tissue irritability has been recommended to aid decision making in several recent clinical practice guidelines. An explicit method for rating tissue irritability was proposed as part of the Staged Algorithm for Rehabilitation Classification: Shoulder Disorders (STAR-Shoulder), but the reliability and validity of this classification are unknown. The purpose of this study was to examine the reliability and concurrent validity of shoulder tissue irritability ratings as part of a system designed to guide appropriate treatment strategy and intensity. METHODS: A clinical measurement, prospective repeated-measures cross-sectional design was used. The 101 consecutive participants with primary complaints of shoulder pain were assessed by pairs of blinded raters (24 raters in total) and rated for tissue irritability. Patients completed 3 patient-reported outcome (PRO) measures reflecting both pain and disability, and these scores were compared with ratings of tissue irritability. Paired ratings of irritability were analyzed for reliability with prevalence-adjusted, bias-adjusted Kappa for ordinal scales. Analysis of variance was used to compare PRO measures across different levels of irritability. Receiver operating characteristic curve analysis was utilized to derive cut-off scores for 3 PRO instruments. RESULTS: Interrater reliability was 0.69 (95% CI = 0.59-0.78), with 67% agreement. All PRO measures were significantly different among 3 levels of tissue irritability. CONCLUSION: There appears to be acceptable reliability and a strong relationship between PRO measures and therapist-rated tissue irritability, supporting the use of the STAR-Shoulder irritability rating system. IMPACT: Several clinical practice guidelines have recommended that clinicians rate tissue irritability as part of their examination. This study provides important new information supporting the reliability and validity of the STAR-Shoulder tissue irritability rating system.

The effect of experimental shoulder pain on contralateral muscle force and activation.

Inhibition of rotator cuff activation and force after local experimental pain has been previously shown. Clinically, strength is often indexed to the uninvolved side in order to quantify deficits during injury and recovery. This study assessed the effect of experimental subacromial pain on contralateral shoulder external rotation (ER) force and activation. We hypothesized that subacromial pain would not affect contralateral shoulder external rotation force and voluntary activation (VA) of the contralateral infraspinatus because we believe that the effects of acute experimental pain will largely exert an ipsilateral, spinal segmental effect. Twenty healthy adults were tested. External rotation force and VA were tested while participants performed maximum voluntary isometric contractions of shoulder external rotation, during which a brief electrical stimulus was applied to the infraspinatus muscle at an intensity that maximized external rotation force. To elicit pain, 1.5 ml of 5% hypertonic saline was injected into the contralateral subacromial space. Mean (SD) pain immediately after injection was 6.3/10 (0.85) resulting in a 7.6% decline in contralateral external rotation force (p < .01) and 3.3% decline in infraspinatus muscle VA (p = .48). A subset of participants (n = 9) showed a more substantial decline in both force (15.4%; p < .000001; d = -3.53) and VA (8.7%; p = .045; d = -0.98). Experimental shoulder pain had a modest effect on contralateral ER force and VA in a subset of participants; therefore, it may be important to index or compare strength bilaterally throughout rehabilitation to capture this bilateral effect as pain resolves.

Voluntary activation of the infraspinatus muscle in nonfatigued and fatigued states.

HYPOTHESIS: Failure of voluntary activation is an important source of weakness in several different muscles after injury or surgery. Despite the high prevalence of shoulder rotator cuff disorders and associated weakness, no test currently exists to identify voluntary activation deficits for the rotator cuff. The purpose of this study was to develop a test to quantify voluntary activation of the infraspinatus. We hypothesized that there would be a consistent relationship between the voluntary activation level and different force levels and that reduced voluntary activation would partially account for reduced force with fatigue. MATERIALS AND METHODS: Twenty healthy volunteers underwent assessment of voluntary activation using an electrical stimulus applied to the infraspinatus muscle during active isometric external rotation. Voluntary activation was assessed across several levels of external rotation effort and during fatigue. RESULTS: The voluntary activation-percent force relationship was best fit using a curvilinear model, and the fatigue test reduced both force and voluntary activation by 46%. DISCUSSION: In the nonfatigued state, the voluntary activation-percent force relationship is similar to that reported for the quadriceps. After fatigue, however, greater failure of voluntary activation was observed compared with reported values for other upper and lower extremity muscles, which may have implications for the understanding and treatment of rotator cuff pathology. CONCLUSION: A measure of voluntary activation for the infraspinatus varied with the percent maximum force in a predictable manner that is consistent with the literature. The infraspinatus may be more susceptible to failure of voluntary activation during fatigue than other muscles.

Comprehensive impairment-based exercise and manual therapy intervention for patients with subacromial impingement syndrome: a case series.

STUDY DESIGN: Case series. BACKGROUND: Few studies have defined the dosage and specific techniques of manual therapy and exercise for rehabilitation for patients with subacromial impingement syndrome. This case series describes a standardized treatment program for subacromial impingement syndrome and the time course and outcomes over a 12-week period. CASE DESCRIPTION: Ten patients (age range, 19-70 years) with subacromial impingement syndrome defined by inclusion and exclusion criteria were treated with a standardized protocol for 10 visits over 6 to 8 weeks. The protocol included a 3-phase progressive strengthening program, manual stretching, thrust and nonthrust manipulation to the shoulder and spine, patient education, activity modification, and a daily home exercise program of stretching and strengthening. Patients completed a history and measures of impairments and functional disability at 2, 4, 6, and 12 weeks. OUTCOMES: Treatment success was defined as both a 50% improvement on the Disabilities of the Arm, Shoulder, and Hand (DASH) score and a global rating of change of at least "moderately better." At 6 weeks, 6 of 10 patients had a successful (mean +/- SD) DASH outcome score (initial, 33.9 +/- 16.2; 6 weeks, 8.1 +/- 9.2). At 12 weeks, 8 of 10 patients had a successful DASH outcome score (initial, 33.1 +/- 14; 12 weeks, 8.3 +/- 6.4). As a group, the largest improvement was in the first 2 weeks. The most common impairments for all 10 patients were rotator cuff and trapezius muscle weakness (10 of 10 patients), limited shoulder internal rotation motion (8 of 10 patients), and reduced kyphosis of the midthoracic area (7 of 10 patients). DISCUSSION: A program aimed at strengthening rotator cuff and scapular muscles, with stretching and manual therapy aimed at thoracic spine and the posterior and inferior soft-tissue structures of the glenohumeral joint appeared to be successful in the majority of patients. This case series describes a comprehensive impairment-based treatment which resulted in symptomatic and functional improvement in 8 of 10 patients in 6 to 12 weeks. LEVEL OF EVIDENCE: Therapy, level 4.

Shoulder muscle force and electromyography activity during make versus break tests.

BACKGROUND: Shoulder muscle force is commonly assessed during clinical examination using both an isometric "make" test against a fixed resistance or a "break" test where the examiner exerts enough force to break the isometric contraction. The purpose of this study was to explain the difference in force produced during these two forms of testing. METHODS: Data were collected on 25 subjects. Both shoulder external rotation and elevation force were measured over three trials, isometrically, for approximately 3 s, after which the examiner exerted enough force to move the arm. Surface EMG was recorded for the infraspinatus for external rotation and middle deltoid for elevation. Peak isometric and break forces, and normalized, averaged EMG data at peak isometric and break forces were compared with paired t-tests. FINDINGS: External rotation peak break force was 46.9% (SD33.6, range - 3% to 108.6%) greater than isometric force (p < 0.01). EMG for the infraspinatus was 17.0% (20.8) greater at break (p < 0.01). For elevation, peak break force was 63% (73.1, range - 3.5 to 238.16%) greater than isometric force (p < 0.01). EMG for the middle deltoid was 11.1% (30.8) greater during peak break force (not significant). INTERPRETATIONS: There is a difference in both force and muscle activity between "make" and "break" tests. Clinicians should use a consistent method when measuring force and a break test will provide the maximum force. The cause of greater force produced during a break test is likely attributable to the brief eccentric contraction rather than greater recruitment. Future analysis will include examining the differences in make and break forces based on activity levels.

Frozen shoulder: evidence and a proposed model guiding rehabilitation.

UNLABELLED: Frozen shoulder or adhesive capsulitis describes the common shoulder condition characterized by painful and limited active and passive range of motion. The etiology of frozen shoulder remains unclear; however, patients typically demonstrate a characteristic history, clinical presentation, and recovery. A classification schema is described, in which primary frozen shoulder and idiopathic adhesive capsulitis are considered identical and not associated with a systemic condition or history of injury. Secondary frozen shoulder is defined by 3 subcategories: systemic, extrinsic, and intrinsic. We also propose another classification system based on the patient's irritability level (low, moderate, and high), that we believe is helpful when making clinical decisions regarding rehabilitation intervention. Nonoperative interventions include patient education, modalities, stretching exercises, joint mobilization, and corticosteroid injections. Glenohumeral intra-articular corticosteroid injections, exercise, and joint mobilization all result in improved short- and long-term outcomes. However, there is strong evidence that glenohumeral intra-articular corticosteroid injections have a significantly greater 4- to 6-week beneficial effect compared to other forms of treatment. A rehabilitation model based on evidence and intervention strategies matched with irritability levels is proposed. Exercise and manual techniques are progressed as the patient's irritability reduces. Response to treatment is based on significant pain relief, improved satisfaction, and return of functional motion. Patients who do not respond or worsen should be referred for an intra-articular corticosteroid injection. Patients who have recalcitrant symptoms and disabling pain may respond to either standard or translational manipulation under anesthesia or arthroscopic release. LEVEL OF EVIDENCE: Level 5.

Effect of the Scapula Reposition Test on shoulder impingement symptoms and elevation strength in overhead athletes.

STUDY DESIGN: Two group, repeated measures design. OBJECTIVES: To determine whether manually repositioning the scapula using the Scapula Reposition Test (SRT) reduces pain and increases shoulder elevation strength in athletes with and without positive signs of shoulder impingement. BACKGROUND: Symptom alteration tests may be useful in determining a subset of those with shoulder pathology who may benefit from interventions aimed at improving scapular motion abnormalities. METHODS AND MEASURES: One hundred forty-two college athletes underwent testing for clinical signs of shoulder impingement. Tests provoking symptoms were repeated with the scapula manually repositioned into greater retraction and posterior tilt. A numeric rating scale was used to measure symptom intensity under both conditions. Isometric shoulder elevation strength was measured using a mounted dynamometer with the scapula in its natural position and with manual repositioning. A paired t test was used to compare the strength between positions. The frequency of a significant increase in strength with scapular repositioning, defined as the minimal detectable change (90% confidence interval), was also assessed. RESULTS: Of the 98 athletes with a positive impingement test, 46 had reduced pain with scapular repositioning. Although repositioning produced an increase in strength in both the impingement (P=.001) and non-impingement groups (P=.012), a significant increase in strength was found with repositioning in only 26% of athletes with, and 29% of athletes without positive signs for shoulder impingement. CONCLUSION: The SRT is a simple clinical test that may potentially be useful in an impairment based classification approach to shoulder problems.

Early Development and Reliability of the Timed Functional Arm and Shoulder Test.

Study Design Repeated-measures clinical measurement reliability study. Background While there are some shoulder functional tests for athletes, no widely used performance test of arm and shoulder function currently exists to assess lower-level upper extremity functional demands in, for example, a nonathlete population or elderly individuals. In these individuals, functional measures rely on patient self-report. Objectives Describe the development of the Timed Functional Arm and Shoulder Test (TFAST), age-related scores, and between-session reliability in a group of asymptomatic high school athletes, young adults, middle-aged adults, older adults, and a preliminary group of symptomatic patients. Methods One hundred forty asymptomatic individuals participated in the study: 36 high school athletes (14-18 years of age), 34 young adults (19-35 years of age), 37 middle-aged adults (36-65 years of age), 33 older adults (over 65 years of age), and 16 symptomatic patients (22-66 years of age). The TFAST is a functional test that includes 3 tasks: hand to head and back, wall wash, and gallon lift. Total repetitions were noted for each task, and the total TFAST score was calculated. Results Mean total TFAST scores were higher for young adults (107.9; 95% confidence interval [CI]: 102.5, 113.4) and middle-aged adults (105.2; 95% CI: 99.1, 111.3) as compared to the high school athletes (89.9; 95% CI: 81.2, 98.5) and older adults (74.5; 95% CI: 65.6, 83.5). All groups were significantly different (P<.05) from each other, except the young and middle-aged adults. For patients, the mean score for the symptomatic side was 100.1 (95% CI: 89.6, 110.5). The between-session reliability values for the total TFAST scores in the asymptomatic individuals were as follows: intraclass correlation coefficient (ICC) = 0.93; 95% CI: 0.60, 0.98; standard error of measurement, 6.7; and minimal detectable change based on a 95% CI, 18.5 repetitions. The ICC values for individual tasks ranged from 0.80 to 0.94 (95% CI range, 0.44-0.98). The reliability for the patient group was 0.83 (95% CI: 0.51, 0.94). Conclusion The TFAST was sensitive to detect differences in functional performance between age groups, demonstrated adequate between-session reliability, and demonstrated feasibility in a symptomatic patient group. Further assessment is needed to refine the TFAST. Development of a feasible and valid test of arm function would enhance clinical evaluation and outcome measurement. J Orthop Sports Phys Ther 2017;47(6):420-431. Epub 3 Mar 2017. doi:10.2519/jospt.2017.7136.

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.

Effects of shoulder muscle fatigue caused by repetitive overhead activities on scapulothoracic and glenohumeral kinematics.

The purpose of this study was to determine the effects of shoulder muscle fatigue on three dimensional scapulothoracic and glenohumeral kinematics. Twenty healthy subjects participated in this study. Three-dimensional scapulothoracic and glenohumeral kinematics were determined from electromagnetic sensors attached to the scapula, humerus, and thorax. Surface electromyographic (EMG) data were collected from the upper and lower trapezius, serratus anterior, anterior and posterior deltoid, and infraspinatus muscles. Median power frequency (MPF) values were derived from the raw EMG data and were used to indicate the degree of local muscle fatigue. Kinematic and EMG measures were collected prior to and immediately following the performance of a shoulder elevation fatigue protocol. Following the performance of the fatigue protocol subjects demonstrated more upward and external rotation of the scapula, more clavicular retraction, and less humeral external rotation during arm elevation. All muscles with the exception of the lower trapezius showed EMG signs of fatigue, the most notable being the infraspinatus and deltoid muscles. In general, greater scapulothoracic motion and less glenohumeral motion was observed following muscle fatigue. Further studies are needed to determine what effects these changes have on the soft tissues and mechanics of the shoulder complex.

Scapulothoracic and glenohumeral kinematics following an external rotation fatigue protocol.

STUDY DESIGN: Repeated-measures experimental design. OBJECTIVE: To determine the effects of shoulder external rotator muscle fatigue on 3-dimensional scapulothoracic and glenohumeral kinematics. BACKGROUND: The external rotator muscles of the shoulder are important for normal shoulder function. Impaired performance of these muscles has been observed in subjects with impingement syndrome and it is possible that external rotator muscle fatigue leads to altered kinematics of the shoulder girdle. METHODS AND MEASURES: Twenty subjects without a history of shoulder pathology participated in this study. Three-dimensional scapulothoracic and glenohumeral kinematics were determined from electromagnetic sensors attached to the scapula, humerus, and thorax. Surface electromyographic (EMG) data were collected from the upper and lower trapezius, serratus anterior, anterior and posterior deltoid, and infraspinatus muscles. Median power frequency (MPF) values were derived from the raw EMG data and were used to indicate the degree of local muscle fatigue. Kinematic and EMG measures were collected prior to and immediately following the performance of a shoulder external rotation fatigue protocol. RESULTS: After completing the fatigue protocol subjects demonstrated less external rotation of the humerus. Additionally, they had less posterior tilt of the scapula in the beginning phase of arm elevation, and more scapular upward rotation and clavicular retraction in the mid ranges of arm elevation. CONCLUSIONS: Performance of an external rotation fatigue protocol results in altered scapulothoracic and glenohumeral kinematics. Further studies are needed to investigate the effects of external rotator muscle fatigue on scapulothoracic and glenohumeral kinematics in subjects with shoulder pathology.

Three-dimensional scapulothoracic motion during active and passive arm elevation.

BACKGROUND: Scapulothoracic muscle activity is believed to be important for normal scapulothoracic motion. In particular, the trapezius and serratus anterior muscles are believed to play an important role in the production and control of scapulothoracic motion. The aim of this study was to determine the effects of different levels of muscle activity (active versus passive arm elevation) on three-dimensional scapulothoracic motion. METHODS: Twenty subjects without a history of shoulder pathology participated in this study. Three-dimensional scapulothoracic motion was determined from electromagnetic sensors attached to the scapula, thorax and humerus during active and passive arm elevation. Muscle activity was recorded from surface electrodes over the upper and lower trapezius, serratus anterior, anterior and posterior deltoid, and infraspinatus muscles. Differences in scapulothoracic motion were calculated between active and passive arm elevation conditions. FINDINGS: Scapular motion was observed during the trials of passive arm elevation; however, there was more upward rotation of the scapula, external rotation of the scapula, clavicular retraction, and clavicular elevation under the condition of active arm elevation. This was most pronounced for scapular upward rotation through the mid-range (90-120 degrees) of arm elevation. INTERPRETATION: The upper and lower trapezius and serratus anterior muscles have an important role in producing upward rotation of the scapula especially throughout the mid-range of arm elevation. Additionally, it appears that capsuloligamentous and passive muscle tension contribute to scapulothoracic motion during arm elevation. Assessment of the upper and lower trapezius and serratus anterior muscles and upward rotation of the scapula should be part of any shoulder examination.

Staged Approach for Rehabilitation Classification: Shoulder Disorders (STAR-Shoulder).

Shoulder disorders are a common musculoskeletal problem causing pain and functional loss. Traditionally, diagnostic categories are based on a pathoanatomic medical model aimed at identifying the pathologic tissues. However, the pathoanatomic model may not provide diagnostic categories that effectively guide treatment decision making in rehabilitation. An expanded classification system is proposed that includes the pathoanatomic diagnosis and a rehabilitation classification based on tissue irritability and identified impairments. For the rehabilitation classification, 3 levels of irritability are proposed and defined, with corresponding strategies guiding intensity of treatment based on the physical stress theory. Common impairments are identified and are used to guide specific intervention tactics with varying levels of intensity. The proposed system is conceptual and needs to be tested for reliability and validity. This classification system may be useful clinically for guiding rehabilitation intervention and provides a potential method of identifying relevant subgroups in future research studies. Although the system was developed for and applied to shoulder disorders, it may be applicable to classification and rehabilitation of musculoskeletal disorders in other body regions.

Shoulder function and 3-dimensional kinematics in people with shoulder impingement syndrome before and after a 6-week exercise program.

BACKGROUND AND PURPOSE: Shoulder impingement syndrome is a common condition and is often managed with an exercise program. The purpose of this study was to examine an exercise program in patients with shoulder impingement syndrome. Specifically, the purpose was to identify changes that might occur in 3-dimensional scapular kinematics, physical impairments, and functional limitations. SUBJECTS: Fifty-nine patients with impingement syndrome were recruited, and 39 patients successfully completed the 6-week rehabilitation program and follow-up testing. Impingement was defined as having at least 3 of 6 predefined clinical signs or symptoms. METHODS: Subjects were assessed before and after a 6-week rehabilitation program and again at 6 months. Pain, satisfaction, and function were measured using the University of Pennsylvania Shoulder Scale. Range of motion, isometric muscle force, and 3-dimensional scapular kinematic data also were collected. Subjects were given a progressive exercise program that included resistive strengthening, stretching, and postural exercises that were done daily at home. Subjects also were given shoulder education related to anatomy, the basic mechanics of impingement, and strategies for reducing load on the shoulder. Each subject attended one physical therapy session per week for a 6-week period, primarily for monitoring and upgrading the exercise program. Pretest and posttest scores were compared using paired t tests and repeated-measures analysis of variance. RESULTS: Passive range of motion increased for both external and internal rotation but not for elevation. Abduction external and internal rotation force all increased. There were no differences in scapular kinematics. Improvements were found for pain, satisfaction, and shoulder function and for Medical Outcomes Study 36-Item Short-Form Health Survey (SF-36) scores related to physical function. At 6-month follow-up, improvements made in pain, satisfaction, and function were maintained. DISCUSSION AND CONCLUSION: The use of this exercise protocol in the management of shoulder impingement syndrome may have a positive impact on patients' impairments and functional limitations. Our findings suggest a relatively simple exercise program combined with patient education may be effective and, therefore, merits study in a larger trial using a control group. Changes in scapular kinematics did not appear to be a primary mechanism underlying improvement in symptoms and function.

Anatomical and biomechanical mechanisms of subacromial impingement syndrome.

Subacromial impingement syndrome is the most common disorder of the shoulder, resulting in functional loss and disability in the patients that it affects. This musculoskeletal disorder affects the structures of the subacromial space, which are the tendons of the rotator cuff and the subacromial bursa. Subacromial impingement syndrome appears to result from a variety of factors. Evidence exists to support the presence of the anatomical factors of inflammation of the tendons and bursa, degeneration of the tendons, weak or dysfunctional rotator cuff musculature, weak or dysfunctional scapular musculature, posterior glenohumeral capsule tightness, postural dysfunctions of the spinal column and scapula and bony or soft tissue abnormalities of the borders of the subacromial outlet. These entities may lead to or cause dysfunctional glenohumeral and scapulothoracic movement patterns. These various mechanisms, singularly or in combination may cause subacromial impingement syndrome.