Comparison of rotator cuff to glenoid proximity based on scapulothoracic upward rotation classification.

BACKGROUND: Recent evidence suggests that internal impingement, or rotator cuff tendon deformation against the glenoid, occurs during overhead motions and may therefore be a mechanism of pathology even in non-athletes. Clinically, knowing how movement impacts potential injury mechanisms would be useful to guide movement-based treatment strategies. OBJECTIVE: To compare the distance between the glenoid and rotator cuff footprint between two groups classified based on scapulothoracic upward rotation (UR) magnitude (i.e., low, high) at 90° humerothoracic elevation. METHODS: Shoulder kinematics were quantified during scapular plane abduction in 60 participants using single-plane fluoroscopy. Of these, 40 were subsequently classified as having high or low scapulothoracic UR based on the sample's distribution. The minimum distance between the glenoid and rotator cuff footprint was calculated along with the locations of closest proximity (i.e., proximity centers). Minimum distances and proximity center locations were compared between groups using 2-factor mixed-model ANOVAs. The prevalence of glenoid-to-footprint contact was also compared. RESULTS: Glenoid-to-footprint distances consistently decreased as humerothoracic elevation angle increased, and the anterior aspect of the footprint was closest to the posterosuperior glenoid. Minimum distances were not significantly different between UR groups (p≥0.16). However, group differences existed in proximity center locations (p<0.01). Glenoid-to-footprint contact was identified in 75.0% of participants at an average (SD) of 133.6° (3.2°) humerothoracic elevation. CONCLUSION: The results of this study suggest that decreased UR as classified and assessed in this study does not significantly impact glenoid-to-footprint distances but does alter the location of the contact, which occurred in most participants.

National Collegiate Athletic Association Swimmers With Glenohumeral Multidirectional Laxity Have an Increased Glenohumeral Joint Range of Motion Profile.

CONTEXT: Adaptations in glenohumeral joint laxity and range of motion (ROM) are prevalent in competitive swimmers. Increased glenohumeral laxity in swimmers has been found to exist in multiple directions. However, it is unclear if swimmers with multidirectional laxity (MDL) possess altered glenohumeral ROM compared with swimmers without MDL. The purpose of this study was to compare the glenohumeral ROM characteristics of external rotation (ER), internal rotation (IR), total arc of motion (ER + IR), and total arc of motion ratio (ER/IR) between swimmers with MDL and without MDL. Our secondary objective was to investigate the effect of MDL on self-reported pain and function. DESIGN: Observational study. METHODS: Twenty-nine NCAA Division I swimmers (females: 15 and males: 14; age 19.5 [1.2] y; body mass index 23.9 [2.0] km/m2) participated in a preseason physical assessment including measures of glenohumeral ROM and joint laxity. These measures were used to determine the presence or absence of MDL for both shoulders of each participant. Glenohumeral ROM characteristics were compared between shoulders with MDL and shoulders without MDL with independent t tests. Self-reported pain and function scores were recorded biweekly across the season with a modified Kerlan-Jobe Orthopedic Clinic questionnaire. The seasonal average Kerlan-Jobe Orthopedic Clinic questionnaire scores were compared between swimmers with MDL and swimmers without MDL with analysis of variance, with factors of sex and MDL status. RESULTS: Shoulders with MDL possessed increased glenohumeral IR (P < .001; effect size: 0.65) and total arc of motion (P < .004; effect size: 0.45) compared with shoulders without MDL. There were no differences in ER. There was no difference in self-reported pain and function between groups. CONCLUSIONS: Shoulders with MDL possess increased glenohumeral IR and total arc of motion compared with shoulders without MDL. The presence of MDL may not affect self-reported pain and function in competitive swimmers.

Changing our Diagnostic Paradigm Part II: Movement System Diagnostic Classification.

Diagnostic classification is a foundational underpinning of providing care of the highest quality and value. Diagnosis is pattern recognition that can result in categories of conditions that ideally direct treatment. While pathoanatomic diagnoses are common and traditional in orthopaedic practice, they often are limited with regard to directing best practice physical therapy intervention. Replacement of pathoanatomic labels with non-specific regional pain labels has been proposed, and occurs frequently in clinical practice. For example non-specific low back pain or shoulder pain of unknown origin. These labels avoid some disadvantages of tissue specific pathoanatomic labels, but are not specific enough to direct treatment. A previously introduced movement system diagnostic framework is proposed and updated with application to shoulder conditions. This framework has potential for broad development and application across musculoskeletal physical therapist practice. Movement system diagnostic classification can advance and streamline practice if considered while recognizing the inherent movement variability across individuals.

The effect of tactile and verbal guidance during scapulothoracic exercises: An EMG and kinematic investigation.

BACKGROUND: Clinician-led training through tactile and verbal guidance to improve muscle activity and joint motion are a common but understudied focus of therapeutic interventions for shoulder pain. The purpose of this study was to determine if clinician guidance changes scapulothoracic muscle activity and kinematics compared to unguided shoulder exercises. METHODS: Eleven participants with shoulder pain were studied. Electromyographic (EMG) sensors were placed on the serratus anterior and upper and lower trapezii. Scapulothoracic and sternoclavicular kinematics were collected using electromagnetic sensors. Five common resisted shoulder exercises were performed with the following guidance: unguided, combined (verbal and tactile cues), and verbal guidance only. One-way repeated measures ANOVAs determined the effect of guidance versus unguided conditions for each exercise. RESULTS: Nine of ten combinations of exercise and guidance techniques demonstrated a significant effect of guidance for either muscle activity or joint kinematics. The guidance condition with the most frequent significant improvements across all variables was the combined condition. The exercises with the most frequent significant improvements across all variables were the external rotation exercises. Variables improved most frequently were: upper:lower trapezius EMG ratio (up to 11%), sternoclavicular elevation (up to 6°) and scapulothoracic internal rotation positioning (up to 8°), and sternoclavicular retraction displacement (up to 5°). CONCLUSION: Shoulder muscle activity and kinematics during exercises can be modified by tactile and verbal guidance. Most improvements in muscle activity occurred with verbal guidance during external rotation exercises. Most improvements in joint positioning and movement occurred with combined guidance during external rotation exercises.

Supraspinatus-to-Glenoid Contact Occurs During Standardized Overhead Reaching Motion.

BACKGROUND: Rotator cuff tears may result from repeated mechanical deformation of the cuff tendons, and internal impingement of the supraspinatus tendon against the glenoid is one such proposed mechanism of deformation. PURPOSE: To (1) describe the changing proximity of the supraspinatus tendon to the glenoid during a simulated overhead reaching task and (2) determine the relationship between scapular morphology and this proximity. Additionally, the patterns of supraspinatus-to-glenoid proximity were compared with previously described patterns of supraspinatus-to-coracoacromial arch proximity. STUDY DESIGN: Descriptive laboratory study. METHODS: Shoulder models were created from magnetic resonance images of 20 participants. Standardized kinematics were imposed on the models to simulate functional reaching, and the minimum distances between the supraspinatus tendon and the glenoid and the supraspinatus footprint and the glenoid were calculated every 5° between 0° and 150° of humerothoracic elevation. The angle at which contact between the supraspinatus and the glenoid occurred was documented. Additionally, the relationship between glenoid morphology (version and inclination) and the contact angle was evaluated. Descriptive statistics were calculated for the minimum distances, and glenoid morphology was assessed using Pearson correlation coefficients and simple linear regressions. RESULTS: The minimum distances between the tendon and the glenoid and between the footprint and the glenoid decreased as elevation increased. Contact between the tendon and the glenoid occurred in all participant models at a mean elevation of 123° ± 10°. Contact between the footprint and the glenoid occurred in 13 of 20 models at a mean of 139° ± 10°. Less glenoid retroversion was associated with lower tendon-to-glenoid contact angles (r = -0.76; R 2 = 0.58; P < .01). CONCLUSION: This study found that the supraspinatus tendon progressively approximated the glenoid during simulated overhead reaching. Additionally, all participant models eventually made contact with the glenoid by 150° of humerothoracic elevation, although anatomic factors influenced the precise angle at which contact occurred. CLINICAL RELEVANCE: Contact between the supraspinatus and the glenoid may occur frequently within the range of elevation required for overhead activities. Therefore, internal impingement may be a prevalent mechanism for rotator cuff deformation that could contribute to cuff pathology.