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.

Roles And Responsibilities Of The Physical Therapist In Collegiate Athletics: Results Of A National Survey.

Background: Over the past decade, there has been an increased focus on collaboration within collegiate athletics based sports medicine. Specifically, athletic trainers (ATs) and physical therapists (PTs) are working together, often side-by-side, to provide optimal care for the injured athlete. However, the roles and responsibilities of the PT within this model are currently not well described. Purpose: The purpose of this study was to identify educational training, credentials, roles, and responsibilities of the PT working with collegiate athletes. Study Design: Cross-sectional survey. Methods: An anonymous, descriptive online survey focusing on the demographic and occupational characteristics of PTs providing care for collegiate athletes was created and distributed electronically through the American Academy of Sports Physical Therapy (AASPT), a subgroup within the American Physical Therapy Association (APTA). Results: One hundred forty eligible responses were included. Sixty-four percent (90/140) of the respondents were male; 86% of the respondents (120/140) reported working in the National Collegiate Athletic Association (NCAA) Division I setting. Half (70/140) of respondents were also ATs, and 60% (83/140) were board-certified sports clinical specialists (SCS). All respondents (140/140) provide rehabilitation exercises; nearly all provide sports performance enhancement and manual therapy (97%, 136/140 and 96%, 135/140, respectively). Other identified roles and responsibilities included communication with the athletic training staff, event coverage, and personnel management. Conclusions: The role of the PT within collegiate athletics sports medicine is highly varied; years of experience, certification, credentials, and location of patient care are also variable. Clinical Relevance: PTs working in a collegiate athletics sports medicine setting have many paths to entry and diverse job duties. PTs interested in working in this setting should prioritize developing relevant experience and communication skills. Level of Evidence: Level 3b.

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.

Kinematics and biomechanical validity of shoulder joint laxity tests as diagnostic criteria in multidirectional instability.

BACKGROUND: Clinical laxity tests are commonly used together to identify individuals with multidirectional instability (MDI). However, their biomechanical validity in distinguishing distinct biomechanical characteristics consistent with MDI has not been demonstrated. OBJECTIVE: To determine if differences in glenohumeral (GH) joint laxity exist between individuals diagnosed with multidirectional instability (MDI) and asymptomatic matched controls without MDI. METHODS: Eighteen participants (9 swimmers with MDI, 9 non-swimming asymptomatic matched controls without MDI) participated in this observational study. Participants were classified as having MDI with a composite laxity score from three laxity tests (anterior/posterior drawer and sulcus tests). Single plane dynamic fluoroscopy captured joint motion with 2D-3D joint registration to derive 3D joint kinematics. Average GH translations occurring during the laxity tests were compared between groups using an independent sample's t-test. The relationship of composite laxity scores to overall translations was examined with a simple linear regression. Differences of each laxity test translation between groups were analyzed with a two-way repeated measures ANOVA. RESULTS: Mean composite translations for swimmers were 1.7 mm greater (p = 0.04, 95% Confidence Interval (CI): 0.1, 3.3 mm) compared to controls. A moderate association occurred (r2 = 0.40, p = 0.005) between composite laxity scores and composite translation. Greater translations for the posterior drawer (-2.4 mm, p = 0.04, 95% CI: -0.1, -4.6) and sulcus tests (-2.7 mm, p = 0.03, 95% CI: -0.3, -5.0) existed in swimmers compared to controls. CONCLUSION: Significant differences in composite translation existed between symptomatic swimmers with MDI and asymptomatic control participants without MDI during GH joint laxity tests. The results provide initial biomechanically based construct validity for the clinical criteria used to identify individuals with MDI.

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.

The effect of glenohumeral plane of elevation on supraspinatus subacromial proximity.

Shoulder pain is a common clinical problem affecting most individuals in their lifetime. Despite the high prevalence of rotator cuff pathology in these individuals, the pathogenesis of rotator cuff disease remains unclear. Position and motion related mechanisms of rotator cuff disease are often proposed, but poorly understood. The purpose of this study was to determine the impact of systematically altering glenohumeral plane on subacromial proximities across arm elevation as measures of tendon compression risk. Three-dimensional models of the humerus, scapula, coracoacromial ligament, and supraspinatus were reconstructed from MRIs in 20 subjects. Glenohumeral elevation was imposed on the humeral and supraspinatus tendon models for three glenohumeral planes, which were chosen to represent flexion, scapular plane abduction, and abduction based on average values from a previous study of asymptomatic individuals. Subacromial proximity was quantified as the minimum distance between the supraspinatus tendon and coracoacromial arch (acromion and coracoacromial ligament), the surface area of the supraspinatus tendon within 2 mm proximity to the coracoacromial arch, and the volume of intersection between the supraspinatus tendon and coracoacromial arch. The lowest modeled subacromial supraspinatus compression measures occurred during flexion at lower angles of elevation. This finding was consistent across all three measures of subacromial proximity. Knowledge of this range of reduced risk may be useful to inform future studies related to patient education and ergonomic design to prevent the development of shoulder pain and dysfunction.

CHANGING OUR DIAGNOSTIC PARADIGM: MOVEMENT SYSTEM DIAGNOSTIC CLASSIFICATION.

Proper diagnosis is a first step in applying best available treatments, and prognosticating outcomes for clients. Currently, the majority of musculoskeletal diagnoses are classified according to pathoanatomy. However, the majority of physical therapy treatments are applied toward movement system impairments or pain. While advocated within the physical therapy profession for over thirty years, diagnostic classification within a movement system framework has not been uniformly developed or adopted. We propose a basic framework and rationale for application of a movement system diagnostic classification for atraumatic shoulder pain conditions, as a case for the broader development of movement system diagnostic labels. Shifting our diagnostic paradigm has potential to enhance communication, improve educational efficiency, facilitate research, directly link to function, improve clinical care, and accelerate preventive interventions.

Effect of glenohumeral elevation on subacromial supraspinatus compression risk during simulated reaching.

Mechanical subacromial rotator cuff compression is one theoretical mechanism in the pathogenesis of rotator cuff disease. However, the relationship between shoulder kinematics and mechanical subacromial rotator cuff compression across the range of humeral elevation motion is not well understood. The purpose of this study was to investigate the effect of humeral elevation on subacromial compression risk of the supraspinatus during a simulated functional reaching task. Three-dimensional anatomical models were reconstructed from shoulder magnetic resonance images acquired from 20 subjects (10 asymptomatic, 10 symptomatic). Standardized glenohumeral kinematics from a simulated reaching task were imposed on the anatomic models and analyzed at 0, 30, 60, and 90° humerothoracic elevation. Five magnitudes of humeral retroversion were also imposed on the models at each angle of humerothoracic elevation to investigate the impact of retroversion on subacromial proximities. The minimum distance between the coracoacromial arch and supraspinatus tendon and footprint were quantified. When contact occurred, the magnitude of the intersecting volume between the supraspinatus tendon and coracoacromial arch was also quantified. The smallest minimum distance from the coracoacromial arch to the supraspinatus footprint occurred between 30 and 90°, while the smallest minimum distance to the supraspinatus tendon occurred between 0 and 60°. The magnitude of humeral retroversion did not significantly affect minimum distance to the supraspinatus tendon except at 60 or 90° humerothoracic elevation. The results of this study provide support for mechanical rotator cuff compression as a potential mechanism for the development of rotator cuff disease. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:2329-2337, 2017.

Comparison of 3-dimensional shoulder complex kinematics in individuals with and without shoulder pain, part 2: glenohumeral joint.

STUDY DESIGN: Cross-sectional. OBJECTIVES: To compare differences in glenohumeral joint angular motion and linear translations between symptomatic and asymptomatic individuals during shoulder motion performed in 3 planes of humerothoracic elevation. BACKGROUND: Numerous clinical theories have linked abnormal glenohumeral kinematics, including decreased glenohumeral external rotation and increased superior translation, to individuals with shoulder pain and impingement diagnoses. However, relatively few studies have investigated glenohumeral joint angular motion and linear translations in this population. METHODS: Transcortical bone pins were inserted into the scapula and humerus of 12 asymptomatic and 10 symptomatic participants for direct bone-fixed tracking using electromagnetic sensors. Glenohumeral joint angular positions and linear translations were calculated during active shoulder flexion, abduction, and scapular plane abduction. RESULTS: Differences between groups in angular positions were limited to glenohumeral elevation, coinciding with a reduction in scapulothoracic upward rotation. Symptomatic participants demonstrated 1.4 mm more anterior glenohumeral translation between 90° and 120° of shoulder flexion and an average of 1 mm more inferior glenohumeral translation throughout shoulder abduction. CONCLUSION: Differences in glenohumeral kinematics exist between symptomatic and asymptomatic individuals. The clinical implications of these differences are not yet understood, and more research is needed to understand the relationship between abnormal kinematics, shoulder pain, and pathoanatomy.