Quantitative Musculoskeletal Imaging of the Pediatric Shoulder.

ABSTRACT: Pediatric acquired and congenital conditions leading to shoulder pain and dysfunction are common. Objective, quantitative musculoskeletal imaging-based measures of shoulder health in children lag recent developments in adults. We review promising applications of quantitative imaging that tend to be available for common pediatric shoulder pathologies, especially brachial plexus birth palsy and recurrent shoulder instability, and imaging-related considerations of musculoskeletal growth and development of the shoulder. We highlight the status of quantitative imaging practices for the pediatric shoulder and highlight gaps where better care may be provided with advances in imaging technique and/or technology.

Older age is associated with decreased overall shoulder strength but not direction-specific differences in the three-dimensional feasible torque space.

Shoulder strength is reduced in older adults but has only been assessed in planar motions that do not reflect the diverse requirements of daily tasks. We quantified the impact of age on strength spanning the three degrees of freedom relevant to shoulder function, referred to as the feasible torque space. We hypothesized that the feasible torque space would differ with age and expected this age-effect to reflect direction-specific deficits. We measured strength in 32 directions to characterize the feasible torque space of the shoulder in participants without shoulder pain or tendinous pathology (n = 39, 19-86 years). We modeled the feasible torque space for each participant as an ellipsoid, computed the ellipsoid size and direction-specific metrics (ellipsoid position, orientation, and shape), and then tested the effect of age on each metric. Age was negatively associated with ellipsoid size (a measure of overall strength magnitude; -0.0033 ± 0.0007 (Nm/kg)/year, p < 0.0001). Contrary to our expectation, the effect of age on the direction-specific metrics did not reach statistical significance. The effect of age did not differ significantly between male and female participants. Three-dimensional strength measurements allowed us to constrain the direction of participants' maximum torque production and characterize the entire feasible torque space. Our findings support a generalized shoulder strengthening program to address age-related shoulder weakness in those without pain or pathology. Clinical exam findings of imbalanced weakness may suggest underlying pathology beyond an effect of age. Longitudinal studies are needed to determine the positive or negative impact of our results.

External Rotation Strength After TSA in Osteoarthritic Shoulders with Eccentric Deformity Is Not Impacted by Posterior Rotator Cuff Deficiency.

Background: Patients with persistent glenohumeral osteoarthritis symptoms despite nonoperative management may pursue anatomic total shoulder arthroplasty (TSA). TSA revision rates are higher in patients with preoperative eccentric (asymmetric posterior erosion) compared with concentric (symmetric) glenoid deformity. If posterior rotator cuff deficiency demonstrated preoperatively in patients with eccentric deformity persists after TSA, it may manifest as relative weakness in external compared with internal rotation secondary to deficient activity of the shoulder external rotator muscles. Persistent posterior rotator cuff deficiency is hypothesized to contribute to TSA failures. However, it remains unknown whether rotational strength is impaired after TSA in patients with eccentric deformity. Our goal was to determine if patients with eccentric deformity exhibit relative external rotation weakness that may be explained by posterior rotator cuff deficiency after TSA. Methods: Patients who were >1 year after TSA for primary glenohumeral osteoarthritis and had had preoperative eccentric or concentric deformity were prospectively recruited. Torque was measured and electromyography was performed during maximal isometric contractions in 26 three-dimensional direction combinations. Relative strength in opposing directions (strength balance) and muscle activity of 6 shoulder rotators were compared between groups. Results: The internal (+) and external (-) rotation component of strength balance did not differ in patients with eccentric (mean internal-external rotation component of strength balance: -7.6% ± 7.4%) compared with concentric deformity (-10.3% ± 6.8%) (mean difference: 2.7% [95% confidence interval (CI), -1.3% to 6.7%]; p = 0.59), suggesting no relative external rotation weakness. Infraspinatus activity was reduced in patients with eccentric (43.9% ± 10.4% of maximum voluntary contraction [MVC]) compared with concentric (51.3% ± 10.4% of MVC) deformity (mean difference: -7.4% [95% CI, -13.4% to -1.4%] of MVC; p = 0.04). Conclusions: A relative external rotation strength deficit following TSA was not found, despite evidence of reduced infraspinatus activity, in the eccentric-deformity group. Reduced infraspinatus activity suggests that posterior rotator cuff deficiencies may persist following TSA in patients with eccentric deformities. Longitudinal study is necessary to evaluate muscle imbalance as a contributor to higher TSA failure rates. Level of Evidence: Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Physical Therapist Management of Glenohumeral Joint Osteoarthritis: A Clinical Practice Guideline from the American Physical Therapy Association.

A clinical practice guideline on glenohumeral joint osteoarthritis was developed by an American Physical Therapy Association volunteer guideline development group that consisted of physical therapists, an occupational therapist, and a physician. The guideline was based on systematic reviews of current scientific and clinical information and accepted approaches for physical therapist management of glenohumeral joint osteoarthritis. This clinical practice guideline is available in Spanish; see Supplementary Appendix 8.

Missing The Forest For The Trees: A Lack Of Upper Extremity Physical Performance Testing In Sports Physical Therapy.

Background: Despite shoulder and elbow injuries being common in athletics, return to sport and reinjury rates are less than ideal. These outcomes may be driven by the absence of evidence-informed testing to determine an athlete's readiness for sport. Purpose: The purpose of this study was to explore the reported frequency of physical performance testing for return to sport readiness by physical therapists treating athletes with upper extremity injuries and to identify potential barriers that may limit use of these tests. A secondary aim was to compare practice patterns of clinicians with sports physical therapy specialty certification to clinicians without. Study Design: International, cross-sectional survey using purposive sampling. Methods: A survey instrument was created to assess the frequency of use of physical performance tests by physical therapists treating athletes with upper extremity injuries, as well as the barriers limiting the use of these tests. The 19-question online survey was distributed via email and Twitter among sports physical therapists. Independent t-tests and Chi Square analyses were conducted to determine differences in practice patterns between physical therapists with and without specialization and the frequency of potential barriers that may limit the use of these tests. Results: Four hundred ninety-eight participants met study eligibility and completed the survey. Fewer than half of participants reported using any physical performance test in making return to sport decisions for athletes with upper extremity injuries. The greatest barriers to the use of physical performance tests were a lack of equipment followed by lack of understanding of the literature, lack of time, and lack of supporting literature. Sports specialist clinicians were significantly more likely (p<0.001) to use physical performance tests than non-specialist clinicians (71.6% versus 36.3%). Conclusion: In this survey of physical therapists (n=498), the majority admit to not using physical performance tests when making return to sport decisions for athletes with upper extremity injuries regardless of specialization.Physical therapists have an opportunity to improve the utilization physical performance testing in the upper extremity athlete in hopes of reducing injury recurrence and enhance return to sport rates. Level of Evidence: Level 3b.

Patient Perspectives on Seeking Emergency Care for Acute Low Back Pain and Access to Physical Therapy in the Emergency Department.

STUDY OBJECTIVE: Low back pain is a common reason for visiting the emergency department (ED), yet little is known about patient motivations for seeking emergency care. The purpose of this study was to explore patient perspectives on visiting the ED for low back pain to inform a more patient-centered approach to emergency care. METHODS: We conducted focus group discussions and individual interviews among patients visiting an urban academic ED for acute low back pain. We recruited participants from an ongoing prospective study of 101 patients receiving either ED-initiated physical therapy or usual care. We conducted discussions, and interviews using an a priori developed discussion guide. We audio recorded, transcribed, and iteratively content analyzed the data using a consensual qualitative approach until thematic saturation was reached. RESULTS: We conducted 4 focus group discussions among 18 participants (median age 46.5 years, 66.7% women, 61.1% Black) and individual interviews with 27 participants (median age 45 years, 55.6% women, 44.4% White). No new themes emerged during the fourth and final focus group. We identified 5 summary themes: (1) the decision to seek emergency care for low back pain is motivated by severe pain, resulting disability, and fears about a catastrophic diagnosis, (2) participants sought various goals from their ED visit but emphasized the primacy of pain control, (3) participants were reluctant to use pain medications but also acknowledged their benefit, (4) participants perceived a number of benefits from direct access to an ED physical therapist in the ED, and (5) participation in physical therapy ultimately facilitated recovery, but the pain was a barrier to performing exercises. CONCLUSIONS: These patient perspectives and resulting themes may be used to inform a more patient-centered emergency care experience and contextualize quantitative research findings on ED care for low back pain.

No Strength Differences Despite Greater Posterior Rotator Cuff Intramuscular Fat in Patients With Eccentric Glenohumeral Osteoarthritis.

BACKGROUND: When nonoperative measures do not alleviate the symptoms of glenohumeral osteoarthritis (OA), patients with advanced OA primarily are treated with anatomic total shoulder arthroplasty (TSA). It is unknown why TSAs performed in patients with eccentric (asymmetric glenoid wear) compared with concentric (symmetric glenoid wear) deformities exhibit higher failure rates, despite surgical advances. Persistent disruption of the posterior-to-anterior rotator cuff (RC) force couple resulting from posterior RC intramuscular degeneration in patients with eccentric deformities could impair external rotation strength and may contribute to eventual TSA failure. Pain and intramuscular fat within the RC muscles may impact external rotation strength measures and are important to consider. QUESTIONS/PURPOSES: (1) Is there relative shoulder external rotation weakness in patients with eccentric compared with concentric deformities? (2) Is there higher resting or torque-dependent pain in patients with eccentric compared with concentric deformities? (3) Do patients with eccentric deformities have higher posterior-to-anterior RC intramuscular fat percent ratios than patients with concentric deformities? METHODS: From February 2020 to November 2021, 65% (52 of 80) of patients with OA met study eligibility criteria. Of these, 63% (33 of 52) of patients enrolled and provided informed consent. From a convenience sample of 21 older adults with no history of shoulder pain, 20 met eligibility criteria as control participants. Of the convenience sample, 18 patients enrolled and provided informed consent. In total for this prospective, cross-sectional study, across patients with OA and control participants, 50% (51 of 101) of participants were enrolled and allocated into the eccentric (n = 16), concentric (n = 17), and control groups (n = 18). A 3-degree-of-freedom load cell was used to sensitively quantify strength in all three dimensions surrounding the shoulder. Participants performed maximal isometric contractions in 26 1-, 2-, and 3-degree-of-freedom direction combinations involving adduction/abduction, internal/external rotation, and/or flexion/extension. To test for relative external rotation weakness, we quantified relative strength in opposing directions (three-dimensional [3D] strength balance) along the X (+adduction/-abduction), Y (+internal/-external rotation), and Z (+flexion/-extension) axes and compared across the three groups. Patients with OA rated their shoulder pain (numerical rating 0-10) before testing at rest (resting pain; response to "How bad is your pain today?") and with each maximal contraction (torque-dependent pain; numerical rating 0-10). Resting and torque-dependent pain were compared between patients with eccentric and concentric deformities to determine if pain was higher in the eccentric group. The RC cross-sectional areas and intramuscular fat percentages were quantified on Dixon-sequence MRIs by a single observer who performed manual segmentation using previously validated methods. Ratios of posterior-to-anterior RC fat percent (infraspinatus + teres minor fat percent/subscapularis fat percent) were computed and compared between the OA groups. RESULTS: There was no relative external rotation weakness in patients with eccentric deformities (Y component of 3D strength balance, mean ± SD: -4.7% ± 5.1%) compared with patients with concentric deformities (-0.05% ± 4.5%, mean difference -4.7% [95% CI -7.5% to -1.9%]; p = 0.05). However, there was more variability in 3D strength balance in the eccentric group (95% CI volume, % 3 : 893) compared with the concentric group (95% CI volume, % 3 : 579). In patients with eccentric compared with concentric deformities, there was no difference in median (IQR) resting pain (1.0 [3.0] versus 2.0 [2.3], mean rank difference 4.5 [95% CI -6.6 to 16]; p = 0.61) or torque-dependent pain (0.70 [3.0] versus 0.58 [1.5], mean rank difference 2.6 [95% CI -8.8 to 14]; p = 0.86). In the subset of 18 of 33 patients with OA who underwent MRI, seven patients with eccentric deformities demonstrated a higher posterior-to-anterior RC fat percent ratio than the 11 patients with concentric deformities (1.2 [0.8] versus 0.70 [0.3], mean rank difference 6.4 [95% CI 1.4 to 11.5]; p = 0.01). CONCLUSION: Patients with eccentric deformities demonstrated higher variability in strength compared with patients with concentric deformities. This increased variability suggests patients with potential subtypes of eccentric wear patterns (posterior-superior, posterior-central, and posterior-inferior) may compensate differently for underlying anatomic changes by adopting unique kinematic or muscle activation patterns. CLINICAL RELEVANCE: Our findings highlight the importance of careful clinical evaluation of patients presenting with eccentric deformities because some may exhibit potentially detrimental strength deficits. Recognition of such strength deficits may allow for targeted rehabilitation. Future work should explore the relationship between strength in patients with specific subtypes of eccentric wear patterns and potential forms of kinematic or muscular compensation to determine whether these factors play a role in TSA failures in patients with eccentric deformities.

Embedded emergency department physical therapy versus usual care for acute low back pain: a protocol for the NEED-PT randomised trial.

INTRODUCTION: Low back pain is a common problem and a substantial source of morbidity and disability worldwide. Patients frequently visit the emergency department (ED) for low back pain, but many experience persistent symptoms at 3 months despite frequent receipt of opioids. Although physical therapy interventions have been demonstrated to improve patient functioning in the outpatient setting, no randomised trial has yet to evaluate physical therapy in the ED setting. METHODS AND ANALYSIS: This is a single-centre cluster-randomised trial of an embedded ED physical therapy intervention for acute low back pain. We used a covariate-constrained approach to randomise individual physicians (clusters) at an urban academic ED in Chicago, Illinois, USA, to receive, or not receive, an embedded physical therapist on their primary treatment team to evaluate all patients with low back pain. We will then enrol individual ED patients with acute low back pain and allocate them to the embedded physical therapy or usual care study arms, depending on the randomisation assignment of their treating physician. We will follow patients to a primary endpoint of 3 months and compare a primary outcome of change in PROMIS-Pain Interference score and secondary outcomes of change in modified Oswestry Disability Index score and patient-reported opioid use. Our primary approach will be a modified intention-to-treat analysis, whereby all participants who complete at least one follow-up data time point will be included in analyses, regardless of their or their physicians' adherence to their assigned study arm. ETHICS AND DISSEMINATION: This trial is funded by the US Agency for Healthcare Research and Quality (R01HS027426) and was approved by the Northwestern University Institutional Review Board. All physician and patient participants will give written informed consent to study participation. Trial results will be submitted for presentation at scientific meetings and for publication in peer-reviewed journals. TRIAL REGISTRATION NUMBER: ClinicalTrials.gov (NCT04921449).

Experimentally quantifying the feasible torque space of the human shoulder.

Daily tasks rely on our ability to generate multi-dimensional shoulder torques. When function is limited, strength assessments are used to identify impairments and guide treatment. However, these assessments are often one-dimensional and limited in their sensitivity to diagnose shoulder pathology. To address these limitations, we have proposed novel metrics to quantify shoulder torque capacity in all directions. To quantify the feasible torque space of the shoulder, we measured maximal volitional shoulder torques in 32 unique directions and fit an ellipsoid model to these data. This ellipsoid model was used to quantify overall strength magnitude, strength balance, and the directions in which participants were strongest and weakest. We used these metrics to characterize three-dimensional shoulder strength in healthy adults and demonstrated their repeatability across days. Finally, using musculoskeletal simulations, we showed that our proposed metrics can distinguish between changes in muscle strength associated with aging or rotator cuff tears and quantified the influence of altered experimental conditions on this diagnostic capacity. Our results demonstrate that the proposed metrics can robustly quantify the feasible torque space of the shoulder and may provide a clinically useful description of the functional capacity of the shoulder in health and disease.

Interprofessional Inconsistencies in the Diagnosis of Shoulder Instability: Survey Results of Physicians and Rehabilitation Providers.

BACKGROUND: Clinicians of many specialties within sports medicine care for athletes with shoulder instability, but successful outcomes are inconsistent. Consistency across specialties in the diagnosis of shoulder instability is critical for care of the athlete, yet the extent of divergence in its diagnosis is unknown. HYPOTHESIS: Physicians differ from rehabilitation providers in which findings they deem clinically important to differentiate shoulder instability from impingement, and in how they diagnose athlete scenarios with atraumatic shoulder instability. STUDY DESIGN: Cross-sectional study. METHODS: Physicians (orthopaedic surgeons, primary care sports medicine physicians) and rehabilitation providers (physical therapists, athletic trainers) were asked via an online survey to rate clinical factors used to diagnose shoulder instability. Clinicians were also asked to diagnose two athlete scenarios with concurrent clinical findings of atraumatic shoulder instability and impingement, differentiated by the absence or presence of a positive sulcus sign. RESULTS: Responses were recorded from 888 clinicians. Orthopaedic surgeons (N=170) and primary care sports medicine physicians (N=108) ranked physical examination factors as more important for the diagnosis of shoulder instability than patient history factors, whereas physical therapists (N=379) and athletic trainers (N=231) preferred patient history factors. Orthopaedic surgeons differed from physical therapists and athletic trainers in their clinical diagnoses for both scenarios (P≤0.001). CONCLUSION: A lack of consistency exists among sports medicine clinicians in recognizing which clinical factors are important when used to diagnose shoulder instability and in diagnoses given with concurrent findings of impingement. LEVEL OF EVIDENCE: Level 3.

Muscle Contraction Has a Reduced Effect on Increasing Glenohumeral Stability in the Apprehension Position.

PURPOSE: Glenohumeral instability accounts for 23% of all shoulder injuries among collegiate athletes. The apprehension position-combined shoulder abduction and external rotation-commonly reproduces symptoms in athletes with instability. Rehabilitation aims to increase glenohumeral stability by strengthening functional positions. However, it is unclear how much glenohumeral stability increases with muscle contraction in the apprehension position. The purpose of this study was to determine whether the ability to increase translational glenohumeral stiffness, a quantitative measure of glenohumeral stability, with muscle contraction is reduced in the apprehension position. METHODS: Seventeen asymptomatic adults participated. A precision-instrumented robotic system applied pseudorandom, anterior-posterior displacements to translate the humeral head within the glenoid fossa and measured the resultant forces as participants produced isometric shoulder torques. Measurements were made in neutral abduction (90° abduction/0° external rotation) and apprehension (90° abduction/90° external rotation) positions. Glenohumeral stiffness was estimated from the relationship between applied displacements and resultant forces. The ability to increase glenohumeral stiffness with increasing torque magnitude was compared between positions. RESULTS: On average, participants increased glenohumeral stiffness from passive levels by 91% in the neutral abduction position and only 64% in the apprehension position while producing 10% of maximum torque production. The biggest decrease in the ability to modulate glenohumeral stiffness in the apprehension position was observed for torques generated in abduction (49% lower, P < 0.001) and horizontal abduction (25% lower, P < 0.001). CONCLUSION: Our results demonstrate that individuals are less able to increase glenohumeral stiffness with muscle contraction in the apprehension position compared with a neutral shoulder position. These results may help explain why individuals with shoulder instability more frequently experience symptoms in the apprehension position compared with neutral shoulder positions.

Imbalance in Axial-plane Rotator Cuff Fatty Infiltration in Posteriorly Worn Glenoids in Primary Glenohumeral Osteoarthritis: An MRI-based Study.

BACKGROUND: Fatty infiltration of the rotator cuff evaluated with CT has been associated with asymmetric glenoid wear and humeral head subluxation in patients with glenohumeral arthritis. The relationship between rotator cuff pathologic findings and abnormal glenoid wear plays an important role in determining the optimal surgical management of advanced glenohumeral osteoarthritis. Compared with CT, MRI has increased sensitivity for identifying rotator cuff conditions; therefore, prior studies using CT may have underestimated the association between fatty infiltration of the rotator cuff and abnormal glenoid wear. QUESTIONS/PURPOSES: (1) Compared with Type A glenoids, which muscles in which Walch subtypes have a greater degree of fatty infiltration using Goutallier scores? (2) What glenoid type is associated with greater imbalance in fatty infiltration, as measured by comparing Goutallier scores between the posterior and anterior rotator cuff muscles? (3) What is the correlation between glenoid version and fatty infiltration of the rotator cuff muscles? (4) Comparing Type B2 and B3 glenoids with Type A glenoids, after accounting for age and sex, is there an increase in fatty infiltration of the infraspinatus muscle? METHODS: A total of 129 shoulders from 129 patients undergoing anatomic total shoulder arthroplasty to treat primary glenohumeral osteoarthritis were retrospectively reviewed. Patients had an average age of 66.4 ± 9.3 years and an average BMI of 30.6 ± 6.7 kg/m2, and 53% (69 of 129) were men. All patients underwent MRI within 12 months before total shoulder arthroplasty to assess glenoid morphology and rotator cuff pathologic findings. Three reviewers assessed the images, and glenoid morphology was assigned using the modified Walch classification system (Types A1, A2, B1, B2, B3, C, and D). Fatty infiltration of the rotator cuff was classified using Goutallier scores. The examiners demonstrated moderate-to-good reliability using these classification systems; the Walch classification system had interrater reliability kappa coefficients (κ) from 0.54 to 0.69 and intrarater reliability κ from 0.60 to 0.64. Goutallier scores using the simplified classification system had interrater reliability κ from 0.64 to 0.68 and intrarater reliability κ from 0.64 to 0.79. Thirty-six percent (46 of 129) of the shoulders had posterior wear patterns (18% [23] were Type B2 glenoids; 18% [23] were Type B3 glenoids). The average Goutallier scores for each rotator cuff muscle were determined, and the amount of fatty infiltration was compared between the various Walch subtypes using independent t-tests. Axial-plane imbalance in fatty infiltration of the rotator cuff was assessed by determining the difference in the average fatty infiltration of the posterior rotator cuff muscles (infraspinatus and teres minor) and anterior rotator cuff muscles (subscapularis) and comparing the differences among the Walch subtypes using independent t-tests. The association between glenoid version and fatty infiltration was assessed using Pearson correlations. Finally, a multivariate logistic regression model was used to assess fatty infiltration of the rotator cuff among the various Walch subtypes while accounting for patient age and sex. RESULTS: Compared with Type A1 glenoids, Type B2 and B3 glenoids had an increased amount of fatty infiltration of the infraspinatus (1.6 ± 0.7 versus 0.7 ± 0.4; mean difference 0.9 [95% CI 0.7-1.2]; p < 0.001 and 1.8 ± 0.4 versus 0.7 ± 0.4; mean difference 1.1 [95% CI 0.9-1.4]; p < 0.001, respectively) and teres minor (1.3 ± 0.7 versus 0.6 ± 0.5; mean difference 0.7 [95% CI 0.4-1.0]; p < 0.001 and 1.6 ± 0.6 versus 0.6 ± 0.5; mean difference 1.0 [95% CI 0.7-1.2]; p < 0.001, respectively). There was greater imbalance in fatty infiltration between the posterior and anterior rotator cuff muscles for Type B2 (0.5 ± 0.3) and B3 (0.6 ± 0.5) glenoids than for Type A1 (0.1 ± 0.3) and A2 (0.1 ± 0.6) glenoids (p < 0.001). Only the infraspinatus's fatty infiltration was strongly correlated with glenoid version (r = 0.64; p < 0.001), while fatty infiltration of the other muscles only correlated weakly or moderately. After accounting for age and sex, fatty infiltration in the infraspinatus was associated with Type B2 (OR 66.1 [95% CI 7.6-577.9]; p < 0.001) and Type B3 glenoids (OR 59.5 [95% CI 5.4-661.3]; p < 0.001) compared with Type A glenoids. CONCLUSION: Compared with concentric wear, posteriorly worn glenoids had an imbalance in axial-plane rotator cuff fatty infiltration and an increased amount of fatty infiltration of the infraspinatus and teres minor compared with the subscapularis. These imbalances may contribute to the higher rates of failure after anatomic total shoulder arthroplasty in patients with posterior wear compared with those with concentric wear. Future research should be directed toward investigating the temporal relationship of these findings, as well as understanding the clinical outcomes for patients undergoing anatomic total shoulder arthroplasty who have posteriorly worn glenoids with a high degree of fatty infiltration of the posterior rotator cuff musculature. CLINICAL RELEVANCE: Providers should consider the increased likelihood of higher-grade fatty infiltration of the posterior rotator cuff in the setting of posteriorly worn glenoids, particularly when treating patients without using MRI. These patients have higher rates of failure postoperatively and may benefit from closer monitoring and altered postoperative rehabilitation protocols that target the posterior rotator cuff.

Clinical Y-view versus 3-dimensional assessments of intramuscular fat in patients with full-thickness rotator cuff tears.

RATIONALE AND OBJECTIVES: Recent evidence suggests an inhomogeneous distribution of intramuscular rotator cuff fat infiltration (FI) in a small sample of individuals with rotator cuff tears, yet clinically just a few slices at the scapular Y-view are used to evaluate FI in patients with rotator cuff tears. The purpose of this study was to determine if assessment of FI using the scapular Y-view is representative of the entire muscle in patients with full-thickness rotator cuff tears, and whether this varies by tear size. MATERIALS AND METHODS: Patients (N = 25) diagnosed with full-thickness rotator cuff tear and confirmed with magnetic resonance imaging (MRI) were included. Fat-water sequences were used to objectively quantify mean FI (%) in the entire 3D muscle and the mean from 3 slices at the Y-view. Mixed-model 2 × 2 ANOVAs were used to assess for differences between methods, and if results vary by tear-size. RESULTS: There were no statistically significant differences between mean amount of FI of the entire 3D muscle and mean Y-view in the supraspinatus or infraspinatus muscles (p > 0.05). Additionally, this did not differ across tear size groups (p > 0.05). CONCLUSION: Results of this study suggest FI assessed in the Y-view is not different (mean difference < 1.0%) from FI of the entire 3D muscle in patients with full-thickness rotator cuff tears. Therefore, the clinical utility of evaluating rotator cuff intramuscular fat infiltration with the Y-view is further supported in patients with full-thickness rotator cuff tears across tear sizes.

Translations of the Humeral Head Elicit Reflexes in Rotator Cuff Muscles That Are Larger Than Those in the Primary Shoulder Movers.

Muscle activation helps stabilize the glenohumeral joint and prevent dislocations, which are more common at the shoulder than at any other human joint. Feedforward control of shoulder muscles is important for protecting the glenohumeral joint from harm caused by anticipated external perturbations. However, dislocations are frequently caused by unexpected perturbations for which feedback control is essential. Stretch-evoked reflexes elicited by translations of the glenohumeral joint may therefore be an important mechanism for maintaining joint integrity, yet little is known about them. Specifically, reflexes elicited by glenohumeral translations have only been studied under passive conditions, and there have been no investigations of how responses are coordinated across the functional groupings of muscles found at the shoulder. Our objective was to characterize stretch-evoked reflexes elicited by translations of the glenohumeral joint while shoulder muscles are active. We aimed to determine how these responses differ between the rotator cuff muscles, which are essential for maintaining glenohumeral stability, and the primary shoulder movers, which are essential for the large mobility of this joint. We evoked reflexes using anterior and posterior translations of the humeral head while participants produced voluntary isometric torque in six directions spanning the three rotational degrees-of-freedom about the shoulder. Electromyograms were used to measure the stretch-evoked reflexes elicited in nine shoulder muscles. We found that reflex amplitudes were larger in the rotator cuff muscles than in the primary shoulder movers, in part due to increased background activation during torque generation but more so due to an increased scaling of reflex responses with background activation. The reflexes we observed likely arose from the diversity of proprioceptors within the muscles and in the passive structures surrounding the shoulder. The large reflexes observed in the rotator cuff muscles suggest that feedback control of the rotator cuff augments the feedforward control that serves to compress the humeral head into the glenoid. This coordination may serve to stabilize the shoulder rapidly when preparing for and responding to unexpected disturbances.

Scapular movement impairments in individuals with subacromial pain syndrome based on scapular assistance test and scapula reposition test outcomes.

BACKGROUND: Individuals with subacromial pain present with a variety of contributing impairments related to the movement problem. The scapular assistance test (SAT) and scapula reposition test (SRT) are proposed to identify shoulder pain related to abnormal scapular movement or position. It remains unknown if scapular movement related impairments are present in those with positive tests. OBJECTIVES: To determine if scapular motion related impairments differ based on the result of the SAT or SRT in individuals with subacromial pain syndrome. DESIGN: Cross-sectional METHOD: Sixty individuals with subacromial pain syndrome were included. Prior to obtaining results of the SAT and SRT, a single examiner measured scapular upward rotation and posterior tilt active and passive motion, pectoralis minor length, and strength of the middle trapezius, lower trapezius, and serratus anterior. Dynamic scapular motion was qualitatively assessed with the Scapular Dyskinesis Test. The Mann-Whitney U test assessed for differences based on the outcome of the SAT and SRT. RESULTS: There was a significant difference (P = .023) in pectoralis minor length for the SAT. Participants with a positive SAT had decreased muscle length compared to those who tested negative. There were no significant differences in scapular motion or strength based on the result of either the SAT or SRT. CONCLUSIONS: A positive SAT was associated with greater pectoralis minor length impairment, but not muscle strength or mobility. The SRT did not identify greater impairments in any of the scapular movement related impairments assessed. Individuals may vary in contributing impairments related to SAT or SRT results.

Comparing expert opinion within the care team regarding postoperative rehabilitation protocol following rotator cuff repair.

INTRODUCTION: There is no established consensus regarding the optimal rehabilitation protocol following rotator cuff repair, including duration of immobilization, timing to initiate range of motion and resistance exercises, and the importance of supervised, formal therapy. The purpose of this study was to determine agreement in opinion regarding rotator cuff rehabilitation between orthopedic surgeons and physical therapists (PTs). METHODS: A 50-question survey was created on a secure data capture system and distributed via e-mail to members of professional organization affiliations. Surgeon participants were recruited from the American Shoulder and Elbow Surgeons, and PTs were recruited from the American Society of Shoulder and Elbow Therapists and the Academy of Orthopaedic Physical Therapy of the American Physical Therapy Association. Survey responses were analyzed for interprofessional differences in majority opinion and distribution of answer choices. RESULTS: A total of 167 surgeons and 667 PTs responded to the survey. Of the 39 questions evaluated, surgeons and PTs reached intraprofessional majority agreement in 26 (67%) and 28 (72%) statements, respectively, with agreements matching in 17 instances and differing in 4. The 2 groups had different answer preferences in 32 questions (82%). PTs were more likely to support shorter immobilization intervals (P < .001), earlier strengthening (P < .001), and more frequent home exercises (P = .002), whereas surgeons endorsed more conservative weight-bearing restrictions (P < .001), time-based phase transitions (P < .001), and web-based technological platforms for rehabilitation (P < .001). CONCLUSION: Our findings show that although significant discrepancy of opinion exists within professions, greater differences in preferences exist between surgeons and PTs regarding rotator cuff repair rehabilitation.

Three Key Findings When Diagnosing Shoulder Multidirectional Instability: Patient Report of Instability, Hypermobility, and Specific Shoulder Tests.

Shoulder instability has varying mechanisms of injury, direction, and severity. Classification systems based on clustering signs and symptoms have been developed to define subgroups of shoulder instability. Despite this attempt at homogeneity, multidirectional instability (MDI) suffers from the same lack of diagnostic clarity as low back pain. In this Viewpoint, the authors outline 3 key areas to address when diagnosing MDI: patient interview, medical comorbidities, and specific shoulder tests and measures. J Orthop Sports Phys Ther 2020;50(2):52-54. doi:10.2519/jospt.2020.0602.

Development of 3D method to assess intramuscular spatial distribution of fat infiltration in patients with rotator cuff tear: reliability and concurrent validity.

BACKGROUND: Intramuscular fat infiltration is a critical factor in surgical decision-making and is the most important factor used to prognosticate surgical repair outcomes in patients with rotator cuff tears. Quantitative 3D assessment of total rotator cuff fat infiltration in patients with rotator cuff tears has been realized. However, a reproducible method to evaluate 3D spatial distribution of rotator cuff intramuscular fat has not been established. The objective of this study was to establish the reproducibility, change detectable beyond error, and concurrent validity of a semi-automated method to evaluate the 3D spatial distribution of fat infiltration and muscle volume in patients with rotator cuff tears. METHODS: Thirteen consecutive patients diagnosed with symptomatic rotator cuff pathology and 3.0 T MRI confirmation at a single center were included. Fat-water imaging was used to quantify 3D intramuscular fat (%fat) in sagittal oblique sequences and intramuscular spatial distribution with the semi-automated technique. Each rotator cuff muscle was manually segmented yielding %fat in four axial intramuscular quartile-regions (superior-inferior; Q1-4) and three sagittal (medial/ intermediate/ lateral) regions. Reliability and concurrent validity of %fat and whole muscle volume were calculated with intraclass correlation coefficients (ICC). RESULTS: Intra-rater reliability for intramuscular sagittal divisions (ICC = 0.93-0.99) and axial divisions (ICC = 0.78-0.99) was good/excellent. Inter-rater reliability for %fat (ICC = 0.82-0.99) and volume (ICC = 0.92-0.99) was good/excellent. Concurrent validity with commercialized software showed good/excellent agreement (ICC = 0.66-0.99). CONCLUSIONS: A new semi-automated method to assess 3-dimensional intramuscular distribution of fat infiltration in patients with rotator cuff tears using advanced MR imaging demonstrates high intra and inter-rater reliability and good concurrent validity. Minimal detectable change thresholds established facilitate clinical interpretation for future clinical application of this technique to assess change and treatment efficacy in patients with rotator cuff tears.

The Comparative Effects of Upper Thoracic Spine Thrust Manipulation Techniques in Individuals With Subacromial Pain Syndrome: A Randomized Clinical Trial.

BACKGROUND: Subacromial pain syndrome (SPS) accounts for as much as 44% of shoulder pain encountered by physical therapists. Thoracic spine thrust manipulation (TSTM) is effective in the short term for improving pain and function in individuals with SPS, but its mechanisms remain elusive. Furthermore, it is unknown whether individuals with SPS respond differently based on the TSTM technique received. OBJECTIVES: To compare the immediate effects of a supine TSTM, seated TSTM, and sham manipulation on the primary outcomes of self-reported pain, function, and satisfaction and secondary biomechanical impairments examined in individuals with SPS. METHODS: Participants in this randomized clinical trial were randomized to receive a seated TSTM (n = 20), supine TSTM (n = 20), or sham manipulation (n = 20). The primary outcomes of self-reported pain, function, and satisfaction were measured via the Penn Shoulder Score. Secondary outcomes were changes in scapular upward rotation and posterior tilt; peak force generated in tests for the middle trapezius, lower trapezius, and serratus anterior; and pectoralis minor muscle length. Impairment measures were immediately reassessed, and the Penn Shoulder Score was reassessed after 48 hours. RESULTS: There were no significant between-group differences in immediate or short-term follow-up outcomes. CONCLUSION: Two TSTM techniques resulted in no differences in pain, satisfaction, and function when compared to a sham manipulation. Thoracic spine thrust manipulation did not have an immediate effect on the scapular impairments examined. LEVEL OF EVIDENCE: Therapy, level 1. J Orthop Sports Phys Ther 2019;49(10):716-724. Epub 12 Mar 2019. doi:10.2519/jospt.2019.8484.

NEUROMUSCULAR ADAPTIONS FOLLOWING A DAILY STRENGTHENING EXERCISE IN INDIVIDUALS WITH ROTATOR CUFF RELATED SHOULDER PAIN: A PILOT CASE-CONTROL STUDY.

BACKGROUND: The goal of therapeutic exercise is to facilitate a neuromuscular response by increasing or decreasing muscular activity in order to reduce pain and improve function. It is not clear what dosage of exercise will create a neuromuscular response. PURPOSE: The purpose of this study was to assess the effects following a three-week home program of a daily single exercise, the prone horizontal abduction exercise (PHA), on neuromuscular impairments of motor control as measured by scapular muscle EMG amplitudes, strength, and secondarily outcomes of self-reported pain and function between individuals with and without subacromial pain syndrome. STUDY DESIGN: Prospective Case-Control, Pilot Study. METHODS: Twenty-five individuals participated; eleven with shoulder pain during active and resistive motions (Penn Shoulder Score: 77 ± 11) and 14 matched healthy controls (Penn Shoulder Score: 99 ± 27) (p < 0.001). Participants underwent baseline and follow up testing at three weeks including surface electromyography (EMG) of the serratus anterior, upper, and lower trapezius of the involved (painful group) or matched shoulder (control group) during an elevation task and maximal isometric shoulder strength testing. All participants were instructed in a PHA exercise to be performed daily (3 sets; 10 reps). Subjects logged daily exercise adherence. Neuromuscular adaptations were defined by changes in EMG amplitudes (normalized to MVIC) of serratus anterior, upper trapezius, and lower trapezius and strength. Secondary outcomes of self-reported pain and function were also compared between groups following the three-week intervention. RESULTS: After three weeks of a daily PHA exercise, the painful group demonstrated a greater decrease in baseline-elevated EMG amplitudes in the lower trapezius by 7% (95%CI 2.6-11%) during the concentric phase of the overhead lifting task (p 0.006). EMG amplitudes of the healthy control group did not change at three-week follow-up. Additionally, the change in serratus anterior mean EMG amplitude in the painful group -1.6% (IQR -22.9 to 0.8%) was significantly greater (p 0.033) than the healthy group change score, 2.5% (IQR -2.3 to 5.7%) during the eccentric phase (p 0.034). While the painful group was weaker in abduction and flexion at baseline and at follow up, both groups had a significant increase in all strength measures (p≤0.014). Concurrent with increased strength and normalizing EMG amplitudes, the painful group significantly improved on the Penn Shoulder Score with a mean change 9.8 points (95%CI 7.0, 12.6) (p < 0.001). CONCLUSION: In this pilot case-control study, a single home exercise performed daily for three weeks demonstrated neuromuscular adaptations with improvements in muscle activity and strength. These were concurrent with modest, yet significant improvements pain and function in individuals with mild rotator cuff related shoulder pain. LEVEL OF EVIDENCE: 3.