The role of the scapula in preventing and treating shoulder instability

Effects of Using a Special Weighted Vest on Muscle Activity around the Scapula during Knee Push-Up Plus in Healthy Subjects

Muscle imbalances in the upper body can lead to ineffective movement patterns and potential injury. The purpose of this study was to investigate the muscle activity, impact, and muscle activation ratio of the serratus anterior (SA), upper trapezius (UT), lower trapezius (LT), and pectoralis major (PM) during the knee push-up plus (KPUP) exercise under various loads.

METHOD

Electromyography assessed scapular muscle activity in 32 healthy adults (15 males, 17 females) during three KPUP variations.

RESULTS

PM and UT showed no significant activity differences across loads, whereas SA and LT did. SA activity was significantly higher in the weighted KPUP (WKPUP) 3 kg than that in KPUP and WKPUP 1 kg. LT activity was also significantly higher in WKPUP 3 kg compared to KPUP and WKPUP 1 kg, with KPUP showing higher activity than WKPUP 1 kg. PM/SA ratios remained consistent across loads, while UT/LT ratios varied significantly, being notably lower at 3 kg compared to 0 kg and 1 kg. Similarly, UT/SA ratios differed significantly among loads, being notably lower at 3 kg and 1 kg compared to 0 kg.

CONCLUSION

WKPUP with 3 kg demonstrated significantly higher SA and LT activity compared to KPUP and WKPUP 1 kg. The lowest UT/LT ratio was observed during the WKPUP 3 kg, suggesting its effectiveness for optimizing muscle activation balance during KPUP exercises. These findings may inform the development of exercise protocols aimed at improving scapular stabilization.

Editorial Commentary: Evidence That the Shoulder Latarjet Procedure Results in Scapular Dyskinesia Is Not Compelling

The Latarjet procedure was first described in 1954. It is a nonanatomic procedure that requires transfer of the coracoid process, together with the conjoint tendon, to the anterior glenoid margin. The aim is to prevent recurrent anterior shoulder dislocation through a "triple blocking" effect, which includes restoring bone loss, providing a dynamic sling effect, and performing capsulolabral repair. Despite the long history of the Latarjet procedure, studies evaluating its impact on scapulothoracic kinematics are sparse. However, there is a concern that scapulothoracic dyskinesia may occur owing to anatomic changes, including release of the coracoacromial ligament and pectoralis minor tendon, a change in the working length and vector of the conjoint tendon, subscapularis split, and capsular closure. The existing literature has major limitations and comprises predominantly small conflicting series that identify either no scapulothoracic dyskinesia after Latarjet or the presence of scapular protraction or retraction. Given that scapular dyskinesia is very common in shoulder instability patients and even asymptomatic general populations, the evidence that the Latarjet procedure results in dyskinesia is not compelling.

Changes in Scapular Function, Shoulder Strength, and Range of Motion Occur After Latarjet Procedure

Purpose

To evaluate the current literature on the effects of anatomic changes caused by the Latarjet procedure and to identify areas for future research.

Methods

English-language studies that addressed the consequences of anatomic alterations after the open Latarjet procedure were included. Articles written in languages other than English, reviews, and case reports were excluded. Titles and abstracts were screened by 2 authors. Studies that met the inclusion criteria were screened by the same authors. The following data were extracted from the included studies: authors, year of publication, journal, country of origin, aims or purpose, study population and sample size, methods, procedure, intervention type, and key findings that relate to the scoping review questions.

Results

Twenty-two studies were included for analysis, yielding the following findings: First, the Latarjet procedure may change the position of the scapula owing to pectoralis minor tenotomy and/or transfer of the conjoint tendon. Second, dissection of the coracoacromial ligament may result in increased superior translation of the humeral head. The impact of this increased translation on patients' function remains unclear. Third, the subscapularis split shows, overall, better internal rotation strength compared with subscapularis tenotomy. Fourth, passive external rotation may be limited after capsular repair. Fifth, despite the movement of the conjoint tendon, elbow function seems unchanged. Finally, the musculocutaneous nerve is lengthened with a changed penetration angle into the coracobrachialis muscle, but the clinical impact seems limited.

Conclusions

The Latarjet procedure leads to anatomic and biomechanical changes in the shoulder. Areas of future research may include better documentation of scapular movement (bilateral, as well as preoperative and postoperative) and elbow function, the effect of (degenerative) rotator cuff ruptures after the Latarjet procedure on shoulder function, and the impact of capsular closure and its contribution to the development of glenohumeral osteoarthritis.

Clinical Relevance

This comprehensive overview of anatomic changes after the Latarjet procedure, with its effects on shoulder and elbow function, showed gaps in the current literature. Orthopaedic shoulder surgeons and physical therapists could use our findings when providing patient information and performing future clinical research.

Accuracy of measuring scapular position and motion with a novel motion capture system

Background

Scapula kinematics is recognized to be a crucial variable in shoulder dysfunction. Nevertheless, quantitative scapula tracking and measurement are not part of the current clinical evaluation. The main concern is measurement accuracy.

Methods

To assess the accuracy of the wearable sensor technology Showmotion a cadaver experiment was designed, allowing a direct comparison between sensors directly pinned to the scapula and superficial sensors. A measurement protocol was adopted to evaluate errors in measurement, mimicking the suggested in vivo evaluation. Sensors were simultaneously placed above (supraspinal) and below (infraspinal) the scapular spine to determine if one placement resulted in fewer errors compared to the other.

Results

Mean and standard deviations of the supraspinal sensor root mean square error (RMSE) in flexion-extension movements resulted in 3.59° ± 2.36°, 4.73° ± 2.98°, and 6.26° ± 3.62° for upward-downward rotation (up-down), anterior-posterior tilt and internal-external (intra-extra) rotation, respectively, while 2.16° ± 1.21°, 2.20° ± 1.02°, and 4.46° ± 2.16° for the infraspinal sensor. In abduction-adduction movements, mean and standard deviations of the supraspinal sensor RMSE resulted in 4.26° ± 2.98°, 5.68° ± 4.22°, and 7.04° ± 4.36° for up-down rotation, anterior-posterior tilt, and intra-extra rotation, respectively, while 2.38° ± 1.63°, 2.47° ± 1.77°, and 4.92° ± 3.14° for the infraspinal sensor. The same behavior was confirmed in shrug movements, where 4.35° ± 3.24°, 4.63° ± 3.09°, and 5.34° ± 6.67° are mean and standard deviations of the supraspinal sensor RMSE for up-down rotation, anterior-posterior tilt, and intra-extra rotation, respectively, while 2.76° ± 1.87°, 2.83° ± 2.53°, and 4.68° ± 5.22° for the infraspinal sensor.

Conclusion

This method of quantitative assessment of scapular motion is shown to have good accuracy and low error between the sensor measurements and actual bone movement in multiple planes of scapular motion, both over the entire range of motion and in its individual segment intervals. The decreased amount of error with the infraspinal sensor placement suggests that placement is ideal for clinical quantitative assessment of scapular motion.

Advances in the Non-Operative Management of Multidirectional Instability of the Glenohumeral Joint

Multidirectional instability (MDI) of the glenohumeral joint refers to symptomatic subluxations or dislocations in more than one direction. The aetiology of MDI is multifactorial, which makes the classification of this condition challenging. A shoulder rehabilitation program is the initial recommended treatment for MDI, however available rehabilitation programs have varying levels of evidence to support their effectiveness. In 2016, we published the details of an evidence-based program for MDI that has been evaluated for efficacy in two single-group studies and a randomised controlled trial. In 2017, we published a clinical commentary on the aetiology, classification, and treatment of this condition. The aim of this paper is to provide an update on the components of these publications with a particular focus on new advances in the non-operative management of this condition.

Impairment of scapular control in individuals with chronic obstructive pulmonary disease (COPD): Systematic review and meta-analysis

BACKGROUND

Upper quadrant geometrical changes in individuals with chronic obstructive pulmonary disease (COPD) appear to have negative influences on geometrical arrangements of the thorax and scapula.

OBJECTIVE

The purpose of this systematic review was to assess the impairment of scapular control in individuals with COPD as compared with healthy controls.

METHODS

We systematically searched seven electronic databases from inception to June 2021 and updated the searches again in December 2021. Eligible studies included the participants with COPD and compared scapular control outcomes (scapular/shoulder kinematic or related muscle activity) with a control group. Two researchers independently searched for, screened, extracted data from, and evaluated the quality of all articles.

RESULTS

Seven studies met the inclusion criteria and only five studies with 190 subjects were included in the meta-analyses. Subgroup analyses showed that the control group exhibited more scapular anterior tilt (SMD: 0.46; 95% CI: 0.01 to 0.90) and shoulder flexion (SMD: -1.02; 95% CI: -1.79 to -0.26) as compared with the COPD group. Conversely, the COPD group exhibited more scapular elevation (SMD: -1.03; 95% CI: -1.69 to -0.37), internal rotation (SMD: -1.65; 95% CI: -3.19 to -0.10), and protraction (SMD: -0.75; 95% CI: -1.18 to -0.32) compared with the control group. All other outcomes revealed non-significant findings.

CONCLUSION

This review demonstrated scapular control impairments, such as scapular elevation, internal rotation, protraction, and anterior tilt in a static position in patients with COPD. To validate these findings, high-quality randomized control trials with large sample sizes and reliable outcome measures should be conducted.

Maximizing Muscle Function in Cuff-Deficient Shoulders: A Rehabilitation Proposal for Reverse Arthroplasty

Purpose

The purpose of this review is to describe the role of altered joint biomechanics in reverse shoulder arthroplasty and to propose a rehabilitation protocol for a cuff-deficient glenohumeral joint based on the current evidence.Methods and Materials: The proposed rehabilitation incorporates the principles of pertinent muscle loading while considering risk factors and surgical complications.

Results

In light of altered function of shoulder muscles in reverse arthroplasty, scapular plane abduction should be more often utilized as it better activates deltoid, teres minor, upper trapezius, and serratus anterior. Given the absence of supraspinatus and infraspinatus and reduction of external rotation moment arm of the deltoid in reverse arthroplasty, significant recovery of external rotation may not occur, although an intact teres minor may assist external rotation in the elevated position.

Conclusion

Improving the efficiency of deltoid function before and after reverse shoulder arthroplasty is a key factor in the rehabilitation of the cuff deficient shoulders. Performing exercises in scapular plane and higher abduction angles activates deltoid and other important muscles more efficiently and optimizes surgical outcomes.

Four weeks of exercise regimen for sedentary workers with rounded shoulder posture: a randomized controlled study

BACKGROUND

Rounded shoulder (RS) posture causes neck and shoulder pathologies. Mechanical correction taping (MCT) is often incorporated into postural corrective therapies; however, its effects on muscle stiffness are unclear.

OBJECTIVE

We investigated the effect of MCT with different tape fabrics, along with exercise, on upper trapezius and pectoralis minor muscle stiffness and the posture of sedentary workers.

DESIGN AND SETTING

A randomized controlled study was performed at Aydın Adnan Menderes University, Aydın, Turkey.

METHODS

The study included 39 workers with RS posture. Two intervention groups (performance tape: PT and classic tape: CT) were taped twice a week and administered a home exercise program for 4 weeks. The control (C) group performed only home exercises. RS was measured using an acromion-testing table (AT), stiffness using shear wave elastography ultrasound, and shoulder angle (SA) using a smartphone application at baseline and 4 weeks. Time and group interactions were determined using 3 × 2 mixed analysis of variance.

RESULTS

Intragroup analyses revealed a significant main effect of time on AT distance (η2 = 0.445) and SA (η2 = 0.325) in the PT and C groups (P < 0.05) and left upper trapezius stiffness (η2 = 0.287) in the CT and C groups (P < 0.05). In the post hoc analyses, no difference was noted between the groups from baseline to 4 weeks (P > 0.05).

CONCLUSION

Scapular MCT added to postural exercises did not show any difference between the intervention groups and controls in terms of muscle stiffness and posture in sedentary workers.

Team Approach: Treatment of Shoulder Instability in Athletes

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Shoulder instability is a complex problem with a high rate of recurrence in athletes. Treatment of a first-time subluxation or dislocation event is controversial and depends on patient-specific factors as well as the identified pathology.

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Athletic trainers and physical therapists are an integral part of the treatment team of an in-season athlete who has experienced a shoulder instability event. Through comprehensive physiological assessments, these providers can effectively suggest modifications to the patient's training regimen as well as an appropriate rehabilitation program.

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Surgical intervention for shoulder stabilization should use an individualized approach for technique and timing.

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A team-based approach is necessary to optimize the care of this high-demand, high-risk population.

Reaching higher: External scapula assistance can improve upper limb function in humans with irreversible scapula alata

Background

Scapular dyskinesis, i.e., the deviant mobility or function of the scapula, hampers upper limb function in daily life. A typical sign of scapular dyskinesis is a scapula alata—a protrusion of the shoulder blade during arm elevation. While some reversible causes of scapula alata can be treated with therapy, other, irreversible causes require invasive surgical interventions. When surgery is not an option, however, severe limitations arise as standard approaches for assisting the scapula in daily life do not exist. The aim of this study was to quantify functional improvements when external, i.e., non-invasive, scapula assistance is provided.

Methods

The study was designed as a randomized controlled crossover trial. Eight participants with a scapula alata due to muscular dystrophy performed arm elevations in shoulder flexion and abduction while unassisted (baseline), externally assisted by a trained therapist, and externally assisted by a novel, textile-based scapula orthosis.

Results

With therapist assistance, average arm elevation increased by 17.3° in flexion (p < 0.001, 95% confidence interval of the mean \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$C{I}_{95\%}=\hspace{0.17em}\left[9.8^\circ , 24.9^\circ \right]$$\end{document}CI95%=9.8∘,24.9∘), and by 11.2° in abduction (p < 0.01, \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$C{I}_{95\%}=\left[4.7^\circ , 17.7^\circ \right]$$\end{document}CI95%=4.7∘,17.7∘), constituting the potential of external scapula assistance. With orthosis assistance, average arm elevation increased by 6.2° in flexion (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$C{I}_{95\%}=\left[0.4^\circ ,11.9^\circ \right]$$\end{document}CI95%=0.4∘,11.9∘) and by 5.8° in abduction (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$C{I}_{95\%}=\left[3.0^\circ ,8.5^\circ \right]$$\end{document}CI95%=3.0∘,8.5∘). Remarkably, in three participants, the orthosis was at least as effective as the therapist. Moreover, orthosis assistance reduced average perceived exertion by 1.25 points (Borg Scale) when elevating a filled bottle during a simulated daily living task.

Conclusion

These findings indicate a large potential for future advancements in orthotics. Already now, the textile-based scapula orthosis presented here is a feasible tool for leveraging the benefits of external scapula assistance when a therapist is unavailable, as encountered in daily life scenarios.

Trial Registration ClincalTrials.gov (ID NCT04154098). Registered: November 6th 2019, https://clinicaltrials.gov/ct2/show/NCT04154098?term=scapula+orthosis&draw=2&rank=1

Graphic abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s12984-021-00926-z.

Scapular Dyskinesis Is Not an Isolated Risk Factor for Shoulder Injury in Athletes: A Systematic Review and Meta-analysis

BACKGROUND

Scapular dyskinesis has been considered a risk factor for athletic shoulder injury; however, findings in the prospective literature have demonstrated mixed results.

PURPOSE

To determine if scapular dyskinesis increases the risk of shoulder injury in athletes.

STUDY DESIGN

Meta-analysis.

METHODS

A systematic search was conducted on the MEDLINE, CINAHL Plus, SPORTDiscus, and Embase databases to identify prospective studies examining scapular dyskinesis and shoulder injury risk in athletes. Studies were included if they assessed participants using a dynamic scapular assessment at baseline and monitored for the development of shoulder injury. Data from the studies were subject to meta-analysis using the Mantel-Haenszel method to produce a pooled risk ratio.

RESULTS

Seven studies were eligible for inclusion, resulting in 212 shoulder injuries observed across 923 athletes. Scapular dyskinesis was present in 46% of participants, and these athletes had an injury rate of 25%. The presence of scapular dyskinesis displayed a trend to increase the risk of shoulder injury, but this was not statistically significant (risk ratio, 1.07; 95% CI, 0.85-1.34; P = .59).

CONCLUSION

Scapular dyskinesis was not significantly associated with the development of shoulder injury in athletes.

REGISTRATION

CRD42019133089 (PROSPERO).

Rehabilitation Exercises for Dysfunction of the Scapula: Exploration of Muscle Activity Using Fine-Wire EMG

BACKGROUND

Scapular muscle activity during shoulder exercises has been explored with surface electromyography (EMG). However, knowledge about the activity of deeper-layer scapular muscles is still limited.

PURPOSE

To investigate EMG activation of the deeper-layer scapular stabilizers (levator scapulae [LS], rhomboid major [RM], pectoralis minor [Pm] muscles) together with superficial muscle activity (upper [UT], middle [MT], and lower trapezius [LT] and serratus anterior [SA]) during 4 exercises often used for training scapular function. Based on the amplitude EMG of the deeper-layer muscles, scapular muscle activation ratios for the 4 exercises were calculated, hereby providing knowledge of the optimal muscle balance.

STUDY DESIGN

Descriptive laboratory study.

METHODS

A total of 26 healthy participants performed 4 shoulder exercises (side-lying external rotation [ER], side-lying forward flexion, prone horizontal abduction with ER, and prone extension) while simultaneously measuring scapular muscle activity. Intramuscular electrodes were used for the deeper layer, in contrast to surface electrodes for the superficial muscles. All data were normalized to percentage of maximal voluntary isometric contraction (%MVIC), and the activation ratios (the muscle activity of the deeper layer relative to the other muscles) were calculated. A 1-way analysis of variance with Bonferroni correction was applied for statistical analysis.

RESULTS

Moderate activity was found in all exercises for the LS and RM (25%-45% MVIC). The Pm resulted in low activity during both side-lying exercises (13%-18% MVIC). Ratios involving LS or RM showed values >1 for all exercises (1.28-12.41) except for LS/MT, LS/LT, and LS/RM (0.85-0.98) during side-lying ER, and LS/MT, RM/MT and RM/LS (0.85-0.99) during side-lying forward flexion. Likewise, values <1 were found when MT (0.85) and LS (0.99) were involved with RM in the numerator during side-lying forward flexion. Ratios with Pm in the numerator showed values <1, apart from the ratios with UT and SA in the denominator.

CONCLUSION

The study provides extended knowledge about the deeper-layer scapular muscle activity and related ratios during the 4 shoulder exercises mentioned here. Putting theory into practice, based on our results, we advise both side-lying exercises to be performed to strengthen LT and MT, even in case of hyperactivity of the Pm. However, the 4 exercises should be given carefully to patients with hyperactivity in the LS and/or RM.

CLINICAL RELEVANCE

The findings of this study may assist clinical decision making in exercise selection for restoring scapular function.

A computer tablet software can quantify the deviation of scapula medial border from the thoracic wall during clinical assessment of scapula dyskinesis

PURPOSE

Aim of this study is to establish an objective and easily applicable method that will allow clinicians to quantitatively assess scapular dyskinesis during clinical examination using a computer tablet software. Hypothesis is that dyskinetic scapulae present greater motion-deviation from the thoracic wall-compared to the non-dyskinetic ones and that the software will be able to record those differences.

METHODS

Twenty-five patients and 19 healthy individuals were clinically evaluated for the presence of dyskinesis or not. According to the clinical diagnosis, the observations were divided into three groups; A. Dyskinetic scapulae with symptoms (n = 25), B. Contralateral non-dyskinetic scapulae without symptoms (n = 25), C. Healthy control scapulae (n = 38). Then, all individuals were tested using a tablet with the PIVOT™ image-based analysis software (PIVOT, Impellia, Pittsburgh, PA, USA). The motion produced by the scapula medial border and inferior angle deviation from the thoracic wall was recorded.

RESULTS

The deviation of the medial border and inferior angle of the scapula from the thoracic wall was 24.6 ± 7.3 mm in Group A, 14.7 ± 4.9 mm in Group B, and 12.4 ± 5.2 mm in Group C. The motion recorded in the dyskinetic scapulae group was significantly greater than both the contralateral non-dyskinetic scapulae group (p < 0.01) and the healthy control scapulae group (p < 0.01).

CONCLUSION

The PIVOT™ software was efficient to detect significant differences in the motion between dyskinetic and non-dyskinetic scapulae. This system can support the clinical diagnosis of dyskinesis with a numeric value, which not only contributes to scapula dyskinesis grading but also to the evaluation of the progress and efficacy of the applied treatment, thus providing a feedback to the clinician and the patient.

LEVEL OF EVIDENCE

IV, laboratory study.

Use of unstable exercises in periscapular muscle activity: A systematic review and meta-analysis of electromyographic studies

BACKGROUND

The use of unstable surfaces has been proposed to increase the neuromuscular demand. This strategy has been adopted to generate an increase in the activity of periscapular muscles due to its role in the stabilization of the scapula. However, the influence of this instability on the EMG activity remains uncertain. The aim of this study was to analyze the effects of using unstable surfaces on the EMG activity of the periscapular muscles.

METHODS

A comprehensive search in the PubMed, EMBASE, SCIELO, Web of Science, SCOPUS, Cochrane and LILACS databases was undertaken from their year of inception up to December 2019. Studies which directly investigated the EMG activity of periscapular muscles in healthy individuals while performing exercises for the upper limbs in stable and unstable conditions.

RESULTS

A total of 33 studies which evaluated a total of 678 healthy individuals were found according to the eligibility criteria. A meta-analysis identified that the EMG activity of the upper trapezius showed a trivial increase with the insertion of the unstable surface (P = 0.04; SMD = 0.14 [95%CI 0.00, 0.27]). No significant effects were observed on the middle trapezius (P = 0.10) and lower trapezius (P = 0.25). A decrease of the anterior serratus EMG activity with a small effect size was observed by implementing an unstable surface (P = 0.01; SMD = -0.21 [95%CI -0.36, -0.05]).

CONCLUSION

The use of unstable surfaces generated a trivial increase in the upper trapezius activity, and a slight decrease in the anterior serratus activity. No effect was observed on the middle and lower trapezius.

Electromyographic muscle activity and three-dimensional scapular kinematics in patients with multidirectional shoulder instability

OBJECTIVE

To investigate differences in EMG muscle activity and scapular kinematics during elevation in the scapular plane between healthy controls, participants with multidirectional shoulder laxity (MDL), and patients with multidirectional shoulder instability (MDI) who are diagnosed with hypermobile Ehlers-Danlos syndrome (hEDS) or Hypermobility Spectrum Disorder (HSD).

METHODS

Twenty-seven women with hEDS/HSD and MDI, 27 female healthy control subjects, and 28 female subjects with MDL participated in this study. Scapular 3D kinematic data were obtained using 8 Oqus Qualisys cameras. Simultaneously, surface electromyography (EMG) was used to measure muscle activity of the upper, middle, and lower trapezius, infraspinatus, latissimus dorsi, serratus anterior, posterior deltoid, and pectoralis major during arm elevation in the scapular plane. Group differences were assessed using statistical parametric mapping.

RESULTS

Regarding scapular kinematics, significantly less upward rotation was observed in hEDS/HSD patients with MDI compared to both healthy controls and MDL subjects. Significantly less posterior tilt was seen in hEDS/HSD patients compared to MDL subjects. Furthermore, significantly higher EMG activity of the infraspinatus, middle trapezius, and posterior deltoid was found in hEDS/HSD patients with MDI.

CONCLUSION

hEDS/HSD patients with MDI demonstrate altered scapular kinematics and increased EMG muscle activity compared to subjects without MDI. These findings could serve as stepping stone for future research regarding treatment strategies in patients belonging to the hypermobility spectrum.

Muscle activity and scapular kinematics in individuals with multidirectional shoulder instability: A systematic review

BACKGROUND

Several studies reported the importance of glenohumeral and scapular muscle activity and scapular kinematics in multidirectional shoulder instability (MDI), yet a systematic overview is currently lacking.

OBJECTIVE

This systematic review evaluates and summarizes the evidence regarding muscle activity and shoulder kinematics in individuals with MDI compared to healthy controls.

METHOD

The electronic databases PubMed and Web of Science were searched in September 2020 with key words regarding MDI (population), muscle activity, and glenohumeral and scapular movement patterns (outcomes). All studies that compared muscle activity or scapular kinematics between shoulders with MDI and healthy shoulders were eligible for this review, except for case reports and case series. All articles were screened on the title and abstract, and remaining eligible articles were screened on full text. The risk of bias of included articles was assessed by a checklist for case-control data, as advised by the Cochrane collaboration.

RESULTS

After full text screening, 12 articles remained for inclusion and one study was obtained by hand search. According to the guidelines of the Dutch Institute for Healthcare Improvement, most studies were of moderate methodological quality. We found moderate evidence that MDI individuals show increased or prolonged activity of several rotator cuff muscles that control and centre the humeral head. Furthermore, we found evidence of decreased and/or shortened activity of muscles that move or accelerate the arm and shoulder girdle as well as increased and/or lengthened activity of muscles that decelerate the arm and shoulder girdle. The most consistent kinematic finding was that MDI individuals show significantly less upward rotation and more internal rotation of the scapula during elevation of the arm in the scapular plane as compared with controls. Finally, several studies also suggest that the humeral head demonstrates increased translations relative to the glenoid surface.

CONCLUSION

There is moderate evidence for altered muscle activity and altered humeral and scapular kinematics in MDI individuals as compared with controls.

Scapular Dyskinesis: From Basic Science to Ultimate Treatment

Background: This study intends to summarize the causes, clinical examination, and treatments of scapular dyskinesis (SD) and to briefly investigate whether alteration can be managed by a precision rehabilitation protocol planned on the basis of features derived from clinical tests. Methods: We performed a comprehensive search of PubMed, Cochrane, CINAHL and EMBASE databases using various combinations of the keywords “Rotator cuff”, “Scapula”, “Scapular Dyskinesis”, “Shoulder”, “Biomechanics” and “Arthroscopy”. Results: SD incidence is growing in patients with shoulder pathologies, even if it is not a specific injury or directly related to a particular injury. SD can be caused by multiple factors or can be the trigger of shoulder-degenerative pathologies. In both cases, SD results in a protracted scapula with the arm at rest or in motion. Conclusions: A clinical evaluation of altered shoulder kinematics is still complicated. Limitations in observing scapular motion are mainly related to the anatomical position and function of the scapula itself and the absence of a tool for quantitative SD clinical assessment. High-quality clinical trials are needed to establish whether there is a possible correlation between SD patterns and the specific findings of shoulder pathologies with altered scapular kinematics.

Shoulder Pain Among Patients With Amyotrophic Lateral Sclerosis: A Case Series

IMPORTANCE

Evidence has demonstrated that shoulder pain constitutes a functional impairment for patients with amyotrophic lateral sclerosis (ALS). No studies have yet examined the efficacy of scapular mobilization of the painful shoulder among patients with ALS.

OBJECTIVE

Our retrospective case series evaluated the effects of scapular mobilization on pain and shoulder motion among patients with ALS.

DESIGN

Retrospective case series over 2 yr.

SETTING

A multidisciplinary outpatient clinic at an academic medical institution.

PARTICIPANTS

Twenty-eight patients with ALS who had shoulder pain and range of motion (ROM) limitations. Patients were excluded if information on visual analog scale (VAS) score for pain and shoulder ROM was not available.

INTERVENTION

Scapular mobilization, ROM, and caregiver education. All patients also received standard occupational therapy treatment for this patient population.

OUTCOMES AND MEASURES

The primary outcome was VAS shoulder pain scores; the secondary outcome was shoulder flexion ROM.

RESULTS

The median VAS pain score was 2 before treatment and 0 after treatment, with a significant median reduction of 2. Median shoulder flexion ROM was 100° before mobilization treatment and 130° after treatment, with a significant median increase of 25°.

CONCLUSION AND RELEVANCE

The results provide strong evidence that both VAS pain score and shoulder ROM noticeably improve after mobilization treatment.

WHAT THIS ARTICLE ADDS

Occupational therapists can effectively promote shoulder care techniques such as scapular mobilization to both patients and care providers to reduce pain and improve quality of life for patients with ALS.

Can a short neuromuscular warmup before tackling improve shoulder joint position sense in rugby players?

BACKGROUND

In rugby the tackle is a complex task requiring joint position sense (JPS). Injuries commonly occur during the tackle and these account for significant time lost from training and play. Simulated tackling tasks have previously shown a reduction in shoulder joint position sense and it is possible that this may contribute to injury. There is growing evidence in support of injury prevention programs, but none so far are dedicated specifically to tackling. We postulate that a brief neuromuscular warmup could alter the negative effects of fatigue on shoulder JPS.

METHODS

In this field based, repeated measures design study, 25 semi-professional Rugby players participated. JPS was measured at criterion angles of 45° and 80° of right arm shoulder external rotation. Reproduction accuracy prior to and following a neuromuscular warmup and simulated tackling task was then assessed.

RESULTS

In pre-warmup JPS measures, the spread of angle errors were larger at the 80° positions. Adding the warmup, the spread of the angle errors at the 80° positions decreased compared to pre-intervention measures. Two one-sided tests (TOST) analysis comparing pre- and post-testing angle errors, with the addition of the warmup, indicated no difference in JPS.

CONCLUSIONS

The neuromuscular warmup resulted in a decrease in JPS error variance meaning fewer individuals made extreme errors. The TOST analysis results also suggest the neuromuscular warmup used in this study could mitigate the negative effects of tackling on JPS that has been seen in prior research. This neuromuscular warmup could play a role in preventing shoulder injuries. It can easily be added to existing successful injury prevention programs.

Concurrent validity of handheld dynamometer measurements for scapular protraction strength

BACKGROUND

Handheld dynamometers (HHD) provide quick and low-cost assessments of muscle strength and their use has been increasing in clinical practice. There is no available data related to the validity of HHD for this measurement.

OBJECTIVE

To verify the concurrent validity of scapular protraction measurements using an HHD.

METHODS

Individuals with traumatic anterior glenohumeral instability were allocated in Instability Group (n=20), healthy swimmers were allocated in Athletes Group (n=19) and healthy subjects were allocated in Sedentary Group (n=21). Concurrent validity was verified by the Pearson correlation test between HHD and isokinetic measurements. The agreement between instruments was verified by Bland-Altman plots, for each of the two HHD positions.

RESULTS

A moderate correlation was observed between seated (r=0.59) and lying supine HHD (r=0.54) and isokinetic dynamometer measurements for the all groups. Separated group analysis exhibited a strong correlation between seated HHD and isokinetic dynamometer measurements in the Instability Group (r=0.80), Sedentary Group (r=0.79) and Athletes Group (r=0.76). The Bland-Altman plot showed greater agreement in the seated position than the lying supine position when comparing measurements with the HHD and isokinetic in both the general sample and separated groups.

CONCLUSION

The HHD may be considered a valid tool for assessing scapular protraction muscle strength among healthy athletes, non-athletes and subjects with shoulder instability. We recommend to assess subjects in the seated position and to be aware that the HHD tends to overestimate the peak force, compared with the gold-standard isokinetic dynamometer.

A preliminary exploration of plain-film radiography in scapular dyskinesis evaluation

BACKGROUND

Evaluation of scapular dyskinesis is of clinical interest because it is believed to be associated with pathologies of the shoulder. This study investigated the feasibility of plain-film radiography in evaluating scapular dyskinesis.

METHODS

Subjects with unilateral disorders of the shoulder (n = 186) who underwent plain-film radiography of bilateral scapulae were divided into 4 categories of scapular dyskinesis patterns according to the Kibler classification and analyzed. Coracoid upward shift distance (CUSD), length of the scapular spine line (LSS), and scapular upward rotation angle (SURA) were measured on the radiographs. Intrarater and inter-rater reliability were tested, and the characteristics of these parameters in each type were analyzed. The differences (d) between bilateral scapulae (d-CUSD, d-LSS, and d-SURA) among the 4 categories were compared.

RESULTS

Intrarater and inter-rater reliability were excellent for all parameters. Significant differences between the scapulae were observed in CUSD in type I and in LSS in type II categories. No significant difference in any of the parameters was found in type III. Compared with the other categories, d-CUSD in type I and d-LSS in type II were significantly larger. The cutoff values of d-CUSD and d-LSS were 1.1 mm and 1.2 mm, respectively. No significant difference in d-SURA was found among the 4 categories.

CONCLUSIONS

The measurement of CUSD, LSS, and SURA on plain-film radiography had excellent reliability. d-CUSD and d-LSS were characteristic parameters of type I and type II, respectively; however, type III had no distinguishing characteristics among the parameters.

Hand reach star excursion balance test: An alternative test for dynamic postural control and functional mobility

Tests of dynamic postural control eliciting full-body three-dimensional joint movements in a systematic manner are scarce. The well-established star excursion balance test (SEBT) elicits primarily three-dimensional lower extremity joint movements with minimal trunk and no upper extremity joint movements. In response to these shortcomings we created the hand reach star excursion balance test (HSEBT) based on the SEBT reach directions. The aims of the current study were to 1) compare HSEBT and SEBT measurements, 2) compare joint movements elicited by the HSEBT to both SEBT joint movements and normative range of motion values published in the literature. Ten SEBT and HSEBT reaches for each foot were obtained while capturing full-body kinematics in twenty recreationally active healthy male subjects. HSEBT and SEBT areas and composite scores (sum of reaches) for total, anterior and posterior subsections and individual reaches were correlated. Total reach score comparisons showed fair to moderate correlations (r = .393 to .606), while anterior and posterior subsections comparisons had fair to good correlations (r = .269 to .823). Individual reach comparisons had no to good correlations (r = -.182 to .822) where lateral and posterior reaches demonstrated the lowest correlations (r = -.182 to .510). The HSEBT elicited more and significantly greater joint movements than the SEBT, except for hip external rotation, knee extension and plantarflexion. Comparisons to normative range of motion values showed that 3 of 18 for the SEBT and 8 of 22 joint movements for the HSEBT were within normative values. The findings suggest that the HSEBT can be used for the assessment of dynamic postural control and is particularly suitable for examining full-body functional mobility.

Scapular motion adaptations in junior overhead athletes: a three-dimensional kinematic analysis in tennis players and non-overhead athletes

Adult overhead athletes without a history of shoulder injury show scapular adaptations. There is a lack of detailed assessment of scapular kinematics in junior overhead athletes. This study aims to investigate three-dimensional scapular kinematics in junior overhead athletes. We recruited a total of 20 junior tennis players and 20 healthy children without participation in any overhead sports in this study. Bilateral scapular kinematic data were recorded using an electromagnetic tracking device for scapular plane glenohumeral elevation. The data were further analysed at 30°, 45°, 60°, 90° and 120° during glenohumeral elevation and lowering. Statistical comparisons of the data between groups (junior overhead athletes and non-overhead athletes) and sides (serve dominant and non-dominant shoulders of the overhead athletes) were analysed with the ANOVA. Comparisons showed that, in general, the scapula was more upwardly rotated and anteriorly tilted in overhead athletes when compared to non-overhead athletes, however there was no side-to-side differences when serve dominant and non-dominant shoulders compared in junior overhead athletes. The serve dominant arm of junior overhead athletes had alternations in scapular kinematics when compared with the non-overhead athletes. These findings provide clinical evaluation implications and the need for clinicians to assess for potential adaptations in junior overhead athletes.

Neuromuscular adaptations in shoulder function and dysfunction

Neuromuscular activity, organized in coordinated patterns, forms the basis of task-specific function in sports and exercise. The content and extent of these patterns may be variable, but include elements of activation/inhibition, co-activation, concentric/eccentric activation, proximal-to-distal activation, plyometric activation, and preactivation stiffness. They may be based on inherent neuromuscular architecture, but are commonly affected by positive or negative adaptations to imposed functional demands. Positive neuromuscular adaptations improve the efficiency of performing the task, which can result in less energy expenditure, maximum force delivered to the task, and protection of involved joints from excessive loads/motions, and improve the effectiveness of task performance. They frequently result from specific training in task mechanics and optimal conditioning of the neuromuscular structures involved in the task. Negative neuromuscular maladaptations can affect the efficiency of performing the task, increase energy expenditure and loads, decrease the effectiveness of task performance, and can be associated with clinical presentation of injury symptoms. They can result from overload, injury, and/or limited recovery. This chapter will focus specifically on shoulder joint function to provide examples of positive adaptations and negative maladaptations. It will then provide guidelines for clinical evaluation, treatment of clinical injury, and training/conditioning, based on understanding the neuromuscular activation.

Current Concepts in Rehabilitation for Traumatic Anterior Shoulder Instability

PURPOSE OF REVIEW

The objectives of this review are to evaluate the current evidence-based literature and concepts surrounding rehabilitation in patients with anterior shoulder instability injuries and surgical repair.

RECENT FINDINGS

The current literature evidence for shoulder rehabilitation for anterior shoulder instability and labral repair is limited. As a result, there are variations among surgeons and physical therapists in rehabilitation protocols after anterior shoulder instability injuries and repair. While general consensus on certain rehabilitation parameters exists, the evidence for the importance of rehabilitation and functional performance test for return to sport in future injury prevention is still lacking in literature. Rehabilitation after anterior shoulder instability injury and anterior labral repair is paramount in the injured or post-operative shoulder. Restoration of soft tissue mobility, dynamic glenohumeral joint stability, and balance and strength around the shoulder not only protect healing of injured or repaired soft tissues but also potentially minimizes future re-injury or recurrence risk.

Multidirectional Shoulder Instability: Treatment

Background:

The treatment of multidirectional instability of the shoulder is complex. The surgeon should have a clear understanding of the role of hiperlaxity, anatomical variations, muscle misbalance and possible traumatic incidents in each patient.

Methods:

A review of the relevant literature was performed including indexed journals in English and Spanish. The review was focused in both surgical and conservative management of multidirectional shoulder instability.

Results:

Most patients with multidirectional instability will be best served with a period of conservative management with physical therapy; this should focus in restoring strength and balance of the dynamic stabilizers of the shoulder. The presence of a significant traumatic incident, anatomic alterations and psychological problems are widely considered to be poor prognostic factors for conservative treatment. Patients who do not show a favorable response after 3 months of conservative treatment seem to get no benefit from further physical therapy.

When conservative treatment fails, a surgical intervention is warranted. Both open capsular shift and arthroscopic capsular plication are considered to be the treatment of choice in these patients and have similar outcomes. Thermal or laser capsuloraphy is no longer recommended.

Conclusion:

Multidirectional instability is a complex problem. Conservative management with focus on strengthening and balancing of the dynamic shoulder stabilizers is the first alternative. Some patients will fare poorly and require either open or arthroscopic capsular plication.

Concomitant glenohumeral pathologies associated with acute and chronic grade III and grade V acromioclavicular joint injuries

PURPOSE

The purpose of this study was to identify the risk of concomitant glenohumeral pathologies with acromioclavicular joint injuries grade III and V.

METHODS

Patients who underwent arthroscopically-assisted stabilization of acromioclavicular joint injuries grade III or grade V between 01/2007 and 12/2015 were identified in the patient databases of two surgical centres. Gender, age at index surgery, grade of acromioclavicular joint injury (Rockwood III or Rockwood V), and duration between injury and index surgery (classified as acute or chronic) were of interest. Concomitant glenohumeral pathologies were noted and their treatment was classified as debridement or reconstructive procedure.

RESULTS

A total of 376 patients (336 male, 40 female) were included. Mean age at time of arthroscopic acromioclavicular joint reconstruction surgery was 42.1 ± 14.0 years. Overall, 201 patients (53%) had one or more concomitant glenohumeral pathologies. Lesions of the biceps tendon complex and rotator cuff were the most common. Forty-five patients (12.0%) had concomitant glenohumeral pathologies that required an additional repair. The remaining 156 patients (41.5%) received a debridement of their concomitant pathologies. Rockwood grade V compared to Rockwood grade III (p = 0.013; odds ratio 1.7), and chronic compared to acute injury were significantly associated with having a concomitant glenohumeral pathology (p = 0.019; odds ratio 1.7). The probability of having a concomitant glenohumeral pathology was also significantly associated with increasing age (p < 0.0001).

CONCLUSIONS

Concomitant glenohumeral pathologies were observed in 53% of surgically treated patients with an acute or chronic acromioclavicular joint injury of either grade III or V. Twenty-two percent of these patients with concomitant glenohumeral pathologies received an additional dedicated repair procedure. Although a significant difference in occurrence of concomitant glenohumeral pathologies was seen between Rockwood grades III and V, and between acute and chronic lesions, increasing age was identified as the most dominant predictor.

LEVEL OF EVIDENCE

Level IV, case series.

Use of shoulder pacemaker for treatment of functional shoulder instability: Proof of concept

Background

Functional shoulder instability (polar type III) is caused by underactivity of rotator cuff and periscapular muscles, which leads to subluxation or dislocation during shoulder movement. While surgical treatment has shown no benefits, aggravates pain, and frequently diminishes function even further, conservative treatment is often ineffective as well.

Objectives

The aim was to investigate the effectiveness of a “shoulder pacemaker” device that stimulates underactive muscles in patients with functional instability during shoulder movement in order to re-establish glenohumeral stability.

Patients and methods

Three patients with unsuccessfully treated functional shoulder instability causing pain, emotional stress, as well as limitations during daily activities and sports participation were enrolled in this pilot project. The device was used to stimulate the external rotators of the shoulder and retractors of the scapula. Pain level, subjective shoulder instability, range of motion, visible aberrant muscle activation, and signs of dislocation were compared when the device was switched on and off.

Results

No changes were observed when the device was attached but switched off. When the device was switched on, all patients were able to move their arms freely without pain, discomfort, or subjective or objective signs of instability. All patients rated this as an excellent experience and volunteered to train further with the device. No complications were observed.

Conclusion

The electric stimulation of hypoactive rotator cuff and periscapular muscles by means of the shoulder pacemaker successfully re-establishes stability in patients with functional shoulder instability during the time of application.

 Video online

The online version of this article (doi: 10.1007/s11678-017-0399-z) contains the video: “The Shoulder-Pacemaker: treatment of functional shoulder instability with pathological muscle activation pattern”. Video by courtesy of P. Moroder, M. Minkus, E. Böhm, V. Danzinger, C. Gerhardt and M. Scheibel, Charité Universitätsmedizin Berlin 2017, all rights reserved