Differences in 3-dimensional shoulder kinematics between persons with multidirectional instability and asymptomatic controls

Children and adolescents with all forms of shoulder instability demonstrate differences in their movement and muscle activity patterns when compared to age- and sex-matched controls

HYPOTHESIS AND BACKGROUND

Shoulder instability (SI) is a complex impairment, and identifying biomarkers that differentiate subgroups is challenging. Children and adolescents with SI (irrespective of etiology) have differences in their movement and muscle activity profiles compared to age- and sex-matched controls (2-tailed). There are limited fundamental movement and muscle activity data for identifying different mechanisms for SI in children and adolescents that can inform subgrouping and treatment allocation.

METHODS

Young people between 8 and 18 years were recruited into 2 groups of SI and age- and sex-matched controls (CG). All forms of SI were included, and young people with coexisting neurologic pathologies or deficits were excluded. Participants attended a single session and carried out 4 unweighted and 3 weighted tasks in which their movements and muscle activity was measured using 3-dimensional (3D) movement analysis and surface electromyography (sEMG). Statistical parametric mapping was used to identify between-group differences.

RESULTS

Data were collected for 30 young people (15 SI [6 male, 9 female] and 15 CG [8 male, 7 female]). The mean (standard deviation) age of the participants was 13.6 years (3.0). The SI group demonstrated consistently more protracted and elevated sternoclavicular joint positions during all movements. Normalized muscle activity in latissimus dorsi was lower in the SI group and had the most statistically significant differences across all movements. Where differences were identified, the SI group also had increased normalized activity of their middle trapezius, posterior deltoid, and biceps muscles but decreased activity of their latissimus dorsi, triceps and anterior deltoid muscles compared with the CG group. No statistically significant differences were found for the pectoralis major across any movements. Weighted tasks produced fewer differences in muscle activity patterns compared with unweighted tasks.

DISCUSSION AND CONCLUSION

Young people with SI may adapt their movements to minimize glenohumeral joint instability. This was demonstrated by reduced variability in acromioclavicular and sternoclavicular joint angles, adoption of different movement strategies across the same joints, and increased activity of the scapular stabilizing muscles, despite achieving similar arm positions to the CG. Young people with SI demonstrated consistent differences in their muscle activity and movement patterns. Consistently observed differences at the shoulder girdle included increased sternoclavicular protraction and elevation accompanied by increased normalized activity of the posterior scapula-stabilizing muscles. Existing methods of measurement may be used to inform clinical decision making; however, further work is needed to evaluate the prognostic and clinical utility of derived 3D and sEMG data for informing decision making within SI.

Relation between spine alignment and scapular position by plain radiograph examination

Background

Both scapular dynamics and static scapular position are important in the treatment of shoulder dysfunction. This study aimed to create an index that can evaluate scapular position on plain radiographs and evaluate the relation between scapular position and posture accurately.

Methods

Using four fresh frozen cadavers, we developed a glenoid angle grade based on the degree of overlap between the shadow of the coracoid inflection point and the upper edge of the scapula on frontal plain radiographs: grade 1, no overlap; grade 2, overlaps by less than half of the shadow; grade 3, overlaps by more than half. We then performed a retrospective cohort study that included 329 shoulders of 329 patients who underwent spine surgery. Spine alignment parameters (SPAPs), including cervical lordosis (CL), thoracic kyphosis (TK), lumbar lordosis (LL), pelvic incidence, pelvic tilt, sacral slope, and sagittal vertical axis were measured on standing lateral plain radiographs. Glenoid anterior tilt (GAT) and glenoid anteversion angle (GAVA) were calculated on frontal radiographs and three-dimensional computed tomography scans. Correlations between SPAPs and each angle were investigated, and independent influencing factors were sought in multivariate analysis. Individual factors, GAT, GAVA, and SPAPs were compared among the grades.

Results

SPAPs associated with GAT were sagittal vertical axis (R = 0.14, P = .011), TK (R = 0.12, P = .026), and LL (R = -0.11, P = .046). Multivariate analysis identified TK and LL as independent influencing factors (TK, P = .001; LL, P = .008). SPAPs associated with GAVA were CL (R = 0.17, P = .002), TK (R = 0.29, P < .001), and LL (R = 0.25, P < .001). Multivariate analysis identified CL, TK, and LL as independent influencing factors (CL, P = .01; TK, P = .03; LL, P = .03). There were 183, 127, and 19 cases categorized as grades 1, 2, and 3. GAT (grade 1, 24.0 ± 7.8; 2, 32.4 ± 7.0; 3, 41.0 ± 7.8), GAVA (1, 29.3 ± 7.6; 2, 33.7 ± 9.5; 3, 31.5 ± 8.3), and TK (1, 30.6 ± 13.6; 2, 35.1 ± 14.2; 3, 43.1 ± 20.4) differed significantly according to grade.

Conclusion

We identified factors that influence scapular position and demonstrated that scapular position can be estimated by a grading system using plain radiographs.

Analysis of the three-dimensional scapular kinematics and associated scapular muscle activity during scapular muscle exercises

OBJECTIVE

To compare scapular kinematics and muscle activity among various scapular muscle exercises.

DESIGN

A cross-sectional study.

SETTING

A university research laboratory.

PARTICIPANTS

Eighteen healthy men participated in this study.

MAIN OUTCOME MEASURES

Three-dimensional scapular kinematics was measured with an electromagnetic motion capture system. Activities of the upper trapezius (UT), lower trapezius (LT), and serratus anterior (SA) were measured by using surface electromyography (EMG). In addition, the ratio of LT to the UT (LT/UT) and SA to the UT (SA/UT) was calculated. A repeated one-way analysis of variance and Shaffer's post-hoc analysis were used to detect the differences in each outcome during five exercises.

RESULTS

The scapula was rotated upwardly during all exercises except push-up plus. The LT/UT ratio during side-lying external rotation and side-lying flexion were significantly higher than that for scapular plane elevation (P < .05), although the highest activity of the lower trapezius was produced during scapular plane elevation. The activities of the serratus anterior and SA/UT ratio during horizontal adducted elevation and push-up plus were significantly higher than that during scapular plane elevation (P < .05).

CONCLUSION

Horizontal adducted elevation might be more appropriate for increasing scapular upward rotation with high serratus anterior activity and SA/UT ratio than push-up plus.

Effectiveness of specific scapular therapeutic exercises in patients with shoulder pain: a systematic review with meta-analysis

Background

Therapeutic exercise has been considered a useful tool to rehabilitate shoulder pain, namely through its influence on scapular dynamics. Accordingly, the effectiveness of scapular therapeutic exercise needs to be explored. The present study aims to evaluate the effectiveness of scapular therapeutic exercises in shoulder pain and to identify the most effective exercise type (focal or multijoint) and ways of delivering them (as dose and progression).

Methods

Search was conducted at EMBASE, Cochrane Library, MEDLINE via PubMed, Web of Science, PEDro (Physiotherapy Evidence Database), and trial registration databases. The meta-analysis considered randomized controlled/crossover trials that compared the effect of scapular exercises against other types of intervention in the shoulder pain, shoulder function, scapular motion, and/or muscular activity. The risk of bias was assessed through the PEDro scale.

Results

From the 8318 records identified, 8 (high to low risk of bias- scoring from 4 to 8 on the PEDro scale) were included. The overall data, before sensitivity analysis, indicated that the scapular therapeutic exercises are: a) more effective than comparators in improving shoulder function (standardized mean difference [SMD] = 0.52 [95% Cl: 0.05, 0.99], P = .03, I2 = 76%); and b) as effective as comparators in reducing shoulder pain (SMD = 0.32 [95% Cl: -0.09, 0.73], P = .13, I2 = 70%). Subgroup analysis revealed that scapular exercises are more effective in improving shoulder function when the program duration is equal to or higher than 6 weeks (SMD = 0.43 [95% Cl: 0.09, 0.76] P = .01, I2 = 21%) and/or when the maximum number of exercise repetitions per session is lower than 30 (SMD = 0.79 [95% Cl: 0.15, 1.42], P = .01, I2 = 77%). Only 1 study considered scapular motion as an outcome measure, revealing therapeutic exercise effectiveness to improve scapular range of motion.

Conclusions

Intervention programs involving scapular therapeutic exercises are effective in improving shoulder function, presenting benefits when performed for 6 or more weeks and/or when used up to a maximum of 30 repetitions per exercise, per session.

Differences in Osseous Shoulder Morphology, Scapulothoracic Orientation, and Muscle Volume in Patients With Constitutional Static Posterior Shoulder Instability (Type C1) Compared With Healthy Controls

BACKGROUND

Constitutional static posterior humeral decentering (type C1 according to ABC Classification) has been recognized as a pre-osteoarthritic deformity that may lead to early-onset posterior decentering osteoarthritis at a young age. Therefore, it is important to identify possible associations of this pathologic shoulder condition to find more effective treatment options.

PURPOSE

To perform a comprehensive analysis of all parameters reported to be associated with a C1 shoulder-including the osseous shoulder morphology, scapulothoracic orientation, and the muscle volume of the shoulder girdle in a single patient cohort.

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

A retrospective, comparative study was conducted analyzing 17 C1 shoulders in 10 patients who underwent magnetic resonance imaging (MRI) with the complete depiction of the trunk from the base of the skull to the iliac crest, including both humeri. The mean age of the patients was 33.5 years, and all patients were men. To measure and compare the osseous shoulder morphology (glenoid version, glenoid offset, humeral torsion, anterior acromial coverage, posterior acromial coverage, posterior acromial height, and posterior acromial tilt) and scapulothoracic orientation (scapular protraction, scapular internal rotation, scapular upward rotation, scapular translation, scapular tilt, and thoracic kyphosis), these patients were matched 1 to 4 according their age, sex, and affected side with shoulder-healthy patients who had received positron emission tomography (PET)-computed tomography. To measure and compare the muscle volume of the shoulder girdle (subscapularis, infraspinatus/teres minor, supraspinatus, trapezius, deltoid, latissimus dorsi/teres major, pectoralis major, and pectoralis minor), patients were matched 1 to 2 with patients who had received PET-MRI. Patients with visible pathologies of the upper extremities were excluded.

RESULTS

The C1 group had a significantly higher glenoid retroversion, increased anterior glenoid offset, reduced humeral retrotorsion, increased anterior acromial coverage, reduced posterior acromial coverage, increased posterior acromial height, and increased posterior acromial tilt compared with controls (P < .05). Decreased humeral retrotorsion showed significant correlation with higher glenoid retroversion (r = -0.742; P < .001) and higher anterior glenoid offset (r = -0.757; P < .001). Significant differences were found regarding less scapular upward rotation, less scapular tilt, and less thoracic kyphosis in the C1 group (P < .05). The muscle volume of the trapezius and deltoid was significantly higher in the C1 group (P < .05).

CONCLUSION

Patients with C1 shoulders differ from healthy controls regarding osseous scapular and humeral morphology, scapulothoracic orientation, and shoulder girdle muscle distribution. These differences may be crucial in understanding the delicate balance of glenohumeral centering.

Scapular muscle dynamic stiffness of asymptomatic subjects and subjects with chronic shoulder pain, at rest and isometric contraction conditions

Muscle stiffness had a crucial role in joint stability, particularly, at the shoulder complex. Although changes in upper trapezius muscle stiffness have been described for shoulder pain, contradictory findings have been obtained. Also, existing data regarding scapular muscles are, majorly, about trapezius. Myotonometry is a method used to assess stiffness; however, the reliability values of scapular muscle stiffness through this method have not been assessed in shoulder pain conditions. The present study aims to compare scapular muscles' stiffness (trapezius, serratus anterior, and levator scapulae) between subjects with and without chronic shoulder pain and to evaluate the related test-retest reliability. Twenty-two symptomatic and twenty-two asymptomatic subjects participated in a cross-sectional study. The dynamic muscular stiffness of scapular muscles, at rest and during an isometric contraction, was measured bilaterally with myotonometry, in two moments. The differences in bilateral averaged values between symptomatic and asymptomatic subjects and the effect of the group (group presenting pain in the dominant or non-dominant side, and asymptomatic group) and of the limb (unilateral painful or asymptomatic limb, and bilateral asymptomatic limbs) were investigated. Test-retest intra-rater reliability was determined. An effect of the group was observed at rest, for middle trapezius stiffness, and during contraction, for middle and lower trapezius stiffness. For middle trapezius, increased values were observed in the group presenting pain in non-dominant side comparing to both groups or to group presenting pain in dominant side. The intraclass correlation coefficient, majorly, ranged between 0.775 and 0.989. Participants with pain in the non-dominant side presented an increased middle trapezius' stiffness. Globally, high reliability was observed for scapular muscles dynamic stiffness.

Surgical Intervention Following a First Traumatic Anterior Shoulder Dislocation Is Worthy of Consideration

Up to 60% of patients experience recurrence after a first traumatic anterior shoulder dislocation (FTASD), which is often defined as having experienced either dislocation or subluxation. Thus surgical intervention after FTASD is worthy of consideration and is guided by the number of patients who need to receive surgical intervention to prevent 1 redislocation (i.e., number needed to treat), (subjective) health benefit, complication risk, and costs. Operative intervention through arthroscopic stabilization can be successful in reducing recurrence risk in FTASD, as has been shown in multiple randomized controlled trials. Nevertheless, there is a large "gray area" for the indication of arthroscopic stabilization, and it is therefore heavily debated which patients should receive operative treatment. Previous trials showed widely varying redislocation rates in both the intervention and control group, meta-analysis shows 2% to 19% after operative and 20% to 75% after nonoperative treatment, and redislocation rates may not correlate with patient-reported outcomes. The literature is quite heterogeneous, and a major confounder is time to follow-up. Furthermore, there is insufficient standardization of reporting of outcomes and no consensus on definition of risk factors. As a result, surgery is a reasonable intervention for FTASD patients, but in which patients it best prevents redislocation requires additional refinement.

Defining humeral axial rotation with optical motion capture and inertial measurement units during functional task assessment

Humeral motion can be challenging to measure and analyze. Typically, Euler/Cardan sequences are used for humeral angle decomposition, but choice of rotation sequence has substantial effects on outcomes. A new method called True axial rotation calculation may be more precise. The objective of this study is to compare humeral axial rotation measured from two systems (optical motion capture and inertial measurement units (IMUs)) and calculated with two methods (Euler angles and True axial). Motion of torso and dominant humerus of thirty participants free from any upper limb impairments was tracked using both systems. Each participant performed a functional tasks protocol. Humeral axial rotation was calculated with Euler decomposition and the True axial method. Waveforms were compared with two-way ANOVA statistical parametric mapping. A consistent pattern emerged: axial rotation was not different between motion capture systems when using the True axial method (p > .05), but motion capture systems showed relatively large magnitude differences (~ 20-30°) when using Euler angle calculation. Between-calculation method differences were large for both motion capture systems. Findings suggest that the True axial rotation method may result in more consistent findings that will allow for precise measurements and comparison between motion capture systems. Two methods for calculating humeral axial rotation measured from optical motion capture and inertial measurement units were compared.

Effects of elevation on shoulder joint motion: comparison of dynamic and static conditions

BACKGROUND

Although visual examination and palpation are used to assess shoulder motion in clinical practice, there is no consensus on shoulder motion under dynamic and static conditions. This study aimed to compare shoulder joint motion under dynamic and static conditions.

METHODS

The dominant arm of 14 healthy adult males was investigated. Electromagnetic sensors attached to the scapular, thorax, and humerus were used to measure three-dimensional shoulder joint motion under dynamic and static elevation conditions and compare scapular upward rotation and glenohumeral joint elevation in different elevation planes and angles.

RESULTS

At 120° of elevation in the scapular and coronal planes, the scapular upward rotation angle was higher in the static condition and the glenohumeral joint elevation angle was higher in the dynamic condition (P&lt;0.05). In scapular plane and coronal plane elevation 90°- 120°, the angular change in scapular upward rotation was higher in the static condition and the angular change in scapulohumeral joint elevation was higher in the dynamic condition (P&lt;0.05). No differences were found in shoulder joint motion in the sagittal plane elevation between the dynamic and static conditions. No interaction effects were found between elevation condition and elevation angle in all elevation planes.

CONCLUSIONS

Differences in shoulder joint motion should be noted when assessing shoulder joint motion in different dynamic and static conditions. Level of evidence: Level III, diagnostic cross-sectional study.

Defining repeatability for scapulothoracic and thoracohumeral motion during the novel work-related activities and functional task (WRAFT) protocol

Upper limb motion can be challenging to measure and analyze during work or daily life tasks. Further, humeral angle calculation method substantially influences angle outcomes. Therefore, the purpose of this study was to assess the repeatability of scapular and humeral kinematics and compare thoracohumeral angle calculation during a work-related and functional task (WRAFT) protocol. Thirty healthy young adults completed the WRAFT protocol (Comb Hair, Wash Axilla, Tie Apron, Overhead Reach, Side Reach, Forward Transfer, Floor Lift, and Overhead Lift) on two separate occasions. Peak humeral angles and select scapular angles were extracted for each task. Intra-class correlation coefficients (ICCs), standard error of measurement, and minimal detectable change (MDC) were examined. Humeral angles were compared using the XZY and ZXY rotation sequences and "true" axial rotation for incidence of gimbal lock and amplitude coherence. Results showed that for scapular kinematics, elevation-based WRAFTs produced overall better ICC scores (0.23-0.90) compared to those tasks primarily driven by lateral humeral motion (0.02-0.84). MDCs ranged from 7°-78°, suggesting some tasks demonstrated good repeatability (Comb Hair, Overhead Reach, Floor Lift), while others had very high variability (Side Reach, Tie Apron). Amplitude coherence for thoracohumeral angles was best for ZXY for all tasks except the Comb Hair and Tie Apron, for which XZY is recommended. "True" axial rotation demonstrated good coherence for all but Tie Apron. The WRAFT protocol may be used for functionally relevant scapular and humeral kinematic assessment for select task and posture combinations.

The influence of three-dimensional scapular kinematics on arm elevation angle in healthy subjects

BACKGROUND

We often clinically observe individual differences in arm elevation angles, but the motion producing these differences remains unclear, partly because of the difficulty of accurately measuring scapular motion. The aim of this study was to determine whether the scapular or glenohumeral (GH) motion has more influence on differences in the arm elevation angles by capturing not only the humerus and scapula but also the trunk using two- (2D) and three-dimensional (3D) shape-matching registration techniques.

METHODS

Fifteen healthy subjects (13 male and 2 female; mean age: 27.7 years) were instructed to elevate their arms in the sagittal, scapular, and coronal planes. They were divided into high and low groups based on the average of arm elevation angle measured by a goniometer. The 3D scapular, thoracohumeral, and glenohumeral motions were evaluated using 2D/3D single-plane registration. To compare 3D motions between groups, we performed a two-way repeated measures analysis of variance.

RESULTS

Eight subjects were assigned to the high group, while seven subjects were assigned to the low groups based on an average elevation angle of 172°. The low group demonstrated a significant larger scapular protraction during elevation in all planes (P = 0.0002 for flexion; P = 0.0047 for scaption; P = 0.0314 for abduction), and smaller posterior tilting only during flexion (P = 0.0157). No significant differences occurred in scapular upward rotations or the glenohumeral positions and rotations.

CONCLUSIONS

This study revealed that insufficient scapular retraction and posterior tilting results in lower arm elevation angles, suggesting that improving the flexibility and activation of muscles surrounding the scapula may be important to achieve complete arm elevation.

The influence of shoulder position during multi-joint exercises in the relative scapular muscles activity in symptomatic and asymptomatic conditions

BACKGROUND

Scapular muscles changes, as increased upper trapezius activity and decreased middle and lower trapezius and serratus anterior muscle activity, have been demonstrated in shoulder pain specific or non-specific conditions. Shoulder external rotation exercises have been recommended to improve scapular activity in shoulder pain.

OBJECTIVE

To evaluate the relative scapular muscles activity during multi-joint exercises combining shoulder external rotation, trunk rotation and scapular squeeze.

METHODS

Forty-one participants with and without shoulder pain were assessed in a cross-sectional study. They performed isometric multi-joint exercises at 0∘ and 90∘ of shoulder abduction with and without support. The relative activity of upper, middle, and lower trapezius and serratus anterior (upper/middle and lower portions) was measured through electromyography. The scapular muscular balance was assessed by the ratio between relative activity of the upper trapezius and the other muscles.

Three-dimensional shoulder kinematics: Upright four-dimensional computed tomography in comparison with an optical three-dimensional motion capture system

Although shoulder kinematics have been analyzed by various methods, dynamic shoulder motion is difficult to track. This study aimed to validate the shoulder kinematic analysis using upright four-dimensional computed tomography (4DCT) and to compare the results with optical three-dimensional motion capture. During active elevation, bilateral shoulders of 10 healthy volunteers were tracked using 4DCT and motion capture. The scapulothoracic and glenohumeral rotations and the scapulohumeral rhythm (SHR) at each position were calculated, and the differences between 4DCT and motion capture were compared. During 10-140° of humerothoracic elevation, the scapulothoracic joint showed upward rotation, internal rotation, and posterior tilting, and the glenohumeral joint showed elevation, external rotation, and anterior plane of elevation in both analyses. In scapulothoracic rotations, the mean differences between the two analyses were -2.6° in upward rotation, 13.9° in internal rotation, and 6.4° in posterior tilting, and became significant with humerothoracic elevation ≥110° in upward rotation, ≥50° in internal rotation, and ≥100° in posterior tilting. In glenohumeral rotations, the mean differences were 3.7° in elevation, 9.1° in internal rotation, and -8.8° in anterior plane of elevation, and became significant with humerothoracic elevation ≥110° in elevation, ≥90° in internal rotation, and ≥100° in anterior plane of elevation. The mean overall SHRs were 1.8 in 4DCT and 2.4 in motion capture, and the differences became significant with humerothoracic elevation ≥100°. The 4DCT analysis of in vivo shoulder kinematics using upright computed tomography scanner is feasible, but the values were different from those by skin-based analysis at the elevated arm positions.

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.

[Rebalancing theory of shoulder stability mechanism for the diseases related to the shoulder instability and dysfunction of motion]

Objective

To introduce a new theory of shoulder stability mechanism, rebalancing theory, and clinical application of this new theory for the shoulder instability and dysfunction of motion.

Methods

Through extensive review of the literature related to shoulder instability and dysfunction of the motion in recent years, combined with our clinical practice experience, the internal relation between passive stability mechanism and dynamic stability mechanism were summarized.

Results

Rebalancing theory of shoulder stability mechanism is addressed, namely, when the shoulder stability mechanism is destructive, the stability of the shoulder can be restored by the rebalance between dynamic stability mechanism and passive stability mechanism. When dynamic stability is out of balance, dynamic stability can be restored by rebalancing the different parts of dynamic stability mechanism or to strengthen the passive stability mechanism. When passive stability mechanism is out of balance, passive stability can be restored by rebalancing the soft tissue and bone of the shoulder.

Conclusion

Rebalancing theory of shoulder stability mechanism could make a understanding the occurrence, development, and prognosis of shoulder instability and dysfunction from a comprehensive and dynamic view and guide the treatment effectively.

Changing our Diagnostic Paradigm Part II: Movement System Diagnostic Classification

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

Effectiveness of conservative treatment of multidirectional instability of the shoulder joint. Literature review and meta-analysis

<br><b>Introduction:</b> Multidirectional shoulder instability (MDI) occurs when the shoulder is dislocating in at least two directions. The patient usually experiences pain with apprehension and a clicking sensation inside the joint. So far, a few classification scales of shoulder instability have been made. Despite this fact, MDI is highly problematic for clinicians in diagnosis and treating.</br> <br><b>Aim:</b> This article presents the current trends in the conservative treatment of multidirectional instability, assess effectiveness of rehabilitation and indicates the directions of MDI research.</br> <br><b>Material and methods:</b> In order to find current literature and conduct a critical analysis, the following scientific database was used: Cochrane Library, Physiotherapy Evidence Database (PEDro), MEDLINE and PubMed. We chose four articles which included a comparison of conservative and operative treatment, and four which evaluate the effectiveness of rehabilitation.</br> <br><b>Results:</b> Low quality evidence shows priority of surgical treatment over conservative treatment. The protocol developed by Watson obtains a statistically significant advantage over the Burkhead and Rockwood protocol. Discussion: The effectiveness of rehabilitation reaches different levels. Rehabilitation should last from 3 to 12 months. If rehabilitation does not achieve a sufficient effect, arthroscopic methods of reducing the volume of the articular capsule should be considered. Due to the small number of scientific reports and their quality, the obtained data should be interpreted with caution. Much further research is required to create a precise and most effective algorithm.</br> <br><b>Conclusion:</b> Rehabilitation exercises play an important role in the treatment of multidirectional instability of the shoulder joint, especially when the patient has not had an injury. Exercise types and load should be dosed individually. At present, the protocol described by Watson is the most effective.</br>

Serratus Anterior Fatigue Reduces Scapular Posterior Tilt and External Rotation During Arm Elevation

CONTEXT

Fatigue of the scapular stabilizing muscles resulting from repeated arm motion has been reported to alter scapular kinematics, which could result in shoulder pathology, especially impingement.

OBJECTIVE

This study aimed to examine the effects of fatigue of the serratus anterior muscle on scapular kinematics, specifically, decrease scapular posterior tilt and upward scapular rotation during arm elevation.

DESIGN

Repeated measures.

SETTING

Laboratory.

PARTICIPANTS

Thirty participants were included in the investigation.

INTERVENTIONS

Scapular kinematics and shoulder strength were measured before and immediately following a serratus anterior fatigue protocol.

MAIN OUTCOME

Scapular 3-dimensional position during arm elevation.

RESULTS

No difference in upward rotation of the scapula between prefatigue and postfatigue conditions (ascending: P = .188; descending: P = .798). Scapular posterior tilt decreased during arm elevation following the fatigue protocol between 60° and 90° and 90° and 120° of arm elevation during the ascent (P = .004) and the descent (P = .013). Fatigue by arm elevation angle interaction was found for clavicular elevation during the ascent (P = .050) between 90° and 120° of arm elevation. Scapular internal rotation increased during the ascent (P = .027). There was no difference in clavicular protraction between the prefatigue and postfatigue conditions (ascending: P ≤ .001; descending: P ≤ .001).

CONCLUSION

Fatigue of the serratus anterior decreases posterior scapular tilt and greater clavicular elevation and scapular internal rotation at higher arm elevation angles. These findings are consistent with the scapular kinematic patterns associated with shoulder pain. Improving serratus anterior endurance might delay the changes in scapular kinematics associated with repeated arm motion and shoulder injury mechanisms.

Scapulothoracic Dyskinesis: A Concept Review

PURPOSE OF REVIEW

Scapulothoracic dyskinesis (SD) occurs when there is a noticeable disruption in typical position and motion of the scapula, which can result in debilitating pain. The purpose of this review is to describe the current knowledge regarding the diagnosis and management of scapulothoracic dyskinesis by providing an evidence-based overview of clinical exams and treatment modalities available for orthopedic surgeons and provide insight into which treatment modalities require further investigation.

RECENT FINDINGS

SD is highly prevalent in athletes, particularly those participating in overhead activities (e.g., baseball, tennis, and swimming) and can coexist with several shoulder pathologies. A holistic approach in the diagnosis of SD has been supported in the literature; however, it is important to recognize that diagnosis is currently limited to the absence of a quantitative SD clinical assessment. The main goal of the treatment of SD is to regain proper scapular positioning and dynamics. The standard of care for the management of SD is conservative interventions aimed at optimizing scapular kinematics. Surgical intervention is only considered in the presence of concomitant pathology requiring surgery. Due to the complexity of coordinated movement of the shoulder girdle, recent literature has begun to move away from the use of traditional orthopedic tests, in favor of a more system-based approach for the diagnosis of SD. We present a concise review of clinical exams and treatment modalities available for orthopedic surgeons in the management of SD.

Differences in scapular motion and parascapular muscle activities among patients with symptomatic and asymptomatic rotator cuff tears, and healthy individuals

Background

Altered scapular motion is thought to be one of the factors associated with the development of symptomatic rotator cuff tears. However, the differences in kinematics and muscle activities of scapular upward/downward rotation between patients with symptomatic and asymptomatic tears are unclear. The purpose of this study was to compare the differences in kinematics and muscle activities of scapular rotation among patients with symptomatic and asymptomatic tears, and healthy individuals.

Methods

Twenty-three patients with rotator cuff tears and 9 healthy individuals (healthy group) participated in this study. Based on a visual analog scale (VAS, 0-100 mm), the patients were divided into symptomatic (13 patients; VAS ≥20 mm) and asymptomatic (10 patients; VAS <20 mm) groups. Scapular upward rotation was measured with a digital inclinometer. Elasticities of the upper trapezius, levator scapulae, and rhomboid major were assessed by using ultrasound real-time tissue elastography to quantify their muscle activities. All measurements were performed at 0°, 60°, 90°, and 120° of active arm elevation in the scapular plane.

Results

Scapular upward rotation was significantly less in the symptomatic group (9.4° ± 5.6°) compared with the asymptomatic group (15.7° ± 6.0°; P = .022) at 90° of arm elevation. The activity of the levator scapulae was significantly higher in the symptomatic group compared with the asymptomatic and healthy groups (P = .013 and P = .005, respectively) at 90° of arm elevation. The activity of the upper trapezius was significantly higher in the symptomatic group compared with the healthy group (P = .015) at 120° of arm elevation.

Conclusion

Patients with symptomatic rotator cuff tears showed less scapular upward rotation and higher activity of the levator scapulae at 90° of arm elevation compared to patients with asymptomatic rotator cuff tears.

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.

The repeatability of 3-dimensional scapular kinematic analysis during bilateral upper extremity movements

Although three-dimensional electromagnetic systems are widely used to evaluate the 3-dimensional scapular kinematics their reliability when testing bilateral upper extremity tasks is unknown. The purpose of this study was to investigate the repeatability of the scapular kinematic analyses using the Flock of Birds (FOB) system during bilateral upper extremity movements. Twenty-one volunteers without shoulder problems were included (aged 24.8 years; body mass index averaged 21.2 kg/m²) to the study. Scapular internal-external rotation, upward-downward rotation, and anterior-posterior tilt was recorded during bilateral arm elevation on sagittal, scapular and frontal planes. Measurements were repeated at 5-7 days intervals. Intra-session and inter-session repeatability were determined using intraclass correlation coefficients (ICC) scores and standard errors of measurements (SEM). The ICC scores were found to be 0.81 to 0.99 for intra-session measurements and 0.60 to 0.83 for inter-session measurements. The SEM scores were 0.8°-3.4° and 2°-7.2° for the intra and inter-session measurements respectively. The repeatability of the FOB system was excellent for the intra-session measurements, but it was weaker for the inter-session measurements. These results support the use of the FOB system for assessing scapular orientation but the analyses should be conducted more carefully when it is applied to the longitudinal measurements.

Measurement of Pectoralis Minor Muscle Length in Women Diagnosed With Breast Cancer: Reliability, Validity, and Clinical Application

BACKGROUND

Decreased pectoralis minor muscle length is common after primary breast cancer treatment and can result in an abnormal position of the scapula. This position can contribute to shoulder pain and pathomechanics and can lead to problems such as impingement syndrome, rotator cuff tears, and frozen shoulder. Currently, there are limited reliable methods for measuring pectoralis minor length.

OBJECTIVE

The objective of this study was to examine the reliability and validity of measuring pectoralis minor length in women diagnosed with breast cancer.

DESIGN

This was a cross-sectional reliability and validity study.

METHODS

Bilateral pectoralis minor length (in centimeters) was assessed using a palpation meter in women (N = 29) diagnosed with breast cancer by 2 licensed physical therapists who were masked to the measures. Bilateral pectoralis minor length was also measured using a motion capture system to assess validity.

RESULTS

Intratester reliability (intraclass correlation coefficient, ICC [3,k] = 0.971; 95% confidence interval [CI] = 0.939-0.986; standard error of measurement [SEM] = 0.16 cm) and intertester reliability (ICC[3,k] = 0.915; 95% CI = 0.81-0.962; SEM = 0.31 cm) were excellent for the palpation meter on the affected side and the unaffected side (intratester reliability: ICC[3,k] = 0.951; 95% CI = 0.897-0.977; SEM = 0.19 cm; intertester reliability: ICC[3,k] = 0.945; 95% CI = 0.877-0.975; SEM = 0.22 cm). Significant correlations were found between the motion capture system and the palpation meter on the affected side (r = 0.87) and the unaffected side (r = 0.81). Bland-Altman plots between the palpation meter and the motion capture system demonstrated that all the measures fell within the limits of agreement.

LIMITATIONS

This study encountered possible errors with the accuracy of the motion capture system tracking because of the proximity of the markers and inherent volumetric restrictions.

CONCLUSIONS

The palpation meter is a reliable, valid, easily administered, and cost-effective tool for assessing pectoralis minor length in women with breast cancer.

Subacromial space outlet in female patients with multidirectional instability based on hypermobile Ehlers-Danlos syndrome and hypermobility spectrum disorder measured by ultrasound

OBJECTIVE

The objective of the study was to compare the acromiohumeral distance (AHD) between patients diagnosed with hypermobility type of the Ehlers-Danlos syndrome (hEDS) or hypermobility spectrum disorder (HSD) and healthy controls by evaluating the relative amount the tendon occupies in the subacromial area. Furthermore, the aim was to evaluate if there was a change in AHD with arm elevation within and between groups.

METHODS

Twenty-nine female patients with hEDS/HSD (aged 34 ± 12.9 years) and 20 healthy controls (aged 33 ± 10.8 years) participated in the study. The supraspinatus tendon (SST) thickness and AHD were measured using ultrasound. The interplay between the SST and the AHD was expressed as the occupation ratio (OcAHD), calculated as the SST thickness as a percentage of AHD. The measures were performed in the resting position and in subsequently 45° and 60° of active arm elevation in the scapular plane.

RESULTS

The main finding is that patients with hEDS/HSD have a larger subacromial space outlet compared with the controls when measured by ultrasound. Furthermore, in both groups, we found an increased OcAHD during active arm elevation compared with the resting position, which indicates that similar mechanisms occur for patients with hEDS/HSD and healthy controls.

CONCLUSION

Patients with hEDS/HSD have a larger available subacromial space outlet compared with healthy individuals. OcAHD increased during active arm elevation compared with the resting position in both groups. This knowledge is important when designing rehabilitation exercise programs for shoulder instability patients with abnormal glenohumeral biomechanics.

Comparison of scapular kinematics and muscle strength between those with a positive and a negative Scapular Assistance Test

BACKGROUND

The Scapular Assistance Test was suggested to directly assess the influence of scapular motion on pain and indirectly measure the function of the scapular rotators. However, it is still not clear if individuals with a positive Scapular Assistance Test actually present changes in scapular motion and muscle strength. This study compared scapular kinematics and muscle strength between those with a positive Scapular Assistance Test and those with a negative Scapular Assistance Test.

METHODS

Fifty individuals with shoulder pain were randomly allocated to: positive (n = 25) or negative Scapular Assistance Test (n = 25) group. Scapular kinematics was measured during elevation and lowering of the arm. Strength of the serratus anterior and lower trapezius was also measured. Two-way analysis of variance was used to compare kinematics between groups. Unpaired Student's t-test and Mann-Whitney test were used to compare strength of serratus anterior and lower trapezius, respectively.

FINDINGS

There were no differences (P > 0.05) in scapular internal rotation and upward rotation between both groups. For scapular tilt, there was group main effect (P < 0.05) during elevation and lowering of the arm, whereas the positive Scapular Assistance Test group presented greater scapular anterior tilt. There was no difference (P > 0.05) in strength between groups.

INTERPRETATION

Individuals with a positive Scapular Assistance Test are more likely to present decreased scapular posterior tilt in those with shoulder pain. Strength of the scapular muscles seems to be same in those with a positive and a negative Scapular Assistance Test.

The Coupled Kinematics of Scapulothoracic Upward Rotation

BACKGROUND

Scapulothoracic upward rotation (UR) is an important shoulder complex motion allowing for a larger functional work space and improved glenohumeral muscle function. However, the kinematic mechanisms producing scapulothoracic UR remain unclear, limiting the understanding of normal and abnormal shoulder movements.

OBJECTIVE

The objective of this study was to identify the coupling relationships through which sternoclavicular and acromioclavicular joint motions contribute to scapulothoracic UR.

DESIGN

This was a cross-sectional observational study.

METHODS

Sixty participants were enrolled in this study; 30 had current shoulder pain, and 30 had no history of shoulder symptoms. Shoulder complex kinematics were quantified using single-plane fluoroscopy and 2D/3D shape matching and were described as finite helical displacements for 30-degree phases of humerothoracic elevation (30 degrees-60 degrees, 60 degrees-90 degrees, and 90 degrees-120 degrees). A coupling function was derived to estimate scapulothoracic UR from its component motions of acromioclavicular UR, sternoclavicular posterior rotation, and sternoclavicular elevation as a function of acromioclavicular internal rotation. The proportional contributions of each of the component motions were also calculated and compared between phases of humerothoracic elevation and groups.

RESULTS

Scapulothoracic UR displacement could be effectively predicted using the derived coupling function. During the 30- to 60-degree humerothoracic elevation phase, acromioclavicular UR accounted for 84.2% of scapulothoracic UR, whereas sternoclavicular posterior rotation and elevation each accounted for < 10%. During later phases, acromioclavicular UR and sternoclavicular posterior rotation each accounted for 32% to 42%, whereas sternoclavicular elevation accounted for < 11%.

LIMITATIONS

Error due to the tracking of sternoclavicular posterior rotation may have resulted in an underprediction of its proportional contribution and an overprediction of the proportional contribution of acromioclavicular UR.

CONCLUSIONS

Acromioclavicular UR and sternoclavicular posterior rotation are the predominant component motions of scapulothoracic UR. More research is needed to investigate how these coupling relationships are affected by muscle function and influenced by scapular dyskinesis.

Three-Dimensional Analysis of Scapular Kinematics During Arm Elevation in Baseball Players With Scapular Dyskinesis: Comparison of Dominant and Nondominant Arms

Background: The knowledge of 3-dimensional scapular kinematics is essential for understanding the pathological lesions of the shoulder and elbow in throwing athletes. Many studies about alterations of the resting scapular position, dynamic scapular motion, or scapular dyskinesis (SD) have been conducted, yet none of them have identified a consistent pattern of altered scapular kinematics in throwing athletes. Hypothesis/Purpose: To analyze the 3-dimensional scapular kinematics of dominant and nondominant arms in baseball players with a pathological condition of the shoulder or elbow. Study Design: Cross-sectional study. Methods: Bilateral scapular positions, consisting of upward rotation (UR), superior translation (ST), internal rotation (IR), protraction (PRO), and anterior tilting (AT) with an arm at rest and at 150° forward elevation, were measured among 319 baseball players with SD using 3-dimensional computed tomography. Angular values of scapula were compared between dominant and nondominant arms with statistical analysis. Level of Evidence: Level III, diagnostic study. Results: The scapular position of dominant arms showed significantly more AT, less ST at rest and more UR and IR and less ST, PRO, and AT at 150° full forward elevation compared with the nondominant arms. The magnitude of mean change of UR, IR, PRO, and AT during arm elevation increased significantly between the paired arms (P value: UR, ST, PRO, and AT: <.001 and IR: .001). Conclusion: When compared with the nondominant arms, UR, AT, and PRO with the arm at 150° forward elevation of dominant symptomatic arms in baseball players tilted toward positive compensation, whereas IR altered toward negative decompensation. In addition, the angular increment of the scapula increased significantly in dominant symptomatic arms compared with the nondominant arms.

Alterations in the 3-dimensional scapular orientation in patients with non-specific neck pain

BACKGROUND

Although it is thought that there is a relationship between neck pain and scapular dysfunction, there are controversial results and no clear information in the literature regarding this issue. This study aimed to investigate the alterations in the 3-Dimensional scapular orientation on patients with non-specific neck pain.

METHOD

Thirty-four patients with chronic non-specific neck pain [age, 29.1 (5) years; height, 165.3 (6.1) centimeters; weight, 62.1 (9.6) kilogram] and 29 healthy controls [age, 28.2 (3.3) years; height, 166.8 (8.1) centimeters; weight, 60.9 (8.5) kilogram] were included in the study. 3-Dimensional scapular kinematics were obtained during arm elevation and lowering trials in the sagittal, scapular, and frontal planes.

FINDINGS

Compared to healthy controls, the patients with neck pain demonstrated significantly reduced upward scapular rotation on both the dominant and non-dominant sides in all three planes. Patients with neck pain had increased internal rotation in the sagittal and frontal planes on the dominant side and increased external rotation in the frontal plane on the non-dominant side. No difference was observed between groups considering posterior scapular tilt.

INTERPRETATION

There are alterations in the 3-Dimensional scapular orientations in patients with chronic non-specific neck pain compared to healthy controls. Therefore, the scapular control may also be examined in patients with neck pain and it can be included in the rehabilitation program if needed.

Evaluation and Management of Scapular Dyskinesis in Overhead Athletes

PURPOSE OF REVIEW

This review will outline scapular function in throwing, discuss scapular dyskinesis as an impairment of function that can be associated with throwing injuries and altered performance, and present an algorithm that encompasses guidelines for evaluation and can serve as a basis for treatment.

RECENT FINDINGS

Optimal scapular function is integral to optimal shoulder function. Multiple roles of the scapula in arm function and throwing have been identified while scapular dysfunction continues to be associated with various shoulder pathologies. Although scapular motion alterations may be common in overhead athletes, various reports have shown that identification and management of the alterations can result in improved rehabilitation and performance outcomes. Baseball throwing occurs as the result of integrated, multisegmented, sequential joint motion, and muscle activation within the kinetic chain. The scapula is a key component link within the chain through its function to maximize the scapulohumeral rhythm and efficient throwing mechanics. Evaluation and management beginning with the scapula can produce improved outcomes related to shoulder pathology in overhead athletes.

A three-dimensional scapular motion analysis in patients with arthroscopic anterior capsulolabral repair of the shoulder: The effect of scapular stabilization taping

BACKGROUND

The aim of this study was to investigate the scapular kinematics during dynamic humeral movements in patients with arthroscopic anterior capsulolabral repair of the shoulder along with the potential biomechanical corrective effects of scapular stabilization taping.

METHODS

Twenty patients with unilateral traumatic anterior shoulder instability and arthroscopic anterior capsulolabral repair participated in the study. Dynamic shoulder kinematics were assessed during the scapular plane shoulder elevation for both the operated and non operated shoulders and also under two conditions: no-taping and taping. Statistical analysis to compare sides and conditions was performed with analysis of variance models.

RESULTS

The scapula was more internally rotated position in operated shoulders than in non operated shoulders. Furthermore, the scapula was less internally rotated and more downwardly rotated at 120° of elevation in the taping condition.

CONCLUSIONS

Operated shoulders demonstrated kinematics alterations when compared to non operated shoulders underwent arthroscopic anterior capsulolabral repair. Additionally, changes in the scapular orientation with the taping was very small but followed a pattern, which would be suggested to be an orientation that potentially produce more scapular stability and to increase stress on the inferior glenohumeral ligament.

Analysis of Shoulder Complex Function After Posterior Spinal Fusion in Adolescents With Idiopathic Scoliosis

BACKGROUND

Nonsurgically treated patients with AIS demonstrate altered scapular kinematics and decreased patient-reported shoulder function compared with typically developing adolescents. It is unknown whether surgical correction of the spine deformity has beneficial or detrimental effects on scapulothoracic joint function, as previous assessments of shoulder function following surgery have only focused on humerothoracic motion. The objective of this study was to perform a comprehensive analysis of scapular kinematics before and after PSF and compare postoperative scapular kinematics in AIS to those of a typically developing cohort.

METHODS

Typically developing adolescents (n=33) and patients with AIS (n=20) with a planned PSF surgery were recruited. Motion capture was used to analyze scapular kinematics at rest and in full abduction. AIS subjects were evaluated before surgery and at a 6-month follow-up. Individual changes following surgery were assessed, and postoperative scapular kinematics were compared with the typically developing subjects.

RESULTS

Patients with AIS patients in this study demonstrated significant losses of scapulothoracic range of motion for the convex side shoulder and gains of scapulothoracic range of motion for the concave side shoulder following PSF. When compared with typically developing adolescents, the resting scapular position of the postoperative AIS group seemed normalized, but the AIS group still exhibited altered scapular motion, particularly along the upward rotation and tilt axes.

CONCLUSIONS

Patients with AIS demonstrated significant changes at the scapulothoracic joint following PSF. Compared with typically developing adolescents, scapular resting position normalized, but the AIS group still demonstrated altered scapular kinematics, including patterns associated with shoulder pathology. The results of this study will inform the course of short-term postoperative rehabilitation by addressing the upper extremity implications of PSF for individuals with AIS.

LEVEL OF EVIDENCE

Level III.

A positive scapular assistance test is equally present in various shoulder disorders but more commonly found among patients with scapular dyskinesis

OBJECTIVE

Assess the frequency of a positive scapular assistance test (SAT) in different shoulder disorders and establish its association with scapular dyskinesis.

DESIGN

Cross-sectional.

SETTING

Shoulder clinic.

PARTICIPANTS

Seventy-four patients.

MAIN OUTCOME MEASURES

The SAT and visual assessment of scapular movement were performed by a physical therapist. An orthopaedic surgeon classified participants into 4 diagnostic categories: rotator cuff disease, superior labrum anterior posterior lesion (SLAP), shoulder instability, and other.

RESULTS

Twenty-seven (36.5%) participants presented with a positive SAT. The SAT was positive among 9 of 28 participants (32.1%) with rotator cuff disease, 7 of 23 participants (30.4%) with SLAP lesions, 9 of 21 participants (42.9%) with shoulder instability, and 2 of 2 participants (100.0%) with other pathologies. The frequency of a positive SAT did not differ between the various diagnostic categories (P = 0.64). The SAT was more frequently positive among participants with scapular dyskinesis (48.5% versus 26.8%, P = 0.05).

CONCLUSIONS

The SAT is found similarly positive among patients with various common shoulder disorders. Although associated with scapular dyskinesis, the SAT was positive in less than half of those demonstrating scapular dyskinesis suggesting the SAT may help identify patients in whom altered scapular movement is contributing to shoulder pain.

Multidirectional Instability of the Shoulder: Treatment Options and Considerations

Multidirectional instability (MDI) is a debilitating condition that involves chronic subluxation or dislocation of the shoulder in >1 direction. Numerous proposed mechanisms of MDI exist, which occurs in the setting of redundant capsular tissue. Symptoms can range from recurrent dislocations or subluxations to vague aching pain that disrupts activities of daily living. Magnetic resonance imaging is often performed during evaluation of this condition, although magnetic resonance arthrography may provide more detailed images of the patulous capsule. In the absence of a well-defined traumatic cause, such as a labral tear, initial treatment for MDI is a structured rehabilitation program with exercises aimed at strengthening the rotator cuff and periscapular muscles to improve scapular kinematics. Patients with recalcitrant symptoms may benefit from surgical stabilization, including open capsular shift or arthroscopic capsular plication, aimed at decreasing capsular volume and improving stability.

Shoulder Complex Mechanics in Adolescent Idiopathic Scoliosis and Their Relation to Patient-perceived Function

BACKGROUND

Proper contribution of the scapulothoracic joint is necessary for adequate shoulder complex function. Associations between trunk shape and abnormal scapular kinematics and subsequent shoulder dysfunction have been established; however, the extent of shoulder dysfunction in adolescent idiopathic scoliosis (AIS) is still poorly understood. The purpose of this study was to perform a comprehensive analysis of scapular kinematics during multiplanar arm motion in patients with AIS and compare kinematics and patient-reported function with that of a typically developing cohort.

METHODS

Typically developing adolescents (n=33) and patients with AIS (n=26) with no history of spine or shoulder surgery were recruited for this study. A 3-dimensional optoelectronic motion capture system was used to analyze scapular kinematics in 4 positions: rest, full abduction, forward reach, and hand to spine. Subjects in each group also completed the Disabilities of the Arm, Shoulder, and Hand (DASH) questionnaire as a measure of patient-reported function.

RESULTS

The convex shoulders of the patients with AIS exhibited deficits in scapular upward rotation and posterior tilt in all positions and reduced protraction range of motion during reaching. The AIS group also reported worse patient-perceived shoulder function than the typically developing group; however, this dysfunction was not related to specific scapular kinematic patterns.

CONCLUSIONS

Patients with AIS show alterations in scapular kinematics that are associated with shoulder pathology. Despite displaying an unaffected ability to place the hand in space, the underlying joint mechanics place these adolescents at risk for future pathology. Accordingly, consideration of scapulothoracic and glenohumeral joint function is warranted in the treatment of AIS.

LEVEL OF EVIDENCE

Level III-cross-sectional comparison.

Influence of Brassiere Wearing on Shoulder Kinematics

Objective

Gender differences in scapular kinematics during arm elevation have been reported. Because women wear brassieres (bras) daily, their scapular motion may be restricted by the garment; however, the influence of bra wearing on this motion has not been reported. Therefore, using a three-dimensional electromagnetic tracking device, we investigated the influence of bra wearing on shoulder kinematics during arm elevation.

Methods

The subjects were 19 healthy women, and the shoulder on the dominant side was evaluated. Subjects performed scapular plane arm elevation while wearing or not wearing bras. Kinematic data were recorded using an electromagnetic tracking device. The glenohumeral elevation angle, scapular upward and internal rotation angles, and the posterior tilt angle were determined from the recorded data. The angles were calculated at 20°-120° arm elevation, and the data were compared between the two conditions.

Results

The scapular upward and internal rotation angles and the posterior tilt angle were significantly smaller with the subjects wearing bras than not wearing bras. In contrast, the glenohumeral elevation angle was significantly greater when bras were warn.

Conclusions

Bra wearing may influence shoulder kinematics. Consequently, great care should be taken to account for this factor during the evaluation of kinematics in female subjects.

Glenohumeral Instability Related to Special Conditions: SLAP Tears, Pan-labral Tears, and Multidirectional Instability

Glenohumeral instability is one of the more common conditions seen by sports medicine physicians, especially in young, active athletes. The associated anatomy of the glenohumeral joint (the shallow nature of the glenoid and the increased motion it allows) make the shoulder more prone to instability events as compared with other joints. Although traumatic dislocations or instability events associated with acute labral tears (ie, Bankart lesions) are well described in the literature, there exists other special shoulder conditions that are also associated with shoulder instability: superior labrum anterior/posterior (SLAP) tears, pan-labral tears, and multidirectional instability. SLAP tears can be difficult to diagnose and arthroscopic diagnosis remains the gold standard. Surgical treatment as ranged from repair to biceps tenodesis with varying reports of success. Along the spectrum of SLAP tears, pan-labral tears consist of 360-degree injuries to the labrum. Patients can present complaining of either anterior or posterior instability alone, making the physical examination and advanced imaging a crucial component of the work up of the patients. Arthroscopic labral repair remains a good initial option for surgical treatment of these conditions. Multidirectional instability remains one of the more difficult conditions for the sports medicine physician to diagnose and treat. Symptoms may only be reported as vague pain versus frank instability making the diagnoses particularly challenging, especially in a patient with overall joint laxity. Conservative management to include physical therapy is the mainstay initial treatment in patients without an identifiable structural abnormality. Surgical management of this condition has evolved from open to arthroscopic capsular shifts with comparable results.

A comprehensive rehabilitation program for posterior instability of the shoulder

Posterior shoulder instability is recognised as being less prevalent than anterior instability, however the diagnosis of this pathology is easily overlooked or missed and this may contribute to an underestimation of prevalence. Recently, there has been increasing recognition of this condition and consequently a greater requirement for knowledge of diagnostic procedures and treatment directions. Currently there is limited research into the conservative management of posterior instability, although it is recommended as first-line treatment prior to surgical review, particularly in those with an atraumatic instability mechanism. The aim of this paper is to outline a comprehensive rehabilitation program for the conservative management of posterior instability with a focus on scapular and humeral head control. The information provided includes extensive written information, flowcharts, figures and a table of management parameters that will provide therapists with adequate detail to replicate the program in the clinical setting.

Kinematic patterns in normal and degenerative shoulders. Part II: Review of 3-D scapular kinematic patterns in patients with shoulder pain, and clinical implications

BACKGROUND

The global range of motion of the arm is the result of a coordinated motion of the shoulder complex including glenohumeral (GH), scapulothoracic, sternoclavicular and acromioclavicular joints.

METHODS

This study is a non-systematic review of kinematic patterns in degenerated shoulders. It is a based on our own research on the kinematics of the shoulder complex and clinical experience.

RESULTS

For patients with subacromial impingement syndrome without rotator-cuff tears, most kinematic studies showed a small superior humeral translation relative to the glenoid and decreased scapular lateral rotation and posterior tilt. These scapular kinematic modifications could decrease the subacromial space and favor rotator-cuff tendon injury. For patients with shoulder pain and restricted mobility, the studies showed a significant increase in scapular lateral rotation generally seen as a compensation mechanism of GH decreased range of motion. For patients with multidirectional GH instability, the studies found an antero-inferior decentering of the humeral head, decreased scapular lateral rotation and increased scapular internal rotation.

CONCLUSION

The clinical or instrumented assessment of the shoulder complex with a degenerative pathology must include the analysis of scapula-clavicle and trunk movements complementing the GH assessment. Depending on the individual clinical case, scapular dyskinesis could be the cause or the consequence of the shoulder degenerative pathology. For most degenerative shoulder pathologies, the rehabilitation program should take into account the whole shoulder complex and include first a scapular and trunk postural-correcting strategy, then scapulothoracic muscle rehabilitation (especially serratus anterior and trapezius inferior and medium parts) and finally neuromotor techniques to recover appropriate upper-limb kinematic schemas for daily and/or sports activities.

Comparison of 2 Exercise Rehabilitation Programs for Multidirectional Instability of the Glenohumeral Joint: A Randomized Controlled Trial

BACKGROUND

The recommended initial treatment for multidirectional instability (MDI) of the shoulder is a rehabilitation program, yet there is very low-quality evidence to support this approach. Purpose/Hypothesis: The purpose was to compare the Watson MDI program and Rockwood Instability program among patients with nontraumatic, nonstructural MDI. The hypothesis was that the Watson MDI program would produce clinically and statistically superior outcomes over the Rockwood Instability program.

STUDY DESIGN

Randomized controlled trial; Level of evidence, 2.

METHODS

Forty-one participants with MDI were randomly allocated to the Watson MDI or Rockwood Instability program. Participants attended 12 weekly physiotherapy sessions for exercise prescription. Outcomes were assessed at baseline and 6, 12, and 24 weeks after randomization. Primary outcomes were the Melbourne Instability Shoulder Score (MISS) and the Western Ontario Shoulder Index (WOSI). Secondary outcomes included the Orebro Musculoskeletal Pain Questionnaire, pain, muscle strength, scapular upward rotation, scapular coordinates, global rating of change, satisfaction scales, limiting angle in abduction range, limiting factor in abduction range, and incidence of dislocation. Primary analysis was by intention to treat based on linear mixed models.

RESULTS

Between-group differences showed significant effects favoring the Watson program for the WOSI (effect size [ES], 11.1; 95% CI, 1.9-20.2; P = .018) and for the limiting factor in abduction (ES, 0.1; 95% CI, 0.0-1.6; P = .023) at 12 weeks, and for the WOSI (ES, 12.6; 95% CI, 3.4-21.9; P =. 008), MISS (ES, 15.4; 95% CI, 5.9-24.8; P = .002), and pain (ES, -2.0; CI: -2.3 to -0.7, P = .003) at 24 weeks.

CONCLUSION

For people with MDI, 12 sessions of the Watson MDI program were more effective than the Rockwood program at 12- and 24-week follow-up. Registration: ACTRN12613001240730 (Australian New Zealand Clinical Trials Registry).

The effects of a conservative rehabilitation program for multidirectional instability of the shoulder

BACKGROUND

Conservative management is commonly recommended as the first-line treatment for multidirectional instability (MDI) of the shoulder. Despite this, the evidence for efficacy of treatment is limited, and until recently, guidance for clinicians on conservative rehabilitation programs has been inadequate. This study evaluated the effectiveness of a physiotherapy-led exercise program for participants with MDI.

METHODS

In a single-group study design, 43 participants (16 male, 27 female; mean age, 19.8 years, standard deviation, 4.9 years) diagnosed with MDI undertook a 12-week exercise program. Primary outcome measures were the Melbourne Instability Shoulder Score, Western Ontario Shoulder Instability Index, and Oxford Shoulder Instability Score. Secondary outcomes were strength and scapular position. All measures were taken at baseline and repeated at the conclusion of the program. Test differences before and after rehabilitation were evaluated with dependent t tests and single-group effect size calculations (standardized mean difference [SMD]) to provide a measure of the magnitude of the difference.

RESULTS

Large effects were found between pre- and postrehabilitation scores on all functional instability questionnaires, with the Western Ontario Shoulder Instability Index demonstrating the largest effect (SMD, -3.04). Scapular upward rotation improved significantly in the early ranges of abduction (0°-60°), with moderate to large effects (SMDs, 0.54-0.95). All strength measures significantly improved, with large differences identified (SMDs, 0.69-2.08).

CONCLUSION

The identified improvement in functional status, shoulder muscle strength, and scapular positioning after rehabilitation allows greater confidence in the value of conservative management of MDI and informs further research by way of clinical trials in the area.

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.

Effects of a stretching protocol for the pectoralis minor on muscle length, function, and scapular kinematics in individuals with and without shoulder pain

STUDY DESIGN

Parallel-group intervention with repeated measures.

INTRODUCTION

Shortening of the pectoralis minor (PM) may contribute to alterations in scapular kinematics.

PURPOSE OF THE STUDY

To evaluate the effects of a stretching protocol on function, muscle length, and scapular kinematics in subjects with and without shoulder pain.

METHODS

A sample of 25 patients with shoulder pain and 25 healthy subjects with PM tightness performed a daily stretching protocol for 6 weeks. Outcome measures included Disabilities of the Arm, Shoulder, and Hand questionnaire, PM length, and scapular kinematics.

RESULTS

Disabilities of the Arm, Shoulder, and Hand scores decreased (P < .05) in the patient group at post-intervention. No differences (P > .05) were found for PM length in both groups. Scapular anterior tilt increased (P < .05) at 90° of flexion in the healthy group.

DISCUSSION

This study demonstrated that a daily home stretching protocol significantly decreases pain and improves function in subjects with shoulder pain. The mechanism responsible for these improvements does not appear directly related to PM muscle length or scapula kinematics, suggesting that other neuromuscular mechanisms are involved.

CONCLUSION

The PM stretching protocol did not change the PM length or scapular kinematics in subjects with or without shoulder pain. However, pain and function of the upper limbs improved in patients with shoulder pain.

LEVEL OF EVIDENCE

2b.

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.

Multidirectional Instability: Natural History and Evaluation

Background:

Multidirectional instability (MDI) represents a great challenge to the orthopedic surgeon. When treating these patients we must be aware that instability refers to a symptomatic situation, thus multidirectional instability is defined as symptomatic involuntary instability in two or more directions, and should be clearly differentiated from asymptomatic hyperlaxity.

It may be associated with hyperlaxity, either congenital or acquired following repetitive stress, but also may be present without hyperlaxity, which is rare.

Methods:

We searched in the online data bases and reviewed the relevant published literature available.

Results:

Many differences can be seen in the current literature when identifying these patients, unclear definitions and criteria to be included in this patient group are common.

Conclusion:

Understanding the complex shoulder biomechanics as well as being aware of the typical clinical features and the key examination signs, which we review in this article, is of paramount importance in order to identify and classify these patients, allowing the best treatment option to be offered to each patient.

In vivo kinematic analysis of the glenohumeral joint during dynamic full axial rotation and scapular plane full abduction in healthy shoulders

PURPOSE

The purpose of this study was to evaluate the kinematics of healthy shoulders during dynamic full axial rotation and scapular plane full abduction using three-dimensional (3D)-to-two-dimensional (2D) model-to-image registration techniques.

METHODS

Dynamic glenohumeral kinematics during axial rotation and scapular plane abduction were analysed in 10 healthy participants. Continuous radiographic images of axial rotation and scapular plane abduction were taken using a flat panel radiographic detector. The participants received a computed tomography scan to generate virtual digitally reconstructed radiographs. The density-based digitally reconstructed radiographs were then compared with the serial radiographic images acquired using image correlations. These 3D-to-2D model-to-image registration techniques determined the 3D positions and orientations of the humerus and scapula during dynamic full axial rotation and scapular plane full abduction.

RESULTS

The humeral head centre translated an average of 2.5 ± 3.1 mm posteriorly, and 1.4 ± 1.0 mm superiorly in the early phase, then an average of 2.0 ± 0.8 mm inferiorly in the late phase during external rotation motion. The glenohumeral external rotation angle had a significant effect on the anterior/posterior (A/P) and superior/inferior (S/I) translation of the humeral head centre (both p < 0.05). 33.6 ± 15.6° of glenohumeral external rotation occurred during scapular plane abduction. The humeral head centre translated an average of 0.6 ± 0.9 mm superiorly in the early phase, then 1.7 ± 2.6 mm inferiorly in the late phase, and translated an average of 0.4 ± 0.5 mm medially in the early phase, then 1.6 ± 1.0 mm laterally in the late phase during scapular plane abduction. The humeral abduction angle had a significant effect on the S/I and lateral/medial (L/M) translation of the humeral head centre (both p < 0.05).

CONCLUSION

This study investigated 3D translations of the humerus relative to the scapula: during scapular plane full abduction, the humerus rotated 33.6° externally relative to the scapula, and during external rotation motion in the adducted position, the humeral head centre translated an average of 2.5 mm posteriorly. Kinematic data will provide important insights into evaluating the kinematics of pathological shoulders. For clinical relevance, quantitative assessment of dynamic healthy shoulder kinematics might be a physiological indicator for the assessment of pathological shoulders.