The role of scapular kinematics in patients with different shoulder musculoskeletal disorders: A systematic review approach

Residual kinematic deviations of the shoulder during humeral elevation after conservative treatment for mid-shaft clavicle fractures

Despite residual functional deficits clinically observed in conservatively treated mid-shaft clavicle fractures, no study has reported a quantitative assessment of the treatment effects on the kinematics of the shoulder complex during functional movement. Using computerised motion analysis, the current study quantified the 3D residual kinematic deviations or strategies of the shoulder complex bones during multi-plane elevations in fifteen patients with conservatively treated mid-shaft clavicle fractures and fifteen healthy controls. Despite residual clavicular malunion, the patients recovered normal shoulder kinematics for arm elevations up to 60° in all three tested planes. For elevations beyond 60°, normal clavicle kinematics but significantly increased scapular posterior tilt relative to the trunk was observed in the patient group, leading to significantly increased clavicular protraction and posterior tilt relative to the scapula (i.e., AC joint). Slightly different changes were found in the sagittal plane, showing additional changes of increased scapular upward rotations at 90° and 120° elevations. Similar kinematic changes were also found on the unaffected side, indicating a trend of symmetrical bilateral adaptation. The current results suggest that shoulder kinematics in multi-plane arm elevations should be monitored for any compromised integrated motions of the individual bones following conservative treatment. Rehabilitation strategies, including muscle strengthening and synergy stability training, should also consider compensatory kinematic changes on the unaffected side to improve the bilateral movement control of the shoulder complex during humeral elevation.

Differences in Strength and Fatigue Resistance of Scapular Protractors and Retractors Between Symptomatic and Asymptomatic Dyskinesis

CONTEXT

Scapular dyskinesis is a shoulder dysfunction that can be asymptomatic or associated with pain or weakness. Reduced strength and fatigue resistance of the scapular protractor and retractor muscles that stabilize the scapula might contribute to dyskinesis.

OBJECTIVES

To determine the strength and fatigue resistance profiles of participants with symptomatic or asymptomatic scapular dyskinesis and compare them with healthy control (HC) individuals using isokinetic assessment.

DESIGN

Cross-sectional study.

SETTING

University hospital.

PATIENTS OR OTHER PARTICIPANTS

Twenty HC individuals and 21 overhead athletes with symptomatic (n = 10) or asymptomatic (n = 11) scapular dyskinesis.

MAIN OUTCOME MEASURE(S)

Strength (peak torque, maximum work), fatigue resistance (total work), and protraction:retraction ratios measured during a closed chain isokinetic protocol (40 repetitions in concentric mode at 24.4 cm/s).

RESULTS

The scapular protractors' strength and fatigue resistance were higher (P < .01) in HC individuals (peak torque = 5.0 ± 0.9 N/kg, maximum work = 2.4 ± 0.5 J/kg, total work = 72.4 ± 0.6 J/kg) than in asymptomatic (peak torque = 3.4 ± 0.7 N/kg, maximum work = 1.7 ± 0.4 J/kg, total work = 50.0 ± 13.7 J/kg) or symptomatic (peak torque = 3.8 ± 0.6 N/kg, maximum work = 1.8 ± 0.3 J/kg, total work = 58.1 ± 12.9 J/kg) dyskinetic participants. The symptomatic dyskinetic group presented the highest retractor strength and fatigue resistance (P < .01) values (peak torque = 5.2 ± 0.6 N/kg, maximum work = 2.9 ± 0.8 J/kg, total work = 87.7 ± 22.7 J/kg), followed by the HC individuals (peak torque = 4.7 ± 1.0 N/kg, maximum work = 2.1 ± 0.5 J/kg, total work = 65.3 ± 17.9 J/kg) and the asymptomatic dyskinetic participants (peak torque = 3.9 ± 1.0 N/kg, maximum work = 1.9 ± 0.6 J/kg, total work = 58.6 ± 18.5 J/kg). The protraction:retraction ratios showed a gradual decrease (P < .001) from the HC individuals (1.1) to the asymptomatic (0.9) and symptomatic (0.7) dyskinetic participants.

CONCLUSIONS

Scapular dyskinesis is characterized by weaker scapular protractors and reduced agonist:antagonist ratios, especially when patients are symptomatic. Targeting the scapular protractors to achieve a better balance of scapular musculature in rehabilitation and strengthening programs may improve shoulder symptoms and function, but more interventional studies are required.

Comparing and characterizing scapular muscle activation ratios in males and females during execution of common functional movements

Background

The shoulder complex relies on scapular movement controlled by periscapular muscles for optimal arm function. However, minimal research has explored scapular muscle activation ratios during functional tasks, nor how they might be influenced by biological sex. This investigation aims to characterize how sex impacts scapular muscle activation ratios during functional tasks.

Methods

Twenty participants (ten females, ten males) were assessed with surface electromyography (EMG) and motion tracking during seven functional tasks. Activation ratios were calculated from normalized EMG for the three trapezius muscles and serratus anterior. Scapular angles were calculated using a YXZ Euler sequence. Two-way mixed methods ANOVAs (p < .05) were used to assess the effects of sex and humeral elevation level on ratios and angles.

Results

Sex-based differences were present in the Tie Apron task, with males exhibiting higher upper trapezius/lower trapezius and upper trapezius/middle trapezius ratios than females. Males also demonstrated decreased internal rotation in this task. Other tasks showcased significant sex-based differences in scapular upward rotation but not in activation ratios. Humeral elevation generally demonstrated an inverse relationship with scapular muscle activation ratios.

Conclusions

This study highlights sex-based differences in scapular muscle activation ratios during specific functional tasks, emphasizing the need to consider sex in analyses of shoulder movements. Normative activation ratios for functional tasks were provided, offering a foundation for future comparisons with non-normative groups. Further research is warranted to confirm and explore additional influencing factors, advancing our understanding of shoulder activation and movement in diverse populations.

Three-dimensional measurements of scapular kinematics: Interrater reliability and validation of a skin marker-based model against an intracortical pin model

A skin marker-based motion capture model providing measures of scapular rotations was recently developed. The aim of this study was to investigate the concurrent validity and the interrater reliability of the model. Shoulder range of motion (RoM) and activities of daily living (ADL) were tested in healthy volunteers with reflective markers on the scapula and thorax. To investigate the validity, the model was compared to simultaneous data collection from markers on a scapular intracortical pin. The interrater reliability was tested by comparing the skin marker-based protocol performed by two investigators. The mean root mean square error (RMSE) and the intraclass correlation coefficient (ICC(2,1)) were calculated to determine the validity and the interrater reliability, respectively. Eight subjects were included in the validity test: female/male = 2/6, mean (SD) age 35.0 (3.0) and BMI 23.4 (3.3). The mean RMSE of all scapular rotations ranged 2.3-6.7° during shoulder RoM and 2.4-7.6° during ADL. The highest errors were seen during sagittal and scapular plane flexions, hair combing and eating. The reliability test included twenty subjects: female/male = 8/12, mean (SD) age 31.4 (4.9) and BMI 22.9 (1.7). The ICC(2,1) for measuring protraction ranged 0.07-0.60 during RoM and 0.27-0.69 for ADL, for upward rotation the corresponding ICC(2,1) ranged 0.01-0.64 and 0.38-0.60, and anterior tilt 0.25-0.83 and 0.25-0.62. The validity and interrater reliability of the model are task dependent, and interpretation should be made with caution. The model provides quantitative measurements for objective assessment of scapular movements and can potentially supplement the clinical examination in certain motion tasks.

Do Sex and Age Influence Scapular and Thoracohumeral Kinematics During a Functional Task Protocol?

There is mixed evidence on the role that biological sex plays in shoulder biomechanics despite known differences in musculoskeletal disorder prevalence between males and females. Additionally, advancing age may contribute to shoulder kinematic changes. The purpose of this study was to determine if sex and age influenced scapular and thoracohumeral kinematics during a range of functional tasks. Sixty healthy participants aged 19-63 years (30 males; 30 females) completed a functional task protocol while their upper limb motion was recorded. Scapular and humeral angles were calculated and compared with multiple linear regressions to assess the interaction effects of sex and age. Shoulder kinematics were not different between sex and age groups for many of the functional tasks. However, females had lower humeral external rotation in the overhead lift task (15°, P < .001), and less scapular anterior tilt angles in the forward transfer task (6°, P < .001) than males. Age was positively associated with humeral elevation (R2 = .330, P < .001) and scapular rotation (R2 = .299, P < .001) in the Wash Axilla task. There exist some kinematic differences between sex and with advancing age for select functional tasks, which should be considered for musculoskeletal disorder development.

Does Taping Have an Immediate Effect on Shooting the Target?

In overhead shooting athletes may have increased activity of the upper trapezius and inhibition of other shoulder muscles active during upper extremity elevation. In this study, we aimed to increase target retention and shoulder proprioception sense accuracy by taping in a way that would activate the lower trapezius muscle in elite adolescent archers. Our participants were 43 elite young athletes, aged 11-14 years, from the Archers Foundation Sports Club. We gathered athletes' sociodemographic information (age, height, weight, gender, the time they were engaged in archery, and other sports they were involved in), and we assessed their posture via the New York Posture Scale (NYPS) before taping. We evaluated them for the presence of scapular asymmetry using the Lateral Scapular Slide Test (LSST) and assessed their proprioception with the active displacement test and their target-reaching performances with the Archery Shooting Score (ASS). Since testing and scoring with the ASS is different for 11-12 and 13-14 age groups, we divided this sample into two different age groups for all analyses. There were significant changes in ASS and proprioception in both age groups, with medium to large effect sizes. There were between intragroup pre- and post-taping changes in classification according to the presence of scapular asymmetry, and there were significant changes in the archery shooting score and proprioception in both groups, with medium to large effect sizes (p < 0.05). Thus, taping applied to the lower part of the trapezius had a large to medium effect on proprioception and shooting accuracy improvement in these young archers.

Can Shoulder Impairments Be Classified From 3-Dimensional Kinematics Using Inertial Sensors?

Inertial sensors may help clinicians to assess patients' movement and potentially support clinical decision making. Our aim was to determine whether shoulder range of motion during movement tasks measured using inertial sensors is capable of accurately discriminating between patients with different shoulder problems. Inertial sensors were used to measure 3-dimensional shoulder motion during 6 tasks of 37 patients on the waiting list for shoulder surgery. Discriminant function analysis was used to identify whether the range of motion of different tasks could classify patients with different shoulder problems. The discriminant function analysis could correctly classify 91.9% of patients into one of the 3 diagnostic groups based. The tasks that associated a patient with a particular diagnostic group were the following: subacromial decompression: abduction, rotator cuff repair of tears ≤5 cm: flexion and rotator cuff repair of tears >5 cm: combing hair, abduction, and horizontal abduction-adduction. The discriminant function analysis showed that range of motion measured by inertial sensors can correctly classify patients and could be used as a screening tool to support surgery planning.

Exercise for rotator cuff tendinopathy: Proposed mechanisms of recovery

Rotator cuff (RC) tendinopathy is a common recurrent cause of shoulder pain, and resistance exercise is the first-line recommended intervention. Proposed causal mechanisms of resistance exercise for patients with RC tendinopathy consist of four domains: tendon structure, neuromuscular factors, pain and sensorimotor processing, and psychosocial factors. Tendon structure plays a role in RC tendinopathy, with decreased stiffness, increased thickness, and collagen disorganization. Neuromuscular performance deficits of altered kinematics, muscle activation, and force are present in RC tendinopathy, but advanced methods of assessing muscle performance are needed to fully assess these factors. Psychological factors of depression, anxiety, pain catastrophizing, treatment expectations, and self-efficacy are present and predict patient-reported outcomes. Central nervous system dysfunctions also exist, specifically altered pain and sensorimotor processing. Resisted exercise may normalize these factors, but limited evidence exists to explain the relationship of the four proposed domains to trajectory of recovery and defining persistent deficits limiting outcomes. Clinicians and researchers can use this model to understand how exercise mediates change in patient outcomes, develop subgroups to deliver patient-specific approach for treatment and define metrics to track recovery over time. Supporting evidence is limited, indicating the need for future studies characterizing mechanisms of recovery with exercise for RC tendinopathy.

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.

Differences in Tridimensional Shoulder Kinematics between Asymptomatic Subjects and Subjects Suffering from Rotator Cuff Tears by Means of Inertial Sensors: A Cross-Sectional Study

Background: The aim of this study was to analyze differences in three-dimensional shoulder kinematics between asymptomatic subjects and patients who were diagnosed with rotator cuff tears. Methods: This cross-sectional study recruited 13 symptomatic subjects and 14 asymptomatic subjects. Data were obtained from three inertial sensors placed on the humerus, scapula and sternum. Kinematic data from the glenohumeral, scapulothoracic and thoracohumeral joints were also calculated. The participants performed shoulder abductions and flexions. The principal angles of movements and resultant vectors in each axis were studied. Results: The glenohumeral joint showed differences in abduction (p = 0.001) and flexion (p = 0.000), while differences in the scapulothoracic joint were only significant during flexion (p = 0.001). The asymptomatic group showed higher velocity values in all sensors for both movements, with the differences being significant (p < 0.007). Acceleration differences were found in the scapula during abduction (p = 0.001) and flexion (p = 0.014), as well as in the sternum only during shoulder abduction (p = 0.022). Conclusion: The results showed kinematic differences between the patients and asymptomatic subjects in terms of the mobility, velocity and acceleration variables, with lower values for the patients.

Evidence of rotator cuff disease after breast cancer treatment: scapular kinematics of post-mastectomy and post-reconstruction breast cancer survivors

BACKGROUND

Breast cancer survivors may be at risk of experiencing rotator cuff disease after treatment. Biomechanical alterations following surgery potentially predispose survivors to develop this disorder.

OBJECTIVE

To examine scapular kinematics in breast cancer survivors with and without impingement pain during an overhead reach task.

DESIGN

A cross-sectional study.

METHODS

Three surgery groups were included: non-cancer controls, mastectomy-only survivors and post-reconstruction survivors. Breast cancer survivor groups were also categorized by the presence of impingement pain. Scapular motion was tracked during an overhead reach task, performed separately by both arms. Maximum scapular internal rotation, upward rotation and tilt were calculated. Two-way analyses of variance with interactions (p < .05) were used to test the effects of group (control, mastectomy-only, reconstruction) and impingement pain (pain, no pain) on each variable within a (left/right) side.

RESULTS

Scapular kinematics varied with the group by pain interaction. On the right side, the mastectomy-pain group had reduced upward rotation, while the reconstruction-pain group had higher upward rotation (mastectomy-only: 22.9° vs. reconstruction: 31.2°). On the left side, the mastectomy-pain group had higher internal rotation, while the reconstruction-pain group had reduced internal rotation (mastectomy-only: 45.1° vs. reconstruction: 39.3°). However, time since surgery was longer in the mastectomy-pain group than reconstruction-pain group, suggesting there may be a temporal component to kinematic compensations.

CONCLUSIONS

There are kinematic alterations in breast cancer survivors that may promote future development of rotator cuff disease. Compensations may begin as protective and progress to more harmful alterations with time.KEY MESSAGESScapular kinematics varied with surgery and pain interaction: upward rotation was lower and internal rotation higher in mastectomy-pain group, while upward rotation was higher and internal rotation lower in reconstruction-pain group.Kinematics alterations may also be associated with time since surgery, as the mastectomy-pain group had longer time since surgery than the reconstruction-pain group.Kinematic alterations may transition from protective to harmful over time.In-depth analyses by reconstruction type are needed to determine surgery-specific effects on kinematics and their potential impact on the development of rotator cuff disease.

Causal mechanisms of a scapular stabilization intervention for patients with subacromial pain syndrome: a secondary analysis of a randomized controlled trial

Background

Causal mediation analysis is one way to bridge this gap by exploring the causal pathways of a given intervention. The aim of this study was to assess whether scapular motion, position, and periscapular muscle strength are mediators for pain and shoulder disability outcomes following a scapular stabilization intervention for patients with subacromial pain syndrome.

Methods

Sixty patients were randomized into two groups: scapular stabilization or periscapular strengthening exercises. The intervention consisted of three sessions per week for 8 weeks. The primary outcome measures were pain and disability and the following outcome measures were considered as potential mediators: scapular motion, scapular position, periscapular muscle strength, age, duration of symptoms, and side of the complaint. A model-based inference approach with bootstrap simulations was used to estimate the average causal mediation effect, average direct effect, and the average total effect from the data of a randomized clinical trial that evaluated the effect of adding scapular stabilization exercises to a scapulothoracic strengthening program in people with subacromial pain syndrome.

Results

The results demonstrated that none of the putative mediators were influenced by the intervention. However, muscle strength of serratus anterior, upper, middle, and lower trapezius muscles was associated with shoulder disability.

Conclusion

Scapular kinematic and periscapular muscle strength did not mediate the effect of scapular stabilization exercises on shoulder pain or disability scores in subjects with subacromial pain syndrome. Muscle strength of serratus anterior, upper, middle and lower trapezius were associated with shoulder disability scores at 8-weeks follow-up.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40945-022-00138-1.

Three-Dimensional Kinematics during Shoulder Scaption in Asymptomatic and Symptomatic Subjects by Inertial Sensors: A Cross-Sectional Study

Shoulder kinematics is a measure of interest in the clinical setting for diagnosis, evaluating treatment, and quantifying possible changes. The aim was to compare shoulder scaption kinematics between symptomatic and asymptomatic subjects by inertial sensors. Methods: Scaption kinematics of 27 subjects with shoulder symptomatology and 16 asymptomatic subjects were evaluated using four inertial sensors placed on the humerus, scapula, forearm, and sternum. Mobility, velocity, and acceleration were obtained from each sensor and the vector norm was calculated from the three spatial axis (x,y,Z). Shoulder function was measured by Upper Limb Functional Index and Disabilities of the Arm, Shoulder, and Hand questionnaires. One way ANOVA was calculated to test differences between the two groups. Effect size was calculated by Cohen’s d with 95% coefficient Intervals. Pearson’s correlation analysis was performed between the vector norms humerus and scapula kinematics against DASH and ULFI results in symptomatic subjects. Results: The asymptomatic group showed higher kinematic values, especially in the humerus and forearm. Symptomatic subjects showed significantly lower values of mobility for scapular protraction-retraction (Cohen’s d 2.654 (1.819–3.489) and anteriorisation-posteriorisation (Cohen’s d 1.195 (0.527–1.863). Values were also lower in symptomatic subjects for velocity in all scapular planes of motion. Negative correlation showed that subjects with higher scores in ULFI or DASH had lower kinematics values. Conclusion: Asymptomatic subjects tend to present greater kinematics in terms of mobility, velocity, and linear acceleration of the upper limb, and lower humerus and scapula kinematics in symptomatic subjects is associated with lower levels of function.

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.

Three-dimensional kinematic analysis of upper limb movements between individuals with and without subacromial shoulder pain exploring the statistical parametric mapping

Subacromial shoulder pain (SSP) accounts for 44-65% of all cases of shoulder pain. Kinematic alterations in the upper limbs have been observed in individuals with SSP, although there is no consensus on such alterations in the literature. Therefore, the present study aimed to compare the three-dimensional kinematics of the scapula, trunk, and arm during shoulder flexion-extension and abduction-adduction movements in individuals with SSP and a control group using statistical parametric mapping (SPM). We evaluated 117 participants [61 with SSP and 56 in the control group (CG)]. The three-dimensional kinematic analysis was performed starting from arm extension/adduction (0%), moving to flexion/abduction, and ending returning to extension/adduction, respectively (100%) in both groups. SSP group flexed more their trunk (0-100%, p < 0.001) and rotated scapula internally (0-20%, p < 0.001 and 75-100%, p < 0.001); rotated upwards (17-32%, p < 0.005 and 58-87%, p < 0.003) and posteriorly tilted (28-79%,p < 0.001 and 81-95%,p < 0.006) less than CG group during arm abduction-adduction. Through arm flexion-extension, the SSP group flexed (38-82% p < 0.009) less their trunk, rotated upwards (5-10% p = 0.021) less their scapula, and posteriorly tilted scapula (0-100% p < 0.001) more than CG. Combining conventional variables used to describe motion in individuals with SSP, such as minimum and maximum values, range of motion, and results provided by SPM can furnish a detailed description of the compensations and limitations of the patient, enabling a better understanding of the function of the scapular girdle as well as improvements in the evaluation process and clinical decision making.

The role of scapular dyskinesis on rotator cuff tears: a narrative review of the current knowledge

Scapular dyskinesis can be present in healthy individuals as in patients with shoulder pathology.Altered patterns of scapular kinematics can cause or exacerbate rotator cuff tear pathology. However, more research is needed.Regardless of the cause or the consequence of rotator cuff tear, scapular dyskinesis impairs shoulder function, worsens the symptoms, and compromises the success of clinical intervention.The available literature suggests physical therapy as the first treatment for degenerative cuff tears, and scapular dyskinesis should be addressed if present. Non-responsive cases or traumatic tears may require surgery.Postsurgical physical therapy protocols after rotator cuff repair must consider scapular dyskinesia to improve the outcomes. Cite this article: EFORT Open Rev 2021;6:932-940. DOI: 10.1302/2058-5241.6.210043.

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.

The Relationship between Scapular Upward Rotation and Shoulder Internal and External Rotation Isokinetic Strength in Professional Baseball Pitchers

This study aims to assess the relationship between scapular upward rotation (SUR) across varying humeral-elevation angles (HEAs) and shoulder isokinetic strength and ratio in professional baseball pitchers. The subjects were professional baseball pitchers (n = 16) without a history of shoulder injury in the last six months. The subject’s SUR angles were measured with the humerus elevated at HEAs of 0° (at rest), 60°, 90°, and 120° to the scapular plane. Shoulder isokinetic strength was evaluated for shoulder internal rotation (IR) and external rotation (ER) strength (PT%BW and TW%BW), and the ER/IR strength ratios were determined at 60, 120 and 180°/s using an isokinetic dynamometer. The SUR angle at an HEA of 0° was positively correlated with IR strength at 120°/s (r = 0.535) and 180°/s (r = 0.522). The SUR angle at an HEA of 60° was negatively correlated with the ER/IR strength ratios at 60°/s (r = −0.505) and 120°/s (r = −0.500). The SUR angle at an HEA of 90° was negatively correlated with the ER/IR strength ratios at 60°/s (r = −0.574; r = −0.554) and 120°/s (r = −0.521; r = −0.589) as well as with ER strength at 180°/s (r = −0.591, r = −0.556). The SUR angle at an HEA of 120° was negatively correlated with ER strength at 60°/s (r = −0.558), 120°/s (r = −0.504; r = −0.524), and 180°/s (r = −0.543) and the ER/IR strength ratio at 60°/s (r = −0.517). In this study, we found that the ratio of isokinetic strength between ER and IR became closer to the normal range on increasing the SUR angle. In particular, an HEA of 90°, which resembles the pitching motion, showed a clear relationship between SUR, shoulder ER, and the ratio of ER/IR isokinetic strength in professional baseball pitchers.

Scapular movement training versus standardized exercises for individuals with chronic shoulder pain: protocol for a randomized controlled trial

BACKGROUND

Scapular focused exercise interventions are frequently used to treat individuals with shoulder pain. However, evidence for changes in scapular motion after intervention is limited.

OBJECTIVE

To compare the effects of scapular movement training versus standardized exercises for individuals with shoulder pain.

METHODS

This will be a single-blinded randomized controlled trial. Sixty-four individuals with shoulder pain for at least 3 months, scapular dyskinesis, and a positive scapular assistance test will be randomly allocated to one of two groups: Scapular Movement Training (group 1) and Standardized Exercises (group 2). Group 1 will receive education about scapular position and movement, and be trained to modify the scapular movement pattern. Group 2 will perform stretching and strengthening exercises. Both groups will be treated twice a week for eight weeks. Three-dimensional scapular kinematics and muscle activity of the serratus anterior and upper, middle, and lower trapezius during elevation and lowering of the arm will be assessed at baseline and after 8 weeks of treatment. Pain intensity, function, fear avoidance beliefs, and kinesiophobia will be assessed at baseline and after 4 and 8 weeks of treatment, and 4 weeks after the end of treatment.

CONCLUSIONS

The results of this study may contribute to a better understanding of the efficacy of scapular focused treatments for individuals with shoulder pain.

CLINICAL TRIAL REGISTRATION

NCT03528499.

Discriminating the precision of inertial sensors between healthy and damaged shoulders during scaption movement: A cross-sectional study

BACKGROUND

Shoulder assessment in rehabilitation is focused on kinematic properties due to the variability of symptomatology and clinical expression of shoulder injuries.

AIM

To perform a receiver operating characteristic analysis of the kinematic variables involved in the functional mobility of the shoulder that allow the identification of discriminating variables between healthy and diseased shoulders during scaption motion.

METHOD

Analytical cross-sectional study of diagnostic effectiveness was performed in 27 subjects suffering from shoulder damage and 14 asymptomatic controls. Scaption kinematics were evaluated using four inertial sensors placed on the humerus, scapula, forearm and sternum. Three variables (mobility, velocity and acceleration) were obtained from each sensor and the norm of the resultant vector was calculated from each axis. A discriminatory receiver operating characteristic analysis was performed, obtaining the area under the curve, sensitivity and specificity.

FINDINGS

Significant differences from both the resultant vectors and the axis depended on the body segment analysed were observed. Greater movement velocity and acceleration were observed in the asymptomatic group. Receiver operating characteristic analysis, scapular protraction-retraction mobility distinguished with a diagnostic sensitivity of 83.3% and specificity of 90.9% between asymptomatic and shoulder-damaged patients. These diagnosis values were 83.3% and 72.7% for scapular anterior-posterior velocity. Scapular kinematics, in terms of mobility and velocity, are the key variables in shoulder assessment.

INTERPRETATION

This study discriminated between patients suffering from shoulder damage and asymptomatic subjects based on shoulder kinematics during scaption motion. Scapular mobility and velocity were found to be key variables in shoulder assessment, along with the humerus.

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.

Examining assessment methods of scapular motion: Comparing results from planar elevations and functional task performance

BACKGROUND

Scapular kinematics of breast cancer survivors are most often evaluated during arm elevation. However, known compensations exist during functional task performance. The purpose of this study was to determine if scapular kinematics of breast cancer survivors during arm elevation are related to scapular kinematics during functional task performance.

METHODS

Scapular kinematics of 25 non-cancer controls and 25 breast cancer survivors (split by presence of impingement pain) during arm elevation in 3 planes and 3 reaching and lifting functional tasks were measured. Scapular upward rotation and scapulohumeral rhythm (SHR) at 30° increments of arm elevation were calculated. Between-group differences of upward rotation during arm elevation were evaluated with one-way ANOVAs (p < 0.05). The association of upward rotation angle and SHR during arm elevation and functional tasks was tested with Pearson correlations (p < 0.05).

FINDINGS

Scapular upward rotation was reduced for the breast cancer survivor with pain at lower levels of arm elevation in each plane by up to 7.1° (p = .014 to 0.049). This is inconsistent with functional task results, in which upward rotation decrements occurred at higher levels of arm elevation. Upward rotation angles and SHR during arm elevation had an overall weak-to-moderate relationship (r = 0.003 to 0.970, p = .001 to 0.048) to values from functional tasks. Arm elevation during sagittal plane elevation demonstrated scapular upward rotation that was most closely associated to upward rotation during functional task performance.

INTERPRETATION

Inconsistent relationships suggests that clinical evaluations should adopt basic functional movements for scapular motion assessment to complement simple arm elevations.

The Association Between Fear of Movement, Pain Catastrophizing, Pain Anxiety, and Protective Motor Behavior in Persons With Peripheral Joint Conditions of a Musculoskeletal Origin: A Systematic Review

OBJECTIVE

The aim of the study was to investigate alterations in motor behavior related to pain-related beliefs in persons with peripheral joint conditions.

DESIGN

This is a systematic review.

RESULTS

Our database search (PubMed, Web of Science, Embase, PsycINFO) identified 7390 articles (until September 2019), and nine articles (344 participants) were selected based on the eligibility criteria for selecting studies, i.e., studies in adults with primary peripheral joint conditions, assessing the influence of fear of movement, catastrophizing or anxiety on motor behavior in terms of kinematics, kinetics, and muscle activity during active movements.In the acute stage after knee or radius surgery, more catastrophizing and fear were associated with less active joint motion in the operated and adjacent joints. In knee patients in the chronic stage after surgery, increased hip adduction and knee valgus were linked to increased fear of movement during the performance of challenging tasks. Similar results were found in persons with nonsurgical chronic knee pain. During gait, no relation between lower limb kinematics and fear of movement was observed.

CONCLUSIONS

Kinematic alterations appear in tandem with pain-related perceptions in acute stages after surgery. Altered kinematics influenced by pain-related beliefs are also seen in persons with chronic nonsurgical and surgical knee pain, when challenging tasks are performed.

Effects of adding scapular stabilization exercises to a periscapular strengthening exercise program in patients with subacromial pain syndrome: A randomized controlled trial

BACKGROUND

Interventions focused on the scapula should be considered in treating subacromial pain syndrome (SAPS). However, the effect of adding scapular stabilization exercises to protocols of progressive strengthening of the shoulder complex muscles on a non-multimodal approach remains unclear.

OBJECTIVE

To investigate the effect of adding scapular stabilization exercises, emphasizing retraction, and depression of the scapula, to a progressive periscapular strengthening protocol on disability, pain, muscle strength, and ROM in patients with SAPS.

DESIGN

Randomized, controlled, superiority trial, prospectively registered, two-arms, parallel, blind assessor, blind patient, and allocation concealment.

METHODS

Sixty patients with SAPS were randomly allocated into two groups: Periscapular Strengthening (PSG) or Scapular Stabilization (SSG) exercises. The interventions were performed three times a week for eight weeks. The primary outcome function and secondary outcomes (Pain, kinesiophobia, global perceived effect, satisfaction with treatment, the range of motion, scapula position and muscle strength) were measured in the baseline, four weeks, eight weeks (end of intervention) and 16 weeks after baseline. Shoulder pain and function were assessed by the Brazilian version of the Shoulder Pain and Disability Index (SPADI-Br).

RESULTS

A total of 60 patients were included and randomized to PSG (n = 30) or SSG (n = 30) from March 2016 to June 2017. There were no between group differences in primary and secondary outcomes at any time point.

CONCLUSION

The inclusion of the isolated scapular stabilization exercises, emphasizing retraction and depression of the scapula, to a progressive general periscapular strengthening protocol did not add benefits to self-reported shoulder pain and disability, muscle strength, and ROM in patients with SAPS.

TRIAL REGISTRATION

ClinicalTrials.gov.

Scapular Kinematics in Athletes With and Without Rotator Cuff Tendinopathy: A Systematic Review

Context: Rotator cuff tendinopathy is one of the most frequently reported shoulder injuries in athletes of overhead sports. Abnormal scapular kinematics has been proposed as one of the contributing factors of rotator cuff tendinopathy in overhead athletes. Objectives: To review the literature on 3-dimensional scapular kinematics in overhead athletes with and without rotator cuff tendinopathy. Evidence Acquisition: Electronic databases (Cochrane Library, MEDLINE, Embase, and PubMed) were searched from inception to September 2017. In addition, the reference lists of the articles that met the inclusion criteria were also searched. We included studies that compared the changes in 3-dimensional scapular kinematics in athletes with and without rotator cuff tendinopathy. Two reviewers independently examined the quality of studies by using the modified Downs and Black checklist. Evidence Synthesis: A total of 9 studies (a total of 332 athletes, mean age 23.41 [2.62] y) were included in the final analysis. The methodological quality was low (modified Downs and Black checklist = 9/15). Our findings showed a consistent pattern of increased scapular anterior tilting and internal rotation in the dominant shoulders than the nondominant shoulders of athletes who participated in overhead sports. Athletes of overhead sports seem to demonstrate an increase in scapular upward rotation during arm elevation when compared with nonathlete individuals. However, there is no consensus on the scapular kinematics pattern in athletes with rotator cuff tendinopathy when compared with healthy controls. Conclusion: Findings demonstrated that changes in scapular kinematics were observed in overhead athletes. However, all the included studies were cross-sectional studies with small sample size and diverse sports participation, whether changes in scapular kinematics may contribute to rotator cuff tendinopathy in overhead athletes warrants more high-quality prospective studies.

The Effect of Repeated Shoulder Motion on Scapular Dyskinesis in Army ROTC Cadets

INTRODUCTION

Altered or abnormal scapular motion has been associated with increased shoulder pain and dysfunction. Fatigue of the scapular stabilizing muscles resulting from repeated arm motion has been reported to alter scapular kinematics, which could result in the clinical assessment of scapular dyskinesis. The purpose of this study was to characterize the effect of repeated arm motion on the development of scapular dyskinesis. The hypothesis was that repeated arm motion will induce a subtle or obvious scapular dyskinesis.

MATERIALS AND METHODS

About 30 army Reserve Officer Training Corps (ROTC) cadets participated in the research study. The cadets level of shoulder function was determined using the Quick Disabilities of the Arm Shoulder and Hand and Pennsylvania Shoulder Score shoulder scores. Cadets performed an exercise protocol of 30 repetitions of weighted shoulder motion in the frontal plane. Shoulder and scapular musculature strength measurements were recorded prior to and immediately following the exercise protocol using hand-held dynamometry. The scapular dyskinesis test was performed prior to the exercise protocol and during the last five repetitions of the exercise protocol.

RESULTS

Prior to the exercise, protocol 3/30 were categorized with scapular dyskinesis on the left side and 3/30 were categorized with scapular dyskinesis on their right side. Following the exercise, protocol 8/30 were categorized with left-side scapular dyskinesis (χ2 = 9.167, P = 0.002) and 6/30 with right-side dyskinesis (χ2 = 4.537, P = 0.033). Shoulder strength decreased following the exercise protocol for all participants. The participants that developed scapular dyskinesis were weaker than those with normal scapular motion. However, the difference did not reach statistical significance. Participants graded with obvious scapular dyskinesis following the exercise protocol reported higher Quick Disabilities of the Arm Shoulder and Hand scores (P = 0.04) and lower scores on the Pennsylvania Shoulder Score (P = 0.005).

CONCLUSIONS

Repeated shoulder motion increased the frequency of scapular dyskinesis in army ROTC cadets. The cadets that developed scapular dyskinesis also reported greater disability and lower function of the upper extremity. The results provide a link between scapular dyskinesis, upper extremity function, and the strength of the scapular stabilizing muscles. Improving the strength of the scapular stabilizing musculature might reduce the effects of repeated arm motions.

The immediate effects of a shoulder brace on muscle activity and scapular kinematics in subjects with shoulder impingement syndrome and rounded shoulder posture: A randomized crossover design

BACKGROUND

Round shoulder posture (RSP) is one of the potential risks for shoulder impingement syndrome (SIS) due to alignment deviation of the scapula. Evidence on how the characteristics of a shoulder brace affecting the degree of RSP, shoulder kinematics, and associated muscle activity during movements is limited.

RESEARCH QUESTION

The purposes of this study were (1) to compare the effects of a shoulder brace on clinical RSP measurements, muscle activities and scapular kinematics during arm movements in subjects with shoulder impingement syndrome (SIS) and RSP; and (2) to compare the effects of two configurations (parallel and diagonal) and two tensions (comfortable and forced tension) of the brace straps on muscle activities and scapular kinematics during arm movements in subjects with SIS and RSP.

METHODS

Twenty-four participants (12 males; 12 females) with SIS and RSP were randomly assigned into 2 groups (comfortable then forced, and forced then comfortable) with 2 strap configurations in each tension condition. The pectoralis minor index (PMI), acromial distance (AD) and shoulder angle (SA) were used to assess the degree of RSP. Three-dimensional electromagnetic motion analysis and electromyography were used to record the scapular kinematics and muscle activity during arm movements.

RESULTS

All clinical measurements with the brace were significantly improved (p < 0.05). Under forced tension, muscle activities were higher with the diagonal configuration than with the parallel configuration in the lower trapezius (LT) (1.2-2.3% MVIC, p < 0.05) and serratus anterior (SA) (2.3% MVIC, p = 0.015). For upward rotation and posterior tilting of the scapula, the diagonal configuration was larger than the parallel configuration (1.5°, p = 0.038; 0.4°-0.5°, p < 0.05, respectively).

SIGNIFICANCE

Different characteristics of the straps of the shoulder brace could alter muscle activity and scapular kinematics at different angles during arm movement. Based on the clinical treatment preference, the application of a shoulder brace with a diagonal configuration and forced tension is suggested for SIS and RSP subjects.

Altered Scapular Time Series in Individuals With Subacromial Pain Syndrome

Altered scapular movement in subacromial pain syndrome has been demonstrated using discrete data reduction approach. However, this approach does not consider the data collinearity and variability, and scapular translations are poorly investigated in symptomatic individuals. The purpose of this study was to investigate the scapular rotation and translation of asymptomatic individuals and those with subacromial pain syndrome during arm motions using principal component analysis. Scapulothoracic kinematics were evaluated in 47 participants with subacromial pain syndrome and 50 asymptomatic individuals. The symptomatic group had increased range of scapular anterior/posterior tilt during arm elevation (P = .01, effect size = .59) and arm lowering (P < .01, effect size = .61), and increased range of scapular forward/backward translation during arm lowering (P < .01, effect size = .60) compared with the asymptomatic group. In addition, the symptomatic group had a reduced difference in anterior tilt angular velocities between the early-arm and mid-arm lowering phases and between the mid- and late-arm lowering phases compared with the asymptomatic group (P = .03, effect size = .44). This study demonstrated that scapular anterior/posterior tilt motion and angular velocity and scapular forward/backward translation of symptomatic individuals were different from asymptomatic individuals when considering the entire arm movement.

Impingement pain affects kinematics of breast cancer survivors in work-related functional tasks

BACKGROUND

Breast cancer survivors may encounter upper limb morbidities post-surgery. It is currently unclear how these impairments affect arm kinematics, particularly during functional task performance. This investigation examined upper body kinematics during functional tasks for breast cancer survivors and an age-matched control group.

METHODS

Fifty women (aged 35-65) participated: 25 breast cancer survivors who had undergone mastectomy and 25 age-range matched controls. Following basic clinical evaluation, including shoulder impingement tests, motion of the torso and upper limbs were tracked during six upper limb-focused functional tasks from which torso, scapular, and thoracohumeral angles were calculated. Between-group differences were evaluated with independent t-tests (p < .05). The breast cancer group was then divided based upon impingement tests and differences between the three new groups were tested with one-way ANOVAs (p < .05).

FINDINGS

Breast cancer survivors had higher disability scores, lower range of motion, and lower performance scores. The largest kinematic differences existed between the breast cancer survivors with impingement pain and the two non-pain groups. During overhead tasks, right peak scapular upward rotation was significantly reduced (d = 0.80-1.11) in the breast cancer survivors with impingement pain. This group also demonstrated trends of decreased peak humeral abduction and internal rotation at extreme postures (d = 0.54-0.78). These alterations are consistent with kinematics considered high risk for rotator cuff injury development.

INTERPRETATION

Impingement pain in breast cancer survivors influences functional task performance and may be more important to consider than self-reported disability when evaluating pain and potential injury development.

New Tracking System of Human Scapula Using Ultrasonography and Motion Sensors: A Descriptive Test-Retest Design

CONTEXT

Several studies have shown that the kinematics of the scapula is altered in many disorders that affect the shoulder. Description of scapular motion in the chest continues to be a scientific and clinical challenge.

OBJECTIVE

To check the validity and reliability of a new, minimally invasive method of tracking the internal and external rotation of the scapula using ultrasound imaging combined with the signal provided by a 3-dimensional electromagnetic sensor.

DESIGN

A cross-sectional study with a repeated-measures descriptive test-retest design was employed to evaluate this new tracking method. The new method was validated in vitro and the reliability of data over repeated measures between scapula positions was calculated in vivo.

SETTING

University laboratory.

PARTICIPANTS

A total of 30 healthy men and women.

MAIN OUTCOME MEASURE

The validation of the scapula rotation tracking using the in vitro model was calculated by Pearson correlation test between a 2-dimensional cross-correlation algorithm of the new method and another software image. The reliability of the tracking of the scapula rotation was measured using the intraclass correlation coefficient.

RESULTS

In the validation in vitro, the correlation of rotations obtained by the 2 methods was good (r = .77, P = .01). The reliability in vivo had excellent results (intraclass correlation coefficient = .88; 95% confidence interval, .82-.93) in the test-retest analysis of 8 measures. The intrarater analysis of variance test showed no significant differences between the measures (P = .85, F = 0.46).

CONCLUSION

Ultrasound imaging combined with a motion sensor to track the scapula has been shown to be a reliable and valid method for measuring internal and external rotation during separation of the upper limb.

Scapular Dyskinesia, the forgotten culprit of shoulder pain and how to rehabilitate

The improper movement of the scapula during shoulder movement is termed scapular dyskinesis and is an often-forgotten cause of pain and dysfunction. The scapula is a key part of the upper limb kinematic chain and is a vital component of the glenohumeral rhythm; which is a major determinant of the efficiency and efficacy of the upper limb. We provide an overview of the complex regional anatomy of the shoulder girdle and how this allows the scapula to act as a both a dynamic and static stabilizer to the upper limb. We explore the normal biomechanics and the aetiology, epidemiology and pathological occurrences which can disrupt the normal function and lead to scapula dyskinesis. Scapula dyskinesis is a poorly understood condition and provides a challenge for the clinician in both diagnosis and management. We provide a summary of the clinical assessment which is most likely to identify the source of the pathology and guides the treatment which is largely rehabilitation of the musculature with focused and specialized physiotherapy.

Three-dimensional scapular kinematics, shoulder outcome measures and quality of life following treatment for breast cancer - A case control study

BACKGROUND

There are no conclusive results concerning changes in scapular kinematics associated with upper limb dysfunctions after breast cancer surgery.

OBJECTIVE

To compare the three-dimensional (3-D) scapular kinematics during elevation of the arm between women after breast cancer surgery and controls. Shoulder range of motion (ROM), muscle strength, pain intensity, upper limb function, and quality of life were also assessed.

METHODS

Forty-two women were assigned to two groups (surgery group, n = 21; control group, n = 21). 3-D scapular kinematics was collected during elevation of the arm in the scapular plane. ROM was assessed using a digital inclinometer, muscle strength using a manual dynamometer, pain with the Visual Analogue Scale (VAS), upper limb function with the Disabilities of the Arm, Shoulder and Hand (DASH) questionnaire and quality of life with the 36-item Short-Form Health Survey (SF36).

RESULTS

The surgery group presented decreased scapular upward rotation at 120° of arm elevation in the scapular plane (p < .05; d = -0.88), decreased shoulder external rotation ROM and strength of shoulder abduction and external rotation when the affected side was compared to the non-affected side and control group. Moreover, the surgery group also reported higher pain, increased upper limb disability and poorer quality of life compared with healthy controls.

CONCLUSION

Scapular upward rotation seems to be decreased at 120° of arm elevation in women following breast cancer surgery. In addition, shoulder external rotation ROM, abduction strength, external rotation strength, function, and quality of life are also impaired in these women. They also experienced pain during the studied movements.

Immediate effect of scapula-focused exercises performed with kinematic biofeedback on scapular kinematics in individuals with subacromial pain syndrome

BACKGROUND

Given the changes in the patterns of muscular activation and scapular movement in individuals with subacromial pain syndrome, the use of neuromuscular training has been considered in rehabilitation protocols. There is currently no evidence of the effects of the use of three-dimensional (3D) kinematic biofeedback on individuals with subacromial pain syndrome. This study aimed to determine the immediate effect of scapular motor control exercises using 3D kinematic biofeedback on the scapular kinematics, inter-segment coordination and pain of individuals with subacromial pain syndrome.

METHOD

The kinematics of the scapulothoracic joint of 26 subjects with subacromial pain syndrome were assessed in the movement arm elevation and lowering in the sagittal plane before and after performance of three scapula-focused exercises using kinematic biofeedback. The individuals were familiarized with the selected exercises to acquire a greater scapular posterior tilt, while kinematic biofeedback, with visual and auditory stimuli, was used in real time. Scapular kinematics, pain, and subjective perception of exertion were the pre- and post-test measures.

FINDINGS

In the movement of arm elevation and lowering, no differences were found in scapular tilt and on coordination between the segments pre- and post-test and the effect size was considered small.

INTERPRETATION

Our results demonstrate that the performance of scapula-focused exercises using kinematic biofeedback does not cause immediate changes in the magnitude of scapular movement. However, inter-segmental coordination showed evidence of changes for scapular tilt in the lowering of the arm and internal rotation in the elevation and the lowering of the arm in individuals with subacromial pain syndrome.

Effect of flexibility deficit on scapular asymmetry in individuals with and without shoulder pain

BACKGROUND

Many studies have investigated the relationship between soft tissue tightness and shoulder kinematics. However, there is a lack of information on the dynamic properties responsible for side-to-side differences such as scapular asymmetry.

OBJECTIVE

To determine the relationship between a deficit in soft tissue flexibility and scapular asymmetry.

METHODS

A total of 58 individuals (29 patients with shoulder pain and 29 asymptomatic participants) were enrolled. Bilateral shortening of the pectoralis minor muscle and posterior shoulder tightness were assessed. Additionally, side-to-side flexibility deficit was calculated. Scapular kinematics were measured with an electromagnetic tracking device while individuals were standing in a resting position and during arm elevation. The symmetry angle was calculated to quantify scapular asymmetry.

RESULTS

The pectoralis minor and the posterior capsule flexibility deficit showed a significant positive relationship with the symmetry angle in the resting position separately for both asymptomatic (r=0.47, r=0.37 relatively) and symptomatic groups (r=0.58, r=0.38 relatively), indicating that the increased deficit in the pectoralis minor and posterior capsule flexibility were associated with increased scapular asymmetry. However, no significant relationship was found between flexibility deficit and scapular asymmetry during arm elevation and lowering for both asymptomatic and symptomatic groups.

CONCLUSION

The findings of the study provided information on the relationship of a flexibility deficit on the scapular position and orientation in asymptomatic and symptomatic populations.