Heterogeneous MR arthrography findings in patients with subacromial impingement syndrome – Diagnostic subgroups?

Neuromuscular electrical stimulation of humeral adductors in subjects with rotator cuff tear

INTRODUCTION

In symptomatic patients with rotator cuff tear, MRI and radiographic studies have ascribed the pain symptom to insufficient humeral head depression during arm elevations. The arm adductors such as the teres major and pectoralis major may contribute to depression of the humerus head during arm elevations. Researchers have demonstrated that neuromuscular electrical stimulation (NMES) of the serratus anterior and lower trapezius can control scapular motions and improve acromiohumeral distance. It is unknown, however, if adductor neuromuscular training could help patients with rotator cuff tear.

MATERIALS AND METHODS

A cross-sectional study of NMES of the teres major and pectoralis major was conducted on 30 symptomatic subjects with rotator cuff tear. We measured the acromiohumeral distance by ultrasonography and scapular kinematics during arm elevation with a three-dimensional motion tracking system.

RESULTS

The acromiohumeral distance significantly increased during NMES of the teres major (0.73 mm, p < 0.001). However, the distance significantly decreased with NMES of the pectoralis major (0.78 mm, p < 0.001). Additionally, scapular upward rotation was greater during NMES of the teres major than during NMES of the pectoralis major (3.4°, p < 0.001). Scapular external rotation decreased significantly more during NMES of the pectoralis major than during NMES of the teres major (1.6°, p = 0.003).

CONCLUSIONS

NMES of the teres major can increase acromiohumeral distance and scapular upward rotation during arm elevation. However, the decreased upward and external rotation of the scapula during arm elevation with NMES of the pectoralis major may be associated with subacromial impingement.

Terminology and diagnostic criteria used in studies investigating patients with subacromial pain syndrome from 1972 to 2019: a scoping review

INTRODUCTION

There is no recognised terminology, nor diagnostic criteria, for patients with subacromial pain syndrome (SAPS). This is likely to cause heterogeneity across patient populations. This could be a driver of misconceptions and misinterpretations of scientific results. We aimed to map the literature regarding terminology and diagnostic criteria used in studies investigating SAPS.

MATERIALS AND METHODS

Electronic databases were searched from inception to June 2020. Original peer-reviewed studies investigating SAPS (also known as subacromial impingement or rotator cuff tendinopathy/impingement/syndrome) were eligible for inclusion. Studies containing secondary analyses, reviews, pilot studies and studies with less than 10 participants were excluded.

RESULTS

11 056 records were identified. 902 were retrieved for full-text screening. 535 were included. 27 unique terms were identified. Mechanistic terms containing 'impingement' are used less than before, while SAPS is used increasingly. For diagnoses, combinations of Hawkin's, Neer's, Jobe's, painful arc, injection test and isometric shoulder strength tests were the most often used, though this varied considerably across studies. 146 different test combinations were identified. 9% of the studies included patients with full-thickness supraspinatus tears and 46% did not.

CONCLUSION

The terminology varied considerably across studies and time. The diagnostic criteria were often based on a cluster of physical examination tests. Imaging was primarily used to exclude other pathologies but was not used consistently. Patients with full-thickness supraspinatus tears were most often excluded. In summary, studies investigating SAPS are heterogeneous to an extent that makes it difficult, and often impossible, to compare studies.

Alteration in coracohumeral ligament and distance in people with symptoms of subcoracoid impingement

BACKGROUND

Differentiation between subacromial impingement versus subcoracoid impingement are important for the treatment target. We evaluated the correlations between coracohumeral ligament (CHL) thickness and distance (CHD) and characterized the CHL and subscapularis (SSC) in subcoracoid impingement subjects.

METHODS

An observational, cross-sectional study was carried out. Twenty subcoracoid impingement subjects and age/gender matched controls were assessed in 4 different shoulder positions by ultrasonography.

RESULTS

Moderate correlations between CHL thickness with CHD (r = 0.455 in neutral rotation, p = 0.044; r = 0.483 in interior rotation, p = 0.031) were found in subacromial subjects. Subcoracoid impingement subjects had greater CHL thickness (difference = 0.3 mm, effect size = 0.85, p = 0.006), SSC tendon thickness (difference = 0.7 mm, effect size = 0.92, p = 0.01) and SSC/CHD occupation ratio (difference = 8%, effect size = 0.95, p = 0.005) compared with the control.

CONCLUSIONS

Coracohumeral distance is related to ligament thickness, especially in subacromial impingement subjects. Increased coracohumeral ligament and subscapularis thickness as well as decreased subscapularis/coracohumeral distance occupation ratio are characterized in subcoracoid impingement subjects. These quantitative measurements can be useful in identifying patients at risk of subcoracoid impingement from subacromial impingement.

Shoulder movement complexity in the aging shoulder: A cross-sectional analysis and reliability assessment

Healthy individuals perform a task such as hitting the head of a nail with an infinite coordination spectrum. This motor redundancy is healthy and allows for learning through exploration and uniform load distribution across muscles. Assessing movement complexity within repetitive movement trajectories may provide insight into the available motor redundancy during aging. We quantified complexity of repetitive arm elevation trajectories in the aging shoulder and assessed test-retest reliability of this quantification. In a cross-sectional study using 3D-electromagnetic tracking, 120 asymptomatic subjects, aged between 18 and 70 years performed repetitive abduction and forward/anteflexion movements. Movement complexity was calculated using the Approximate Entropy (ApEn-value): [0,2], where lower values indicate reduced complexity. Thirty-three participants performed the protocol twice, to determine reliability (intraclass correlation coefficient [ICC]). The association between age and ApEn was corrected for task characteristics (e.g., sample length) with multiple linear regression analysis. Reproducibility was determined using scatter plots and ICC's. Higher age was associated with lower ApEn-values during abduction (unstandardized estimate: -0.003/year; 95% confidence interval: [-0.005; -0.002]; p < .001). ICC's revealed poor to good reliability depending on differences in sample length between repeated measurements. The results may imply more stereotype movement during abduction in the ageing shoulder, making this movement prone to the development of shoulder complaints. Future studies may investigate the pathophysiology and clinical course of shoulder complaints by assessment of movement complexity. To this end, the ApEn-value calculated over repetitive movement trajectories may be used, although biasing factors such as sample length should be taken into account.

Reduced psychosocial functioning in subacromial pain syndrome is associated with persistence of complaints after 4 years

BACKGROUND

Patients with subacromial pain syndrome (SAPS) frequently present with coexisting psychosocial problems; however, whether this also associates with long-term outcome is currently unknown. We assessed whether psychosocial functioning in patients with SAPS is associated with persistence of complaints after 4 years of routine care.

METHODS

In a longitudinal study, 34 patients with SAPS were selected after clinical and radiologic evaluation and assessed at baseline and after 4 years. For the assessment of psychosocial functioning, the RAND-36 questionnaire domains of social functioning, role limitations due to emotional problems, mental health, vitality, and general health were evaluated. Complaint persistence at follow-up was assessed by (1) an anchor question (reduced, persistent, or increased symptoms), (2) change in pain (change in visual analog scale score), and (3) change in quality of life (change in Western Ontario Rotator Cuff index score).

RESULTS

Lower baseline mental health (odds ratio [OR], 0.92; 95% confidence interval [CI], 0.85-0.98; P = .013), vitality (OR, 0.90; 95% CI, 0.83-0.98; P = .011), and general health (OR, 0.93; 95% CI, 0.88-0.98; P = .009) were associated with persistent complaints as reported by the anchor question, change in visual analog scale score, and change in Western Ontario Rotator Cuff index score.

CONCLUSIONS

Evaluating psychosocial functioning parallel to physical complaints is currently not standard procedure in the treatment of SAPS. In this study, we showed that factors related to psychosocial functioning are associated with long-term persistence of complaints in SAPS. Future studies may investigate whether a multimodal treatment with assessment of psychosocial functioning may facilitate pain relief and recovery in SAPS.

Reduced force entropy in subacromial pain syndrome: A cross-sectional analysis

BACKGROUND

Generating a force at the hand requires moments about multiple joints by a theoretically infinite number of arm and shoulder muscle force combinations. This allows for learning and adaptation and can possibly be captured using the complexity (entropy) of an isometrically generated force curve. Patients with Subacromial Pain Syndrome have difficulty to explore alternative, pain-avoiding, motor strategies and we questioned whether loss of motor complexity may contribute to this. We assessed whether patients with Subacromial Pain Syndrome have reduced entropy of an isometrically generated abduction and adduction force curve.

METHODS

Forty patients and thirty controls generated submaximal isometric ab- and adduction force at the wrist. The force curve was characterized by the magnitude of force variability [standard deviation and coefficient of variation], and the entropy (complexity) of force variability [approximate entropy].

FINDINGS

Patients showed reduced entropy both during the abduction (-0.16, confidence interval: [-0.33; -0.00], p: 0.048) and adduction task (-0.20, confidence interval: [-0.37; -0.03], p: 0.024) and reduced force variability during abduction (standard deviation: -0.006, confidence interval: [-0.011; -0.001], p: 0.013 and coefficient of variation: -0.51, confidence interval: [-0.93; -0. 10], p: 0.016).

INTERPRETATIONS

Isometric force curves of patients with Subacromial Pain Syndrome show reduced complexity compared to asymptomatic controls, which may indicate more narrow and stereotype use of motor options. In future studies, it should be investigated whether the finding of reduced force (motor) entropy indicates functional decline, contributing to decreased ability to acquire and optimize motor strategies in Subacromial Pain Syndrome.

LEVEL OF EVIDENCE

Level II prognostic study.

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.

Middle-aged adults cocontract with arm ADductors during arm ABduction, while young adults do not. Adaptations to preserve pain-free function?

Middle-aged individuals cocontract with adductor muscles during abduction. This may be crucial for counteracting deltoid forces, depressing the humerus and ensuring free passage of subacromial tissues underneath the acromion during abduction. We questioned whether adductor co-contraction is always present, or develops during ageing, in which case it may explain the age-related character of common shoulder conditions such as Subacromial Pain Syndrome. In a cross-sectional analysis with electromyography (EMG), activation patterns of the latissimus dorsi, teres major, pectoralis major and deltoid muscle were assessed during isometric force tasks in 60 asymptomatic individuals between 21 and 60 years old. Cocontraction was expressed as the degree of antagonistic activation relative to the same muscle's degree of agonistic activation, resulting in an activation ratio between -1 and 1, where lower values indicate more cocontraction. Using linear regression analyses, we found age-related decreases in the activation ratio of the latissimus dorsi (regression estimate: -0.004, 95% CI: -0.007 to 0.0, p-value: 0.042) and teres major (regression estimate: -0.013, 95% CI: -0.019 to -0.008, p-value: <0.001). In contrast to young individuals, middle-aged individuals showed a high degree of adductor cocontraction during abduction. This may indicate that during ageing, alterations in activation patterns are required for preserving pain-free shoulder function.

Altered Cocontraction Patterns of Humeral Head Depressors in Patients with Subacromial Pain Syndrome: A Cross-sectional Electromyography Analysis

BACKGROUND

In approximately 29% to 34% of all patients with subacromial pain syndrome (SAPS) there is no anatomic explanation for symptoms, and behavioral aspects and/or central pain mechanisms may play a more important role than previously assumed. A possible behavioral explanation for pain in patients with SAPS is insufficient active depression of the humerus during abduction by the adductor muscles. Although the adductor muscles, specifically the teres major, have the most important contribution to depression of the humerus during abduction, these muscles have not been well studied in patients with SAPS.

QUESTIONS/PURPOSES

Do patients with SAPS have altered contraction patterns of the arm adductors during abduction compared with asymptomatic people?

METHODS

SAPS was defined as nonspecific shoulder pain lasting for longer than 3 months that could not be explained by specific conditions such as calcific tendinitis, full-thickness rotator cuff tears, or symptomatic acromioclavicular arthritis, as assessed with clinical examination, radiographs, and magnetic resonance arthrography. Of 85 patients with SAPS who met the prespecified inclusion criteria, 40 were eligible and agreed to participate in this study. Thirty asymptomatic spouses of patients with musculoskeletal complaints, aged 35 to 60 years, were included; the SAPS and control groups were not different with respect to age, sex, and hand dominance. With electromyography, we assessed the contraction patterns of selected muscles that directly act on the position of the humerus relative to the scapula (the latissimus dorsi, teres major, pectoralis major, and deltoid muscles). Cocontraction was quantified through the activation ratio ([AR]; range, -1 to 1). The AR indicates the task-related degree of antagonist activation relative to the same muscle's degree of agonist activation, equaling 1 in case of sole agonist muscle activation and equaling -1 in case of sole antagonistic activation (cocontraction). We compared the AR between patients with SAPS and asymptomatic controls using linear mixed-model analyses. An effect size of 0.10 < AR < 0.20 was subjectively considered to be a modest effect size.

RESULTS

Patients with SAPS had a 0.11 higher AR of the teres major (95% CI, 0.01-0.21; p = 0.038), a 0.11 lower AR of the pectoralis major (95% CI, -0.18 to -0.04; p = 0.003), and a 0.12 lower AR of the deltoid muscle (95% CI, -0.17 to -0.06; p < 0.001) than control participants did. These differences were considered to be modest. With the numbers available, we found no difference in the AR of the latissimus dorsi between patients with SAPS and controls (difference = 0.05; 95% CI, -0.01 to 0.12; p = 0.120).

CONCLUSIONS

Patients with SAPS showed an altered adductor cocontraction pattern with reduced teres major activation during abduction. The consequent reduction of caudally directed forces on the humerus may lead to repetitive overloading of the subacromial tissues and perpetuate symptoms in patients with SAPS. Physical therapy programs are frequently effective in patients with SAPS, but targeted approaches are lacking. Clinicians and scientists may use the findings of this study to assess if actively training adductor cocontraction in patients with SAPS to unload the subacromial tissues is clinically effective. The efficacy of training protocols may be enhanced by using electromyography monitoring.

LEVEL OF EVIDENCE

Level II, prognostic study.