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.

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.

Increased co-contraction of arm adductors is associated with a favorable course in subacromial pain syndrome.

BACKGROUND: Enhancement of arm adductor activity during abduction (ie, adductor co-contraction), may be effective in the treatment of subacromial pain syndrome (SAPS). We assessed whether an increase of adductor co-contraction is associated with a favorable course of SAPS. METHODS: At baseline and after nearly 4 years of follow-up, electromyography of the latissimus dorsi (LD), teres major (TM), pectoralis major, and deltoid muscle was obtained during isometric abduction and adduction tasks in 26 patients with SAPS. Changes in co-contraction were assessed with change in the activation ratio (ΔAR). The AR ranges between -1 and 1, where lower values indicate more co-contraction. Clinical course was determined from an anchor question (reduced, persistent, or increased complaints), the visual analog scale for pain (VAS), and the Western Ontario Rotator Cuff score (WORC). RESULTS: In patients indicating persistent complaints (31%), the VAS and WORC remained stable. In patients who indicated reduced complaints (69%), the VAS reduced (z score, -3.4; P = .001) and WORC increased (z score, 3.6; P < .001). Unchanged ARs associated with complaints persistence, whereas decreased AR of the LD (ΔARLD, -0.21; 95% confidence interval [CI], -0.36 to -0.06) and TM (ΔARTM, -0.17; 95% CI, -0.34 to -0.00) coincided with reduced complaints. There was a significant between-group difference in ΔARLD (-0.35; 95% CI, -0.60 to 0.10) and ΔARTM (-0.36; 95% CI, -0.66 to -0.05). CONCLUSIONS: Increased co-contraction of the LD and TM is associated with a favorable course of SAPS. This may be explained by widening of the subacromial space accomplished by adductor co-contraction.

Three-dimensional shoulder motion after teres major or latissimus dorsi tendon transfer for posterosuperior rotator cuff tears.

BACKGROUND: Teres major (TM) transfer and latissimus dorsi (LD) transfer are essential treatment options in patients with posterosuperior rotator cuff (RC) tears. The purpose of this study was to quantify shoulder kinematics before and after TM transfer and LD transfer in posterosuperior RC tear patients. METHODS: In this prospective cohort study, we quantitatively measured shoulder movements using an electromagnetic tracking device (Flock of Birds) preoperatively and 1 year after either TM (n = 13) or LD (n = 9) tendon transfer. Additional outcome measures included the Constant score (CS), patient-reported pain, and quantitative range of motion. Scapular kinematics were evaluated during arm abduction. RESULTS: By use of a quantitative assessment, forward flexion (from 87° to 106°, P = .007), abduction (from 86° to 106°, P = .010), and external rotation in abduction (from 52° to 70°, P = .019) improved. Both transfers reduced pain (from 50 to 10 mm, P < .001), and the CS improved (from 37 to 62 points, P < .001). No significant differences in postoperative improvement in pain and function were found between TM and LD tendon transfers. The TM transfer group showed increased scapular lateral rotation compared with the LD transfer group (13°; 95% confidence interval [CI], 4.8° to 21.7°; P = .003). We were unable to detect differences between TM transfer and LD transfer in the change in protraction (3.2°; 95% CI, -6.3° to 12.8°; P = .489) and posterior tilt (3.5°; 95% CI, -3.5° to 10.5°; P = .313). CONCLUSION: Tendon transfer surgery resulted in an overall improvement in CS, pain relief, and quantitative range of motion in the treatment of an irreparable posterosuperior RC tear. Scapular lateral rotation gradually increased after TM transfer, reminiscent of RC function, whereas such an increase was not observed after LD transfer.

Does acromioplasty result in favorable clinical and radiologic outcomes in the management of chronic subacromial pain syndrome? A double-blinded randomized clinical trial with 9 to 14 years' follow-up.

BACKGROUND: The treatment effect of acromioplasty for chronic subacromial pain syndrome (SAPS) on long-term shoulder function and rotator cuff deterioration has still to be determined. This study aimed to determine the long-term clinical and radiologic treatment effect of arthroscopic acromioplasty in patients with chronic SAPS. METHODS: In this double-blind, randomized clinical trial, 56 patients with chronic SAPS (median age, 47 years; age range, 31-60 years) were randomly allocated to arthroscopic bursectomy alone or to bursectomy combined with acromioplasty and were followed up for a median of 12 years. The primary outcome was the Constant score. Secondary outcomes included the Simple Shoulder Test, visual analog scale (VAS) for pain, VAS for shoulder functionality, and rotator cuff integrity assessed with magnetic resonance imaging or ultrasound. RESULTS: A total of 43 patients (77%) were examined at a median of 12 years' follow-up. Intention-to-treat analysis at 12 years' follow-up did not show a significant additional treatment effect of acromioplasty on bursectomy alone in improvement in Constant score (5 points; 95% confidence interval, -5.1 to 15.6), Simple Shoulder Test score, VAS score for pain, or VAS score for shoulder function. The prevalence of rotator cuff tears was not significantly different between the bursectomy group (17%) and acromioplasty group (10%). CONCLUSIONS: There were no relevant additional effects of arthroscopic acromioplasty on bursectomy alone with respect to clinical outcomes and rotator cuff integrity at 12 years' follow-up. These findings bring the effectiveness of acromioplasty into question and may support the idea of a more conservative approach in the initial treatment of SAPS.

Three-dimensional shoulder kinematics normalize after rotator cuff repair.

BACKGROUND: Patients with a rotator cuff (RC) tear often exhibit scapular dyskinesia with increased scapular lateral rotation and decreased glenohumeral elevation with arm abduction. We hypothesized that in patients with an RC tear, scapular lateral rotation, and thus glenohumeral elevation, will be restored to normal after RC repair. METHODS: Shoulder kinematics were quantitatively analyzed in 26 patients with an electromagnetic tracking device (Flock of Birds) before and 1 year after RC repair in this observational case series. We focused on humeral range of motion and scapular kinematics during abduction. The asymptomatic contralateral shoulder was used as the control. Changes in scapular kinematics were associated with the gain in range of motion. Shoulder kinematics were analyzed using a linear mixed model. RESULTS: Mean arm abduction and forward flexion improved after surgery by 20° (95% confidence interval [CI], 2.7°-36.5°; P = .025) and 13° (95% CI, 1.2°-36.5°; P = .044), respectively. Kinematic analyses showed decreases in mean scapular protraction (ie, internal rotation) and lateral rotation (ie, upward rotation) during abduction by 3° (95% CI, 0.0°-5.2°; P = .046) and 4° (95% CI, 1.6°-8.4°; P = .042), respectively. Glenohumeral elevation increased by 5° (95% CI, 0.6°-9.7°; P = .028) at 80°. Humeral range of motion increased when scapular lateral rotation decreased and posterior tilt increased. CONCLUSIONS: Scapular kinematics normalize after RC repair toward a symmetrical scapular motion pattern as observed in the asymptomatic contralateral shoulder. The observed changes in scapular kinematics are associated with an increased overall range of motion and suggest restored function of shoulder muscles.

Predictors of disease-specific quality of life after arthroscopic rotator cuff repair.

PURPOSE: Disease-specific instruments of quality of life (QOL) are more sensitive to disease-specific changes. The purpose of this study is to identify prognostic factors for disease-specific QOL after all-arthroscopic rotator cuff (RC) repair using the Western Ontario Rotator Cuff Index (WORC). METHODS: A total of 140 patients were evaluated after an RC repair with a mean follow-up of 22 ± 6.7 months. Evaluations included the WORC, EQ-5D and anchor questions. Preoperative patient demographics and radiologic characteristics were assessed to identify predictors of disease-specific QOL. RESULTS: Most patients (81.4 %) were satisfied with their surgical result. Minor tear retraction (odds ratio [OR] 2.97, p = 0.030), male gender (OR 3.67, p = 0.003), no social benefits (OR 3.67, p = 0.042) and pre-surgical complaints for more than six months (OR 3.03, p = 0.021) were independent predictors for superior postoperative WORC score in multivariable analysis. None of these factors were predictive for a higher EQ-5D score. CONCLUSION: These findings highlight the important impact of retraction on QOL after RC repair and underline the utility of disease-specific instruments. Future studies should focus on how these significant predictors can be used to improve decision making and to develop new treatment approaches.

The minimal detectable change of the Constant score in impingement, full-thickness tears, and massive rotator cuff tears.

HYPOTHESIS: The purpose of this study was to determine the minimal detectable change (MDC) for the Constant score in patients with impingement, a supraspinatus tear, or a massive rotator cuff (RC) tear as observed changes smaller than the MDC might be the result of measurement error. METHODS: The Constant score was recorded in a total of 180 patients, including 34 patients with impingement, 105 with supraspinatus tears, and 41 with massive RC tears. We assessed the MDC in the 3 subgroups and total group using the samples standard deviation (SD), internal consistency (Cronbach α), and standard error of the measurement. Floor and ceiling effects were also reported. RESULTS: The absolute mean Constant score was 72 (SD, 11.2) in the impingement group, 44 (SD, 14.7) in the supraspinatus tear group, and 46 (SD, 18.9) in the massive RC tear group. There were no floor and ceiling effects for the absolute Constant score. In the total group, the internal consistency was 0.8 and the standard error of the measurement was 8. The MDC was 23 points on the Constant score in the total group and 17, 18, and 23 points on the Constant score for impingement, RC tears, and massive RC tears, respectively. CONCLUSION: This study demonstrates that the MDCs of the Constant score are different in patients with impingement, supraspinatus tears, and massive RC tears. Studies reporting the Constant score should be interpreted by use of the population-specific MDC and minimal clinical important change.

Postpartum pubic symphysis diastasis resulting in a prepubic abscess and osteomyelitis.

Postpartum pubic symphysis diastasis (PSD) refers to an abnormal widening of the pubic symphysis after delivery. It is a rare and underdiagnosed condition that causes severe pain and can be complicated by osteomyelitis and abscess formation. This article reports a case of a para 4 woman in her 30s with postpartum PSD after vaginal delivery who presented with a prepubic abscess. Multimodal treatment consisted of incision and drainage, physiotherapy and prolonged antibiotic treatment.

Pain does not explain reduced teres major co-contraction during abduction in patients with Subacromial Pain Syndrome.

BACKGROUND: Patients with Subacromial Pain Syndrome show reduced co-contraction of the teres major during abduction. Consequent insufficient humeral depressor function may contribute to painful irritation of subacromial tissues and offers a potential target for therapy. A crucial gap in knowledge is whether the degree of teres major co-contraction in these patients is influenced by pain itself. To gain insight into this matter, we assessed whether relief of subacromial pain with local analgesics leads to increased adductor co-contraction in 34 patients with subacromial pain. METHODS: In a single-arm interventional study with 34 patients, electromyographic activity of the latissimus dorsi, pectoralis major, teres major and deltoid was assessed during isometric force tasks in 24 directions before and after subacromial Lidocaine injection. Co-contraction was quantified using the activation ratio; range [-1 (sole antagonistic activation, i.e. co-contraction) to 1 (sole agonistic activation)]. FINDINGS: There were no changes in activation ratio of the teres major after the intervention (Z-score: -0.6, p = 0.569). The activation ratio of the latissimus dorsi increased to 0.38 (quartiles: 0.13-0.76), indicating decreased co-contraction (Z-score: -2.0, p = 0.045). INTERPRETATION: Subacromial analgesics led to a decrease in co-contraction of the latissimus dorsi, whereas no change in the degree of teres major co-contraction was observed. This study shows that decreased teres major co-contraction in patients with subacromial pain, likely is not the consequence of pain itself, opening a window for physical therapy with training of teres major co-contraction to reduce subacromial irritation and pain. LEVEL OF EVIDENCE: Level II treatment study.

The metabolic landscape in chronic rotator cuff tear reveals tissue-region-specific signatures.

BACKGROUND: Degeneration of shoulder muscle tissues often result in tearing, causing pain, disability and loss of independence. Differential muscle involvement patterns have been reported in tears of shoulder muscles, yet the molecules involved in this pathology are poorly understood. The spatial distribution of biomolecules across the affected tissue can be accurately obtained with matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI). The goal of this pilot study was to decipher the metabolic landscape across shoulder muscle tissues and to identify signatures of degenerated muscles in chronic conditions. METHODS: Paired biopsies of two rotator cuff muscles, torn infraspinatus and intact teres minor, together with an intact shoulder muscle, the deltoid, were collected during an open tendon transfer surgery. Five patients, average age 65.2 ± 3.8 years, were selected for spatial metabolic profiling using high-spatial resolution (MALDI-TOF) and high-mass resolution (MALDI-FTICR) MSI in negative or positive ion mode. Metabolic signatures were identified using data-driven analysis. Verifications of spatial localization for selected metabolic signatures were carried out using antibody immunohistology. RESULTS: Data-driven analysis revealed major metabolic differences between intact and degenerated regions across all muscles. The area of degenerated regions, encompassed of fat, inflammation and fibrosis, significantly increased in both rotator cuff muscles, teres minor (27.9%) and infraspinatus (22.8%), compared with the deltoid (8.7%). The intact regions were characterized by 49 features, among which lipids were recognized. Several of the identified lipids were specifically enriched in certain myofiber types. Degenerated regions were specifically marked by the presence of 37 features. Heme was the most abundant metabolite in degenerated regions, whereas Heme oxygenase-1 (HO-1), which catabolizes heme, was found in intact regions. Higher HO-1 levels correlated with lower heme accumulation. CONCLUSIONS: Degenerated regions are distinguished from intact regions by their metabolome profile. A muscle-specific metabolome profile was not identified. The area of tissue degeneration significantly differs between the three examined muscles. Higher HO-1 levels in intact regions concurred with lower heme levels in degenerated regions. Moreover, HO-1 levels discriminated between dysfunctional and functional rotator cuff muscles. Additionally, the enrichment of specific lipids in certain myofiber types suggests that lipid metabolism differs between myofiber types. The signature metabolites can open options to develop personalized treatments for chronic shoulder muscles degeneration.

Arthroscopic bursectomy less effective in the degenerative shoulder with chronic subacromial pain.

BACKGROUND: Varying results after surgery in patients with subacromial pain syndrome (SAPS) have raised the question on whether there is a subgroup of patients that can benefit from surgery. Therefore, we aimed to identify preoperative and peroperative factors associated with a favorable patient-reported outcome after arthroscopic bursectomy in patients with SAPS. METHODS: Patients with chronic SAPS who underwent arthroscopic bursectomy after failed conservative management were included (n = 94). Patients were evaluated at the baseline, and 2 weeks, 8 weeks, 6 months, and 1 year after surgery. The primary outcome was the Western Ontario Rotator Cuff index (WORC) score one year after surgery. The secondary outcome measure was a visual analog scale for pain. Mixed model analyses were used to identify prognostic factors. RESULTS: The mean WORC (mean difference 39%, 95% confidence interval (CI) 32.8-45.3, P < .001) and visual analog scale pain scores (mean difference 41 mm points, 95% CI 3.37-4.88, P < .001) significantly improved one year after surgery. Nineteen patients (20%) developed a postoperative frozen shoulder. A longer duration of preoperative complaints and the peroperative identification of degenerative glenoid cartilage were associated with significantly worse WORC scores, with -0.086% per month (95% CI -0.156 to -0.016, P = .016) and -20% (95% CI -39.4 to -1.26, P = .037), respectively. CONCLUSION: We identified demographic and clinical factors that predict the course after arthroscopic subacromial bursectomy. We found that arthroscopic bursectomy is less effective in patients with SAPS with a degenerative shoulder. This finding suggests that an improved treatment effect of arthroscopic subacromial bursectomy can be expected in patients with chronic SAPS if intra-articular pathologies such as glenohumeral osteoarthritis are sufficiently excluded.

Kinematics and muscle activation in subacromial pain syndrome patients and asymptomatic controls.

BACKGROUND: Conflicting theories exist about the underlying cause of chronic subacromial pain in the middle-aged population. We aim to improve our understanding of kinematics and muscle activation in subacromial pain syndrome to provide insight in its pathophysiology. METHODS: In a cross-sectional comparison of 40 patients with subacromial pain syndrome and 30 asymptomatic controls, three-dimensional shoulder kinematics and electromyography-based co-contraction in 10 shoulder muscles were independently recorded. Glenohumeral and scapulothoracic kinematics were evaluated during abduction and forward flexion. Co-contraction was expressed as an activation ratio, specifying the relative agonistic and antagonistic muscle activity in each muscle. FINDINGS: During abduction and forward flexion, the contribution of glenohumeral motion to elevation and glenohumeral external rotation was lower in subacromial pain syndrome (at 1200 abduction: -9°, 95% CI -14°- -3°; and - 8°, 95% CI -13°--3°, respectively), and was compensated by more scapulothoracic motion. The pectoralis major's activation ratio was significantly lower (Z-score: -2.657, P = 0.008) and teres major's activation ratio significantly higher (Z-score: -4.088, P < 0.001) in patients with subacromial pain syndrome compared to the control group. INTERPRETATION: Reduced glenohumeral elevation and external rotation in subacromial pain syndrome coincided with less teres major antagonistic activity during elevation. These biomechanical findings provide a scientific basis for intervention studies directed at stretching exercises to reduce glenohumeral stiffness in the treatment of subacromial pain syndrome, and teres major strengthening to improve humeral head depressor function.

Reliability and discriminative accuracy of 5 measures for craniocaudal humeral position: an assessment on conventional radiographs.

HYPOTHESIS: This study aimed to examine the reliability and diagnostic discriminative accuracy of 5 different methods that quantity the craniocaudal humeral position with respect to the scapula on conventional radiographs. METHODS: In this retrospective, cross-sectional diagnostic study, 2 observers randomly assessed the conventional anteroposterior shoulder radiographs of 280 subjects with rotator cuff imaging for the (1) acromiohumeral (AH) interval, (2) upward migration index (UMI), (3) glenohumeral center-to-center measurement (GHCC), (4) glenohumeral arc measurement (GHa), and (5) scapular spine-humeral head center method (SHC). Reliability was assessed by means of relative consistency (intraclass correlation coefficient) and absolute consistency. Discriminative accuracy for detecting a rotator cuff tear was calculated. RESULTS: Relative consistency (intraclass correlation coefficient) for the AH interval, UMI, GHCC, GHa, and SHC was 0.961, 0.913, 0.806, 0.924, and 0.726, respectively. The AH interval had the highest absolute consistency with a random residual measurement error of 0.58 mm compared with 1.0-3.2 mm for the other measurements. The discriminative accuracy of the AH interval did not significantly differ from that of the UMI (-0.010; 95% confidence interval [CI], -0.042 to 0.022; P = .545) but was significantly better than that of the GHCC (0.112; 95% CI, 0.043-0.181; P = .001), GHa (0.074; 95% CI, 0.009-0.139; P = .027), and SHC (0.178; 95% CI, 0.100-0.256; P < .001). CONCLUSION: Assessment of the craniocaudal humeral position is performed with good to excellent intraobserver and interobserver reliability. The discriminative accuracy for detecting a rotator cuff tear on a single radiograph was highest for the AH interval and UMI. We recommend using the AH interval or UMI as an indirect measure of the presence of a rotator cuff tear on conventional radiographs.

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.

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.

The presence of a rotator cuff tear interferes with age-dependent muscle atrophy of intact shoulder muscles. An MRI study with 3 years' follow-up.

Rotator cuff muscle atrophy is frequently studied, but it is unknown whether redistribution of mechanical load in the presence of a rotator cuff tear influence muscle atrophy that is observed in patients. We hypothesized that in the presence of a supraspinatus tear, redistribution of mechanical load towards teres minor and deltoid slows down atrophy of these muscles over time. In this retrospective observational study of 129 patients, we measured the cross-sectional surface-areas on MRI of shoulder muscles in an intact rotator cuff (n = 92) and in a supraspinatus-tear group (n = 37) with a mean follow-up of 3 ±â€¯1.8 years. Mixed models were applied to evaluate changes in surface-area of the rotator cuff and deltoid with adjustments for age, sex and follow-up time. In patients with an intact rotator cuff, the mean surface-area of the teres minor decreased 6 mm2/year (95% CI 0.7-11.1, P = 0.026) and the mean deltoid surface-area decreased 75 mm2/year (95% CI 24.5-124.8, P = 0.004). The presence of a rotator cuff tear was associated with less reduction of teres minor and deltoid surface-area in patients <50 years, with an effect of a tear of 22 mm2/year (95% CI 1.7-41.7, P = 0.034) and 250 mm2/year (95% CI 75.8-424.3, P = 0.006), respectively. Whereas the surface-area of teres minor and deltoid decrease over time in patient with an intact rotator cuff, the decline in surface-area of these muscles was substantially less in the presence of a rotator cuff tear. Our findings indicate that atrophy may be reduced if an increase in mechanical load is exerted onto the muscle.

Rotator Cuff Calcific Tendinitis: Ultrasound-Guided Needling and Lavage Versus Subacromial Corticosteroids: Five-Year Outcomes of a Randomized Controlled Trial.

BACKGROUND: Barbotage (needling and lavage) is often applied in the treatment of calcific tendinitis of the rotator cuff (RCCT). In a previously published randomized controlled trial, we reported superior clinical and radiological 1-year outcomes for barbotage combined with a corticosteroid injection in the subacromial bursa (SAIC) compared with an isolated SAIC. There are no trials with a midterm or long-term follow-up of barbotage available. PURPOSE: To compare the 5-year results of 2 regularly applied treatments of RCCT: ultrasound (US)-guided barbotage combined with a SAIC (group 1) versus an isolated US-guided SAIC (group 2). STUDY DESIGN: Randomized controlled trial; Level of evidence, 1. METHODS: Patients were randomly assigned to group 1 or 2 and evaluated before and after treatment at regular time points until 12 months and also at 5 years using the Constant score (CS), the Western Ontario Rotator Cuff Index (WORC), and the Disabilities of the Arm, Shoulder and Hand (DASH). The calcification location and size and Gärtner classification were assessed on radiographs. The rotator cuff condition was evaluated with US. Results were analyzed using t tests, linear regression, and a mixed model for repeated measures. RESULTS: Forty-eight patients were included (mean age, 52.0 ± 7.3 years; 25 [52%] female) with a mean baseline CS of 68.7 ± 11.9. After a mean follow-up of 5.1 ± 0.5 years, the mean CS was 90 (95% CI, 83.0-95.9) in group 1 versus 87 (95% CI, 80.5-93.5) in group 2 ( P = .58). The mean improvement in the CS in group 1 was 18 (95% CI, 12.3-23.0) versus 21 (95% CI, 16.2-26.2) in group 2 ( P = .32). There was total resorption in 62% of group 1 and 73% of group 2 ( P = .45). The US evaluation of the rotator cuff condition showed no significant differences between the groups. With the mixed model for repeated measures, taking into account the baseline CS and Gärtner classification, the mean treatment effect for barbotage was 6 (95% CI, -8.9 to 21.5), but without statistical significance. Follow-up scores were significantly associated with baseline scores and the duration of follow-up. Results for the DASH and WORC were similar. There were no significant complications, but 4 patients in group 1 and 16 in group 2 underwent additional treatment during the follow-up period ( P < .001). CONCLUSION: No more significant differences were found in the clinical and radiological outcomes between barbotage combined with a SAIC versus an isolated SAIC after 5 years of follow-up. Registration: NTR2282 (Dutch Trial Registry).