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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., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Background: Subacromial pain syndrome (SAPS) and scapular dyskinesis are closely associated, but the role of pain is unknown. We hypothesized that pain results in asymmetrical scapular kinematics, and we expected more symmetrical kinematics after infiltration of subacromial anaesthetics., Objective: To investigate the effect of subacromial anaesthetics on scapular kinematics in patients with SAPS., Design: Observational cohort study., Methods: We evaluated shoulder kinematics in 34 patients clinically and radiologically (magnetic resonance arthrography) identified with unilateral SAPS using three-dimensional electromagnetic motion analysis (Flock of Birds). Scapular internal rotation, upward rotation and posterior tilt of the affected shoulder were compared with the kinematics of the unaffected shoulder and following subacromial anaesthetics. Additionally, the association of pain (Visual Analogue Scale, VAS) and scapular rotation was analysed., Results: Compared with the contralateral healthy shoulder, 5° more (95% CI 0.4-9.7, p = 0.034) scapular internal rotation was observed in the affected shoulder at 110-120° of abduction. Following subacromial anaesthetics in the affected shoulder, internal rotation increased (2°, 95% CI 0.5-3.9, p = 0.045) and posterior tilt decreased (3°, 95% CI 1.5-5.0, p = 0.001) at 110-120° of abduction. Less scapular upward rotation was significantly associated with higher pain scores before infiltration (R = 0.45, p = 0.013)., Conclusions: More scapular internal rotation was observed in affected shoulders of patients with SAPS compared with unaffected shoulders. Subacromial infiltration did not restore kinematics toward symmetrical scapular motion. These findings suggest that subacromial anaesthesia is not an effective means to instantly restore symmetry of shoulder motion., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Background: Subacromial Impingement Syndrome (SIS) is frequently diagnosed, but treatment results vary greatly. It is increasingly reported that SIS symptoms are caused by various underlying mechanisms that need distinctive treatment strategies. We evaluated a set of specific MRI Arthrography (MRA) characteristics that have been related with underlying mechanisms for SIS in the literature, in patients with SIS., Methods: In 47 patients diagnosed with SIS, MRA characteristics were evaluated and categorized into categories of potential underlying mechanisms: (1) extrinsic: e.g. acromion shape; (2) intrinsic: e.g. tendinosis; (3) dynamic: e.g. signs of glenohumeral (micro-)instability. Control values were obtained from the literature. With cluster analysis, potential patient subgroups were assessed., Results: In 17 (36.2%) patients originally diagnosed with SIS, specific other conditions were found, including rotator cuff tears and labrum lesions. In the remaining 30, all had positive signs of at least one of the predefined underlying mechanisms. Patients could be categorized into 2 groups: predominantly findings corresponding with extrinsic/structural causes, or with dynamic/(micro)instability., Conclusions: MRA characteristics in patients with SIS symptoms are heterogeneous and many patients have specific other shoulder conditions causing symptoms. Patients without specific other conditions have MRA characteristics associated with either extrinsic (structural), or dynamic (e.g. micro-instability) underlying mechanisms., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Purpose: Clavicular shortening after fracture is deemed prognostic for clinical outcome and is therefore generally assessed on radiographs. It is used for clinical decision making regarding operative or non-operative treatment in the first 2weeks after trauma, although the reliability and accuracy of the measurements are unclear. This study aimed to assess the reliability of roentgen photogrammetry (2D) of clavicular length and shortening, and to compare these with 3D-spatial digitization measurements, obtained with an electromagnetic recording system (Flock of Birds)., Patients and Methods: Thirty-two participants with a consolidated non-operatively treated two or multi-fragmented dislocated midshaft clavicular fracture were analysed. Two observers measured clavicular lengths and absolute and proportional clavicular shortening on radiographs taken before and after fracture consolidation. The clavicular lengths were also measured with spatial digitization. Inter-observer agreement on the radiographic measurements was assessed using the Intraclass Correlation Coefficient (ICC). Agreement between the radiographic and spatial digitization measurements was assessed using a Bland-Altman plot., Results: The inter-observer agreement on clavicular length, and absolute and proportional shortening on trauma radiographs was almost perfect (ICC>0.90), but moderate for absolute shortening after consolidation (ICC=0.45). The Bland-Altman plot compared measurements of length on AP panorama radiographs with spatial digitization and showed that planar roentgen photogrammetry resulted in up to 37mm longer and 34mm shorter measurements than spatial digitization., Conclusion: Measurements of clavicular length on radiographs are highly reliable between observers, but may not reflect the actual length and shortening of the clavicle when compared to length measurements with spatial digitization. We recommend to use proportional shortening when measuring clavicular length or shortening on radiographs for clinical decision making., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Background: The Western Ontario Shoulder Instability Index (WOSI) is a disease-specific shoulder questionnaire to measure quality of life in patients with shoulder instability. The aim of the present study was to translate the WOSI into Dutch and assess its principal measurement properties., Methods: The WOSI was translated into Dutch according to guidelines in the literature. Fifty-two shoulder instability patients completed the questionnaire twice within 2 weeks. We assessed internal consistency (Cronbach's alpha), test-retest reliability [Intraclass Correlation Coefficient (ICC)], standard error of measurement (SEM), smallest detectable change (SDC) and reliable change index. The Bland-Altman analysis was applied to assess test-retest agreement and floor and ceiling effects were calculated., Results: Cronbach's alpha was 0.95 for the total WOSI score (range 0.88-0.95 for the 4 domains). ICC for the total WOSI score was 0.91 (range 0.79-0.90 for domains), SEM was 130.6 for the total WOSI score resulting in a SDC of 362.0, which is 17.3 % of the maximum obtainable score of 2100. Bland-Altman analysis showed no systematic differences or consistent bias between the two assessments. We observed no relevant floor and ceiling effects., Conclusion: The results of the present study suggest the Dutch version of the WOSI is a reliable tool for clinical assessment and scientific evaluation. It shows high values for Cronbach's alpha and ICC implying excellent internal consistency and good test-retest reliability.

Purpose: This study tests the hypothesis that the results of release of elbow stiffness related to heterotopic ossification (HO) are comparable whether there is partial or complete restriction (ankylosis) of flexion and extension., Methods: Eighteen patients who had surgical release of complete bony ankylosis between the humerus and ulna were retrospectively compared to 27 matched patients who had surgical release of partial restriction of elbow flexion and extension related to HO. Patients were evaluated a minimum of 10 months after surgery, using the Disabilities of the Arm, Shoulder, and Hand questionnaire and the Broberg and Morrey rating system., Results: An average of 22 months after surgery (range, 10 to 62 mo), the arc of flexion and extension averaged 95 degrees in the ankylosis cohort and 93 degrees in the partial HO cohort. Forearm rotation averaged 131 degrees versus 134 degrees ; the mean Disabilities of the Arm, Shoulder, and Hand score was 28 versus 30 points; and the mean Broberg and Morrey score was 81 versus 84 points, respectively., Conclusions: After controlling for other factors, patients with elbow stiffness related to HO can recover comparable motion after surgical release at short-term follow-up whether they have complete ankylosis or only partial restriction of motion., Type of Study/level of Evidence: Therapeutic III., (Copyright 2010. Published by Elsevier Inc.)