Injury prevalence in dancers is high, and misaligned turnout (TO) is claimed to bear injury risk. This systematic review aimed to investigate if compensating or forcing TO leads to musculoskeletal... Show moreInjury prevalence in dancers is high, and misaligned turnout (TO) is claimed to bear injury risk. This systematic review aimed to investigate if compensating or forcing TO leads to musculoskeletal injuries.A systematic literature review was conducted according to the PRISMA Guidelines using the databases of PubMed, Embase, Emcare, Web of Science, Cochrane Library, Academic Search Premier, and ScienceDirect. Studies investigating the relationship between compensated or forced TO and injuries in all genders, all ages, and levels of dancers were included. Details on misaligned TO measurements and injuries had to be provided. Screening was performed by two researchers, data extraction and methodological quality assessment executed by one researcher and checked by another.7 studies with 1293 dancers were included. Methodological quality was low due to study designs and a general lack of standardised definition of pathology and methods of assessment of misaligned TO. The studies investigating the lower extremities showed a hip-focus only. Non-hip contributors as well as their natural anatomical variations were not accounted for, limiting the understanding of injury mechanisms underlying misaligned TO. As such no definite conclusions on the effect of compensating or forcing TO on musculoskeletal injuries could be made.Total TO is dependent on complex motion cycles rather than generalised (hip) joint dominance only. Objective dual assessment of maximum passive joint range of motion through 3D kinematic analysis in combination with physical examination is needed to account for anatomical variations, locate sites prone to (overuse)injury, and investigate underlying injury mechanisms. (C) 2020 Elsevier Ltd. All rights reserved. Show less
Klomp, A.; Vlugt, E. de; Groot, J.H. de; Meskers, C.G.M.; Arendzen, J.H.; Helm, F.C.T. van der 2018
Rupture of atherosclerotic plaques is the underlying cause for the majority of acute strokes and myocardial infarctions. Rupture of the plaque occurs when the stress in the plaque exceeds the... Show moreRupture of atherosclerotic plaques is the underlying cause for the majority of acute strokes and myocardial infarctions. Rupture of the plaque occurs when the stress in the plaque exceeds the strength of the material locally. Biomechanical stress analyses are commonly based on pressurized geometries, in most cases measured by in-vivo MRI. The geometry is therefore not stress-free. The aim of this study is to identify the effect of neglecting the initial stress state on the plaque stress distribution. Fifty 2D histological sections (7 patients, 9 diseased coronary artery segments), perfusion fixed at 100 mmHg, were segmented and finite element models were created. The Backward Incremental method was applied to determine the initial stress state and the zero-pressure state. Peak plaque and cap stresses were compared with and without initial stress. The effect of initial stress on the peak stress was related to the minimum cap thickness, maximum necrotic core thickness, and necrotic core angle. When accounting for initial stress, the general relations between geometrical features and peak cap stress remain intact. However, on a patient-specific basis, accounting for initial stress has a different effect on the absolute cap stress for each plaque. Incorporating initial stress may therefore improve the accuracy of future stress based rupture risk analyses for atherosclerotic plaques. (C) 2011 Elsevier Ltd. All rights reserved. Show less
Short-range stiffness (SRS) is a mechanical property of muscles that is characterized by a disproportionally high stiffness within a short length range during both lengthening and shortening... Show moreShort-range stiffness (SRS) is a mechanical property of muscles that is characterized by a disproportionally high stiffness within a short length range during both lengthening and shortening movements. SRS is attributed to the cross-bridges and is beneficial for stabilizing a joint during, e.g., postural conditions. Thus far, SRS has been estimated mainly on isolated mammalian muscles. In this study we presented a method to estimate SRS in vivo in the human wrist joint. SRS was estimated at joint level in the angular domain (N m/rad) for both flexion and extension rotations of the human wrist in nine healthy subjects. Wrist rotations of 0.15 tad at 3 rad/s were imposed at eight levels of voluntary contraction ranging from 0 to 2.1 N m by means of a single axis manipulator. Flexion and extension SRS of the wrist joint was estimated consistently and accurately using a dynamic nonlinear model that was fitted onto the recorded wrist torque. SRS increased monotonically with torque in a way consistent with previous studies on isolated muscles. It is concluded that in vivo measurement of joint SRS represents the population of coupled cross-bridges in wrist flexor and extensor muscles. In its current form, the presented technique can be used for clinical applications in many neurological and muscular diseases where altered joint torque and (dissociated) joint stiffness are important clinical parameters. (C) 2010 Elsevier Ltd. All rights reserved. Show less
Steenbrink, F.; Meskers, C.G.M.; Nelissen, R.G.H.H.; Groot, J.H. de 2010
In patients with rotator cuff tears lost elevation moments are compensated for by increased deltoid activation. Concomitant proximal directed destabilizing forces at the glenohumeral joint are... Show moreIn patients with rotator cuff tears lost elevation moments are compensated for by increased deltoid activation. Concomitant proximal directed destabilizing forces at the glenohumeral joint are suggested to be compensated for by 'out-of-phase' adductor activation, preserving glenohumeral stability. Aim of this study was to demonstrate causality between moment compensating deltoid activation and stability compensating 'out-of-phase' adductor muscle activation. A differential arm loading with the same magnitude of forces applied at small and large moment arms relative to the glenohumeral joint was employed to excite deltoid activation, without externally affecting the force balance. Musculoskeletal modeling was applied to analyze the protocol in terms of muscle forces and glenohumeral (in)stability. The protocol was applied experimentally using electromyography (EMG) to assess muscle activation of healthy controls and cuff tear patients. Both modeling and experiments demonstrated increased deltoid activation with increased moment loading, which was higher in patients compared to controls. Model simulation of cuff tears demonstrated glenohumeral instability and related 'out-of-phase' adductor muscle activation which was also found experimentally in patients when compared to controls. Through differential moment loading, the assumed causal relation between increased deltoid activation and compensatory adductor muscle activation in cuff tear patients could be demonstrated. 'Out-of-phase' adductor activation in patients was attributed to glenohumeral instability. The moment loading protocol discerned patients with cuff tears from controls based on muscle activation. (C) 2010 Elsevier Ltd. All rights reserved. Show less
Fluoroscopic analysis is an important tool for assessing in vivo kinematics of knee prostheses. Most commonly, a single-plane fluoroscopic setup is used to capture the motion of prostheses during a... Show moreFluoroscopic analysis is an important tool for assessing in vivo kinematics of knee prostheses. Most commonly, a single-plane fluoroscopic setup is used to capture the motion of prostheses during a particular task. Unfortunately, single-plane fluoroscopic analysis is imprecise in the out-of-plane direction. This can result in reconstructing physically impossible poses, in which for example the femoral component intersects with the insert, as the normal pose estimation process does not take into account the relation between the components. In the proposed method, the poses of both components are estimated simultaneously, while preventing femur-insert collisions. In a phantom study, the accuracy and precision of the new method in estimating the relative pose of the femoral component were compared to those of the original method. With reverse engineered models, the errors in estimating the out-of-plane position decreased from 2.0 +/- 0.7 to 0.1 +/- 0.1 mm, without effects on the errors in rotations and the in-plane positions. With CAD models, the errors in estimating the out-of-plane position decreased from 5.3 +/- 0.7 mm (mean +/- SD) to 0.0 +/- 0.4 mm, at the expense of a decreased precision for the other position or orientation parameters. In conclusion, collision detection can prevent reconstructing impossible poses and it improves the position and motion estimation in the out-of-plane direction. (C) 2009 Elsevier Ltd. All rights reserved. Show less
Fluoroscopic analysis is an important tool for assessing in vivo kinematics of knee prostheses. Most commonly, a single-plane fluoroscopic setup is used to capture the motion of prostheses during a... Show moreFluoroscopic analysis is an important tool for assessing in vivo kinematics of knee prostheses. Most commonly, a single-plane fluoroscopic setup is used to capture the motion of prostheses during a particular task. Unfortunately, single-plane fluoroscopic analysis is imprecise in the out-of-plane direction. This can result in reconstructing physically impossible poses, in which-for example-the femoral component intersects with the insert, as the normal pose estimation process does not take into account the relation between the components. In the proposed method, the poses of both components are estimated simultaneously, while preventing femur-insert collisions. In a phantom study, the accuracy and precision of the new method in estimating the relative pose of the femoral component were compared to those of the original method. With reverse engineered models, the errors in estimating the out-of-plane position decreased from 2.0+/-0.7 to 0.1+/-0.1mm, without effects on the errors in rotations and the in-plane positions. With CAD models, the errors in estimating the out-of-plane position decreased from 5.3+/-0.7mm (mean+/-SD) to 0.0+/-0.4mm, at the expense of a decreased precision for the other position or orientation parameters. In conclusion, collision detection can prevent reconstructing impossible poses and it improves the position and motion estimation in the out-of-plane direction. Show less
