Friedl de Groote

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Hip loading affects bone remodeling and implant fixation. In this study, we have analyzed the effect of subject-specific modeling of hip geometry on muscle activation patterns and hip contact forces during gait, using musculoskeletal modeling, inverse dynamic analysis and static optimization. We first used sensitivity analysis to analyze the effect of(More)
Symmetrical limb movement requires complex muscle coordination patterns. Consequently, coordination impairments lead to asymmetric gait patterns, as often seen in stroke subjects. Split-belt walking has previously been used to induce limping-like walking in able-bodied adults. The goal of this study is to analyze how muscle coordination patterns that(More)
This paper compares geometry-based knee axes of rotation (transepicondylar axis and geometric center axis) and motion-based functional knee axes of rotation (fAoR). Two algorithms are evaluated to calculate fAoRs: Gamage and Lasenby's sphere fitting algorithm (GL) and Ehrig et al.'s axis transformation algorithm (SARA). Calculations are based on 3D motion(More)
We developed a Kalman smoothing algorithm to improve estimates of joint kinematics from measured marker trajectories during motion analysis. Kalman smoothing estimates are based on complete marker trajectories. This is an improvement over other techniques, such as the global optimisation method (GOM), Kalman filtering, and local marker estimation (LME),(More)
We assessed and compared sensitivities of dynamic simulations to musculotendon (MT) parameters for gait and dynamometer experiments. Our aim with this comparison was to investigate whether dynamometer experiments could provide information about MT-parameters that are important to reliably study MT-function during gait. This would mean that dynamometer(More)
Maintaining mediolateral (ML) balance is very important to prevent falling during walking, especially at very slow speeds. The effect of walking speed on support and propulsion of the center of mass (COM) has been focus of previous studies. However, the influence of speed on ML COM control and the associated coupling with sagittal plane control remains(More)
BACKGROUND The efficacy of dexamethasone (DEX) to reduce morbidity after paediatric tonsillectomy remains controversial. We evaluated the effect of 0.15 and 0.5 mg kg(-1) DEX on the incidence of postoperative nausea and vomiting (PONV) and on pain intensity after paediatric tonsillectomy. METHODS A total of 147 children aged 2-8 yr undergoing elective(More)
OBJECTIVE This study calculated knee contact forces (KCF) and its relations with knee external knee adduction moments (KAM) and/or flexion moments (KFM) during the stance phase of gait in patients with early osteoarthritis (OA), classified based on early joint degeneration on Magnetic Resonance Imaging (MRI). We aimed at assessing if altered KCF are already(More)
Leg kinematics during backward walking (BW) are very similar to the time-reversed kinematics during forward walking (FW). This suggests that the underlying muscle activation pattern could originate from a simple time reversal, as well. Experimental electromyography studies have confirmed that this is the case for some muscles. Furthermore, it has been(More)
During four breeding seasons (2004-2008), 78 necropsy examinations were performed on South American fur seal pups (Arctocephalus australis gracilis) found dead on Guafo Island, southern Chile (43°36'S, 74°43'W). Tissue samples from 65 pups were examined microscopically. The primary causes of death were enteritis with microscopical lesions of bacteraemia(More)