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Motion Sensors in Osteoarthritis: Prospects and Issues
Published in Daniel Tze Huei Lai, Rezaul Begg, Marimuthu Palaniswami, Healthcare Sensor Networks, 2016
In addition to the load-related (i.e., kinetic) movement parameters that have been of interest in OA such as the KAM and impact forces, patients with OA also demonstrate some changes in knee joint kinematics, i.e., the position and angular orientation of the knee joint during gait. These include changes in the sagittal plane knee joint flexion angle at the point of foot–ground contact and later during stance (Astephen et al. 2008; Kaufman et al. 2001; Maly, Costigan, and Olney 2006; Mundermann, Dyrby, and Andriacchi 2005; Rudolph, Schmitt, and Lewek 2007). In the frontal plane, the most common OA of the medial knee compartment is often associated with static varus malalignment (bow legs) (Andriacchi 1994; Brouwer et al. 2007; Cicuttini et al. 2004; Hunter et al. 2007; Sharma et al. 2001). This may also be associated with dynamic changes in frontal plane knee kinematics during gait. Patients with knee OA sometimes exhibit a varus thrust, where the knee undergoes a sudden varus (lateral) movement in the early part of the stance phase after initial contact with the ground, which has been defined as “the dynamic worsening or abrupt onset of varus alignment as the limb accepted weight, with a return to less varus alignment during lift-off and the swing phase of gait” (Chang et al. 2010, p. 1405). It occurs in 20–40% of patients with OA. The origins of the thrust are not clearly understood, but it is possibly associated with static varus malalignment, lateral joint laxity and limitations in muscle control. The varus thrust has been linked to faster progression of OA disease (Chang et al. 2004). Clinicians generally judge the presence of a varus thrust based on simple subjective observation of the patient walking (Hunt, Schache, et al. 2010). Varus–valgus angular motion of the knee has also been measured from frontal plane knee kinematics using conventional optical motion capture (in patients with or without varus thrust), although the significance of this measure is still under investigation (Foroughi et al. 2010; Hunt et al. 2008; Hunt, Schache, et al. 2010; van der Esch et al. 2008). As discussed later, accelerometry has also been used to assess the varus thrust (Ogata, Yasunaga, and Nomiyama 1997).
Investigation of normal knees kinematics in walking and running at different speeds using a portable motion analysis system
Published in Sports Biomechanics, 2021
Rixu Liu, Dongyang Qian, Yushu Chen, Jianyu Zou, Shicong Zheng, Bo Bai, Zefeng Lin, Yu Zhang, Yi Chen
Both transverse and frontal planes of running and walking often link to the risks of disorders and injury (Stefanyshyn et al., 2006). Regarding adduction/abduction, this study showed that the abduction of the knee during normal walking is greater than comfortable walking. Previous studies have found that both knee abduction moment and the peak abduction moment increased, when walking speed has increased (de David et al., 2015). Patients with knee osteoarthritis usually have varus deformity of knees (Felson, 2006). Accelerating the walking speed in a certain extent reduces the angle of varus in knee osteoarthritis patients and slows down the condition (de David et al., 2015; Robbins & Maly, 2009). However, it was found in this study that when the speed had increased, the adduction/abduction ROM of normal walking was greater than that of slow running. The causation could be the shorter stance phase during running than walking (Novacheck, 1998), hence to activate the muscle activities and the viscoelastic behaviour of the soft-tissues. Others also observed non-linear transition from walking to running, indicating that the gait transition was an active reorganisation rather than a passive reaction (Pires et al., 2014, 2018). It is possible that the involvement of the active muscle activities could cause further constrain of the ROM in the adduction/abduction DOF (S. Zhang, et al., 2018).
Predictions of Birmingham hip resurfacing implant offset - In vitro and numerical models
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2019
A. Ramos, Marco P. Soares dos Santos, M. Mesnard
When compared with the intact articulation, experimental results show strain increases in the anterior aspect for the three positions defined for the THR, which are similar results to those previously reported (Little et al. 2007; Pal et al. 2010a). However, we also observed a different behavior in the proximal region for the different offsets: while the negative offset (valgus) induced a strain decrease (−72%) and probably bone loss, the opposite effect is expected using the positive offset (varus) (increase of up to 48%). Consequently, there is an increased risk of neck fracture (+66%) in the varus position due to shear stress. Changing the femur arm alters the bending moments and strains in femur aspects, as obtained in the experimental results.