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Title: Gait asymmetry and the risk of knee osteoarthritis in post-stroke individuals
Author: Alharbi, S.
Awarding Body: University of Salford
Current Institution: University of Salford
Date of Award: 2019
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Background: Gait impairments, including asymmetry of walking, are common following a stroke and unfortunately persist despite rehabilitation efforts. The asymmetry of walking, alongside other factors such as obesity are heightened risk factors for the development of osteoarthritis. It is postulated that the risk of developing OA in the years following a stroke is increased. However, there is a dearth of information available in terms of the typical knee loading profiles, which have been demonstrated as biomechanical impairments in knee osteoarthritis. in stroke survivors to determine the biomechanical risks of chronic stroke survivors developing OA. However, very little is known about the nature of knee load/moment patterns in stroke survivors to be able to test this hypothesis and determine the biomechanical risks of chronic stroke survivors developing OA. This is despite the fact that spatiotemporal asymmetry in other conditions (unilateral amputation and unilateral OA) is linked to the risk of developing knee OA. In these populations, some of the gait deviations seen in stroke (e.g. temporal gait asymmetry and excessive muscle activity), in the context of biological susceptibility, could contribute to secondary musculoskeletal complications, due to the cumulative effects of excessive and repetitive loading in long-term stroke. Nevertheless, it is not known to what extent the promotion of symmetrical gait patterns in stroke survivors affects knee joint loads. Objectives: This research aims to characterise knee joint moments in a cohort of stroke survivors, compared to healthy, speed-matched participants. The secondary aim is to explore the immediate effect of imposing a symmetric gait pattern (based on spatiotemporal symmetry) on knee joint moments in stroke survivors and an asymmetric gait pattern on a healthy group, walking at the same speed. The last aim was to characterise knee joint moments in a cohort of stroke survivors over time (assessed on two occasions: at baseline and a two-year follow-up). Methods: Kinematic and kinetic data were obtained with Three-dimensional (3D) motion analysis from 17 community-dwelling stroke survivors and 18 healthy older adults, walking over a six-metre walkway with embedded force plates, at their own, self-selected pace (healthy older adults also walked at a slow pace, matched with the mean Self-selected Walking Speed (SSWS) of the stroke survivors). In the second study, the participants were asked to walk to temporal (metronome) and spatial targets (stepping targets on the floor), which either imposed asymmetry (for participants who were symmetrical in their usual walking) or symmetry (for participants who were asymmetrical in their walking). The final study was a retrospective case series study based on an analysis of secondary data gathered from a recruited stroke survivors' group, who had already participated in two previous studies as initial measurements with measurements being repeated at a two-year follow-up. Results: Study 1: The stroke survivors' (n=17) knee joint load (peak Knee adduction moment (KAM) and KAM impulse) did not exceed that of the healthy control group (n=18). In contrast, Knee Flexion Moment (KFM) was higher on the non-paretic side (p=0.024) in the cohort of stroke survivors, compared to the healthy controls walking at comparable speeds. In addition, KFM on both the paretic and non-paretic sides in stroke survivors' subgroups with less severe temporal (n=7) (mean=0.64[0.39] Nm/Kg for paretic and mean=0.58[0.30] Nm/Kg for Non-paretic side) and spatial (n=11) (mean=0.53[0.37] Nm/Kg for paretic and mean=0.57[0.29] Nm/Kg for Non-paretic side) asymmetries were higher than in the healthy controls (n=18) (mean=0.28 Nm/Kg, 95% CI= 0.16-0.40 Nm/kg), walking at comparable speed. Study 2: The imposition of temporal and spatial symmetries on the stroke survivors with spatiotemporal asymmetry (n=13) did not show notable changes on knee joint moments (KAM and KFM) on the paretic and non-paretic sides. Study 3: As a case series study (n=9), the stroke survivors' knee joint load changed over time as KAM (peak and impulse) increases and KFM decreases on both sides. However, longitudinal changes of increase walking speed, increase pelvic drop and reduced knee ROM are commonly seen with knee joint moments changes overtime. Discussion: The additional compensatory gait patterns (e.g. pelvic obliquity) and slow walking speed following a stroke provide the side effect of lowering knee joint moments during walking compared to healthy individuals. In contrast, other compensatory mechanisms (e.g. knee range of motion [RoM]) may increase the knee joint load (KFM) and then the risk of patellofemoral pain/OA. Furthermore, no changes were observed in knee joint moment/load (KAM and KFM) across stroke survivors after imposing spatiotemporal symmetry. The possible reason is the demonstrated nature of spatiotemporal asymmetry, in its relative resistance to change (on the imposition of symmetry). However, because with increasing age and high BMI following a stroke, the changes of knee joint loads (as a mechanical stimulus) may lead to the development of knee joint OA. Conclusion: Stroke survivors' knee joint load (moment) is changing over time. However, joint moments appear to be heavily influenced by compensatory gait patterns. Such compensation, as well as the additional neuromuscular impairments, may produce a side-effect of lower frontal plane moment (KAM) and increase the risk of knee OA, due to the increased sagittal plane moment (KFM). Left unchanged, heightened KFM increases the risk of knee joint pain and OA. Knee joint moments did not manifest in notable changes as part of imposing symmetry on the stroke survivors. Furthermore, it is surprising that the stroke survivors with less spatiotemporal asymmetry displayed higher KFM than the healthy controls. These changes with time indicate the importance of considering how joint moments (as mechanical stimuli) change throughout the post-stroke lifespan, especially in light of the biological changes that usually accompany aging and increased Body Mass Index (BMI). However, future longitudinal work is necessary to investigate knee joint load from the very earliest stages of stroke recovery, taking into consideration cumulative load (physical activity), walking speed, and radiographic measurements of joint tissue.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available