The effect of knee replacement on outcomes throughout the disablement model
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The annual incidence of knee replacement (KR) procedures in the United States is predicted to reach over 3.5 million by the year 2030. KR is the current definitive treatment for debilitating knee osteoarthritis (KOA). There has yet to be substantial research regarding the impact of KR on participation in community activities and quality of life. The hypotheses evaluated in this dissertation were that persons following KR will have 1) faster gait speed and 2) lower risk of participation restrictions than persons without KR; and 3) a decreased risk of all-cause mortality compared to persons without KR. To address the first two hypotheses, we collected data from subjects with KOA from the Multicenter Osteoarthritis Study and the Osteoarthritis Initiative, large cohorts of older adults with or at risk of KOA at the time of enrollment. In the first study, KR did not have an effect on gait speed overall and among most subgroups, however subjects with a slow gait speed prior to KR did have an 80% increased risk (RR 1.8, 95% CI 1.1, 3.0) of having a healthy gait speed compared with non-KR subjects. In the second study, KR was associated with a small decreased risk of having participation restriction (RR 0.82, 95% CI 0.67, 0.99). The third study used data on patients with KOA from the Clinical Practice Research Datalink, a database of clinical information on > 8 million people throughout the United Kingdom. There was a decrease in the death rate among KOA subjects who had a KR compared to those who did not, and the hazard of death was reduced by over one half in the first five years after the procedure (HR 0.46 (95% CI 0.43, 0.51). For most subjects, this benefit did not extend longer than five years, and patients least likely to have KR (due to clinical and medical presentation) showed an increased hazard of death compared to the non-KR subjects. In conclusion, the results of this dissertation support the hypotheses that KR confers a positive benefit to activity and participation related pursuits which may extend to survival in the short term for some people.