Life expectancy of osteoarthritic patients after primary total knee arthroplasty.

Background: Although an increased life expectancy has been previously reported in patients with osteoarthritis (OA) after undergoing total knee arthroplasty (TKA), the long-living Japanese population may provide a more accurate cohort for determining 10- and 15-year survival rates. The aims of the present study were to (1) determine the survival of patients after TKA, (2) identify the factors important for survival, and (3) compare the survival rate of the OA patients with that of the standardized general population.

Methods: The 5-, 10-, and 15-year survival rates were assessed in 326 consecutive OA patients treated with TKA from January 1998 to December 2013. Eighty-six of the cases were staged bilateral TKAs. All patients were followed until December 31, 2014 or until the time of death. The survival rate of the patients was compared with that of the standardized general population using Kaplan-Meier survival curves.

Results: Fifty-one of the patients died before the end of the follow-up. The cumulative 5-year patient survival was 93.5%, 10-year survival was 82.1%, and 15-year survival was 66.6%. The standardized mortality ratio was 0.916 (95% confidence interval: 0.682-1.204). A Cox proportional hazards model showed that increased age and unilateral TKA were factors related to higher patient mortality rates.

Conclusions: These data suggest that patients undergoing TKA can expect similar life expectancy as the general population, with 66.6% of such patients surviving for at least 15-years. Additionally, patients undergoing bilateral TKAs may have a longer life expectancy than those undergoing unilateral TKA.