Survivorship analysis of total knee arthroplasty. Cumulative rates of survival of 9200 total knee arthroplasties. From 1971 through 1987, 9200 total knee arthroplasties were performed at the Mayo Clinic. Actuarial analysis was used to estimate cumulative rates of survival. Use of a proportional-hazard, general linear model led to the identification of four independent variables that were associated with a significantly lower risk of failure: primary total knee arthroplasty, a diagnosis of rheumatoid arthritis, an age of sixty years or more, and use of a condylar prosthesis with a metal-backed tibial component. When all four of these favorable variables were present (without regard for radiographic changes and non-disabling symptoms), the probability of an implant being in situ was 97 per cent at both five and ten years. 