Abstract
Background
The knowledge about the common mode of failure and each period in primary and revision TKAs offers useful information to prevent those kinds of failure in each surgery. However, there has been limited report that simultaneously compared the mode of failure between primary and revision TKAs using single prosthesis.
We compared the survival rate, mode of failure, and periods of each mode of failure between primary and revision TKAs.
Methods
A consecutive cohort of 1606 knees (1174 patients) of primary TKA and 258 knees (224 patients) of revision TKA using P.F.C® prosthesis was retrospectively reviewed. The mean follow-up periods of primary and revision TKAs were 10.2 and 10.8 years, respectively. We compared the above variables between primary and revision TKAs.
Results
The average 5-, 10-, 15-year survivor rate of primary TKA were 99.1% (CI 95%, ±0.3%), 96.7% (CI 95%, ±0.7%), and 85.4% (CI 95%, ±2.0%). They were 97.8% (CI 95%, ±1.0%), 91.4% (CI 95%, ±2.5%), and 80.5% (CI 95%, ±4.5%) in revision TKA. The common mode of failure included polyethylene wear, loosening, and infection in both primary and revision TKAs. The most common mode of failure was polyethylene wear in primary TKAs and infection in revision TKAs. The mean periods of polyethylene wear and loosening were not significantly different between primary and revision TKAs, but the mean period of infection was significantly long in revision TKA (4.8 years vs. 1.2 years, p=0.003).
Conclusions
The survival rate decreased with time, especially after 10 years in both primary and revision TKAs. The continuous efforts are required to prevent and detect various modes of failure during the long-term follow-up after primary and revision TKAs. More careful attention is necessary to detect the late infection as a mode of failure after revision TKA.
Level of Evidence
Level III, Therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.
