Factors predicting repeat revision and outcome after aseptic revision total knee arthroplasty: results from the New Zealand Joint Registry.

PURPOSE

The number of Revision TKAs performed continues to increase; however there is limited data on risk factors for failure. Additionally, clinical decisions regarding when and how to revise a failed TKA may be as important as the technical aspects of the procedure. The purpose of this study was to analyze factors predicting repeat revision following aseptic revision TKA.

METHODS

Of 85,769 primary TKAs recorded on the New Zealand National Joint Registry, 1720 patients undergoing subsequent revision for aseptic indications between January 1999 and December 2015 were identified. Re-revision was recorded in 208 patients (12.1%). The analysis included demographic characteristics, surgeon revision case volume, surgical time, surgical ownership of index TKA as independent variables using logistic and linear regression. The primary outcome measure was incidence of subsequent re-revision and Oxford Knee Scores of revised TKAs (OKS). The secondary outcome measure was the influence of component exchange in major revisions on re-revision rate.

RESULTS

Younger patients undergoing a revision (HR 0.974) and male gender (HR 0.666) were predictors of re-revision. Elapsed time since index surgery (unstandardized coefficient 0.060) and lower ASA score (UC - 2.749) were significant predictors of OKS. Femoral component revision was a predictor of re-revision (HR 1.696) and had the lowest OKS, compared to tibial and all component revision (p = 0.003).

CONCLUSIONS

Repeat revision TKA is a rare and complex procedure influenced by a number of confounding factors. Using raw registry data, younger and male patients were found to be at a higher risk of re-revision after aseptic revision TKA. A longer time between primary TKA and revision was associated with better clinical outcomes. Isolated femoral component exchange led to worse outcomes both in terms of survivorship and functional scores.

LEVEL OF EVIDENCE

III.