The present study was designed to evaluate the long-term results (more than 10 years) of mobile bearing total knee arthroplasty (TKA) and to compare the survival of medial pivot axis (MPA) and central pivot axis (CPA) TKAs. The primary hypothesis was that the 10- to 15-year survival rate of MPA TKAs will be better than CPA TKAs.
A national, multicenter, retrospective study was performed in France. In this case-control design, 1154 TKAs were paired into the CPA group (control group: 577 cases) and MPA group (study group: 577 cases) based on a logistic regression analysis of age, gender, body mass index and severity of the coronal deformity, defining the propensity score for each case. Final survival information follow-up was obtained for 946 cases (82%).
There was no significant difference between the control and study groups for any baseline data. Twenty-two prosthetic revisions (2%) were performed for mechanical reasons during the follow-up period. There was no significant difference between the 13-year survival rates of CPA (98%) and MPA (97%) TKAs. There was no significant difference between groups in their final Oxford and Knee Society scores.
Level III.
Our findings do not support the assumption that medialization of the pivot axis of a mobile bearing TKA improves clinical results or survival.