Effect of femoro-tibial component size mismatch on outcome in primary total knee replacement.

BACKGROUND: Most total knee arthroplasty systems allow a degree of femoro-tibial component size mismatch. We aim to investigate the influence of size mismatch on outcome after primary total knee arthroplasty.

METHODS: We reviewed 332 patients with cruciate-retaining Genesis II total knee arthroplasty with regard to femoro-tibial component size mismatch and Oxford Knee Score (OKS). We evaluated effects of Body Mass Index, gender and patellar procedure. Minimum follow-up is five years. We divided patients into four groups (tibial component larger than femoral component, no mismatch, femoral component one size larger and femoral component two sizes larger than tibial component).

RESULTS: There was no statistically significant difference in OKS between the four groups. Size mismatch did not have a statistical significant effect on OKS in a multivariate analysis. Women had mismatched components in 66% of all cases and men in 40% of all cases.

CONCLUSIONS: Our study showed no statistically significant effect of femoro-tibial size mismatch on outcome after total knee replacement. Compared to men, women tend to have more component size mismatch.

LEVEL OF EVIDENCE: Level III, retrospective comparative study.