A retrospective study on the radiographic evaluation of the tibial component alignment in total knee arthroplasty and its postoperative significance

Abstract

BACKGROUND: The goal of tibial component positioning in total knee arthroplasty is to achieve neutral tibial alignment. Malalignment of the tibial component alters the distribution of tibial loading, resulting in increased wear. The purpose of this study was to correlate two radiological parameters (mechanical and anatomical axis) of the tibial component in total knee arthroplasty with patient related outcome measures at 5 years.

METHOD: 91 primary total knee arthroplasties were considered in this study. Tibial component alignment was assessed using post op radiographs. All x-rays were taken immediately post operatively. The Oxford Knee Score was used to quantify the patient’s pain and function following the total knee arthroplasty. Patient follow up at Orthopaedic outpatients and date of discharge were also considered. The radiographic outcome was then correlated with the patient reported outcome over 5 years. Correlation was measured using either the parametric Pearson correlation coefficient (testing for a linear correlation) and its non-parametric counterpart; the Spearman’s rank correlation coefficient.

RESULTS: There is a very weak correlation between the Oxford Knee Score and the varus angle of deviation. The correlation is stronger in the valgus position, but still not statistically significant. There is also a weak negative correlation between the angle of deviation and the number of follow ups at Orthopaedic outpatients.

CONCLUSION: From our study, we can conclude that an angle of deviation of £ 6o in both varus and valgus did not have a negative prognostic effect on patient outcome.