Femoral component malrotation is not correlated with poor clinical outcomes after total knee arthroplasty

PURPOSE: Proper rotational alignment of the femoral component is critical for a successful total knee arthroplasty (TKA). The aim of this systematic review was to analyse the available literature to examine the effect of the TKA femoral component malrotation on clinical outcomes and assess a cut-off value for femoral rotation leading to revision surgery. METHODS: A detailed and systematic search from 1996 to 2019 of the PUBMED, Medline, Cochrane Reviews and Google Scholar databases had been performed using the keyword terms "total knee arthroplasty OR replacement" AND "femoral alignment OR malalignment OR femoral rotation OR malrotation" AND "clinical outcome". We used the methodological index for non-randomized studies (MINORS) to identify scientifically sound articles in a reproducible format. RESULTS: Eleven articles met inclusion criteria. A total of 896 arthroplasties were included in this review; 409 were unexplained painful TKA patients, while 487 were painless TKA patients. The mean age of patients was 67.5 (± 2.1) years. The mean post-operative follow-up delay was 46.8 (± 32.2) months. The mean of MINORS score was 21 points indicating good methodological quality in the included studies. CONCLUSIONS: The present review confirms that the malrotation of the femoral component in TKA does not correlate automatically to poor clinical and functional outcome. The clinical relevance of this study was that, to improve accuracy in femoral component rotation, surgeons should consider the anatomical variability of femur in each knee and perform additional measurements pre- and intra-operatively. Taking a more accurate approach will shed light on unanswered questions in unhappy TKA. LEVEL OF EVIDENCE: III.