The varus cemented femoral stem in total hip arthroplasty: Predictors, implications and The Femoral Access Ratio

Introduction We describe a novel morphological ratio, the Femoral Access Ratio, in the preoperative femur to investigate the predictors of femoral stem malalignment. Methods We reviewed 70 cemented femoral stems. Preoperative 'FAR' score was measured. Postoperative coronal stem alignment was measured and ten year survivorship and functional outcomes investigated. Results There were three predictors of varus stem malalignment-BMI, GT-height and 'FAR' score. Increasing BMI led to higher rates of malalignment (p = 0.048). 'FAR' score <1 lead to 68.4% of varus stems. GT height contributed most to the prediction of varus stem malalignment (p = 0.013). Conclusion FAR score is a simple preoperative radiographic measurement that can predict the likelihood of femoral stem varus malalignment in cemented femoral stems.