Is it Safe to Use a Six-Degree Distal Femoral Valgus Cut in All Genu Varus Patients with Total Knee Arthroplasty?

Background: During a total knee arthroplasty, it is common to make a distal femoral cut based on the femoral mechanical-anatomical angle (FMA), which in most patients is six degrees. However, in patients with a higher FMA, there is not yet a consensus between surgeons regarding the degree of the cutting angle. Objectives: The aim of this study is to assess the treatment outcomes of patients with a FMA of more than seven degrees who were treated by distal femoral cuts of six degrees during a total knee arthroplasty. Methods: We retrospectively reviewed the clinical and radiological results of patients who were treated at our center by a conventional valgus cut of six degrees during a total knee arthroplasty and had a FMA of more than seven degrees. A knee society score (KSS) was completed for all patients during follow-up visits. Results: A total of 31 cases with knee osteoarthritis and a FMA of more than seven degrees were enrolled in this study. The cases consisted of 8 men and 23 women with an average age of 65.41 (range 46 - 77 years) (SD ± 7.61) years and a mean follow-up time of 11.51 months (range 3 - 24 months) (SD ± 6.08). The mean KSS was 148.51 (SD ± 7.43), (range 132 to 167), which is considered good. There was a statistically significant relationship between the lateral distal femoral angle (LDFA) and FMA. However, there was not a statistically significant correlation between LDFA and KSS. Conclusions: Although the overall alignment of the lower extremity in our patients was in varus, this amount of varus does not prove to have an effect on the outcome.