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

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.
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.
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.
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.
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.