Femoral Shaft Bowing Angle in The Coronal Plane Affects Distal Femoral Valgus Cutting Angle: A Radiographic Study

Postoperative limb alignment is important for successful total knee arthroplasty (TKA). Femoral shaft bowing angle (FBA) in coronal plane may influence distal femoral valgus cutting angle (DFVCA) and 5±2º may not perpendicular to mechanical axis.Methods: Sixty-six lower extremity long film x-ray of osteoarthritic knees were collected and analyzed with IntstaRISPACS (digital radiography software). The correlation and linear regression between FBA and DFVCAwere measured using SPSS 24.Results: Our study shows a strong correlation between FBA and DFVCA. Lateral FBA tends to present with DFVCA outside 7º as shown in linear regression test, vice versa.Conclusion: Since DFVCA is influenced by FBA, we recommend preoperative femoral x-ray in all knee replacement candidates.References:Rezende FC, Carneiro M. Is it safe the empirical distal femoral resection angle of 5° to 6°of valgus in the Brazilian geriatric population? Rev Bras Orthop. 2013; 48(5): 421-6.Kim CW, Lee CR. Effects of femoral lateral bowing on coronal alignment and component position after total knee arthroplasty: a comparison of conventional and navigation-assisted surgery. Knee Surg Relat Res. 2018 Mar; 30(1): 64–73.Kim JM, Hong SH, Kim JM, Lee BS, Kim DE, Kim KA, Bin et al. Femoral shaft bowing in the carinal plane has more significant effect on the coronal alignment of TKA than proximal or distal variations of femoral shape. Knee Surg Sports Traumatol Arthrosc. 2015;23(7):1936-42