Is conventional knee radiograph reliable enough to assess the anatomical knee alignment and total knee prosthesis position in Indian population?

Background: The success and survivorship of primary total knee replacement mainly depend on the postoperative alignment and implant position. Long-leg radiograph (LLR) is considered gold standard in assessing knee alignment postoperatively. Studies have reported that bowing of the femoral shaft in the coronal plane is prevalent in Asian population, which is not fully visualized on a conventional knee radiograph (CKR) and may affect the assessment of coronal alignment. However, postoperatively, CKR is easy to perform and has several advantages if it provides similar precision. Purpose: The purpose was to evaluate the validity of CKR in assessing the anatomical knee alignment and prosthesis position as compared with the LLR in Indian population. Materials and Methods: One hundred knees in 83 patients were subjected to CKR and LLR during postoperative follow-up at 6 weeks. Three parameters were evaluated to assess the coronal alignment and the component positions - femoral component angle (FCA), tibial component angle (TCA), and tibiofemoral angle (TFA). Results: There was an excellent correlation between the TCA as measured from the long and CKRs (r = 0.884, P = 0.01). There was a high positive correlation between the FCA (r = 0.703, P = 0.01) and TFA (r = 0.754, P = 0.01) as measured from the long radiographs and the conventional radiographs. Regression analysis defined these relationships to be linear. Conclusion: CKR could be an appropriate alternative for the LLR in evaluating the postoperative knee alignment and total knee prosthesis position despite the fact that there is excessive femoral bowing in Indian population.