The Investigators would like to compare multiradius and single-radius total knee arthroplasty using with association between sagittal patellar offset and anterior knee pain in subjects having undergone bilateral total knee replacement.

A prospective, interventional study. A total of to 494 subjects requiring bilateral multiradius( n=247) and singlerasius(n=247) knee arthroplasty will be enrolled. Anterior femoral offset, femoral diameter and patellar offset will be measured by orthopaedic surgeons. In addition, Visual Analogue Scale Score, Oxford Knee Score, WOMAC, SF12 and SF36 will be evaluated postoperative in patients long-term follow up to see if there is a relationship between anterior femoral offset and anterior knee pain. In the direct lateral knee joint radiograph, the distance between the two parallel axis extending from both cortices of the femur is measured as "femoral diameter".The remaining length between the anterior axis and the maximum peak at the anterior of the prosthesis is considered as an "anterior femoral offset". Sagittal patellar offset is accepted by us as the ratio of the anterior femoral offset to the remaining distance between the maximum anterior point of the patella and the posterior vertex in the direct lateral knee joint radiography.

Inclusion Criteria:

• Clinical and radiological diagnosis of end-stage primary gonarthrosis

Exclusion Criteria:

• History of malignancy,
• Severe extraarticular deformity,
• Posttraumatic and septic arthritis sequel