The aim of this study to evaluate whether the position of the sagittal patellar offset is a predictive factor for anterior knee pain in subjects having undergone bilateral multiradius total knee replacement.

A prospective, observational study. A total of to 80 subjects requiring bilateral multiradius 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"[1]. Sagittal patellar offset defined 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:

• Patients over 50 years of age with primary severe gonarthrosis who will undergo total knee replacement

Exclusion Criteria:

• Patients with severe gonarthrosis, with a history of malignancy, with severe extraarticular deformity, with posttraumatic and septic arthritis sequel

Patients undergoing total knee arthroplasty due to severe gonarthrosis