Duo-condylar knee arthroplasty: hospital for special surgery design.

This is a report of 94 knees in 88 patients with the duo-condylar type of knee arthroplasty. The follow-up period of time was between 2 to 4 years with an average of 3 years. The rheumatoid to osteoarthritic patient ratio was 3 to 1. The overall results were excellent in 37.5 per cent, good in 37.5 per cent, fair in 16 per cent, and poor in 9 per cent. The main causes of failure and poor results were: (1) under or over correction of deformity leading to subluxation and/or instability of the knee; (2) loosening of the tibial component, and (3) symptoms arising from the patellofemoral joint. The revision rate is 5.5 per cent. The progressive radiolucency at the cement bone bond is 26 per cent of which 16 per cent is up to 1 mm and 10 per cent is between 1.5 to 3 mm. To further improve the results of arthroplasty, one should take into consideration (1) replacement of the patellofemoral joint, (2) insertion of the prosthesis in the proper anatomical location under correct tension of the ligaments and capsule with the help of proper instrumentation and (3) improvement in fixation of the tibial component.