Abstract
At our institution, the FINE Total Knee System (FINE) (Nakashima Medical, Okayama, Japan) has been used since December 2001. The femoral component of FINE was designed to automatically reproduce the physiological joint line at an oblique angle of 3° in the posterior condyle. The articular surface of the tibial medial condyle was designed to show high conformity and to obtain an increased conformity rate to the femoral component, thereby leading to enhancement of tibial internal rotation, with stability in the early stage of flexion secured simultaneously. Conversely, the articular surface of the tibial lateral condyle was designed to allow femoral rollback, thereby allowing tibial internal rotation by medial pivot motion. Some possible reasons for these observations are that FINE was designed to allow tibial internal rotation at 25° to approximately 30° and to allow high conformity of the inside and rollback of the outside. The number of operations performed has increased at Toho University, and 1008 joints had been treated by September 2009. The results achieved reflect the medial pivot motion and the clinical performance that were part of the design concept. However, the most important factor is operational technique. For example, it is important to do soft tissue balancing and to perform correct osteotomy and implantation. The implant design requires millimeter accuracy in placement, and care is necessary to avoid the possibility that an error of 1 mm or 1 might invalidate the design concept.
