Characteristics and Problems of Whiteside Ortholoc Total Knee Arthroplasty System—Especially Polyethylene Wear—

Abstract

The Whiteside Ortholoc total knee arthroplasty (TKA) system was the first in the world to adopt the intramedullary instrumentation system and slotted cutting guides for the exact valgus setting angle. In our department, the Whiteside Ortholoc II TKA system was introduced in 1988, making possible minimum resection of both femoral and tibial bones, and achieving rigid fixation between the metal and bone surface, in Japanese patients. The purpose of this study was to define the characteristics and problems of the Whiteside Ortholoc TKA system by clinical evaluation and outcome. In particular, polyethylene (PE) wear problems have been arising several years after TKA, leading to severe difficulties for TKA patients. Therefore, in this study we particularly focused on the problem of PE wear. On X-ray findings, femorotibial angle, femoroprosthesis angle (FPA), tibioprosthesis angle (TPA), lateral FPA, and lateral TPA were set exactly by the intramedullary instrumentation and slotted cutting guide system at primary TKA. It is suggested that the Whiteside Ortholoc TKA system had achieved rigid fixation of the tibial base with four cortex bone screws, six peripheral pegs, and the center stem. The most common complication was PE tibial insert wear, occurring only in osteoarthritic knees. In particular, nine revision PE cases (9/10) were osteoarthritis patients under 65 years old, and 8 mm PE as thickness was used in 8 osteoarthritic knees. These results suggested that special clinical attention must be paid to osteoarthritic TKA cases under 65 years old with 8- or 10-mm thick PE tibial inserts.