[A new total knee arthroplasty with physiologically shaped surfaces. Part 2: First clinical results]

Abstract

The human medial tibial plateau is concave, whereas the lateral tibial plateau is convex. In a normal knee, the convex femoral condyles roll and glide on the tibia during the standing phase of walking. The designs of most commercially available knee prostheses do not take this morphological feature into consideration. The novel design of the AEQUOS G1 knee replacement prosthesis is based on the natural anatomy of the knee joint, with a convex lateral tibia plateau and a sagittal offset of the medial and lateral compartments. Following extensive development and testing, initial clinical results of the AEQUOS G1 prosthesis in a mulitcenter study are presented. From Mai 2005 to March 2007, 158 patients in 4 clinics underwent total knee arthroplasty with the AEQUOS G1 and agreed to participate in the study. Patients were evaluated preoperatively and at 3, 6 and 12 months of follow-up using a standardized protocol that included the American Knee Society Score (AKSS), the Oxford Knee Score (OKS) and the Visual Analog Scale (VAS) for pain. After 3 months, 151 patients appeared for follow up appointments, after 6 months, 134, and after 12 months, 127. The mean range of motion preoperatively was 97.0 degrees (+/-19.9 degrees ) and 107.5 degrees (+/-15.9 degrees ) 12 months after surgery. The AKSS, as well as the modified OKS, significantly improved (p<0.0001) from preoperative scores of 98.8 (+/-35.8) and 37.3 (+/-6.9) points, respectively, to 165.8 (+/-34.1) and 21.9 (+/-7.8) points, preoperatively, and 12 months postoperatively. The VAS score significantly decreased (p<0.001) from 7.4 (+/-1.8) points preoperatively to 1.9 (+/-2.2) points 12 months postoperatively.One implant was revised because of arthrofibrosis and another due to patellar luxation. Two patients required revision because their implants revealed malalignement with ligamentous instability. No infections, aseptic loosening or other implant-specific complications were observed at this early follow-up. Good clinical results were observed at early follow-up with the AEQUOS G1 knee arthroplasty. However, longer follow-up is necessary for a general evaluation of the implant.