Total knee arthroplasty has been increasingly used for young and active patients, and prosthesis durability is important in these patients. The accuracy of implant placement has been one of the major factors that determine the long-term survival of the prosthesis. The purpose of this study was to compare the accuracy of prosthetic alignment between computer-assisted-navigation and conventional total knee arthroplasties.
From March 2007 to June 2008, thirty-two patients with bilateral knee osteoarthritis underwent simultaneous bilateral total knee arthroplasty with the same type of implant in each knee. The subjects included seven men and twenty-five women, with an average age of sixty-three years. For each patient, the bilateral total knee arthroplasty was performed with computer-assisted navigation in one knee and a conventional technique in the other. The operative technique and the order of the surgical procedures were randomized. The patients and surgeons conducting the follow-up study and performing the imaging measurements were blinded to the type of surgical procedure.
There was a significant difference between the two groups with regard to the alignment of the knee prosthesis in the coronal and sagittal planes. Nine knee implants (28%) in the conventional group, compared with no knee implants in the computer-navigation group, deviated >3° from the mechanical axis in the coronal plane. The coefficient variation of data in the conventional group was three times greater than that in the computer-navigation group. There was no significant difference in the rotational angle of the femoral component between the two groups. The Hospital for Special Surgery (HSS) scores at six months postoperatively were substantially increased compared with the preoperative scores in both groups.
Computer-assisted navigation consistently provided coronal plane alignment within 3° of the mechanical axis, which was significantly better than the alignment obtained with conventional total knee arthroplasty.