Fixed-bearing total knee arthroplasty (TKA) implants have excellent long-term survival. Mobile-bearing implants were developed to reduce bone-implant interface stresses and polyethylene insert wear. The primary objective of this study was to analyze the survival rate of a highly congruent mobile-bearing TKA implant (Ceragyr(®)) in patients having a minimum follow-up of 7 years. We hypothesized that the survival rate would be 95-100% at that time point.
A single-center prospective study included all the patients operated for a primary TKA procedure with a Ceragyr(®) implant between 2000 and 2003. All the implants were cemented. Patellar resurfacing was not carried out systematically, but could be carried out secondarily in cases of persistent anterior knee pain. Clinical and radiological data were collected before the surgery, at 3 months postoperative, at 1 year and then at a minimum follow-up of 7 years. The primary endpoint was the overall revision-free survival rate. Secondary endpoints were the survival without mechanical failure, IKS scores, knee range of motion and implant positioning.
One hundred and thirty-four patients (143 Ceragyr(®) TKA cases) were included; 9 patients (10 TKA) were lost to follow-up (6.7%) and the remaining 125 patients (133 TKA) were contacted. At the final review, 7 of the 133 TKA cases (5.3%) had been revised (6 men, 1 women; P = 0.002), 2 (1.5%) because of mechanical failure and 5 (3.8%) because of an infection. The overall revision-free survival rate was 94.8% [95% CI: 89.3-97.5]; survival was 98.4% [95% CI: 93.8-99.6] with mechanical failure as an endpoint. An in-person assessment was conducted on 76 patients (80 TKA cases) (49 women; 27 men) who had an average age of 70.3 ± 8.4 years at the time of the arthroplasty procedure. The patella had been resurfaced during the initial procedure in 49 cases, and was either not resurfaced or secondarily resurfaced in 31 cases. The average follow-up was 8.7 ± 1.1 years. The IKS score had significantly improved relative to the preoperative values (P < 0.00001). Knee flexion and the IKS knee score remained stable over time (P > 0.05). Patients who underwent patella resurfacing during the initial TKA procedure had better clinical results (P = 0.03).
After a minimum follow-up of 7years, the overall revision-free survival rate for the Ceragyr(®) was 94.8%; the survival was 98.4% with mechanical failure as an endpoint. The results were stable over time.