Prospective study of the cementless "New Wave" total knee mobile-bearing arthroplasty: 8-year follow-up.

One of the main factors affecting the survival of a total knee arthroplasty (TKA) is the fixation method. The constraints placed on the bone-implant interface of a mobile-bearing TKA must be taken in account during the design and evaluation phases. For more than two decades, calcium phosphate ceramics, particularly hydroxyapatitis, have been used in Europe to accelerate the bone integration of cementless implants. A prospective study of patients continuously recruited by three senior surgeons at three French private hospitals has been carried out. There were no exclusion criteria. Eighty-four (84) cementless mobile-bearing total knee prosthesis of the brand "New Wave" were implanted in 74 patients over a 2-year period (2004-2005). Implant survival at 8 years was 95% [with a confidence interval of 95%: 80.2-96.4%] when revision for any cause was defined as the endpoint. Five implants required surgical revision to exchange all or part of the implant: two for aseptic loosening of tibial component, one for osteolysis, one for persistent flessum (30°) and one for tibial periprosthetic fracture. Completely integrated implants and event-free outcomes were recorded in 91.4% of the cases at eight-year follow-up. The Hospital for Special Surgery score significantly improved from 56.8/100 points before the surgery to 83.9/100 points at the last follow-up (p < 0.05). Radiologically, only one patient had radiolucent lines around the tibial and femoral components. This cementless total knee prosthesis yielded good medium-term survival. Cementless arthroplasty can generate solid and durable bone fixation in this total weight-bearing implant, and it seems that the hidroxyapathitis surface in this series stimulate the bone integration at the bone-implant interface.