Abstract
Purpose: Despite excellent histological and biomechanical results proving the real efficacy of “biological” implant-bone fixation, use of hydroxyapatite surfacing, widely used for hip implants, remains largely unemployed for knee prostheses. We analysed our ten years experience with hydroxyapatite coated knee implants in a prospective study of 384 cases.
Material and methods: Among the 384 prostheses, 361 were primary implantations, and 331 (92%) were still “in place” after ten years experience. Nineteen patients had died and only one (0.3%) was lost to follow-up; three patients were excluded from the analysis due to other major handicaps. There were five revision procedures including three (0.8%) related to deep infection and two (0.6%) to failure with loosening and pain. Mean age of the patients was 70.4 years (40–89). Indications were basically degenerative disease (91%), inflammatory rheumatoid disease (6.9%) and necrosis (1.7%).
Results: Mean IKS score at five years minimal follow-up for primary surgery patients was 95.4 and 84.2 points for the overall knee score and the functional score respectively, giving 81.1% and 73.1% good and excellent results for the knee and functional score.
Discussion: These clinical results compare well with the best studies reported on total knee arthroplasty with or without cement. Radiographically, we did not have any cases with evidence of an implant-bone interface problem, for femoral or tibial components with the exception of two knees (0.55%) with severe osteolysis and loosening leading to revision surgery. In addition, hydroxyapatite demonstrated its capacity to progressively fill bone-implant gaps over time, confirming the experimental work by Søballe. Cumulative survival was 96.6±0.0688% and 97.37 ± 0.0324% taking ablation and prosthesis-related failure as the endpoint respectively.
Conclusion: These results allow renewed confidence in hydroxyapatite as a prosthesis fixation mode, for the knee as well as for the hip.
The abstracts were prepared by Pr. Jean-Pierre Courpied (General Secretary). Correspondence should be addressed to him at SOFCOT, 56 rue Boissonade, 75014 Paris, France
