Hydroxyapatite (HA) has been applied to joint prostheses as a bioactive coating to prolong their durability. However, HA benefits for cup survival in total hip arthroplasty (THA) remain controversial. In this study, we compared the survival of cups with and without HA coating during a minimum follow-up of 18 years.
In total, 183 THA cases in 163 patients were analyzed, including 73 cups with HA coating (HA+ group) and 110 without HA coating (HA− group); otherwise, the cups had identical titanium-sprayed rough surfaces and were fixed with screws. In both groups, the same conventional polyethylene liners were applied. Zirconia and alumina ceramic heads were used in the HA+ and HA− groups, respectively. We retrospectively analyzed cup survival based on cup revision for any reason or aseptic loosening as end points.
In total, 7 and 8 revisions were performed in the HA− and HA+ groups with survival rates of 86.3% and 90.1%, respectively. Among them, 3 cups in the HA− group and 1 cup in the HA+ group were revised for aseptic loosening in 20 years (survival rates 94.1% and 98.7%, respectively). No significant difference was detected in cup survival rates between the groups based on both end points. There were no stem revisions during the observation period.
The results suggested that HA coating did not have either beneficial or adverse effects on the long-term cup survival in primary cementless THA.