Increasing hydroxyapatite incorporation into poly(methylmethacrylate) cement increases osteoblast adhesion and response

Poly(methylmethacrylate) (PMMA) is the current standard for cement held pro stheses. It forms a strong bond with the implant, but the bond between the cement and the bone is considered to be weak, with fibroblastic cells obser ved at the implant site, rather than direct bone contact, a contributing fa ctor leading to implant failure. Incorporation of hydroxyapatite (HA) incre ases the biological response to the cement from tissue around the implant s ite, thus giving increased bone apposition, In this study, PMMA discs with 0, 4.6 and 8.8 vol%. HA were examined, Primary human osteoblast-like cells (HOBs) were used for the biological evaluation of the response to the cemen ts in vitro. Morphology was observed using scanning electron microscopy (SE M) and confocal laser scanning microscopy (CLSM). Measurement of tritiated thymidine (H-3-TdR) incorporation and alkaline phosphatase (ALP) activity w ere used to assess proliferation and differentiation. A synergy between inc reasing focal contact formation, cytoskeletal organisation, cell proliferat ion and expression of phenotype was observed with increasing HA volume. Pre ferential anchorage of HOBs to HA rather than PMMA was a prominent observat ion. (C) 2001 Elsevier Science Ltd. All rights reserved.