Osteointegration of bioactive glass-coated and uncoated zirconia in osteopenic bone: An in vivo experimental study N. Nicoli Aldini, 1 M. Fini, 1 G. Giavaresi, 1 L. Martini, 1 B. Dubini, 2 M. G. Ponzi Bossi, 2 F. Rustichelli, 2 A. Krajewski, 3 A. Ravaglioli, 3 M. Mazzocchi, 3 R. Giardino 1 , 1 Experimental Surgery Department, Research Institute Codivilla Putti-Rizzoli Orthopaedic Institute, via di Barbiano 1/10, 40136, Bologna, Italy and Chair of Surgical Patophysiology, University of Bologna Medical School, Bologna, Italy 2 Institute of Physical Science, Universita ` Politecnica delle Marche, Ancona, Italy and National Institute for the Physics of the Matter (INFM), Unit of Ancona, Italy 3 Institute for Technological Research on Ceramics of Irtec-CNR, Faenza, Italy Received 10 February 2003; revised 20 June 2003; accepted 18 July 2003 Abstract: In elderly and osteoporotic patients an age-re- lated loss of osteoinductivity could be the biological cause of implant failure regardless of the high quality of the im- planted device. yttria stabilized tetragonal zirconia (YSTZ), either coated with the bioactive glass named RKKP bio- glaze (RKKP) or uncoated, was implanted in the distal femurs of sham-operated and ovariectomized female rats. Animals were sacrificed at 30 and 60 days. Histomorphom- etry and microhardness tests were performed to assess os- teointegration rate as well as bone quality around the im- plants. Significant decreases (p  0.0005) in trabecular bone volume, BV/TV (41%), trabecular bone surface BS/TV (33%), trabecular thickness Tb.Th (20%), and trabecular number Tb.N (32%), together with a significant increase in trabecular separation Tb.Sp (184%), were found for the os- teopenic rats compared with the sham-operated rats. At both experimental times the RKKP coating ensured a better osteointegration rate with higher AI values than the un- coated YSTZ, even when osteopenic rats were used (48% at 30 days and 12% at 60 days). No differences were observed at the bone-biomaterial interfaces for either material when comparing sham-operated with osteopenic rats. The present results demonstrate that the RKKP bioactive glass used as a coating ensures a high osteointegration rate even in osteo- porotic bone, which is already visible from postoperative day 30 and is still apparent on day 60. © 2003 Wiley Peri- odicals, Inc. J Biomed Mater Res 68A: 264 –272, 2004 Key words: osteoporosis; zirconia; bioactive glass; osteointe- gration; animal model INTRODUCTION Tissue replacement and regeneration strictly de- pend on the osteopromotive properties of biomateri- als, which contribute to endogenous tissue healing and biological fixation to the implant surface. The biocompatibility, design, surface structure, mechani- cal properties, and bioactivity as well as osteoinduc- tive and osteoconductive properties of orthopaedic prosthetic devices are of paramount importance for the early and late outcome of implantation surgery. However, it should be borne in mind that average life expectancy is now 80 years, and this increase in survivability means that many people outlive the quality of their connective tissue. 1 Consequently, an age-dependent loss of osteoinductivity due to the loss of bone morphogenetic properties and other bioactive factors as well as to a decrease in the mesenchymal stem cells present in bone could be the biological cause of implant failure irrespectively of the high quality of the implanted device. 2–5 Osteoporosis is a bone disease affecting a wide part of the ageing population, mainly postmenopausal women, although it is diagnosed in men with increas- ing frequency. 6,7 The number of osteoporotic women in the United States is estimated to be about 20 mil- lion. 8,9 Osteoporosis-related bone fractures are known to mainly involve the hip, vertebral column, and fore- arm. 10,11 Surgical treatment often requires the use of prosthetic and fixation devices, which are therefore implanted in a host bone of poor quality where circu- lation and metabolism are compromised by the osteo- porotic disease, ageing, or pharmaceutical therapies. In previous studies 12–14 the behaviour of yttria sta- Correspondence to: R. Giardino; e-mail: roberto.giardino@ ior.it Contract grant Sponsor: Progetto Finalizzato “Materiali Speciali per Tecnologie Avanzate II”. Contract grant sponsor: Rizzoli Orthopaedic Institute grants (Ricerca Corrente) © 2003 Wiley Periodicals, Inc.