Porous HA ceramic for bone replacement: role of the pores and interconnections - experimental study in the rabbit.

Hydroxyapatite (HA) porous ceramics are increasingly used in biomedical applications. Their physical characteristics, such as porous volume, require perfect control of the pore shape, as well as the number and the size of their interconnections. The aim of our study was to evaluate a new HA ceramic using polymethylmethacrylate microbeads (PMMA) as the porous agent.

Relationship between bioceramics sintering and micro-particles-induced cellular damages.

We performed experimental studies to confirm the hypothesis that cellular damages occurring around implanted biphasic bioceramics could be related to a micro-particles release because of an insufficient sintering. First, an in vitro cytotoxicity study was performed on four biphasic ceramic (BCP) samples. Without treatment of the extraction medium, a cytotoxicity was observed, although after centrifugation this cytotoxicity disappeared in all samples.

Gene expression in human osteoblastic cells from normal and heterotopic ossification.

Heterotopic ossification (HO), a possible complication of head injury, develops in sites where it is not normally present like at the vicinity of joints. It may cause pain, decrease motion and in severe cases complete joint ankylosis requiring surgical intervention. To our knowledge, no study has been made to analyze HO at the molecular level on human biopsies, whereas its etiology remains to be determined.

Association of porous hydroxyapatite and bone marrow cells for bone regeneration.

The preparation of hybrid material with osteoinductive capacity may be achieved by association of cultured autologous bone cells with a porous ceramic vehicle. We optimized culture conditions for rabbit marrow stromal stem cells (MSCs), notably by selection from batches of fetal calf serum. Rabbit MSCs formed colony-forming unit-ribroblastic (CFU-Fs) in vitro.

Volume effect on biological properties of a calcium phosphate hydraulic cement: experimental study in sheep.

Injectable calcium phosphate hydraulic cements (CPHC) are a new family of bone substitutes within the class of bone reconstruction biomaterials. In this work, CPHC were tested in two consistencies (preset blocks or liquid paste) in an experimental model of cancellous bone defect in sheep. The defects were eight times larger than those investigated previously in rabbits.

Experimental model of posterolateral spinal arthrodesis in sheep. Part 2. Application of the model: evaluation of vertebral fusion obtained with coral (Porites) or with a biphasic ceramic (Triosite).

Objectives: The authors evaluated two bone substitutes in a posterolateral spinal arthrodesis (PSA) model in sheep: coral porites (99% calcium carbonate, Biocoral, Inoteb, France) and a biphasic ceramic (BCP) (65% hydroxyapatite and 35% B tricalcium phosphate, Triosite, Zimmer International).

Summary Of Background Data: Bone substitutes would be of great interest for PSA. Previous trials began with two kinds of biomaterials: natural coralline calcium carbonate, and phosphate calcium ceramic.

Experimental model of posterolateral spinal arthrodesis in sheep. Part 1. Experimental procedures and results with autologous bone graft.

Objectives: The authors evaluated the reliability in obtaining a posterolateral spinal arthrodesis (PSA) with autologous bone graft.

Summary Of Background Data: Posterolateral spinal arthrodesis using autogenous cancellous bone graft is the most simple and efficient technique to get a spinal graft. No extensive biomechanical study of PSA is available.

Effects of the calcium channel blocker nifedipine on epiphyseal growth plate and bone turnover: a study in rabbit.

The potential effects of a calcium channel blocker (nifedipine) on epiphyseal growth plate and bone remodeling have been investigated in growing rabbits. The treated group received 6 mg/kg/day nifedipine twice daily by gavage for 10 weeks. An untreated group was used as control; with this dose, neither toxic effects nor decrease in the body weight have been observed.

[Effect of a calcium inhibitor, verapamil, on the development of heterotopic ossifications. An experimental study in rats].

After division of the tendo achilles in rats heterotopic bone forms in the muscle and in the tendon stumps. Tenotomy was performed in 26 male rats. Thirteen received Verapamil (36 mm/Kg) for six days per week for five months, and the remainder were not given this drug.