Abstract: A method for the preparation of a carbonated hydroxyapatite composition which has a density of at least 95% of the theoretical density, which method comprises sintering at substantially atmosphere pressure a green carbonated hydroxyapatite composition containing up to 20% by weight of CO.sub.3.sup.2- ions and having a green density of from 25 to 60% of the theoretical density at a temperature in the range of from 750.degree. to 1450.degree. C. in carbon dioxide containing from 0.001 to 0.10 grams of water per liter of gas, the sintering temperature being selected within the above range and the green composition being sintered for a period of time sufficient to cause the green composition to densify to at least 95% of the theoretical density.

Abstract: A composite of a homo- or co-polyolefin having an average molecular weight greater than 100,000 with from 30 to 50% by volume of a particulate inorganic solid for use in endoprosthesis.

Abstract: A passively extensible long bone component in an endoprosthetic bone joint device for a child includes two parts, of which one (10,20) has a bearing portion (22) to serve the articulatory function at one end of the bone, a seat portion (11) to engage the bone one end proximally of the growth plate therein and a stem (21) to pass longitudinally into the bone, and of which the other part (30) is a generally tubular socket adapted to receive the stem in sliding engagement and for securement with the bone distally of the growth plate. The bearing part can be cushioned against shock, at least partially separable, and extend as a further socket between the first socket and the stem. The component can allow rotation of the bearing and stem about the bone long axis or inhibit such rotation.