Nonstoichiometric hydroxyapatite granules for orthopaedic applications.

A new method for the preparation of nonstoichiometric hydroxyapatite (HA) "dense" and porous granules, round in form and up to 8 mm in sizes designed for application in orthopaedic surgery has been developed. The "dense" granules' porosity was up to 32% and they only contained micropores. They differed from that kind of granules by increased values of compression strength (up to 48 MPa). The porous granules contained a system of interconnected micro- and macropores. The porosity value (up to 70%) and the porosity structure were similar to those in the mineral framework of a spongy bone. The compression strength of the porous granules (up to 25 MPa) was high enough for various kinds of application. Granules of both sorts were used in performing 42 operations on the locomotor system. Depending upon localization and supposed level of the injured area loading, "dense" or porous granules were used. The postoperative observations (up to four years in length) have attested to the high quality of the granules.