Nonstoichiometric hydroxyapatite granules for orthopaedic applications

Abstract

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.

Fast precipitation of uniform CaCO3 nanospheres and their transformation to hollow hydroxyapatite nanospheres

“…Recently, the strategy of localized delivery of growth factors or drugs has attracted more attention due to the effective regulation and acceleration of bone formation, and even the prevention of related bone infections [45]. Since then, HA has been developed into porous particles/spheres to serve as the carrier for localized delivery of growth factors or drugs [41,46]. Due to the high surface area, uniform size and light weight, the hollow HA spheres fabricated in this work could be more advantageous as drug carriers for bone repairing or skeletal disease treatment.…”

Polyelectrolyte mediated formation of hydroxyapatite microspheres of controlled size and hierarchical structure

“…[26,27]. Clinically, particulate products are most desirable as fillers or packing materials in specific cases (for example, as bone fillers after the excision of necrotic part) [28]. The biological properties of particulate products could be influenced by their physicochemical properties, including crystallinity, porosity, surface area, and the particle size.…”

Preparation of porous apatite granules from calcium phosphate cement

“…Well-crystallized CaP granules synthesized by Liu [18] had porosity from 24 to 75 vol.%, pore sizes from 100 to 400 lm, and granular sizes from 0.7 to 4 mm. The use of PVB, as the porogen, was also tested by Zyman et al [19] in forming porous granules. The complete burn off of PVB always necessitated high temperatures (\1,150°C).…”