title: Osseo-mechanical induction of extra-cortical plates with reference to their surface properties and geometric designs.
abstract: The purpose of this investigation was to determine which geometric and surface properties encouraged optimal ingrowth and bonding of bone to an extra-cortical plate. Forty-eight titanium extra-cortical plates were attached onto the left and right femora of adult rabbits. The plates were of six different designs and the osseoconductive effects of four surfaces were examined. A roughened titanium surface, a plasma sprayed HA coating of low crystallinity (57%) and a solution precipitated calcium phosphate coating were compared with a plasma sprayed crystalline hydroxyapatite coating (crystallinity 85%). Thin sections were prepared by grinding and polishing. Bone formation and the interface around the plates were investigated histologically and computer and morphometric analyses were used to quantify new bone formation, bone apposition onto the plate, bone porosity and the condition of the HA coating. The study found that a hydroxyapatite coating (with the exception of the solution precipitated coating) had significantly greater interfacial contact with bone when compared to a roughened titanium surface, and that significantly more bone attached to a crystalline HA coating compared with the HA coating of lower crystallinity although significantly more bone formed in the vicinity of the lower crystalline HA coating. Differences in the bony reaction induced by the various geometric designs were evident and the optimal plate design requires either holes or slots along its length as this encouraged bone ingrowth into the plate.
authors.affiliation: Centre for Biomedical Engineering, University College London, Royal National Orthopaedic Hospital Trust, Stanmore, UK.
authors.forename: M J
authors.initials: MJ
authors.lastname: Coathup
authors.forename: P
authors.initials: P
authors.lastname: Bates
authors.forename: P
authors.initials: P
authors.lastname: Cool
authors.forename: P S
authors.initials: PS
authors.lastname: Walker
authors.forename: N
authors.initials: N
authors.lastname: Blumenthal
authors.forename: J P
authors.initials: JP
authors.lastname: Cobb
authors.forename: G W
authors.initials: GW
authors.lastname: Blunn
mesh_terms: D000818:Animals; D001672:Biocompatible Materials; D001696:Biomechanical Phenomena; D001860:Bone Plates; D002130:Calcium Phosphates; D020099:Coated Materials, Biocompatible; D003460:Crystallization; D017886:Durapatite / Q000737:chemistry / Q000302:isolation & purification; D005269:Femur / Q000033:anatomy & histology / Q000601:surgery; D008422:Materials Testing; D016348:Osseointegration; D011474:Prosthesis Design; D011475:Prosthesis Failure; D011817:Rabbits; D013499:Surface Properties; D014025:Titanium
chemical_list: D001672:Biocompatible Materials; D002130:Calcium Phosphates; D020099:Coated Materials, Biocompatible; C485828:alpha-tricalcium phosphate; C485830:tetracalcium phosphate; C485838:calcium phosphate, monobasic, anhydrous; D017886:Durapatite; C020243:calcium phosphate; D014025:Titanium; C485829:calcium phosphate, dibasic, anhydrous