title: In vivo histologic and biomechanical characterization of a biodegradable particulate composite bone cement.
abstract: A biodegradable particulate composite bone cement consisting of a crosslinked gelatin matrix and tricalcium phosphate particles was implanted intraosseously in rabbits for up to 12 weeks. Cured cylindrical implants were inserted in holes drilled in the proximal tibial metaphysis. Sequential fluorochrome labeling and radiographs were done, and specimens were processed for decalcified and nondecalcified histology. At 4 weeks, the cross-sectional diameter of the implant was slightly greater than at implantation. There was considerable dissolution of the matrix and some new bone ingrowth. At 12 weeks, the diameter was reduced to half the original diameter and bone had grown throughout the matrix. In the distal femur, freshly mixed cement was used to stabilize an osteochondral fracture. Mechanical testing of the cement-stabilized fracture revealed a decrease in compressive strength and modulus at 4 weeks followed by an increase to greater than initial values at 12 weeks. Over time, the osteochondral fragment subsided into the underlying cement, but the subsidence did not correlate with mechanical strength. This osteochondral fracture model permits measurement of the overall material properties of a cement simultaneously weakened by resorption and reinforced by ingrowing bone.
authors.affiliation: Department of Orthopaedic Surgery, Charles A. Dana Research Institute, Beth Israel Hospital, Harvard Medical School, Boston, Massachusetts 02215.
authors.forename: T N
authors.initials: TN
authors.lastname: Gerhart
authors.forename: A A
authors.initials: AA
authors.lastname: Renshaw
authors.forename: R L
authors.initials: RL
authors.lastname: Miller
authors.forename: R J
authors.initials: RJ
authors.lastname: Noecker
authors.forename: W C
authors.initials: WC
authors.lastname: Hayes
mesh_terms: D000818:Animals; D001672:Biocompatible Materials; D001673:Biodegradation, Environmental; D001843:Bone Cements; D001842:Bone and Bones / Q000000981:diagnostic imaging / Q000473:pathology; D002130:Calcium Phosphates; D002358:Cartilage, Articular / Q000000981:diagnostic imaging / Q000473:pathology; D005269:Femur; D005780:Gelatin; D008297:Male; D011817:Rabbits; D011859:Radiography; D013977:Tibia
chemical_list: D001672:Biocompatible Materials; D001843:Bone Cements; D002130:Calcium Phosphates; C485828:alpha-tricalcium phosphate; C485830:tetracalcium phosphate; C485838:calcium phosphate, monobasic, anhydrous; D005780:Gelatin; C020243:calcium phosphate; C485829:calcium phosphate, dibasic, anhydrous