title: Macroporous calcium phosphate ceramics for bone substitution: a tracer study on biodegradation with 45Ca tracer.
abstract: The value of artificial materials in bone replacement depends highly on their biocompatibility and biostability. Porous calcium phosphate ceramics have a good compatibility with natural bone. To study the biodegradation process of calcium phosphate bioceramics, labelled [45Ca]-beta-whitlockite and [45Ca]-hydroxyapatite were implanted in the femurs of dogs. The effects accompanying the ingrowth of new bone into the pores of these bioceramics and its replacement by natural bone were investigated. In vivo degradation of the implant material by biochemical dissolution processes was observed. The beta-whitlockite implants showed a conspicuous decrease in radioactive calcium, in contrast to the hydroxyapatite implants. 45Ca was absent in adjacent bones and locally newly formed bone in both beta-whitlockite and hydroxyapatite suggesting a restricted availability of the 45Ca liberated in these processes. Indications of minor mechanical degradation of the materials were also found; in the lymph nodes a very small amount of 45Ca with a high specific activity was detectable. Urine, blood or faeces contained no detectable amounts of 45Ca activity.
authors.affiliation: Department of Nuclear Medicine, Free University Hospital, Amsterdam, The Netherlands.
authors.forename: W
authors.initials: W
authors.lastname: den Hollander
authors.forename: P
authors.initials: P
authors.lastname: Patka
authors.forename: C P
authors.initials: CP
authors.lastname: Klein
authors.forename: G A
authors.initials: GA
authors.lastname: Heidendal
mesh_terms: D000818:Animals; D001672:Biocompatible Materials; D001673:Biodegradation, Environmental; D001842:Bone and Bones / Q000601:surgery*; D002130:Calcium Phosphates / Q000493:pharmacokinetics; D002132:Calcium Radioisotopes; D002516:Ceramics; D004285:Dogs; D005269:Femur / Q000601:surgery; D016348:Osseointegration; D019736:Prostheses and Implants
chemical_list: D001672:Biocompatible Materials; D002130:Calcium Phosphates; D002132:Calcium Radioisotopes; C485828:alpha-tricalcium phosphate; C485830:tetracalcium phosphate; C485838:calcium phosphate, monobasic, anhydrous; C020243:calcium phosphate; C485829:calcium phosphate, dibasic, anhydrous