title: Bone formation and resorption in patients after implantation of beta-tricalcium phosphate blocks with 60% and 75% porosity in opening-wedge high tibial osteotomy.
abstract: Most of the implanted porous beta-tricalcium phosphate (beta-TCP) can be resorbed. However, beta-TCP block with 75% porosity is inadequate for weight-bearing sites until bone incorporation occurs. Thus, the authors have recently developed beta-TCP block with 60% porosity, which is approximately sevenfold greater in terms of compressive strength than that of beta-TCP with 75% porosity. The authors investigated bone formation and resorption of beta-TCP after implantation in patients of beta-TCP blocks with two different porosities. From May 2003 to November 2004, medial opening high tibial osteotomy was performed in 25 patients with a mean age of 66 years. The opened defect was fixed with a Puddu plate. Then 6-8 cm(3) of beta-TCP block with 75% porosity was used to fill the cancellous bone defect, except on the medial side where 2.83-3.18 cm(3) of wedge-shaped beta-TCP block with 60% porosity was implanted. At least 2 years after surgery, the 25 patients had no correction loss, and bone formation was noted in all cases. Complete or nearly complete resorption of beta-TCP with 60 and 75% porosity was obtained within 3.5 years. Thirteen biopsy samples obtained from the 60% porosity implantation sites showed good lamellar bone formation, and the percentage of beta-TCP remaining relative to the newly formed bone plus beta-TCP ranged from 0.3 to 14.5%, with a mean of 6.7%. The authors suspect that mechanical stress loading to the medial side of the tibia facilitated bone formation and resorption of beta-TCP with 60% porosity.
authors.affiliation: Department of Orthopaedic Surgery, NHO Utsunomiya National Hospital, Utsunomiya City, Tochigi 329-1193, Japan. tanakat@e-utunomiya.hosp.go.jp
authors.forename: Takaaki
authors.initials: T
authors.lastname: Tanaka
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Kumagae
authors.forename: Mitsuru
authors.initials: M
authors.lastname: Saito
authors.forename: Masaaki
authors.initials: M
authors.lastname: Chazono
authors.forename: Hirokazu
authors.initials: H
authors.lastname: Komaki
authors.forename: Takahiro
authors.initials: T
authors.lastname: Kikuchi
authors.forename: Seiichiro
authors.initials: S
authors.lastname: Kitasato
authors.forename: Keishi
authors.initials: K
authors.lastname: Marumo
mesh_terms: D000368:Aged; D001862:Bone Resorption; D018786:Bone Substitutes / Q000737:chemistry* / Q000627:therapeutic use; D002130:Calcium Phosphates / Q000627:therapeutic use*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010012:Osteogenesis; D010027:Osteotomy / Q000379:methods*; D016062:Porosity; D013977:Tibia / Q000601:surgery; D016896:Treatment Outcome
chemical_list: D018786:Bone Substitutes; D002130:Calcium Phosphates; C485817:beta-tricalcium phosphate