title: Subchondral defects in caprine femora augmented with in situ setting hydroxyapatite cement, polymethylmethacrylate, or autogenous bone graft: biomechanical and histomorphological analysis after two-years.
abstract: Juxta-articular defects pose significant challenges due to the high risk of fracture of the subchondral plate and articular cartilage. We evaluated the mechanical and histomorphological repair process of caprine subchondral femoral defects augmented with either a bioresorbable in situ setting hydroxyapatite cement (HAC), polymethylmethacrylate (PMMA), autogenous bone graft (AG), or left empty. Twelve-mm subchondral defects were made bilaterally in the medial femoral condyles of skeletally mature goats and augmented with a test material or left empty. Femurs were harvested at varying time periods out to 2 years and evaluated for subchondral stiffness and histomorphological indices. Several defects augmented using autograft or left empty sustained focal fracture of the subchondral plate. No HAC or PMMA augmented defects showed evidence of subchondral fracture. The HAC and PMMA augmented defects showed comparable stiffness at all time points. The mean volume fraction of HAC remaining within the defects progressively decreased from 96% at 24 h to 38% at 2 years. The new bone replacing the HAC appeared to have normal physiological architecture and orientation. In situ setting hydroxyapatite cement may be a viable alternative for the repair of subchondral defects with an important advantage that while undergoing gradual resorption and replacement with host bone, mechanical integrity of the skeletal defect is maintained.
authors.affiliation: Seay Center for Musculoskeletal Research, Texas Scottish Rite Hospital for Children, Dallas 75219, USA. rdwelch@airmail.net
authors.forename: Robert D
authors.initials: RD
authors.lastname: Welch
authors.forename: B Hudson
authors.initials: BH
authors.lastname: Berry
authors.forename: Kevin
authors.initials: K
authors.lastname: Crawford
authors.forename: Hong
authors.initials: H
authors.lastname: Zhang
authors.forename: Mark
authors.initials: M
authors.lastname: Zobitz
authors.forename: Dwight
authors.initials: D
authors.lastname: Bronson
authors.forename: Sumant
authors.initials: S
authors.lastname: Krishnan
mesh_terms: D000818:Animals; D001672:Biocompatible Materials / Q000627:therapeutic use*; D001696:Biomechanical Phenomena; D001843:Bone Cements / Q000627:therapeutic use*; D001847:Bone Diseases / Q000473:pathology / Q000503:physiopathology / Q000628:therapy*; D016025:Bone Transplantation; D017886:Durapatite / Q000627:therapeutic use*; D005269:Femur / Q000473:pathology / Q000503:physiopathology; D005500:Follow-Up Studies; D006041:Goats; D008297:Male; D019904:Polymethyl Methacrylate / Q000627:therapeutic use*; D013997:Time Factors; D014182:Transplantation, Autologous
chemical_list: D001672:Biocompatible Materials; D001843:Bone Cements; D019904:Polymethyl Methacrylate; D017886:Durapatite