title: Crystallographic orientation of the c-axis of biological apatite as a new index of the quality of subchondral bone in knee joint osteoarthritis.
abstract: The aim of the present study was to investigate the preferred orientation of biological apatite (BAp) as a new index of the quality of subchondral bone (SB) in knee joint osteoarthritis (OA). Ten OA and five normal knee joints were obtained. Thickness, quantity and bone mineral density (BMD) of SB were analyzed at the medial condyle of the femur in dry conditions by peripheral quantitative computed tomography. In addition, the preferred crystallographic orientation of the c-axis of BAp was evaluated as bone quality parameter using a microbeam X-ray diffractometer technique. BMD and thickness of SB were significantly increased in OA specimens compared to normal knee specimens (P < 0.01), and the preferred orientation of the c-axis of BAp along the normal direction of SB surface was significantly higher in OA specimens (P < 0.01), reflecting the change in stress of concentration in the pathological portion without cartilage. SB sclerosis in OA results in both proliferation of bone tissues and enhanced degree of preferential alignment of the c-axis of BAp. Our findings could have major implications for the diagnosis of clinical studies, including pathologic elucidation in OA.
authors.affiliation: School of Advanced Materials Engineering, Kookmin University, Seoul, 136-702, Korea.
authors.forename: Jee-Wook
authors.initials: JW
authors.lastname: Lee
authors.affiliation: Department of Orthopaedic Surgery, Osaka City University, Graduate School of Medicine, Osaka, 545-8585, Japan.
authors.forename: Akio
authors.initials: A
authors.lastname: Kobayashi
authors.affiliation: Division of Materials and Manufacturing Science, Graduate School of Engineering, Osaka University, Suita, 565-0871, Japan. nakano@mat.eng.osaka-u.ac.jp.
authors.forename: Takayoshi
authors.initials: T
authors.lastname: Nakano
mesh_terms: D000369:Aged, 80 and over; D001031:Apatites / Q000737:chemistry*; D015519:Bone Density; D002356:Cartilage / Q000473:pathology; D018360:Crystallography, X-Ray; D005269:Femur / Q000473:pathology*; D006801:Humans; D007719:Knee Joint / Q000000981:diagnostic imaging / Q000473:pathology*; D008297:Male; D020370:Osteoarthritis, Knee / Q000000981:diagnostic imaging / Q000473:pathology*; D014057:Tomography, X-Ray Computed
chemical_list: D001031:Apatites
keywords: Apatite orientation; Bone quality; Microbeam X-ray diffractometer (μXRD); Osteoarthritis (OA)