title: Association between subchondral bone structure and osteoarthritis histopathological grade.
abstract: Despite increasing evidence that subchondral bone contributes to osteoarthritis (OA) pathogenesis, little is known about local changes in bone structure compared to cartilage degeneration. This study linked structural adaptation of subchondral bone with histological OA grade. Twenty-five osteochondral samples of macroscopically different degeneration were prepared from tibiae of 14 patients. Samples were scanned with micro-computed tomography (μCT) and both conventional structural parameters and novel 3D parameters based on local patterns were analyzed from the subchondral plate and trabecular bone. Subsequently, samples were processed for histology and evaluated for OARSI grade. Each bone parameter and OARSI grade was compared to assess structural adaptation of bone with OA severity. In addition, thicknesses of cartilage, calcified cartilage, and subchondral plate were analyzed from histological sections and compared with subchondral bone plate thickness from μCT. With increasing OARSI grade, the subchondral plate became thicker along with decreased specific bone surface, while there was no change in tissue mineral density. Histological analysis showed that subchondral plate thickness from μCT also includes calcified cartilage. Entropy of local patterns increased with OA severity, reflecting higher tissue heterogeneity. In the trabecular compartment, bone volume fraction and both trabecular thickness and number increased with OARSI grade while trabecular separation and structure model index decreased. Also, elevation of local patterns became longitudinal in the subchondral plate and axial transverse in trabecular bone with increasing OARSI grade. This study demonstrates the possibility of radiological assessment of OA severity by structural analysis of bone. © 2016 The Authors. Journal of Orthopaedic Research Published by Wiley Periodicals, Inc. J Orthop Res 35:785-792, 2017.
authors.affiliation: Research Unit of Medical Imaging, Physics and Technology, Faculty of Medicine, University of Oulu, Oulu, Finland.|Medical Research Center Oulu, Oulu University Hospital and University of Oulu, Oulu, Finland.|Department of Applied Physics, University of Eastern Finland, Kuopio, Finland.
authors.forename: Mikko A J
authors.initials: MAJ
authors.lastname: Finnilä
authors.affiliation: Research Unit of Medical Imaging, Physics and Technology, Faculty of Medicine, University of Oulu, Oulu, Finland.|Medical Research Center Oulu, Oulu University Hospital and University of Oulu, Oulu, Finland.
authors.forename: Jérôme
authors.initials: J
authors.lastname: Thevenot
authors.affiliation: Medical Research Center Oulu, Oulu University Hospital and University of Oulu, Oulu, Finland.|Cancer and Translational Medicine Research Unit, Faculty of Medicine, University of Oulu, Oulu, Finland.
authors.forename: Olli-Matti
authors.initials: OM
authors.lastname: Aho
authors.affiliation: Institute of Biomedicine, Anatomy, University of Eastern Finland, Kuopio, Finland.
authors.forename: Virpi
authors.initials: V
authors.lastname: Tiitu
authors.affiliation: Research Unit of Medical Imaging, Physics and Technology, Faculty of Medicine, University of Oulu, Oulu, Finland.|Medical Research Center Oulu, Oulu University Hospital and University of Oulu, Oulu, Finland.|Department of Applied Physics, University of Eastern Finland, Kuopio, Finland.
authors.forename: Jari
authors.initials: J
authors.lastname: Rautiainen
authors.affiliation: Research Unit of Medical Imaging, Physics and Technology, Faculty of Medicine, University of Oulu, Oulu, Finland.
authors.forename: Sami
authors.initials: S
authors.lastname: Kauppinen
authors.affiliation: Research Unit of Medical Imaging, Physics and Technology, Faculty of Medicine, University of Oulu, Oulu, Finland.|Medical Research Center Oulu, Oulu University Hospital and University of Oulu, Oulu, Finland.|Department of Diagnostic Radiology, Oulu University Hospital, Oulu, Finland.
authors.forename: Miika T
authors.initials: MT
authors.lastname: Nieminen
authors.affiliation: Department of Laboratory Medicine and Pathobiology, University of Toronto and Mount Sinai Hospital, Toronto, Ontario, Canada.
authors.forename: Kenneth
authors.initials: K
authors.lastname: Pritzker
authors.affiliation: Department of Surgery, Oulu University Hospital, Oulu, Finland.
authors.forename: Maarit
authors.initials: M
authors.lastname: Valkealahti
authors.affiliation: Medical Research Center Oulu, Oulu University Hospital and University of Oulu, Oulu, Finland.|Cancer and Translational Medicine Research Unit, Faculty of Medicine, University of Oulu, Oulu, Finland.|Department of Surgery, Oulu University Hospital, Oulu, Finland.
authors.forename: Petri
authors.initials: P
authors.lastname: Lehenkari
authors.affiliation: Research Unit of Medical Imaging, Physics and Technology, Faculty of Medicine, University of Oulu, Oulu, Finland.|Medical Research Center Oulu, Oulu University Hospital and University of Oulu, Oulu, Finland.|Department of Diagnostic Radiology, Oulu University Hospital, Oulu, Finland.
authors.forename: Simo
authors.initials: S
authors.lastname: Saarakkala
mesh_terms: D000368:Aged; D001842:Bone and Bones / Q000000981:diagnostic imaging / Q000503:physiopathology*; D002114:Calcinosis; D002356:Cartilage / Q000000981:diagnostic imaging / Q000503:physiopathology; D002358:Cartilage, Articular / Q000000981:diagnostic imaging / Q000473:pathology; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional; D008297:Male; D010003:Osteoarthritis / Q000000981:diagnostic imaging* / Q000503:physiopathology; D012720:Severity of Illness Index; D013977:Tibia / Q000000981:diagnostic imaging / Q000503:physiopathology; D055114:X-Ray Microtomography
keywords: OARSI grading; bone sclerosis; histomorphometry; micro-computed tomography; osteoarthritis