title: Characterization of subchondral bone histopathology of facet joint osteoarthritis in lumbar spinal stenosis.
abstract: Facet joint osteoarthritis may be a cause of low back pain in degenerative spine diseases including lumbar spinal stenosis. Subchondral bone is regarded as a potential therapeutic target for osteoarthritis treatment. The goal of this study was to characterize subchondral bone histopathology in osteoarthritic facet joints from lumbar spinal stenosis patients. Fifteen patients with degenerative spinal stenosis scheduled for transforaminal lumbar interbody fusion surgery were recruited for this study. Osteoarthritis severity was graded on T1- and T2-weighted MRI images using Weishaupt scoring system. Dissected osteoarthritic facet joints were subjected to histological and immunohistochemistry analyses to study relative abundance of osteoblast, osteoclasts, and macrophages using van Gieson's, tartrate-resistant acid phosphatase and CD68-antibody staining, respectively. Presence of nerve fibers was evaluated by PGP9.5-antibody staining. Differential bone histopathology, independent from radiological osteoarthritis grade, was observed in facet joints. Extensive de novo bone formation was found in subchondral bone tissues of eight of fifteen specimens. Regions of bone formation showed high abundance of blood vessels and CD68-positive macrophages, but were devoid of multinucleated osteoclasts. Additional pathological changes in subchondral marrow spaces, including inflammatory infiltration and enhanced osteoclast activity, were characterized by macrophage-rich tissues. PGP9.5-positive nerve fibers were detected near arterioles, but not in regions displaying bone pathology. Individual histopathological parameters did not associate with clinical features or radiological osteoarthritis severity. Subchondral bone histopathology of facet joint osteoarthritis in lumbar spinal stenosis is characterized by marrow infiltration by macrophage-rich tissues and enhanced de novo bone formation. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:1475-1480, 2016.
authors.affiliation: Spine Surgery, University Hospital Basel, Spitalstrasse 21, Basel 4031, Switzerland.
authors.forename: Cordula
authors.initials: C
authors.lastname: Netzer
authors.affiliation: Spine Surgery, University Hospital Basel, Spitalstrasse 21, Basel 4031, Switzerland.
authors.forename: Karin
authors.initials: K
authors.lastname: Urech
authors.affiliation: Department of Orthopaedic, Osteoarthritis Research Center Basel, University Hospital Basel, Spitalstrasse 21, Basel 4031, Switzerland.
authors.forename: Thomas
authors.initials: T
authors.lastname: Hügle
authors.affiliation: Department of Radiology, Musculoskeletal Diagnostics, University Hospital Basel, Petersgraben 4, Basel 4031, Switzerland.
authors.forename: Robyn Melanie
authors.initials: RM
authors.lastname: Benz
authors.affiliation: Spine Surgery, University Hospital Basel, Spitalstrasse 21, Basel 4031, Switzerland.|Department of Orthopaedic, Osteoarthritis Research Center Basel, University Hospital Basel, Spitalstrasse 21, Basel 4031, Switzerland.
authors.forename: Jeroen
authors.initials: J
authors.lastname: Geurts
authors.affiliation: Spine Surgery, University Hospital Basel, Spitalstrasse 21, Basel 4031, Switzerland.
authors.forename: Stefan
authors.initials: S
authors.lastname: Schären
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D003094:Collagen / Q000378:metabolism; D005260:Female; D006801:Humans; D008159:Lumbar Vertebrae / Q000098:blood supply / Q000294:innervation / Q000378:metabolism / Q000473:pathology*; D008264:Macrophages; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D055013:Osteoarthritis, Spine / Q000150:complications / Q000000981:diagnostic imaging / Q000378:metabolism / Q000473:pathology*; D010006:Osteoblasts; D010010:Osteoclasts; D012189:Retrospective Studies; D013130:Spinal Stenosis / Q000150:complications* / Q000000981:diagnostic imaging; D021801:Zygapophyseal Joint / Q000098:blood supply / Q000294:innervation / Q000378:metabolism / Q000473:pathology*
chemical_list: D003094:Collagen
keywords: MRI; facet joint; lumbar spinal stenosis; osteoarthritis; subchondral bone