title: Osteophyte formation after ACL rupture in mice is associated with joint restabilization and loss of range of motion.
abstract: Osteophytes are a typical radiographic finding during osteoarthritis (OA). Osteophytes are thought to form in response to joint instability; however, the time course of osteophyte formation and joint stabilization following joint injury is not well understood. In this study, we investigated the time course of osteophyte formation and joint function following non-invasive knee injury in mice. We hypothesized that initial joint instability following knee injury would initiate osteophyte formation, which would in turn restabilize the joint and reduce range of motion (ROM). Mice were subjected to non-invasive anterior cruciate ligament (ACL) rupture. Anterior-posterior (AP) joint laxity, ROM, and chondro/osteophyte formation were measured immediately after injury, and 2, 4, 6, and 8 weeks post-injury. Chondrophyte areas at each time point were measured with histology, while mineralized osteophyte volume was determined using micro-computed tomography. Immediately after ACL rupture, AP joint laxity was increased twofold, while ROM was increased 11.7%. Chondrophytes appeared by 2 weeks post-injury, corresponding with a decrease in AP joint laxity and ROM. By 8 weeks post-injury, considerable osteophyte formation was observed around the joint, AP joint laxity returned to control levels, and joint ROM decreased to 61% of control values. These data support a role for chondro/osteophytes in joint restabilization after injury, and provide crucial insight into the time course and pathology of joint degeneration during OA development in the mouse. Statement of Clinical Significance: Results from this study increase understanding of conditions leading to osteophyte formation.© 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:466-473, 2017.
authors.affiliation: Biomedical Engineering Graduate Group, University of California-Davis, Davis, California.
authors.forename: Allison W
authors.initials: AW
authors.lastname: Hsia
authors.affiliation: Albany Medical College, Albany, New York.
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Anderson
authors.affiliation: Biomedical Engineering Graduate Group, University of California-Davis, Davis, California.
authors.forename: Mollie A
authors.initials: MA
authors.lastname: Heffner
authors.affiliation: Department of Orthopaedic Surgery, University of California-Davis Medical Center, Research Building I, Suite 2000, 4635 2nd Avenue, Sacramento, California 95817.
authors.forename: Earl P
authors.initials: EP
authors.lastname: Lagmay
authors.affiliation: Department of Anatomy, Physiology and Cell Biology, School of Veterinary Medicine, University of California-Davis, Davis, California.
authors.forename: Regina
authors.initials: R
authors.lastname: Zavodovskaya
authors.affiliation: Biomedical Engineering Graduate Group, University of California-Davis, Davis, California.|Department of Orthopaedic Surgery, University of California-Davis Medical Center, Research Building I, Suite 2000, 4635 2nd Avenue, Sacramento, California 95817.
authors.forename: Blaine A
authors.initials: BA
authors.lastname: Christiansen
mesh_terms: D000818:Animals; D000070598:Anterior Cruciate Ligament Injuries / Q000150:complications / Q000473:pathology / Q000503:physiopathology*; D005260:Female; D007596:Joints / Q000473:pathology; D008810:Mice, Inbred C57BL; D054850:Osteophyte / Q000000981:diagnostic imaging / Q000209:etiology* / Q000473:pathology; D016059:Range of Motion, Articular; D055114:X-Ray Microtomography
keywords: joint laxity; knee injury; osteophytes; post-traumatic osteoarthritis; range of motion