title: Coronal tibial slope is associated with accelerated knee osteoarthritis: data from the Osteoarthritis Initiative.
abstract: Accelerated knee osteoarthritis may be a unique subset of knee osteoarthritis, which is associated with greater knee pain and disability. Identifying risk factors for accelerated knee osteoarthritis is vital to recognizing people who will develop accelerated knee osteoarthritis and initiating early interventions. The geometry of an articular surface (e.g., coronal tibial slope), which is a determinant of altered joint biomechanics, may be an important risk factor for incident accelerated knee osteoarthritis. We aimed to determine if baseline coronal tibial slope is associated with incident accelerated knee osteoarthritis or common knee osteoarthritis.
  
  
  
  We conducted a case-control study using data and images from baseline and the first 4 years of follow-up in the Osteoarthritis Initiative. We included three groups: 1) individuals with incident accelerated knee osteoarthritis, 2) individuals with common knee osteoarthritis progression, and 3) a control group with no knee osteoarthritis at any time. We did 1:1:1 matching for the 3 groups based on sex. Weight-bearing, fixed flexion posterior-anterior knee radiographs were obtained at each visit. One reader manually measured baseline coronal tibial slope on the radiographs. Baseline femorotibial angle was measured on the radiographs using a semi-automated program. To assess the relationship between slope (predictor) and incident accelerated knee osteoarthritis or common knee osteoarthritis (outcomes) compared with no knee osteoarthritis (reference outcome), we performed multinomial logistic regression analyses adjusted for sex.
  
  
  
  The mean baseline slope for incident accelerated knee osteoarthritis, common knee osteoarthritis, and no knee osteoarthritis were 3.1(2.0), 2.7(2.1), and 2.6(1.9); respectively. A greater slope was associated with an increased risk of incident accelerated knee osteoarthritis (OR = 1.15 per degree, 95 % CI = 1.01 to 1.32) but not common knee osteoarthritis (OR = 1.04, 95 % CI = 0.91 to 1.19). These findings were similar when adjusted for recent injury. Among knees with varus malalignment a greater slope increases the odds of incident accelerated knee osteoarthritis; there is no significant relationship between slope and incident accelerated knee osteoarthritis among knees with normal alignment.
  
  
  
  Coronal tibial slope, particularly among knees with malalignment, may be an important risk factor for incident accelerated knee osteoarthritis.
authors.affiliation: Division of Rheumatology, Tufts Medical Center, 800 Washington Street, Box #406, Boston, MA, 02111, USA. jeffrey.driban@tufts.edu.
authors.forename: Jeffrey B
authors.initials: JB
authors.lastname: Driban
authors.affiliation: Division of Rheumatology, Tufts Medical Center, 800 Washington Street, Box #406, Boston, MA, 02111, USA.
authors.forename: Alina C
authors.initials: AC
authors.lastname: Stout
authors.affiliation: Department of Radiology, Brigham & Women's Hospital and Harvard Medical School, 75 Francis Street, Boston, MA, 02115, USA.
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Duryea
authors.affiliation: Medical Care Line and Research Care Line, Houston Health Services Research and Development (HSR&D) Center of Excellence Michael E. DeBakey VAMC, 2002 Holcombe Blvd, Houston, TX, 77030, USA.|Section of Immunology, Allergy, and Rheumatology, Baylor College of Medicine, 1 Baylor Plaza, BCM-285, Houston, TX, 77030, USA.
authors.forename: Grace H
authors.initials: GH
authors.lastname: Lo
authors.affiliation: Division of Rheumatology, Tufts Medical Center, 800 Washington Street, Box #406, Boston, MA, 02111, USA.
authors.forename: William F
authors.initials: WF
authors.lastname: Harvey
authors.affiliation: The Institute for Clinical Research and Health Policy Studies, Tufts Medical Center, Boston, MA, 02111, USA.|Tufts Clinical and Translational Science Institute, Tufts University, 800 Washington Street, Box #63, Boston, MA, 02111, USA.
authors.forename: Lori Lyn
authors.initials: LL
authors.lastname: Price
authors.affiliation: Department of Radiology, Tufts Medical Center, 800 Washington Street, Box #299, Boston, MA, 02111, USA.
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Ward
authors.affiliation: Center for Primary Care and Prevention, Alpert Medical School of Brown University, 111 Brewster St, Pawtucket, RI, 02860, USA.
authors.forename: Charles B
authors.initials: CB
authors.lastname: Eaton
authors.affiliation: Department of Anatomy and Cell Biology, Temple University School of Medicine, 3500 North Broad Street, Philadelphia, PA, 19140, USA.
authors.forename: Mary F
authors.initials: MF
authors.lastname: Barbe
authors.affiliation: Division of Rheumatology, Immunology & Allergy, Brigham & Women's Hospital and Harvard Medical School, 75 Francis Street, Boston, MA, 02115, USA.
authors.forename: Bing
authors.initials: B
authors.lastname: Lu
authors.affiliation: Division of Rheumatology, Tufts Medical Center, 800 Washington Street, Box #406, Boston, MA, 02111, USA.
authors.forename: Timothy E
authors.initials: TE
authors.lastname: McAlindon
mesh_terms: D000368:Aged; D017760:Bone Malalignment / Q000150:complications* / Q000000981:diagnostic imaging; D016022:Case-Control Studies; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007719:Knee Joint / Q000000981:diagnostic imaging / Q000502:physiology; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000000981:diagnostic imaging* / Q000209:etiology; D011859:Radiography; D016059:Range of Motion, Articular; D012307:Risk Factors; D013977:Tibia / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D016474:Weight-Bearing
keywords: Alignment; Bone; Knee; Osteoarthritis; Radiography