title: The varus alignment and morphologic alterations of proximal tibia affect the onset of medial knee osteoarthritis in rural Japanese women: Case control study from the longitudinal evaluation of Matsudai Knee Osteoarthritis Survey.
abstract: BACKGROUND
  Relationship malalignment of the knee and the onset of knee OA are unclear. Moreover, it has not been clarified whether malalignment of the knee affects the morphological change of the proximal tibia. The purpose of current study was to investigate whether varus knee alignment and morphological change of the proximal medial tibia influence the onset of medial knee OA and to clarify the relationship between them.
  
  
  METHODS
  The subjects comprised 736 knees from 390 women that went under both the first survey in 1979 and the fourth survey in 2000 in the Matsudai district in Niigata Prefecture in Japan. None of the subjects demonstrated radiographic knee OA at the first survey. OA was graded according to the Kellgren-Lawrence classification and the subjects were divided according to the OA grades in the forth survey into the 3 groups (non-OA, early OA, and advanced OA). Age, BMI, Femorotibial angle (FTA), the tibial plateau angle and medial tibial cortical bone thickness (MTCBT) were measured. We performed multivariate logistic regression analysis using the stepwise method to identified the risk factors regarding onset of knee OA and calculated the odds ratio (OR) and 95% confidence intervals (95% CI).
  
  
  RESULTS
  Advanced OA had a significantly higher OR compared to non-OA in 1979 with the tibial plateau angle (OR: 1.15) and MTCBT (OR: 2.11). And also advanced OA had a significantly higher OR compared to early-OA in 1979 with the tibial plateau angle (OR: 1.17) and MTCBT (OR: 1.62).
  
  
  CONCLUSIONS
  In the advanced OA, varus alignment of the proximal tibia had already existed before the onset of knee OA. In addition, we thought that varus alignment due to the proximal tibia had influenced the morphologic alterations of proximal medial tibia.
authors.affiliation: Department of Orthopedic Surgery, Tsuruoka Municipal Shonai Hospital, Yamagata, Japan; Division of Orthopedic Surgery, Department of Regenerative and Transplant Medicine, Niigata University Graduate School of Medicine and Dental Science, Niigata, Japan. Electronic address: higanoy@msn.com.
authors.forename: Yukimasa
authors.initials: Y
authors.lastname: Higano
authors.affiliation: Department of Orthopedic Surgery, Saiseikai Niigata Daini Hospital, Niigata, Japan.
authors.forename: Tadashi
authors.initials: T
authors.lastname: Hayami
authors.affiliation: Center of Transdisciplinary Research, Niigata University, Niigata, Japan.
authors.forename: Go
authors.initials: G
authors.lastname: Omori
authors.affiliation: Department of Orthopedic Surgery, Niigata Medical Center, Nigata, Japan.
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Koga
authors.affiliation: Department of Physical Therapy, Niigata University of Health and Welfare, School of Medical Technology, Niigata, Japan.
authors.forename: Kazuo
authors.initials: K
authors.lastname: Endo
authors.affiliation: Division of Orthopedic Surgery, Department of Regenerative and Transplant Medicine, Niigata University Graduate School of Medicine and Dental Science, Niigata, Japan.
authors.forename: Naoto
authors.initials: N
authors.lastname: Endo
mesh_terms: D000328:Adult; D000368:Aged; D017760:Bone Malalignment / Q000150:complications* / Q000453:epidemiology / Q000503:physiopathology; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D007564:Japan / Q000453:epidemiology; D007719:Knee Joint / Q000000981:diagnostic imaging / Q000503:physiopathology*; D008875:Middle Aged; D016017:Odds Ratio; D020370:Osteoarthritis, Knee / Q000175:diagnosis / Q000453:epidemiology / Q000209:etiology*; D011859:Radiography / Q000379:methods*; D012189:Retrospective Studies; D012307:Risk Factors; D011795:Surveys and Questionnaires; D013977:Tibia / Q000000981:diagnostic imaging*