title: A radiographic analysis of alignment of the lower extremities--initiation and progression of varus-type knee osteoarthritis.
abstract: OBJECTIVE
  This study aimed to investigate alignment based on age in normal knees and alignment based on deformity in osteoarthritis (OA) knees using detailed radiographic parameters.
  
  
  METHODS
  Various parameters were measured from weight-bearing long leg radiographs of 1251 legs (797 normal and 454 OA knees) as a cross-sectional study. Normal knees were classified by age (young, middle aged, aged, and elderly) and symptomatic OA knees on the basis of the alignment (femorotibial angle (FTA): mild, moderate, severe and profound). The mean measurements in each group were calculated and compared within each group.
  
  
  RESULTS
  The femoral shaft showed medially bowed curvature (femoral bowing) of approximately 2° in the young normal group, which shifted to lateral bowing with age. However, OA knees showed larger lateral bowing with OA grade, which might reduce the condylar-shaft angle and subsequently shifted the mechanical axis medially. Progression of mild to moderate OA might be associated with a decreasing condylar-shaft angle (femoral condylar orientation) and widening condylar-plateau angle (joint space narrowing) rather than decreasing tibial plateau flattering. Steeping of the tibial plateau inclination due to increasing tibial plateau shift (tibial plateau compression) rather than medial tibial bowing might be the main contributor to worsening of varus deformity in knees with severe and profound OA.
  
  
  CONCLUSIONS
  This cross-sectional study might provide the possibility of OA initiation and progression. The lateral curvature of the femoral shaft associated with aging may contribute to the initiation of varus-type OA of the knee. These changes in the femur may be followed by secondary signs of OA progression including varus femoral condylar orientation, medial joint space narrowing, and tibial plateau compression.
authors.affiliation: Department of Orthopaedic Surgery, Kobe University Graduate School of Medicine, Kobe, Hyogo, Japan. Electronic address: matsun@m4.dion.ne.jp.
authors.forename: T
authors.initials: T
authors.lastname: Matsumoto
authors.affiliation: Department of Orthopaedic Surgery, Yasue Orthopaedic Clinic, Kobe, Hyogo, Japan. Electronic address: m-hasshi@gaia.eonet.ne.jp.
authors.forename: M
authors.initials: M
authors.lastname: Hashimura
authors.affiliation: Department of Orthopaedic Surgery, Kobe University Graduate School of Medicine, Kobe, Hyogo, Japan. Electronic address: kojitakayama78@yahoo.co.jp.
authors.forename: K
authors.initials: K
authors.lastname: Takayama
authors.affiliation: Department of Orthopaedic Surgery, Kobe Kaisei Hospital, Kobe, Hyogo, Japan. Electronic address: wavedreamer17@yahoo.co.jp.
authors.forename: K
authors.initials: K
authors.lastname: Ishida
authors.affiliation: Department of Orthopaedic Surgery, Kobe University Graduate School of Medicine, Kobe, Hyogo, Japan. Electronic address: yohei_kawakami@hotmail.com.
authors.forename: Y
authors.initials: Y
authors.lastname: Kawakami
authors.affiliation: Department of Orthopaedic Surgery, Kobe University Graduate School of Medicine, Kobe, Hyogo, Japan. Electronic address: tokiomatsuzaki@yahoo.co.jp.
authors.forename: T
authors.initials: T
authors.lastname: Matsuzaki
authors.affiliation: Department of Orthopaedic Surgery, Kobe University Graduate School of Medicine, Kobe, Hyogo, Japan. Electronic address: naokix1981@yahoo.co.jp.
authors.forename: N
authors.initials: N
authors.lastname: Nakano
authors.affiliation: Department of Orthopaedic Surgery, Kobe University Graduate School of Medicine, Kobe, Hyogo, Japan. Electronic address: matsushi@med.kobe-u.ac.jp.
authors.forename: T
authors.initials: T
authors.lastname: Matsushita
authors.affiliation: Department of Orthopaedic Surgery, Kobe University Graduate School of Medicine, Kobe, Hyogo, Japan. Electronic address: kurodar@med.kobe-u.ac.jp.
authors.forename: R
authors.initials: R
authors.lastname: Kuroda
authors.affiliation: Department of Orthopaedic Surgery, Kobe University Graduate School of Medicine, Kobe, Hyogo, Japan. Electronic address: kurosaka@med.kobe-u.ac.jp.
authors.forename: M
authors.initials: M
authors.lastname: Kurosaka
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D003430:Cross-Sectional Studies; D018450:Disease Progression; D005260:Female; D056305:Genu Varum / Q000150:complications / Q000000981:diagnostic imaging*; D006801:Humans; D035002:Lower Extremity / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000145:classification / Q000000981:diagnostic imaging* / Q000209:etiology; D011859:Radiography; D055815:Young Adult
keywords: Initiation; Osteoarthritis; Progression