title: Correlation between knee and hindfoot alignment in patients with rheumatoid arthritis: The effects of subtalar joint destruction.
abstract: OBJECTIVE
  Compensatory hindfoot alignment for deformities at the knee level has been demonstrated in patients with knee osteoarthritis. However, this phenomenon has not been elucidated in patients with rheumatoid arthritis (RA). The aim of this study is to investigate the relationship between knee deformity and hindfoot alignment and the effect of subtalar joint destruction in patients with RA.
  
  
  METHODS
  We retrospectively investigated RA patients (110 patients, 205 limbs) using radiographs in the standing anteroposterior knee, standing lateral foot, and hindfoot alignment views. The grade of destruction at the knee and subtalar joints was assigned using Larsen's grading system. The correlation between the femorotibial and tibiocalcaneal angles and the effect of joint destruction on this correlation were analyzed using Pearson's correlation coefficients.
  
  
  RESULTS
  There was moderate correlation between the femorotibial and tibiocalcaneal angles in a group of knees with a Larsen grade of ≥ 4 (r = 0.544, p = 0.0239). This correlation was stronger in a group with less damaged subtalar joints with a Larsen grade of ≤ 3 (r = 0.705, p = 0.0049).
  
  
  CONCLUSIONS
  These findings emphasized the importance of examining foot and ankles in patients with RA who undergo total knee arthroplasty.
authors.affiliation: a Department of Rheumatology , Yugawara Hospital , Kanagawa , Japan.
authors.forename: Izumi
authors.initials: I
authors.lastname: Nakada
authors.forename: Ichiro
authors.initials: I
authors.lastname: Nakamura
authors.forename: Takuo
authors.initials: T
authors.lastname: Juji
authors.forename: Katsumi
authors.initials: K
authors.lastname: Ito
authors.forename: Takumi
authors.initials: T
authors.lastname: Matsumoto
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001172:Arthritis, Rheumatoid / Q000000981:diagnostic imaging*; D019645:Arthroplasty, Replacement, Knee; D003430:Cross-Sectional Studies; D005260:Female; D005528:Foot / Q000000981:diagnostic imaging; D006801:Humans; D007717:Knee / Q000000981:diagnostic imaging; D007719:Knee Joint / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D011859:Radiography; D012189:Retrospective Studies; D013380:Subtalar Joint / Q000000981:diagnostic imaging*
keywords: Hindfoot alignment; Knee deformity; Larsen grade; Rheumatoid arthritis; Subtalar joint