title: Knee adduction moment, serum hyaluronan level, and disease severity in medial tibiofemoral osteoarthritis.
abstract: OBJECTIVE
  The adduction moment at the knee during gait is the primary determinant of medial-to-lateral load distribution. If the adduction moment contributes to progression of osteoarthritis (OA), then patients with advanced medial tibiofemoral OA should have higher adduction moments. The present study was undertaken to investigate the hypothesis that the adduction moment normalized for weight and height is associated with medial tibiofemoral OA disease severity after controlling for age, sex, and pain level, and to examine the correlation of serum hyaluronan (HA) level with disease severity and with the adduction moment in a subset of patients.
  
  
  METHODS
  Fifty-four patients with medial tibiofemoral OA underwent gait analysis and radiographic evaluation. Disease severity was assessed using the Kellgren-Lawrence (K-L) grade and medial joint space width. In a subset of 23 patients with available sera, HA was quantified by sandwich enzyme-linked immunosorbent assay. Pearson correlations, a random effects model, and multivariate regression models were used.
  
  
  RESULTS
  The adduction moment correlated with the K-L grade in the left and right knees (r = 0.68 and r = 0.60, respectively), and with joint space width in the left and right knees (r = -0.45 and r = -0.47, respectively). The relationship persisted after controlling for age, sex, and severity of pain. The partial correlation between K-L grade and adduction moment was 0.71 in the left knees and 0.61 in the right knees. For every 1.0-unit increase in adduction moment, there was a 0.63-mm decrease in joint space width. In the subset of patients in whom serum HA levels were measured, HA levels correlated with medial joint space width (r = -0.55), but not with the adduction moment.
  
  
  CONCLUSIONS
  There is a significant relationship between the adduction moment and OA disease severity. Serum HA levels correlate with joint space width but not with the adduction moment. Longitudinal studies will be necessary to determine the contribution of the adduction moment, and its contribution in conjunction with metabolic markers, to progression of medial tibiofemoral OA.
authors.affiliation: Northwestern University, Chicago, Illinois 60611, USA.
authors.forename: L
authors.initials: L
authors.lastname: Sharma
authors.forename: D E
authors.initials: DE
authors.lastname: Hurwitz
authors.forename: E J
authors.initials: EJ
authors.lastname: Thonar
authors.forename: J A
authors.initials: JA
authors.lastname: Sum
authors.forename: M E
authors.initials: ME
authors.lastname: Lenz
authors.forename: D D
authors.initials: DD
authors.lastname: Dunlop
authors.forename: T J
authors.initials: TJ
authors.lastname: Schnitzer
authors.forename: G
authors.initials: G
authors.lastname: Kirwan-Mellis
authors.forename: T P
authors.initials: TP
authors.lastname: Andriacchi
mesh_terms: D000368:Aged; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005684:Gait; D006801:Humans; D006820:Hyaluronic Acid / Q000097:blood*; D007719:Knee Joint / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D010003:Osteoarthritis / Q000097:blood* / Q000000981:diagnostic imaging / Q000503:physiopathology*; D011859:Radiography; D012720:Severity of Illness Index
chemical_list: D006820:Hyaluronic Acid