title: Knee joint loading differs in individuals with mild compared with moderate medial knee osteoarthritis.
abstract: OBJECTIVE
  To compare the knee joint loading patterns in individuals with differing radiographic grades of knee osteoarthritis (OA) for characterization of the mechanical implications of different structural states, and to compare the knee adduction angular impulse, a measure of gait complementary to the commonly used peak knee adduction moment.
  
  
  METHODS
  Asymptomatic subjects (those without knee OA) having a Kellgren/Lawrence (K/L) radiographic severity grade of 0 or 1 (n = 28) and subjects with symptomatic knee OA having K/L grades of 2 (n = 66) or 3 (n = 23) were recruited. Gait analysis was used to calculate the peak external knee adduction moment and the external knee adduction angular impulse for the whole stance and for the 4 subdivisions of stance.
  
  
  RESULTS
  Both the peak knee adduction moment and the knee adduction angular impulse increased with K/L radiographic grade (P < 0.05). However, only the knee adduction angular impulse differed between subjects with moderate (grade 3) and those with mild (grade 2) radiographic knee OA (P < 0.05).
  
  
  CONCLUSIONS
  The differences between mild and moderate symptomatic radiographic knee OA are not only structural but also functional, based on the magnitude of load in the medial knee joint. Moreover, knee adduction angular impulse provides additional information beyond that available from the peak knee adduction moment, and may therefore be an important gait parameter to include in OA research. These findings are important for our understanding of the pathophysiologic mechanisms of OA.
authors.affiliation: Rush University Medical Center, Chicago, Illinois 60612, USA.
authors.forename: Laura E
authors.initials: LE
authors.lastname: Thorp
authors.forename: D Richman
authors.initials: DR
authors.lastname: Sumner
authors.forename: Joel A
authors.initials: JA
authors.lastname: Block
authors.forename: Kirsten C
authors.initials: KC
authors.lastname: Moisio
authors.forename: Susan
authors.initials: S
authors.lastname: Shott
authors.forename: Markus A
authors.initials: MA
authors.lastname: Wimmer
mesh_terms: D001175:Arthrography; D005080:Exercise Test; D005260:Female; D005684:Gait / Q000502:physiology*; D006801:Humans; D007719:Knee Joint / Q000000981:diagnostic imaging / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000145:classification / Q000175:diagnosis / Q000503:physiopathology*; D016059:Range of Motion, Articular / Q000502:physiology; D016037:Single-Blind Method; D016474:Weight-Bearing / Q000502:physiology