title: Influences of alignment and obesity on knee joint loading in osteoarthritic gait.
abstract: OBJECTIVE
  To determine the influences of frontal plane knee alignment and obesity on knee joint loads in older, overweight and obese adults with knee osteoarthritis (OA).
  
  
  METHODS
  Cross-sectional investigation of alignment and obesity on knee joint loads using community dwelling older adults (age ≥ 55 years; 27 kg m(-2) ≥ body mass or body mass index (BMI) ≤ 41 kg m(-2); 69% female) with radiographic knee OA that were a subset of participants (157 out of 454) enrolled in the Intensive Diet and Exercise for Arthritis (IDEA) clinical trial.
  
  
  RESULTS
  A higher BMI was associated with greater (P = 0.0006) peak knee compressive forces [overweight, 2411 N (2182, 2639), class 1 obesity, 2772 N (2602, 2943), class 2+ obesity, 2993 N (2796, 3190)] and greater (P = 0.004) shear forces [overweight, 369 N (322, 415), class 1 obesity, 418 N (384, 453), class 2+ obesity, 472 N (432, 513)], independent of alignment, and varus alignment was associated (P < 0.0001) with greater peak external knee adduction moments, independent of BMI [valgus, 18.7 Nm (15.1, 22.4), neutral, 27.7 Nm (24.0, 31.4), varus, 37.0 Nm (34.4, 39.7)].
  
  
  CONCLUSIONS
  BMI and alignment were associated with different joint loading measures; alignment was more closely associated with the asymmetry or imbalance of loads across the medial and lateral knee compartments as reflected by the frontal plane external adduction moment, while BMI was associated with the magnitude of total tibiofemoral force. These data may be useful in selecting treatment options for knee OA patients (e.g., diet to reduce compressive loads or bracing to change alignment).
authors.affiliation: Department of Health and Exercise Science, Wake Forest University, Winston-Salem, NC, USA; Section on Gerontology and Geriatric Medicine, Wake Forest University, School of Medicine, USA. Electronic address: messier@wfu.edu.
authors.forename: S P
authors.initials: SP
authors.lastname: Messier
authors.affiliation: Department of Health and Exercise Science, Wake Forest University, Winston-Salem, NC, USA. Electronic address: mhoops2@uic.edu.
authors.forename: M
authors.initials: M
authors.lastname: Pater
authors.affiliation: Department of Public Health Sciences, Wake Forest School of Medicine, Winston-Salem, NC, USA.
authors.forename: D P
authors.initials: DP
authors.lastname: Beavers
authors.affiliation: Department of Public Health Sciences, Wake Forest School of Medicine, Winston-Salem, NC, USA. Electronic address: clegault@wfubmc.edu.
authors.forename: C
authors.initials: C
authors.lastname: Legault
authors.affiliation: Division of Rheumatology, Allergy and Immunology Thurston Arthritis Research Center, University of North Carolina-Chapel Hill, USA. Electronic address: rloeser@wfubmc.edu.
authors.forename: R F
authors.initials: RF
authors.lastname: Loeser
authors.affiliation: Rheumatology Department, Northern Clinical School, University of Sydney, Sydney, Australia. Electronic address: david.hunter@sydney.edu.au.
authors.forename: D J
authors.initials: DJ
authors.lastname: Hunter
authors.affiliation: Department of Kinesiology, East Carolina University, Greenville, NC, USA. Electronic address: devitap@ecu.edu.
authors.forename: P
authors.initials: P
authors.lastname: DeVita
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology; D001696:Biomechanical Phenomena / Q000502:physiology; D015992:Body Mass Index; D017760:Bone Malalignment / Q000150:complications / Q000503:physiopathology*; D003430:Cross-Sectional Studies; D018450:Disease Progression; D005260:Female; D005684:Gait / Q000502:physiology*; D006801:Humans; D007719:Knee Joint / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000150:complications / Q000503:physiopathology*; D020370:Osteoarthritis, Knee / Q000503:physiopathology*; D016474:Weight-Bearing / Q000502:physiology*
keywords: Body mass index; Knee joint force; Varus