The knee adduction moment and knee osteoarthritis symptoms: relationships according to radiographic disease severity.
To investigate relationships between external knee adduction moment parameters (KAM) and osteoarthritis (OA) symptoms according to disease severity.



164 participants with symptomatic medial knee OA were included. Radiographic severity was graded by (1) Kellgren & Lawrence (KL) scale (Grade 2, n = 49; Grade, n = 52; Grade 4, n = 63) and; (2) medial tibiofemoral joint space narrowing (JSN) (Grade 1, n = 47; Grade 2, n = 50; Grade 3, n = 67). KAM-related parameters (peak KAM, KAM impulse and cumulative load) were determined from three-dimensional gait analysis and pedometry. Cumulative load was determined by multiplying KAM impulse by the average number of steps/day recorded over at least 5 days. Symptoms were assessed via numeric rating scale ((NRS), pain) and Western Ontario and McMaster Universities (WOMAC) Osteoarthritis Index (pain and physical function). Relationships between KAM parameters (independent variables) and symptoms (dependent variables) were evaluated by radiographic severity using linear models, adjusting for covariates.



In mild disease (either KL Grade 2 or JSN Grade 1), there were no associations between KAM and symptoms. In moderate disease of KL Grade 3, higher KAM impulse was associated with greater WOMAC pain. In severe disease (KL Grade 4), higher KAM impulse was associated with less WOMAC pain (KL Grade 4), while higher peak KAM was associated with better function (KL Grade 4). Higher cumulative knee adduction load was associated with less pain on both NRS and WOMAC (JSN Grade 3) as well as better function (both JSN Grade 3 and KL Grade 4).



Relationships between KAM-related parameters and symptoms differ according to underlying radiographic OA severity.
Centre for Health, Exercise and Sports Medicine, Department of Physiotherapy, School of Health Sciences, Melbourne, The University of Melbourne, VIC, Australia.
M
M
Hall
Centre for Health, Exercise and Sports Medicine, Department of Physiotherapy, School of Health Sciences, Melbourne, The University of Melbourne, VIC, Australia.
K L
KL
Bennell
Centre for Health, Exercise and Sports Medicine, Department of Physiotherapy, School of Health Sciences, Melbourne, The University of Melbourne, VIC, Australia.
T V
TV
Wrigley
Centre for Health, Exercise and Sports Medicine, Department of Physiotherapy, School of Health Sciences, Melbourne, The University of Melbourne, VIC, Australia.
B R
BR
Metcalf
Centre for Health, Exercise and Sports Medicine, Department of Physiotherapy, School of Health Sciences, Melbourne, The University of Melbourne, VIC, Australia.
P K
PK
Campbell
Centre for Health, Exercise and Sports Medicine, Department of Physiotherapy, School of Health Sciences, Melbourne, The University of Melbourne, VIC, Australia; Department of Epidemiology and Preventive Medicine, School of Public Health and Preventive Medicine, Monash University, VIC, Australia.
J
J
Kasza
Centre for Health, Exercise and Sports Medicine, Department of Physiotherapy, School of Health Sciences, Melbourne, The University of Melbourne, VIC, Australia.
K L
KL
Paterson
Institute of Bone and Joint Research, The Kolling Institute, Sydney Medical School, The University of Sydney, Sydney, Australia; Rheumatology Department, Royal North Shore Hospital, Sydney, Australia.
D J
DJ
Hunter
Centre for Health, Exercise and Sports Medicine, Department of Physiotherapy, School of Health Sciences, Melbourne, The University of Melbourne, VIC, Australia. Electronic address: ranash@unimelb.edu.au.
R S
RS
Hinman
D005260:Female; D006801:Humans; D007719:Knee Joint / Q000000981:diagnostic imaging / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000000981:diagnostic imaging* / Q000473:pathology / Q000503:physiopathology*; D011859:Radiography; D016059:Range of Motion, Articular; D012720:Severity of Illness Index
Disease severity; Knee joint loading; Pain; Physical function