Association of pain with frequency and magnitude of knee loading in knee osteoarthritis
Article first published online: 29 JUN 2011
Copyright © 2011 by the American College of Rheumatology
Arthritis Care & Research
Volume 63, Issue 7, pages 991–997, July 2011
How to Cite
Robbins, S. M., Birmingham, T. B., Callaghan, J. P., Jones, G. R., Chesworth, B. M. and Maly, M. R. (2011), Association of pain with frequency and magnitude of knee loading in knee osteoarthritis. Arthritis Care Res, 63: 991–997. doi: 10.1002/acr.20476
- Issue published online: 29 JUN 2011
- Article first published online: 29 JUN 2011
- Accepted manuscript online: 11 APR 2011 01:08PM EST
- Manuscript Accepted: 18 MAR 2011
- Manuscript Received: 11 SEP 2010
- Natural Sciences and Engineering Research Council of Canada. Grant Number: 353715
- Fowler Kennedy Sports Medicine Clinic
- Joint Motion Program, a CIHR Training Program in Musculoskeletal Health Research and Leadership
- Physiotherapy Foundation of Canada through an Ann Collins Whitmore Memorial Award
Although the relationship between pain and the magnitude of medial knee loading has been previously studied, the contribution of frequency of loading has not. The objective of this study was to determine whether the addition of loading frequency (steps/day) to loading magnitude (knee adduction moment [KAM] impulse) helps explain variance in knee pain in people with knee osteoarthritis (OA).
Participants were adults with symptomatic knee OA with radiographic signs in the medial knee compartment (n = 38, 10 women). Pain was measured using the pain subscale of the Knee Injury and Osteoarthritis Outcome Score. Participants wore an accelerometer for 1 week to determine the average number of steps/day. The external KAM impulse was calculated from 3-dimensional gait analysis as participants ambulated at self-selected speeds. Knee extensor strength was measured with an isokinetic dynamometer. Linear regression was used to examine the relationship between pain and steps/day after controlling for the KAM impulse, knee extensor strength, and body mass index (BMI).
After controlling for BMI (R2 = 0.02), knee extensor strength (R = 0.26, P < 0.05), and KAM impulse (R = 0.11, P < 0.05), steps/day contributed an additional 9% of variance in pain (P < 0.05). This model accounted for a total of 49% of the variance in pain (F[4,33] = 7.77, P < 0.05).
Increased knee loading frequency and magnitude were associated with increased pain. Objective measures of loading frequency should be considered when investigating the incidence and progression of knee OA.