Background Subjects with knee osteoarthritis (OA) and self-reported knee instability have a higher fall incidence than healthy older adults1. Increased risk of falls might be associated with knee instability related factors: muscle weakness, impaired proprioception, high varus-valgus joint laxity and knee pain2.
Objectives To establish the associations between knee muscle strength, knee joint proprioception, varus-valgus knee joint laxity, knee pain and falls in patient reporting knee instability and with established knee OA.
Methods Data of 301 subjects (203 females, 98 males, 35-82 year) with diagnosed knee OA and self-reported knee instability were analysed. The experience of at least one fall in the previous 3 months was assessed by questionnaire. Knee muscle strength, knee proprioception, and varus-valgus knee joint laxity were assessed using specifically designed measurement devices and pain was assessed with a numeric rating scale (NRS). Differences in biomechanical factors between fallers and non-fallers were calculated. To assess the associations between biomechanical factors and falls, logistic regression analyses were performed.
Results Over 10% (31 out of 301) of subjects reported a fall in the previous 3 months. Between fallers and non-fallers, significant differences were found for knee extension muscle strength (p=0.017), knee flexion muscle strength (p=0.041) and knee pain (p<0.001). Knee extension muscle strength (OR 0.3, 95% CI 0.1-0.8, p=0.022), knee flexion muscle strength (OR 0.2, 95% CI 0.0-1.0, p=0.048) and knee pain (OR 1.4, 95% CI 1.2-1.6, p<0.001) were associated with falls. No significant associations were found for knee proprioception and varus-valgus knee joint laxity. The association between knee muscle strength (extension and flexion) and falls was not affected by knee proprioception or varus- valgus knee joint laxity. Knee pain was independently associated with falls. In multivariate regression analyses, both knee extension and flexion strength were not associated with falls when pain was included in analyses.
Conclusions Low knee extension and flexion muscle strength, and high knee pain are associated with an increased risk of falls in patients with knee OA and self-reported knee instability
Hoops ML, Rosenblatt NJ, Hurt CP, Crenshaw J, Grabiner MD. Does lower extremity osteoarthritis exacerbate risk factors for falls in older adults? Women's Health. 2012;8(6):685-98.
Sturnieks DL, Tiedemann A, Chapman K, Munro B, Murray SM, Lord SR. Physiological risk factors for falls in older people with lower limb arthritis. The Journal of Rheumatology. 2004;31(11):2272-9.
Disclosure of Interest None declared
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