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Arthritis Care Res (Hoboken). 2013 Mar;65(3):406-13. doi: 10.1002/acr.21825.

Perception and presentation of function in patients with unilateral versus bilateral knee osteoarthritis.

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University of Delaware, Department of Physical Therapy, Newark, DE 19716, USA.



Lower extremity functional performance and perception of functional abilities influence clinical management in people diagnosed with unilateral or bilateral knee osteoarthritis (OA). The purpose of this study was to determine if there were differences in perception of function and performance during functional tasks between individuals with unilateral and bilateral knee OA.


The functional abilities of patients with symptomatic and radiographic diagnosed unilateral (n = 84) or bilateral (n = 68) knee OA were evaluated with self-report measures and performance-based tests. Self-report measures included the Knee Outcome Survey, the Global Rating Scale, and the physical component of the Short Form 36 health survey; functional tests included the Timed Up-and-Go Test, the Stair Climbing Test, and the 6-Minute Walk Test. Multivariate analyses of variance were performed separately for men and women to determine if perception (self-report measures) and performance (functional tests) were dependent on the number of involved knees.


No significant main effects were observed in functional performance between groups for either sex. Similarly, the perception measures did not differ between groups. In general, individuals diagnosed with unilateral and bilateral knee OA both performed functional tasks and perceived their functional ability similarly.


Regardless of the number of involved knees, individuals with knee OA perform and perceive their functional ability similarly, which suggests that clinicians need to consider other factors, such as how long the disease has been progressing or how functional abilities have changed, when treating patients with knee OA.

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