Knee Confidence as It Relates to Self-reported and Objective Correlates of Knee Osteoarthritis: A Cross-sectional Study of 220 Patients

Study Design Cross-sectional study. Objective The objective was to validate, if possible, previously reported associations and to investigate other potential associations between knee confidence and various self-reported and objective measures in an independent cohort of patients with knee osteoarthritis (OA). Background Lack of knee confidence is a frequent symptom in patients with knee OA, but little is known of associations between knee confidence and other common correlates of knee OA. Methods Baseline data from 220 patients with knee OA were applied in ordinal regression analyses, with knee confidence, assessed using item Q3 of the Knee injury and Osteoarthritis Outcome Score, as the dependent variable and self-reported (pain on walking, general health, fear of movement, self-efficacy, function, and previous serious injury) and objective measures (muscle strength, 20-m walk time, and radiographic severity of tibiofemoral OA) as predictor variables. Results Most (95%) of the participants reported lack of knee confidence, and 54% experienced severe or extreme lack of knee confidence. Fear of movement (odds ratio [OR] = 2.06; 95% confidence interval [CI]: 1.15, 3.68), pain on walking (OR = 1.21; 95% CI: 1.09, 1.34), and general health (OR = 0.024; 95% CI: 0.002, 0.259) explained 19% of the variance in knee confidence (P<.001). Conclusion Severe lack of knee confidence is a common finding in individuals with knee OA. Pain on walking was confirmed as a correlate of knee confidence, whereas muscle strength was not. Fear of movement and poor general health were new variables associated with lack of knee confidence. The noncorrelations or poor correlations with other tested variables suggest that a lack of knee confidence may represent an independent treatment target in knee OA of importance to improve mobility. Trials registered at ClinicalTrials.gov (NCT01410409 and NCT01535001). J Orthop Sports Phys Ther 2015;45(10):765-771. Epub 24 Aug 2015. doi:10.2519/jospt.2015.5864.