Arthritis & Rheumatism, Volume 63,
November 2011 Abstract Supplement

Abstracts of the American College of
Rheumatology/Association of Rheumatology Health Professionals
Annual Scientific Meeting
Chicago, Illinois November 4-9, 2011.


Muscle Parameters and Function Self-Efficacy in Knee Osteoarthritis.

Colbert,  Carmelita J., Hayes,  Karen W., Almagor,  Orit, Chmiel,  Joan S., Chang,  Alison H., Moisio,  Kirsten, Cahue,  September

Background/Purpose:

Self-efficacy has been associated with physical function outcome in persons with knee osteoarthritis (OA). Efforts to understand factors contributing to self-efficacy may identify targets to improve self-efficacy. Little is known about how hip and knee motor activity relate to self-efficacy in knee OA. Quantitative gait analysis provides insight into dynamic muscle unit function during gait. We hypothesized that knee extensor, hip abductor, and hip external rotator strength and the knee extensor and hip abductor moments during gait are each associated with function self-efficacy.

Methods:

250 persons with knee OA were evaluated. Isokinetic knee extensor and isometric hip abductor and external rotator average peak torques were determined using a Biodex dynamometer. Quantitative gait analysis at self-selected walking speed was performed using external passive reflective markers and an 8-camera motion analysis system to calculate knee and hip joint moments (internal moments normalized to %BW*Ht). Self-efficacy was assessed using the Arthritis Self-Efficacy Scale function subscale. Data were also collected using: questionnaire adaptation of the Charlson index, Geriatric Depression Scale, WOMAC pain scale, Pain Catastrophizing Scale, and Physical Activity Scale for the Elderly. Multiple linear regression analysis was used to evaluate the association of self-efficacy (dependent variable) with each muscle factor. We used the worse (of the two limbs) value for the factor to derive the unadjusted regression coefficients and associated 95% CI, and the coefficient (95% CI) adjusting for age, gender, BMI, comorbidity, depressive symptoms, knee pain severity, pain catastrophizing, and physical activity.

Results:

250 participants had a mean age of 64.8 (SD 10.2), BMI 28.6 (5.6), and 189 (76%) were women. Mean self-efficacy score was 25.2 (5.4), hip abductor strength 57.5 Nm (17.7), hip external rotator strength 27.0 Nm (11.0), knee extensor strength 63.3 Nm (24.6), hip abductor moment during gait 4.1 (0.8), knee extensor moment during gait 1.25 (0.4). The table shows the coefficients (95% CI), with significant results bolded. In an additional model including knee extensor strength, hip abductor moment, and hip external rotator strength and the covariates noted above, knee extensor strength, hip abductor moment during gait, BMI, knee pain severity, and depressive symptoms were each significantly associated with self-efficacy (R2 of this model 0.48).

Factors Associated with Function Self–Efficacy

 Unadjusted Coefficient (95% CI)Adjusted Coefficient (95% CI)
Knee extensor strength (per 10 Nm)0.73 (0.47, 0.99)0.80 (0.50, 1.09)
Knee extensor moment during gait (per 1%BWxHT)2.73 (1.25, 4.21)1.39 (0.03, 2.74)
Hip abductor strength (per 10 Nm)0.69 (0.32, 1.06)0.25 (-0.16, 0.65)
Hip abductor moment during gait (per 1%BWxHT)0.86 (0.01, 1.70)1.14 (0.41, 1.87)
Hip external rotator strength (per 10 Nm)1.12 (0.52, 1.72)1.25 (0.55, 1.95)

Conclusion:

Knee extensor strength and hip abductor moment during gait (as well as BMI, knee pain severity, and depressive symptoms) were independently associated with function self-efficacy in analyses adjusting for potential confounders. Longitudinal analyses will help to elucidate the direction of these relationships towards the goal of enhancing intervention to improve function self-efficacy in knee OA and lessen its deleterious consequences.

To cite this abstract, please use the following information:
Colbert, Carmelita J., Hayes, Karen W., Almagor, Orit, Chmiel, Joan S., Chang, Alison H., Moisio, Kirsten, et al; Muscle Parameters and Function Self-Efficacy in Knee Osteoarthritis. [abstract]. Arthritis Rheum 2011;63 Suppl 10 :1985
DOI:

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