WITHDRAWN: Predictive potentials of 8 muscle strength actions, KOOS-pain, and Örebro-psychosocial difficulties on self-reported activities-of-daily-life function in patients with knee osteoarthritis: an exploratory regression-based cross-sectional study

Abstract

BackgroundThe aim of the study was to explore the relative predictive potentials of a discriminative and comprehensive set of lower-limb muscle strength factors onto self-reported physical-activities-of-daily-life-function (SR-ADL-function) in patients with knee osteoarthritis (KOA), when adjusting for prior known strong prospective predictors in a statistical model which covers the functional domains of the International Classification of Function, Disability, and Health (ICF). MethodsThe design was exploratory, patient-only, cross-sectional, and multivariable regression-based, rotating 8 strength-variables onto a hierarchical model. The setting was an Osteoarthritis-school in a secondary-care hospital in Norway. The participants were 28 Caucasian patients with mild-to-moderate symptomatic and radiographic KOA (mean age 61; 64% women) referred by general physicians to an osteoarthritis-school. Excluded patients had trauma to the lower limbs, BMI >35, and age beyond 45 to 70. The dependent/outcome variable was SR-ADL-function (Knee Injury and Osteoarthritis Outcome Score [KOOS-ADL]). The known predictors were prior documented discriminative KOOS-Pain and psychosocial difficulties (Örebro Musculoskeletal Pain Questionnaire), together with 8 candidate predictor lower-limb muscle-strength actions (Biodex and Commander II dynamometer recorded).ResultsMutually adjusted for pain and psychosocial difficulties (R2 = 0.71), the predicting muscle-strength actions explained the following unique variances in SR-ADL-function: hip external rotation 7.6% (p<0.010), ankle eversion 4.0% (p=0.050), hip internal rotation 3.8% (p=0.060), ankle inversion 3.6% (p=0.066). The remaining 4 muscle-strength actions explained from 2.0% to 1.2% (p>0.099), where knee extensor strength explained the least unique variance. Flipped, the current three best potential prediction models explained the following substantial proportions of variance in SR-ADL-function: 1) KOOS-pain, 66%; 2) KOOS-pain and Örebro psychosocial difficulties, 71%; and 3) KOOS-pain, Örebro psychosocial difficulties, and hip external rotation strength, 78%.ConclusionsAdjusted for pain and psychosocial difficulties, hip rotations and ankle eversion-inversion strength indicate substantial cross-sectional potentials for predicting SR-ADL-function for patients with KOA aged 45 to 70 in primary/hospital health-care. Relevant for future prevention and prediction/treatment studies, however, we suggest clinical researchers to consider the current muscle-strength actions together with the even stronger biopsychosocial predictors KOOS-pain and Örebro psychosocial difficulties for future ICF domain-covering models of SR-ADL. Future confirmative studies are needed to refute or generalize these pioneering exploratory conclusions.