Prevalence of Strength Deficits of Core and Hip Stabilizers in Knee Osteoarthritis: A Cross-Sectional Study.

BACKGROUND: Deficits in proximal hip and trunk stabilizers may increase mechanical stress on the knee and contribute to the progression of knee osteoarthritis (OA). The aim of the present study was to determine the prevalence of core and hip muscle deficits in individuals with knee OA compared with asymptomatic controls. METHODS: 152 participants with knee OA and 235 asymptomatic individuals aged 40-70 years were recruited from the community. Core muscle activation was assessed using a pressure biofeedback unit, and hip stabilizer's muscle strength was measured using a hand-held hydraulic dynamometer. Descriptive statistics, independent t-test, prevalence estimates, odds ratios (OR), risk ratios (RR), and 95% confidence intervals (CI) were used for data analysis. RESULTS: Deep core muscle deficits were present in 94.07% of individuals with knee OA, with 83.91% unable to activate the transversus abdominis (TrA). Hip muscle weakness was substantially more prevalent in the OA group, affecting hip extensors (61.18%-64.47%), abductors (65.13%-73.68%), and external rotators (36.84%-51.97%). In contrast, the prevalence of hip strength and core activation deficits in asymptomatic individuals was significantly much lower. Individuals with knee OA had nearly fourfold higher odds ratio of TrA weakness and 2.5 to 8 fold higher odds of hip muscle weakness than asymptomatic participants. CONCLUSION: Core muscle and hip muscle deficits are significantly prevalent in individuals with knee OA. These findings support the inclusion of proximal strengthening exercises in rehabilitation programs, in addition to local knee strengthening exercises, for patients with knee OA. TRIAL REGISTRATION: CTRI/2021/02/031534.