Correlation between the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) Scores and the Stability Metrics in Patients with Knee Osteoarthritis

The aim of the present study was to assess the correlation between the stability metrics related to the center of pressure excursion measurements and the WOMAC questionnaire scores.

Method and Materials:

Fourteen patients with moderate knee osteoarthritis and fourteen healthy age-matched individuals were participated to stand with open and closed eyes, and on firm and rocking support on a force platform. The WOMAC questionnaire was obtained from the patient group. One-way ANOVA was utilized to determine the effects of knee osteoarthritis, vision, and support on postural stability metrics. Spearman’s correlation was also used to indicate the correlation between the stability metrics and the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) sub scores.

The anterior-posterior variability of the center of pressure was significantly greater in patients (2.7 mm, p=.003). Elimination of the visual feedback and the rocking support affected the sway area and the AP (p<.001), and the ML variability (p<.024). The pain subscore of the WOMAC questionnaire was negatively and strongly correlated to the AP total mean velocity (open-eyes: r=-.466, closed-eyes: r=-.779). The pain was positively and strongly correlated to the AP variability (open-eyes: r=.796, closed-eyes: r=.744). Patients with knee osteoarthritis showed more postural instabilities.

The instability in the anterior-posterior was more eminent than in the lateral direction. The pain was the most role-playing factor in the destabilization of the posture among the patients with knee osteoarthritis but may be disregarded in physically-difficult conditions of standing.