Assessment of Knee Pain in Obese and Non-Obese Individuals Diagnosed with Osteoarthritis of the Knee Before and After Performance-Based Tests: A Pilot Study

Abstract

Objective: 1) To examine whether self-reported pain, measured with the Western Ontario McMaster University Osteoarthritis Index pain subscale and Visual Analog Scale, of individuals diagnosed with knee Osteoarthritis would change after performance-based tests were completed; irrespective of their body weight and Body Mass Index. 2) To assess whether self-reported pain before and after performance-based tests differs between obese and non-obese individuals and whether both VAS and WOMAC scales of pain would demonstrate similar changes from before to after the completion of performance-based tests in obese and non-obese individuals with knee OA. 3) To observe whether depressive symptoms and BMI explain the variance of self-reported pain before and after performance based tests.

Methods: This pilot study included 31 participants diagnosed with radiographic knee osteoarthritis by an orthopedic surgeon using the Kellgren-Lawrence Scale. The sample was divided in two groups of obese individuals with knee Osteoarthritis and non-obese individuals with knee osteoarthritis. Two self-reported measures, the Western Ontario McMaster University Osteoarthritis Index and Visual Analog Scale assessed knee pain before and after performance-based tests in these two groups of individuals. Depressive symptom was obtained with Back depression questionnaire II.

Results: The Visual Analog Scale ratings showed a significant increase in pain in both groups, but the Western Ontario McMaster University Osteoarthritis Index pain subscale only captured a significant increase in the obese osteoarthritis group. A significant proportion of variance in pain before and after functional activities was explained by depressive symptoms and obesity, with higher levels of depression and obesity predicting worse reports of pain.

Conclusion: The Visual Analog Scale pain rating may be a better tool for assessing knee pain of obese and non-obese individuals diagnosed with knee osteoarthritis. Furthermore, symptoms of depression might predict increase in knee pain and disability in obese individuals.