Joint Off-loading Therapies For Knee Osteoarthritis: A Pilot Randomized Clinical Trial

PURPOSE: Moderate walking exercise has known benefits in individuals with knee osteoarthritis (KOA); however, joint loading can increase pain, limiting engagement. Joint off-loading therapies reduce load on joints, potentially increasing exercise engagement. However, there are minimal trials of this treatment for KOA. Our objective was to determine longitudinal changes in joint pain, function, and systemic biomarkers associated with KOA, using a lower-body positive pressure (LBPP) treadmill or aquatic walking program compared to a control group with no active treatment. METHODS: Randomized clinical trial. 49 adults, aged>50 with KOA were enrolled in 3 groups for 8-weeks: (1) LBPP treadmill (2/wk), (2) Aquatic walking (2/wk), (3) Control (exercise recommendations). Primary outcome: Knee Injury and Osteoarthritis Outcome Score (KOOS). Secondary outcomes: 6-min. walk test (6-MWT), gait kinematics, Quality-of-Life survey (EQ-5D), and biomarkers in three domains: (1) Inflammatory mediators, (2) Cartilage degenerative enzymes, (3) Transforming growth factors. RESULTS: The LBPP group had a significant improvement in KOOS pain at 4-wk (p = 0.055), 8-wk (p = 0.008), and 3-6mo (p = 0.019), not observed in other groups. The LBPP group had significant improvements at 4-wk (p = 0.015) and at 8-wk in 6-MWT (p = 0.001). At 8-wk, aquatic walking had a significant improvement in KOOS sports subscale only (p = 0.012). Compared to baseline, LBPP was associated with significant change in abduction/adduction angle at 4- and 8-wk (p < 0.005). Only the LBPP group had a significant improvement in quality of life on the EQ-5D (p < 0.001). Both the control and aquatic groups saw significant increases in TGF-β1 concentration (p < 0.05). However, the control had a significant increase in the pro-inflammatory mediator, IL-1β (p = 0.03), and its associated protein IL-1ra (p = 0.009), not observed in either interventional group. Additionally, the aquatic group had an increase in MMP-7 concentration (p = 0.05), which is an enzyme associated with tissue remodeling. CONCLUSIONS: This is the first study to show that LBPP treadmill walking significantly improved symptoms and knee function. Additionally, longitudinal off-loaded walking therapies were not associated with an increase in systemic inflammation observed in the control. Supported by: Northwestern Pepper Center