Can single limb support objectively assess the functional severity of knee osteoarthritis?

There is a lack in objective measurements that can assess the symptoms of knee osteoarthritis (KOA). In a previous study it was shown that pain and function are in higher correlation with the single-limb support gait parameter than with radiographic KOA stage. Single limb support represents a phase in the gait cycle when the body weight is entirely supported by one limb, while the contra-lateral limb swings forward. The purpose of this study was to further examine the relationship between single-limb support and the level of pain and function in patients with KOA. 125 adults with bilateral KOA underwent a physical and radiographic evaluation, and completed the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and the SF-36 health survey. Patients walked barefoot at a self-selected speed on a computerized mat. Statistical analysis was used to divide the patients into quintiles based on single-limb support phase value and determine the differences in WOMAC and SF-36 scores between quintiles. Significant differences were found in WOMAC and SF-36 sub-category scores between the single-limb support quintiles. The means of the WOMAC-pain and WOMAC-function sub-categories decreased gradually over single-limb support quintiles (P < 0.001), and the means of the SF-36 sub-categories increased gradually over the quintiles (P < 0.001). Results show that single-limb support quintiles can help determine the level of pain, function and quality of life in patients with KOA. These results suggest that single-limb support quintiles may be added as an additional scale for generally assessing the symptomatic stage of KOA.