Effect of Comorbid Chronic Low Back Pain on Patient-Reported Outcome and Gait Parameters in Patients with Symptomatic Knee Osteoarthritis

Knee osteoarthritis and chronic low back pain are common and often coexist. There are limited studies on the impact of coexisting musculoskeletal disorders on gait parameters and its association with self-assessed functional outcome. This study compared gait parameters, self-assessed functional outcome measurements, and quality-of-life scales between patients with knee osteoarthritis against those with coexisting knee osteoarthritis and chronic low back pain using gait analysis, Western Ontario and McMaster Osteoarthritis Index, and Short Form-36. Three hundred sixty-seven patients underwent gait analysis after the question-based functional outcome measurement. Pain, function, and quality of life were worse in the coexisting knee osteoarthritis and chronic low back pain group (n = 197) compared with the knee osteoarthritis only group (n = 170, P = 0.017, P = 0.004, P < 0.001, P = 0.004, respectively). The coexisting knee osteoarthritis and chronic low back pain group had significantly lower gait velocity and cadence than the knee osteoarthritis group (P = 0.028 and P = 0.003). The Western Ontario and McMaster Osteoarthritis Index Pain subscore was associated with gait velocity (P < 0.001) in the knee osteoarthritis group, whereas Short Form-36 physical composite was associated with gait velocity (P < 0.001) in the coexisting knee osteoarthritis and chronic low back pain group. Comorbid chronic low back pain in patients with knee osteoarthritis was associated with worse pain, function, quality of life, gait velocity, and cadence. Compared with the Western Ontario and McMaster Osteoarthritis Index, Short Form-36 may be a more suitable tool to track mobility outcome measure, such as gait velocity, in the management of the coexisting knee osteoarthritis and chronic low back pain.