With a biomechanical treatment in knee osteoarthritis, less knee pain did not correlate with synovitis reduction

BACKGROUND Braces are used to treat pain in patellofemoral joint osteoarthritis (PFJOA). In a trial, we previously reported pain improvement after 6-weeks brace use. The pain reduction did not correlate with changes in Magnetic Resonance Imaging (MRI) assessed Bone Marrow Lesion volume or static synovial volume. Studies show that changes in the synovium on dynamic contrast enhanced (DCE) MRI are more closely associated with symptom change than static synovial volume changes. We hypothesised change in synovitis assessed using dynamic imaging could explain the reduction in pain. METHOD One hundred twenty-six men and women aged 40-70 years with painful radiographically confirmed PFJOA were randomised to either brace wearing or no brace for 6-weeks. Pain assessment and DCE-MRI were performed at baseline and 6 weeks. DCE data was analysed using Tofts's equation. Pain measures included a VAS of pain on nominated aggravating activity (VASNA), and the KOOS pain subscale. Paired t-tests were used to determine within person change in outcome measures and Spearman's correlation coefficients were used to determine the correlation between change in pain and change in the DCE parameters. RESULTS Mean age of subjects was 55.5 years (SD = 7.5) and 57% were female. There was clear pain improvement in the brace users compared to controls (VASNA - 16.87 mm, p = <0.001). There was no significant change to the dynamic synovitis parameters among brace users nor was pain change correlated with change in dynamic synovitis parameters. CONCLUSION The reduction in knee pain following brace wearing in patients with PFJOA is not explained by changes in synovitis. TRIAL REGISTRATION Trial registration number UK. ISRCTN50380458 /Registered 21.5.2010.