The study, published by Journal of Clinical Ultrasound in 2011, included 99 patients with radiographically confirmed knee osteoarthritis without effusion. The absence of effusion, fluid in the joint, makes finding the intra-articular space more difficult. Normally a physician would draw back synovial fluid to confirm accurate needle placement before injecting supplemental fluids. In cases of ‘dry knee’ osteoarthritis, clinicians cannot confirm needle placement with this method, which makes the use of ultrasound imaging essential.
Patients were randomly assigned to a control or test group. All patients were diagnosed 6 or more months prior to the study and experienced painful symptoms on most days in the 3 months before treatment. Both groups received a single superolateral injection with a 1.5 inch 21 gauge needle and a three-way stopcock. The ancillary valve allowed the simultaneous injection of hyaluronic acid and iopromide, an ultraviolet contrast dye solution. A single physician completed the procedure for both groups– a necessary variable to control.