Ultrasound-guided steroid injections for knee osteoarthritis are less painful, provide more pain relief, and cost less than conventional palpation.
Ultrasound (US) guidance is superior to conventional palpation for placement of steroid injections in patients with knee osteoarthritis (OA). Injections placed under US guidance were much less painful, resulted in better and longer pain relief, and reduced medical costs compared with conventional placement. With proper placement of injection, there were few side effects in a randomized controlled trial reported at the 2010 Annual Scientific Sessions of the American College of Rheumatology.
Studies of physicians who inject the knee have shown that they believed they correctly place corticosteroid injections 95% of the time, but data show that correct placement was documented only 50% to 90% of the time, explained Wilmer Sibbitt, Jr., MD, University of New Mexico Health Sciences Center, Albuquerque, NM, who presented results at an official ACR press conference.
“Injections are commonly done by interventional radiologists, but now that US is less expensive, rheumatologists are using it,” he said. Machines can cost anywhere from $20,000 to $200,000, and with reduced costs of machines, use of ultrasound guidance has accelerated in rheumatology, orthopedic surgery, and sports medicine, he added.
For the study presented at ACR, 94 patients with knee OA were randomized to receive injections under the traditional mode (palpation) versus US guidance. Both injections involved one needle with a syringe attached. The syringe entered the joint and removed fluid from it; then the first syringe was removed from the needle and a second syringe was attached through the same needle to inject lidocaine and then 80 mg of corticosteroid. This was done to ensure that the medication was injected in the correct site. US guidance was able to confirm correct needle placement as well as administration of lidocaine and corticosteroid during the procedure.
US placement resulted in a 50% reduction in peri-procedural pain and a 60% reduction in significant peri-procedural pain, Sibbitt said. After two weeks, pain scores were 42% lower in the group that underwent US guidance for injection. Moreover, US guidance also achieved a 107% increase in the number of people who responded to treatment as well as a 51.6% reduction in those who did not.
The length of time that participants experienced pain relief following the injection was increased by 35.5% in the US guidance group. “The effects of the medication lasted about a month longer in patients randomized to US guidance, presumably because the injection was given in the correct place. The need for further therapy was delayed in patients randomized to ultrasound, which reduced associated costs,” he told listeners.
A cost-effectiveness analysis showed that US led to a 14.6% reduction ($48 per procedure) in cost per year and a 58.8% reduction ($593) in the cost per hospital-outpatient participants who received their injections under US guidance.
“There is a tendency for rheumatologists and other doctors who give steroid injections to the knee to believe that they don’t need US. Patients should be aware that joint injections are likely to be more effective and less painful if given under US guidance, and physicians should be aware of this as well,” he said.