Ultrasound needle guidance improves performance and outcomes of knee injections

The use of ultrasound needle guidance improves the performance, outcomes and the cost-effectiveness of knee injections in people with osteoarthritis, according to research presented this week at the American College of Rheumatology Annual Scientific Meeting in Atlanta.

Osteoarthritis, or OA as it is commonly called, is the most common joint disease affecting middle-age and older people. It is characterized by progressive damage to the joint cartilage—the cushioning material at the end of long bones—and causes changes in the structures around the joint. These changes can include fluid accumulation, bony overgrowth, and loosening and weakness of muscles and tendons, all of which may limit movement and cause pain and swelling.

Researchers recently set out to determine if the use of ultrasound guidance would affect the outcomes of intraarticular injections—injections of medicine into, or removal of fluid from, arthritic joints—in people with knee OA. "Ultrasound, the use of sound waves to visualize the human body, is useful to physicians to guide the needle into the joint to inject medications to treat arthritis," explains Wilmer Sibbitt, Jr., MD; professor of rheumatology and neurology, University of New Mexico Health Sciences Center, Albuquerque, N.M. and an investigator in the study.

Dr. Sibbitt's research team studied 94 knees, which were randomly selected for injection administered either by the conventional palpation-guided method or by the newer ultrasound-guided method (which allowed researchers to watch, in real time, the needle entering and exiting the joint).

Both the palpation and ultrasound-guided methods involved one needle, with a syringe attached, entering the joint to remove fluid from it. After that was accomplished, the first syringe was removed (with the needle remaining inserted) and a second syringe was used to inject 80mg of a corticosteroid through the same needle. This technique ensured the medication was injected into the correct place. When using the ultrasound-guided method, researchers were able to perform the procedure while confirming needle placement as well as administration of the lidocaine and the corticosteroid by viewing the procedure as it occurred.

Each participant's initial pain, pain during the procedure, and knee pain at the end of two weeks and six months were studied. Researchers looked at who responded to the treatment, the length of time the participants experienced pain relief after the injection, how often participants needed to be reinjected, the total cost of the procedure, and the cost per participant who responded to the treatment.

When compared to the palpation-guided method, researchers found the use of the ultrasound-guided method to provide improved results - including a 107 percent increase in the number of people who responded to the treatment and a 51.6 percent reduction in the number of people who did not.

Additionally, researchers noted a 47 percent reduction in pain during the procedure, a 41.7 percent reduction in pain two weeks after the injection, and a 35.5 percent increase in the length of time the participants experienced pain relief after the injection.

Finally, researchers compared the cost effectiveness of the ultrasound-guided method to the traditional palpation method. They found that the ultrasound method led to a 14.6 percent ($48) reduction in cost per participant per year and a 58.8 percent ($593) reduction in the cost per hospital-outpatient participant who responded to the treatment.

These results have led researchers to believe that the use of ultrasound-guidance in intraarticular injections is an approach that can improve the overall treatment of knee OA, which will improve treatment costs as a patient's need for additional expensive treatments can be reduced.

"The study demonstrates that when physicians use ultrasound and a technique called hydrodissection performed with precise new mechanical syringes to inject the joint, the patient experiences less pain, improved safety, a better response to medications, and less need for other medical therapy," says Dr. Sibbitt. "Rheumatologists are increasingly using ultrasound, and patients should be aware that joint injections may be more effective and less painful if their physician offers this option to them."

Patients should talk to their rheumatologists to determine their best course of treatment.