What Is Ultrasound-Guided Hip and Knee Injections?
Diagnostic ultrasound uses sound waves, not radiation, to create a live picture of the tissues under your skin. A small handheld probe is placed on your hip or knee with a layer of gel, and the image appears on a screen. Your physician can see the joint, the surrounding tendons and the bursae (small fluid-filled sacs that cushion tendons over bone), and watch the needle as it moves toward the target.
Guidance matters most for deeper areas such as the hip joint, and when the target is small. It can also help your physician check for fluid in the joint and draw it off before injecting. What is injected depends on your condition:
- Cortisone (a corticosteroid), a medicine that calms inflammation, often mixed with a numbing medicine
- Hyaluronic acid, a gel that supplements joint fluid, which is FDA-approved for knee osteoarthritis and used off-label in the hip
- Platelet-rich plasma (PRP), prepared from your own blood, for selected patients; evidence is still developing and results vary
Our separate pages on hyaluronic acid and PRP injections explain those treatments in more detail.
Performed in our office using diagnostic ultrasound, usually during a short visit.
Who Is a Candidate?
An ultrasound-guided injection may be recommended if you have:
- Hip arthritis or knee osteoarthritis that still hurts despite activity changes, physical therapy and medicines
- Hip bursitis, causing pain on the outside of the hip, that has not settled with rest and therapy
- Pain where the source is unclear, such as hip pain that could be coming from the joint, a bursa or the lower back
A diagnostic injection uses a numbing medicine placed in a specific spot. If your pain eases for the next few hours, that suggests the area injected is a source of your pain, which can help guide further treatment, including decisions about surgery. You should not have an injection if the skin over the area or the joint is infected. Tell us about allergies, blood thinners and diabetes, since cortisone can raise blood sugar for a few days.
Dr. Kerr, a hip and knee replacement surgeon, offers ultrasound-guided hip and knee injections in our office. Dr. Adelman is dual board-certified in family medicine and sports medicine (CAQSM) and has advanced expertise in interventional musculoskeletal ultrasound.
What to Expect
Your physician first reviews your history, examines you and looks at your X-rays, which can be taken on site. You lie on the exam table, and the physician scans the area to find the target. The skin is cleaned, and a numbing medicine may be used. The needle is then guided into place while your physician watches the screen, and the medicine is injected.
Most injection visits are short. You walk out afterward, though you may want someone to drive you if your leg feels numb or unsteady from the numbing medicine. If the injection was diagnostic, your physician may ask you to note how your pain feels over the next several hours.
Risks and Side Effects
Ultrasound-guided injections are generally well tolerated. Possible side effects include:
- Soreness at the injection site for a day or two, and sometimes a short-lived flare of pain after cortisone
- Bruising, or temporary numbness or weakness in the leg from the numbing medicine
- A temporary rise in blood sugar after cortisone if you have diabetes
- Rare risks such as infection, bleeding or allergic reaction
Recovery
Most people return to normal daily activity the same day or the next day. Your physician may ask you to avoid strenuous exercise for a day or two. Cortisone often begins to work within several days, while hyaluronic acid and PRP tend to work more gradually. How long any relief lasts varies from person to person.
An injection is usually one part of a larger plan. Our physical therapists work in the same office and share your chart, so a strengthening program can start once the pain has eased.
Physical therapy happens in our office, with therapists who share your chart. Learn about on-site physical therapy.
Insurance and Cost
Cortisone injections are usually covered by Medicare and commercial plans when medically necessary, subject to your co-pay, co-insurance and deductible. Coverage for the ultrasound guidance itself varies by plan, so ask our team.
Hyaluronic acid is FDA-approved for the knee and is often covered there when criteria are met; in the hip it is off-label and usually not covered. PRP is usually not covered by insurance. Our team verifies your benefits and explains any costs when you call.
When to Talk to a Specialist
Call our office if hip or knee pain limits your walking, sleep or daily activities, or if earlier treatments are no longer helping.
After an injection, go to the emergency room or call 911 if you have fever, spreading redness, warmth or drainage at the injection site, which can be signs of infection, or if your hip suddenly gives way or you suddenly cannot bear weight on the leg once the numbing medicine has worn off.
