The hip joint is a large joint where the leg joins the pelvis, functioning as a ball and socket joint. The top of the thigh bone (the femur) is a round ball, which fits into the socket formed by a cavity in the pelvic bone. The ball is held in the socket by a grouping of ligaments that form a capsule around the joint. This capsule of ligaments contains a lubricating synovial fluid and cartilage, which allows the two bones to move against each other with minimal friction.
The Hip Joint injection procedure targets the hip joint thought to be responsible for a patient’s pain. The joint is injected and anesthetized with the intent of relieving this pain. The hip injection procedure delivers a low volume of concentrated medication directly into the affected hip joint. Hip pain usually arises from a degenerated or osteoarthritic hip. However, occasionally it can be “referred” pain, meaning that the patient feels the pain in the hip, but it is actually coming from the lumbar spine, and less commonly from the knee on the same side.
The hip joint injection is useful in both the diagnosis and the treatment of hip pain; therefore, it is both a diagnostic as well as a therapeutic procedure. In other words, if we inject a medication within the suspected hip joint space and the pain improves, we are fairly confident that the hip joint is responsible for the pain; conversely, if we inject a medication and the pain is no better, this implies that the pain is likely referred, most often from the lower back or the knee.
Frequently a dye is injected in order to evaluate the appearance of the joint and verify positioning of the injected medications.
II. The Hip Joints
The Hip Joints contain joint fluid and are lined by cartilage.
Like any other joint in the body, hip joints can become diseased, and thereby become painful.
By far the most common disease affecting the hip joints is arthritis. This is a degenerative, inflammatory condition that over time results in loss of joint cartilage, bone overgrowth (‘osteophytes’ or ‘spurs’), erosions of the joint, and ultimately instability of the joint itself.
The hip joints and their surrounding tissues are lined with nerves. As this degenerative, inflammatory condition progresses, the nerve endings become irritated and inflamed; this produces the sensation of pain. Any and all of this degenerative process may be painful.
The primary role for imaging studies prior to the procedure is to evaluate for other arthritis, or other less likely causes of back pain.
III. Patient Selection
Unfortunately, while imaging studies (X-rays, MRI and CT scans) are helpful in screening the hips for a potential cause of pain, but are often unreliable in determining whether or not a given hip joint may be the source of pain.
They help in identifying and characterizing the extent of hip degeneration, but like any other joint in the body, the extent of degeneration doesn’t necessarily correlate with the amount of pain. In other words, some patients may show severely degenerated hip joints on imaging studies, but be relatively asymptomatic. Conversely, some patients experiencing severe pain from the hip joints may show relatively mild degenerative findings on imaging studies. For this reason, the patient’s history and physical exam are very important in helping to clarify the source responsible for pain.
IV. Procedure: Hip Join Injection
The procedure is explained to the patient, questions are answered and informed consent is obtained. The patient is placed on the fluoroscopic table, and the symptomatic hip is sterilely cleansed with povidone-iodine (Betadine) and alcohol.
The exact level is located with the fluoroscope, and the skin overlying this area is anesthetized (numbed) with lidocaine. A needle is sterilely advanced into the hip joint. A small amount of water-soluble contrast (dye) is injected to confirm proper needle tip position. Once this is confirmed, a mixture of anesthetic (lidocaine or bupivacaine) and anti-inflammatory medication (steroid) is injected. The needle is slowly withdrawn. This procedure is performed with Fluoroscopic (X-RAY) guidance.
The injection itself only takes a few minutes, but the overall procedure will usually take between thirty and sixty minutes. After the hip joint injection procedure, the patient typically remains resting on the table for twenty to thirty minutes, and then is asked to move the area of usual discomfort to try to provoke the usual pain. Patients may or may not obtain pain relief in the first few hours after the injection, depending upon whether or not the joint that was injected is the main source of the patient’s pain. On occasion, the patient may feel numb or experience a slightly weak or odd feeling in the leg for a few hours after the injection.
Shortly after the procedure, the interventional pain physician will examine the patient to determine if there has been improvement.
Some individuals may have pain that mimics pain from the hip joint but is actually coming from bursitis adjacent to the hip.
The trochanteric bursa is located over the prominent bone on the side of the hip. Women and middle-aged to older people are more often affected by this type of bursitis. It may occur spontaneously without specific injury. Also, walking abnormally due to arthritis in the hip, knee, ankle, foot, or back can cause it. Symptoms include pain gradually occurring over the side of the hip (and sometimes traveling down the thigh); pain when sleeping on the side affected by bursitis, rising from a deep chair, sitting in a car, or climbing stairs; and occasionally, pain when walking.
The ischial bursa is located below the bone in your buttock called the ischium. Inflammation may occur as a result of injury or prolonged sitting on hard surfaces. Symptoms include pain when sitting or lying down on the buttocks and pain that travels to the back of the thigh. Ischial bursitis is also called “weaver’s bottom” or “tailor’s seat.”
Potential Risks of Hip Joint Injections
- Allergic reactions to medication or dye used
- Infection (occurs in less than 1 per 15,000 injections)
- Post-injection flare (joint swelling and pain several hours after the corticosteroid injection)
- Depigmentation (a whitening of the skin)
- Local fat atrophy (thinning of the skin)
- Rupture of a tendon located in the path of the injection
- Bleeding, nerve injury, organ injury and death are rare but possible