An arthrogram is a specialized medical imaging procedure used to obtain detailed pictures of a joint, such as the shoulder, hip, or knee. This test is performed when standard X-rays or other non-invasive scans do not provide enough information to diagnose a joint issue. The procedure requires the injection of a liquid contrast material, often called a dye, directly into the joint space. This substance temporarily outlines the structures within the joint capsule, making them visible on subsequent imaging scans.
What is an Arthrogram and When is it Used
The primary function of an arthrogram is to visualize the soft tissues inside a joint that are difficult to evaluate with conventional imaging alone. These tissues include the cartilage, ligaments, tendons, and the joint capsule itself, which do not show up clearly on standard X-rays because they are not dense bone material. The contrast material acts as an internal spotlight, filling the joint space and any small tears or defects within these structures.
This procedure is typically ordered when a patient experiences unexplained joint pain, discomfort, or a loss of motion that other tests have failed to clarify. Common joints examined include the shoulder, knee, hip, wrist, and ankle. Arthrograms are highly effective for diagnosing specific issues like labral tears, partial-thickness tendon tears, or loose bodies within the joint. The contrast material allows a radiologist to see if fluid leaks out of the joint, indicating a tear or rupture. The procedure is often followed by a Computed Tomography (CT) scan or Magnetic Resonance Imaging (MRI), creating a CT or MR arthrogram.
Preparing for the Procedure and the Steps Involved
Preparing for an arthrogram involves discussing your current health status and medications with your physician and the radiology team. It is important to inform the doctor about any known allergies, especially to iodine or contrast media, and if you are taking blood-thinning medications like aspirin or other anticoagulants. Depending on the type of imaging to follow the injection, such as an MRI, you may also need to remove all jewelry and metal objects before the test.
The procedure begins with the patient positioned comfortably on an examination table. The skin over the joint is thoroughly cleaned with an antiseptic solution and sterile drapes are placed around the area to maintain a sterile field. A local anesthetic is then injected using a small needle to numb the skin and surrounding tissue, which helps minimize discomfort during the main injection.
Using a real-time X-ray technique called fluoroscopy or an ultrasound machine, the physician precisely guides a thin needle into the joint space. This imaging guidance ensures the contrast material is delivered accurately into the joint capsule. If excess fluid is present, the physician may remove a small sample through the needle before injecting the contrast material.
The contrast agent is then injected into the joint. After the injection, the patient may be asked to gently move the joint to help distribute the contrast material evenly across the internal surfaces. The patient is then moved immediately to the CT or MRI scanner so the detailed images can be taken before the contrast material is absorbed by the body.
After the Test and What the Results Reveal
Following the arthrogram, you should plan to rest the affected joint and avoid strenuous activity for 12 to 24 hours. It is common to experience a temporary feeling of fullness or mild swelling in the joint due to the injected fluid, which typically resolves within a day. Over-the-counter pain relievers, such as acetaminophen or ibuprofen, are generally sufficient to manage any soreness at the injection site.
A radiologist analyzes the detailed pictures created by the arthrogram. The contrast material provides a clear visual boundary, allowing the detection of abnormalities that were previously invisible. If there is a tear in the joint capsule or a ligament, the contrast agent will leak out into the surrounding tissue or fill the defect, clearly outlining the injury. The radiologist compiles a diagnostic report, which is then sent to the referring physician to determine the next steps for treatment.