Arthrography is the radiologic examination of soft tissue structures in the joints following an injection of a contrast agent with or without air. The structures demonstrated are the menisci, ligaments, tendons, articular cartilage, and bursae.
Purpose
The most commonly studied joints are the knee and shoulder, but this procedure may also be done on the hip, wrist, elbow, ankle and temporomandibular joints. Arthrography of the knee or a knee arthrogram is the most frequently performed arthrographic procedure; it is requested for patients with persistent pain, decrease in range of motion, or locking of the knee. Arthrography of the shoulder may be used to demonstrate partial or complete tears of the rotator cuff. A hip arthrogram is often used to detect a loose hip prosthesis or a congenital abnormality. Arthrography of the temporomandibular joints is ordered to detect abnormalities of the articular disk due to trauma or loosening of the ligaments. In many cases, however, an MRI may be obtained instead of an arthrogram.
Precautions
Patients who are or may be pregnant should not have this procedure unless the benefits of the findings out-weigh the risk of radiation exposure. Patients who are known to be allergic to iodine should discuss this complication with their physician. Routine x rays of the affected joint must be taken before starting an arthrogram to ensure that there is no fracture or dislocation.
Description
The patient is asked to change into a hospital gown for a hip, knee, or shoulder arthrogram. Since arthrography is done in a sterile field to prevent infection, the x-ray technologist must be trained to work with the radiologist under sterile conditions. All needles, syringes, contrast material, local anesthetic, extension tubing, and cleansing solutions are prepared in advance by the x-ray technologist depending on the part to be examined.
Routine x rays of the affected joint are done by the x-ray technologist if no recent x-rays have been taken. The films are reviewed by the radiologist to ensure that there is no fracture or dislocation in the joint.
The radiologist begins the procedure by cleansing the skin of the affected joint and applying a sterile drape. The x-ray technologist places all the required needles and syringes onto the sterile tray using proper sterile technique and assists the radiologist by drawing up the anesthetic and contrast material into the various syringes.
Once the area of skin over the joint has been numbed with a local anesthetic, the radiologist will place the needle into the joint, using x-ray images to guide placement. Additional fluid in the joint may be aspirated and sent for analysis, particularly if a joint infection is suspected. A small test injection of the contrast medium is done to confirm accurate needle placement. The contrast medium is then injected either with or without air depending on the area under investigation. The needle is removed and a small self-adhesive dressing is applied. The joint is then manipulated to properly distribute the contrast medium over the entire joint space.
Before the contrast medium can be absorbed by the joint itself, several films will be taken by the radiologist. The patient will be asked to move the joint into a series of positions, keeping still between positioning. During a knee arthrogram, the knee is manually stressed by the radiologist to open the joint space. Patients may experience some tingling or discomfort during the procedure. These are normal reactions, caused by the contrast material and air inside the joint as well as the manual positioning of the painful joint.
Following fluoroscopic tracking of the contrast medium, standard x rays of the area are taken by the x ray technologist. An overexposed lateral x ray of the knee flexed at 90 degrees is usually done in addition to the routine AP (anteroposterior) internal and external oblique x rays in order to visualize the cruciate ligaments. An axillary view of the shoulder is usually requested as well as an AP (anteroposterior) view of the shoulder with the arm rotated internally and externally. The procedure is usually completed within 30 minutes.
Preparation
It is important to alert the physician to any known sensitivity to local anesthetics or iodine prior to an arthrogram. Routine x rays of the affected joint should be taken before starting the arthrogram to make sure there is no fracture or dislocation, and to verify the diameter of the joint space before the needle is inserted. A small section of the knee may be shaved before starting the arthrogram.
Aftercare
The affected joint should be rested for approximately 12 hours following the procedure. Swelling may occur and can be treated with an application of ice or cold packs. A mild pain reliever may also be necessary to lessen discomfort for the first 12 hours. Noises in the joint such as cracking or clicking are normal for a few hours following an arthrogram. These noises are the result of the extra liquid (contrast) and air in the joint.
Complications
Some patients may have allergic reactions to iodine, ranging from mild nausea or a rash to severe cardiac and resiratory problems. Since the contrast material is injected directly into a joint, however, rather than the venous circulation, allergic reactions are rare. Facilities licensed to perform contrast examinations should meet requirements for emergency equipment, supplies and staff training in order to handle a possible severe reaction. Non-ionic contrast material is also available in most radiology departments.
Arthrographic studies should not be done on patients with a known joint infection, bleeding problems, or severe active arthritis.
Results
A normal arthrogram demonstrates a normal joint space with no damage to the articular cartilage, tendons, ligaments or bursae. Partial or incomplete tears of the rotator cuff are better demonstrated using MRI imaging.
Abnormal results of an arthrogram may indicate partial or complete tears of the rotator cuff, demonstrated as a leakage of contrast material out of the joint and into the bursa. In a knee arthrogram, meniscal tears are demonstrated as well as problems with the ligaments or evidence of a popliteal cyst, commonly referred to as a Baker's cyst. A Baker's cyst is demonstrated on the radiographs
as an extension of fluid into the popliteal fossa located behind the knee. Dislocations of the hip are visible as well as a loose hip prosthesis. Joint space narrowing and arthritis are also visualized on an arthrogram.
Health care team roles
Since a reaction to an iodine-based contrast medium is always a risk in arthrography, the x-ray technologist must be familiar with emergency procedures in place to deal with a cardiac arrest. The x-ray technologist works closely with the radiologist during this procedure and must be familiar with sterile techniques in order to prevent infection.
Patient education
The radiography technologist explains the procedure to the patient and inquires about any known allergies and the possibility of pregnancy. Since many patients are nervous about an injection directly into the joint, the x-ray technologist must assure the patient that the area will be numbed in advance with a local anesthetic. During a knee arthrogram the radiologist manually positions the patient, so the patient must be encouraged to relax the knee completely. All radiography technologists must be certified and registered with the A.S.R.T. and are required to obtain continued education credits to maintain their credentials.
Following the arthrogram, the patient is also instructed to put ice on the affected joint and to take a mild pain reliever if necessary.
KEY TERMS
Aspirate—To remove fluids by suction, often through a needle.
Bursa—A closed space between two moving surfaces containing a small amount of lubricating fluid to reduce friction in the joint.
Contrast (agent, medium)—A substance injected into the body that outlines certain structures that would otherwise be hard to see on the radiograph (film).
Fluoroscope—An under-table x-ray tube used to visualize structures in real time on a television screen.
Fossa—An anatomical cavity or hollow.
Meniscus—A wedge of cartilage that separates the articulating bones in certain joints.
Popliteal—Pertaining to the area at the back of the knee.
Rotator cuff—A group of muscles lying outside the shoulder joint that allow the joint to move in many directions.
X ray—A form of electromagnetic radiation with shorter wavelengths than normal light. X-rays can penetrate most structures.
BOOKS
Ballinger, Phillip. Merill's Atlas of Radiographic Positioning, 6th ed. St. Louis, MO: CV Mosby Publishing.
Eisenberg, Ronald. Clinical Imaging: Atlas of Differential Diagnosis, 3rd ed. New York: Thieme Publishing, 1997.
ORGANIZATIONS
American College of Radiology. 1891 Preston White Drive. Reston, VA 22091. (800) ACR-LINE. <http://www.acr.org>.
The Arthritis Foundation. 1330 West Peachtree Street. Atlanta, GA 30309. (800) 283-7800. <http://www.arthritis.org>.
