Joint Replacement Institute

To assist us in selecting the most appropriate method of treatment, additional studies may be required on an outpatient basis. For the studies noted below, our office will gladly assist you with scheduling.

Aspiration and Arthrogram

Radionuclide Scans

MRI

CAT Scan

Bone Densitometry

Aspiration and Arthrogram

Aspiration is desirable to obtain information about the presence or absence of infection, particularly if you have had previous surgery. The surgeon may be able to aspirate fluid directly from the hip joint which will provide valuable information. Final culture results are usually available in 7 - 10 days. On occasion or if a second aspiration is needed, the procedure may be done in Radiology by a radiologist who, at the same time, may perform an Arthrogram (insert dye into the hip joint) to outline the cavity surrounding the joint itself. In general, these procedures are not painful, although local anesthesia is utilized in the skin. On occasion, mild discomfort may be associated with the study. Most often it is transitory and usually can be relieved by medications. These tests have been most helpful in ruling out or establishing the presence of infection, and in some cases, outlining the areas of loosening.

Radionuclide Scans

If there is a concern about infection, you may be scheduled for an Indium-111 Radioisotope Scan. This requires removing some of your own blood and labeling it with an isotopic material (Indium-111) which is then re-injected. You will return one day later and the area of the joint will be scanned. This procedure is sometimes used in combination with other more routine types of scanning agents so as to evaluate patients with infection or sepsis.

All of the isotopic agents are relatively innocuous. The amount of radiation is generally not much more than a single x-ray exposure. Complications have been minimal. Computerized scanning is sometimes combined with injection of these agents to better define the changes in a three-dimensional way.

MRI

Magnetic Resonance Imaging is a special study that uses a large magnetic field and radio waves to obtain images of the inside of the body. This technique may be useful in evaluating the soft tissues around the hip or detecting the early stages of osteonecrosis. It cannot be used if you already have a hip replacement.

CAT Scan

A CAT scan (computerized axial tomography) is a specialized x-ray scan that can provide additional information about the anatomy of the pelvis or thigh bones and the amount of bone stock available. It is frequently necessary in such conditions as congenital dysplasia, Legg-Perthes disease, or osteonecrosis, or if a custom-type prosthesis may be needed.

Bone Densitometry

Your bone changes in quality and quantity with increasing age (osteoporosis) and also in response to an implant. Bone densitometry is a new technique which can more accurately quantitate these changes.