Acetabular Wear in Total Hip Arthroplasty Workup

Updated: Oct 30, 2015
  • Author: Hari P Bezwada, MD; Chief Editor: William L Jaffe, MD  more...
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Workup

Laboratory Studies

Laboratory evaluation prior to any surgical intervention should include a complete blood count (CBC), coagulation studies, and routine chemistries. Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) are useful, especially in excluding indolent infection. In cases where infection is a serious consideration, preoperative aspiration may also prove helpful in further evaluation.

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Imaging Studies

Radiography

Standard anteroposterior (AP) hip and pelvis views and frog-leg lateral views are central to the evaluation of acetabular wear in total hip arthroplasty (THA). Most information can be gathered from these views. Serial radiography over time confers additional information regarding wear and prosthetic loosening.

In the setting of significant osteolysis, additional views may be helpful in defining the extent of these lesions and the extent of any bony deficiencies. These include Judet oblique views to evaluate the integrity of both the anterior and posterior columns and the false profile view and sitting lateral view.

Computed tomography

Computed tomography (CT) may provide supplemental information regarding the pelvis and help differentiate contained bony deficiencies from significant pelvic discontinuity.

Nuclear scanning

Although bone scintigraphy has been available for more than 30 years, it plays a limited role in the evaluation of a painful hip prosthesis. The main determinants of technetium (Tc)-99m methylene diphosphate (Tc-99m MDP) tracer uptake in bone are blood flow and metabolic bone activity. Increased tracer uptake may be observed for 12-24 months after implantation of a total hip prosthesis because of bone remodeling.

The appearance of abnormal uptake surrounding a painful prosthesis has been used to differentiate loosening from infection. Loose prostheses tend to show increased uptake in the trochanters, at the stem tip, and possibly the acetabular shell. Bone scintigraphy is sensitive for infection but lacks specificity. [22]

Gallium scanning may be useful in the assessment of infection. Gallium binds to serum transferrin and carries an accuracy of 75% in detecting a periprosthetic infection. It has more intense uptake than Tc-99m MDP, and combining these tests may be effective in the evaluation of a painful prosthesis.

Indium-labeled white blood cells (WBCs) accumulate in the region of infection because of chemotaxis. Mixed WBC lines are used in the preparation and may account for the similar sensitivity for acute and chronic infections of 82%.

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