Progression of Acetabular Periprosthetic Osteolytic Lesions Measured with Computed Tomography

Background: A better understanding of the factors associated with the size and/or progression of osteolytic lesions has been hampered by a lack of sensitivity of radiographic measurement techniques. Methods: We retrospectively analyzed quantitative computed tomography scans that had been made with use of a high-resolution multi-slice scanner with a metal artifact-suppression protocol. The scans had been made to determine the volume of osteolytic lesions around thirty-five cementless Harris-Galante acetabular components that had been in situ for at least ten years. Repeat scans of thirty hips allowed for the measurement of progression in the size of os-teolytic lesions over a one-year period. Associations between the volume of osteolytic lesions, progression in the size of the lesions, polyethylene wear since the time of implantation, change in component position, and patient-related variables (age, gender, body mass index, activity level, walking limitations, joint pain, and function) were determined. Results: In sixteen of the thirty hips that had repeat computed tomography scans, the lesions progressed in size dur-ing the study period. The median size of the lesions in these sixteen hips was 10.3 cm3 at the time of the initial scan, compared with 13.3 cm3 at a median of fifteen months later (p = 0.001). Osteolytic lesions measuring>10 cm3 in vol-ume on the initial scan were 2.5 times (95 % confidence interval 1.3 to 4.8 times) more likely to progress in size over one year than smaller lesions were. Patients with greater polyethylene wear rates, higher activity levels, no walking limitations, and larger prosthetic femoral head dimensions (26 or 28 mm) had significantly larger osteolytic lesion