Periacetabular bone density after total hip arthroplasty a postmortem analysis.

To clinically verify the bony response to a press-fit acetabular component, this study assessed 5 postmortem-retrieved pelves with unilateral total hip arthroplasties. Changes in periacetabular bone density between implanted and contralateral bone were assessed with dual energy x-ray absorptiometry and computed tomography. At a mean of 9.1 years postarthroplasty, bone density decreased an average of 1.5% to 7.1% proximal and 12.8% medial to the cup. This supports shorter-term in vivo investigations demonstrating periacetabular stress shielding proximal to press-fit cups as well as computer models predicting bone loss medially, but in much greater magnitudes. Unlike femoral remodeling, the average magnitudes of pelvic bone loss are not extensive; therefore, we question whether periacetabular remodeling should be a primary concern for orthopedic surgeons.

A randomized prospective evaluation of outcomes after total hip arthroplasty using cross-linked marathon and non-cross-linked Enduron polyethylene liners.

Cross-linked liners were introduced with the promise that they would substantially reduce polyethylene wear. In 1999, our institution initiated a prospective study to compare the outcome of total hip arthroplasty patients who were randomized to non-cross-linked Enduron liners with that of total hip arthroplasty patients who were randomized to Marathon polyethylene liners that had been cross-linked with 5 Mrad (50 kGy) of gamma-irradiation and heat-treated to eliminate free radicals. At a mean follow-up of 5.7 years, the clinical outcomes among the Marathon and Enduron liners were similar. However, the mean wear rate was 0.01 +/- 0.07 mm/y for the Marathon group, which represents a 95% reduction compared with the mean wear rate of 0.19 +/- 0.12 mm/y for the Enduron group. In addition, the incidence of osteolysis was lower in the Marathon group.

The value of anteroposterior pelvic radiographs for evaluating pelvic osteolysis.

We investigated the role of conventional radiographs and computed tomography scans for the routine followup of total hip arthroplasty patients. Among 92 total hip arthroplasties with a mean followup of 8.5 years, 94 acetabular lesions were detected among 63 hips using computed tomography and 42 of these hips had osteolysis diagnosed on radiograph. Using computed tomography as a gold standard, the sensitivity of anteroposterior pelvic radiographs for the detection of acetabular osteolysis was 67% and the specificity was 72%. Although smaller lesions were more frequently missed, osteolysis was diagnosed on radiograph in 20 of 22 total hip arthroplasties with lesion volumes of at least 10 mL. Because larger osteolytic lesions were generally detected on radiograph, two-dimensional and three-dimensional lesion sizes correlated. However, the limits of agreement for the volume estimates based on the radiograph area were -14.6 to 18.7 mL. Although radiographs can be useful to screen for clinically important pelvic osteolysis, computed tomography images are necessary to accurately measure lesion volumes.