Pelvic osteolysis relationship to radiographs and polyethylene wear.

The relationship of radiographic pelvic osteolysis to computed tomographic (CT) volume and polyethylene wear remains controversial. We evaluated the sensitivity and specificity of radiographs in detecting osteolysis considering CT scan as the true value, in 118 hips with cementless cups. Correlation between osteolysis volume in CT, area of osteolysis in radiograph, and linear wear of polyethylene was assessed. The sensitivity and specificity of anteroposterior radiographs for detection of osteolysis was 57.6% and 92.9%, respectively. Addition of oblique radiographs increased the sensitivity to 64.4% without changing the specificity. The sensitivity increased to 92.8% for lesion more than 1000 mm(3). There was good correlation between 2-dimensional (2D) osteolytic area in radiograph and 3-dimensional (3D) volume (r = 0.74) in CT scan and linear wear of polyethylene showed good correlation with 3D CT volume (r = 0.62) and 2D area in radiograph (r = 0.60). Thus radiographs are useful to screen clinically significant osteolysis.