Acetabular revision with the Contour antiprotrusio cage: 2- to 5-year followup

The Contour cage introduced in 1999 was designed to improve fixation and provide a surface for bone ongrowth. To determine whether the rates of radiographic loosening and/or revision have been reduced with the Contour design, we retrospectively reviewed the medical records and radiographs of 29 patients (average age, 68.1 years) undergoing 31 acetabular revisions with a Contour cage. The minimum followup was 24 months (mean 30 months, range, 24-58 months). Based on the Paprosky classification, two hips were Type 2B, seven were Type 3A, and 22 were Type 3B. Two hips (7%) were revised for loosening; one of these two was also infected. An additional five hips (16%) had signs of radiographic loosening. The mean Harris hip score improved from 45 to 80; functional scores improved less than the pain scores. Only 14 hips (45%) had an excellent or good clinical result and three of these 14 hips had radiographic signs of loosening; presuming these three hips eventually fail, only 35% of the hips had a good or excellent result. We found an association between number of previous surgeries and radiographic loosening and revision. Our data suggest the Contour cage offers little advantage over other antiprotrusio cages and highlight the substantial limitations of current methods available for treating patients with extensive acetabular bone loss.