Long-term results of total hip arthroplasty in protrusio acetabuli

Ninety-three total hip arthroplasties were examined radiographically and clinically to investigate the best method of correction in protrusio acetabuli. Fifty-three percent were treated with cement alone, 36% with mesh or protrusio shell, and 11% with bone graft. Long-term follow-up study revealed a high percentage of immediate and late radiolucent lines. The highest rate of loosening, 50%, occurred in the cement alone group, which had not been corrected to within 10 mm of anatomic position. Sex, cause of protrusio, age at operation, and degree of osteopenia were not significantly different between the groups. The follow-up period was longer in the cement alone group, but this did not account for the excessively high rate of loosening. Correction of the anatomic position in protrusio deformity is vital, whether accomplished with cement, mesh, protrusio shell, or bone graft. Late radiolucent lines are common and do not reliably indicate loosening.