Abstract
Background: An intraoperative fracture of the acetabulum during primary total hip arthroplasty is a rare complication. Until now, there has been no report evaluating the use of computed tomography (CT) for this complication. Occult fracture which can not be confirmed by intraoperative findings or by postoperative radiography can be assessed by evaluating the acetabulum using postoperative CT.
Methods: Between 2004 and 2012, 549 primary total hip arthroplasties (THA) with uncemented components were performed at our institution. We excluded 94 hips with a history of pelvic osteotomy, trauma and infection; thus, the study included 455 hips. Acetabular component designs were categorized as true hemispherical and PSL cups, and then each design was analyzed for fracture risk. In 243 hips with PSL cups, reaming was carried out of the acetabulum bed to 1.8 mm under the true largest external diameter, as the component to be inserted. We used preoperative and postoperative CT imaging to evaluate fractures. We reconstructed CT images of axial, sagittal and coronal sections. All potential fractures lines were evaluated in at least two planes.
Results: In two hips (0.43%), periprosthetic fractures of the acetabulum were found intraoperatively. In 41 hips (9.0%), occult fractures of the acetabulum were confirmed using postoperative CT whereas they had not been identified perioperatively or by postoperative standard radiography. These fractures do not require particular additional treatment and may remain subclinical in the postoperative period. PSL cups were associated with a significantly higher fracture rate than were hemisherical cups (p < 0.05).
Discussion and Conclusions: The fracture rate of acetabulae that occurred during THA, associated with uncemented components, was 0.4%. The intraoperative occult fracture rate of acetabulae, associated with uncemented components, was 9.0%. We found a high rate of fracture in association with the use of PSL components.
