LAUSR

Introduction and Aims: The use of routine postoperative computerized tomography (CT) scan after acetabular fracture reconstruction remains controversial. CT scan may provide more accurate detail regarding metalwork position, retained intra-articular fragments, and quality of reduction but does expose the patient to additional radiation dosage and incurs increased cost. The aim of this study was to evaluate a protocol of routine postoperative CT scan for all acetabular fractures after surgical fixation and assess the effect this has on patient management. Patients and Methods: The perioperative fluoroscopic images and postoperative plain radiographs of 122 patients who underwent surgical stabilization of a displaced acetabular fracture were reviewed and categorized into 3 groups: (1) safe, when there was no suspicion of metalwork malposition or intra-articular fragments; (2) inconclusive, when it was not possible to exclude malposition; or (3) definite malposition or intra-articular penetration of implants. The findings were compared with postoperative CT scans. The quality of reduction of the acetabular fracture was graded on plain radiographs using the Matta criteria and compared with the CT scan using a standardized technique. Results: Fractures that were categorized as safe on plain radiographs were confirmed to have no metalwork malposition on CT scan in 94% of the cases, with the other 6% having insignificant findings that did not require revision surgery. When plain radiographs were inconclusive (n = 17), 4 patients had metalwork malposition documented on CT scan and 2 of these required revision surgery. There was an increased risk of implant malposition with use of spring plates for posterior wall stabilization. There was significant variation between the quality of reduction when assessed with plain radiographs as compared with CT scans (P < 0.001). In 42% of the patients who were thought to have anatomic reduction on plain radiographic assessment, the reduction was either imperfect or poor based on CT assessment. Conclusions: CT scans were more accurate than plain radiographs in detecting metalwork malposition and in assessing quality of reduction of the acetabular fracture. The use of postoperative CT scans may be restricted to a group of fractures that have inconclusive or definite malpositioning of implants on perioperative or postoperative radiographs, especially with use of spring pates or to those patients in whom quality of reduction needs more accurate assessment for quality assurance or prognostic reasons. Level of Evidence: Level IV; Diagnostic -Investigating a diagnostic test.