Effect of computerized tomography on classification and treatment plan for patellar fractures

To evaluate the impact of computerized tomography (CT) scan on both fracture classification and surgical planning of patellar fractures.

Prospective study.

Academic level I trauma center.

Four fellowship-trained orthopaedic trauma surgeons analyzed radiographs of 41 patellar fractures. Each fracture was classified (OTA/AO classification), and a treatment plan was developed using plain radiographs alone. The process was repeated (4-6 weeks later) with addition of CT scan. After 12 months, the 2-step analysis was repeated and interobserver reliability and intraobserver reproducibility were assessed.

Suboptimal intra- and interobserver reliability was found for the surgical plan and classification using the OTA/AO system, despite the addition of a CT scan. After addition of CT, reviewers modified the classification in 66% of cases and treatment plan in 49%. CT frequently demonstrated a distinctive and severely comminuted distal pole fracture; this fracture pattern was present in 88% of cases and was unappreciated on plain radiographs in 44% of those cases. This pattern is unaccounted for by the present OTA/AO classification.

CT facilitates improved delineation of patellar fracture patterns. Understanding the distal pole fracture pattern is fundamental in choosing a fixation construct. A fracture-specific classification system, based on CT scans, should be developed.