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

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

DESIGN: Prospective study.

SETTING: Academic level I trauma center.

PATIENTS AND METHODS: 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.

RESULTS: 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.

CONCLUSIONS: 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.