ORIGINAL ARTICLE Is the Absence of an Ipsilateral Fibular Fracture Predictive of Increased Radiographic Tibial Pilon Fracture Severity? David P. Barei, MD, FRCSC, Sean E. Nork, MD, Carlo Bellabarba, MD, and Bruce J. Sangeorzan, MD Objective: Despite their frequent occurrence, there is little clinical or biomechanical data associating the status of the fibula with any injury pattern of the tibial plafond. Similarly, the integrity of the fibula is not assessed in the commonly used tibial pilon fracture classi- fication schemes. The purpose of this study was to determine whether there is a difference in the radiographic severity of tibial pilon injuries with fibular fractures compared with those without fibular fractures by using a rank-order method. Design: Case-control, radiographic review. Setting: Urban level-1, university trauma center. Patients: During a 36-month period, 20 consecutive tibial pilon injuries without associated fibular fractures were retrospectively identified by using a prospectively gathered trauma database (group 1). During the same time period, an additional 197 tibial pilon injuries with fibula fractures were identified and classified according to the AO/OTA System. This included 48 AO/OTA 43B-type (24.4%) and 149 AO/OTA 43C-type (75.6%) fractures. From this larger group of patients, an age- (65 years) and gender- matched cohort of 20 tibial pilon injuries with fibular fractures were randomly selected electronically (group 2). Intervention: Digital concealment of the fibula on the anteropos- terior and lateral injury radiographs. Main Outcome Measure: Before definitive fixation, 3 orthopae- dic traumatologists independently ranked the digitized anteroposte- rior and lateral radiographs of all 40 patients according to severity with 40 representing the most severe injury. Results: Interobserver agreement between the 3 evaluators showed a significant positive association (Kendall’s concordance coefficient = 0.87; P = 0.0001). The overall mean rank score for tibial pilon injuries with fibula fractures was 24.4, whereas those without fibula fractures was 16.7 (t test = 0.02). When evaluated within the AO/OTA classi- fication system, the mean rank score for C-type tibial pilon fracture patterns was 10.3 in group 1 and 8.7 in group 2 (P = 0.5). AO/OTA C-type tibial pilon fracture patterns were observed more commonly in group 2 than in group 1 (P = 0.006). Conclusions: This study demonstrates that, overall, tibial pilon injuries with fibular fractures were statistically ranked as more radio- graphically severe than those without fibular fractures. Fibular frac- tures are more commonly associated with C-type injuries than B-type injuries. There was no difference in severity in C-type injuries with or without fibular fractures; however, C-type injuries were ranked, as a group, significantly more radiographically severe than B-type injuries. Key Words: tibial pilon fracture, fibula fracture, rank order (J Orthop Trauma 2006;20:6–10) F ibular fractures occur commonly as a component of the overall injury pattern in tibial pilon fractures. There is little clinical or biomechanical data, however, associating the status of the fibula with any injury pattern of the tibial plafond. Similarly, the integrity of the fibula is not assessed in the commonly used tibial pilon fracture classification schemes. 1,2 Schatzker and Tile 3 previously have suggested a mechanistic and morphologic difference in distal tibial injuries that occur with and without fibula fractures. The authors further noted that a spectrum of injury severity exists and is, in part, dependent on the status of the fibula. Assuming that the distal tibia absorbs the entire injurious mechanism, we hypothesized that tibial pilon fractures with an intact fibula represent a more severe injury compared with those with a fractured fibula. The null hypothesis is that there is insufficient energy to fracture the fibula and, therefore, the injury to the distal tibia should be less severe. The purpose of this study was to determine whether there is a difference in the radiographic severity of tibial pilon injuries with fibular fractures compared with those without fibular fractures by using a rank-order method. MATERIALS AND METHODS Between January 1997 and February 2000, 20 consec- utive tibial pilon injuries without associated fibular fractures (group 1) were retrospectively identified by using a pro- spectively gathered trauma database. Since 1989, this database records all operatively managed fractures at our institution. Fractures are entered and coded according to the AO/OTA system by orthopaedic trauma fellows trained in the AO/OTA fracture classification system. The time period was specifically chosen to allow identification of this study group (group 1), Accepted for publication September 22, 2005. From the Department of Orthopaedic Surgery, Harborview Medical Center, Seattle, WA. No financial support of this project has occurred. The authors have received nothing of value. The manuscript submitted does not contain information about medical devices. Reprints: David P. Barei, MD, FRCSC, Harborview Medical Center, Department of Orthopaedic Surgery, Box 359798, 325 Ninth Avenue, Seattle, WA 98104 ( e-mail: barei@u.washington.edu). Copyright Ó 2006 by Lippincott Williams & Wilkins 6 J Orthop Trauma  Volume 20, Number 1, January 2006 Copyright ' Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.