When Is an Isolated Olecranon Fracture Pathognomonic for Osteogenesis Imperfecta?

Abstract

Isolated fractures of the olecranon process of the ulna in pediatric patients with open physes are classically considered pathognomonic for osteogenesis imperfecta (OI). The purpose of this study was to distinguish the clinical manifestations of isolated olecranon fractures in patients with and without OI to help practitioners assess when further evaluation for OI may be necessary. All patients younger than 18 years old who were treated for an isolated olecranon fracture at a pediatric tertiary care center between 2009 and 2021 were identified. Patients without radiographs available for review, those with known skeletal dysplasia other than OI, and patients with multiple fractures (eg, polytraumas) or with concomitant dislocations were excluded. Of the 701 patients identified, 403 were included for analysis. Demographic variables, mechanism of injury, treatment type, and determination of OI diagnosis were collected. Patients with a previously confirmed diagnosis of OI or with genetic confirmation of OI following their fracture were designated as OI (+), and the remainder were designated OI (-). The Mann-Whitney U and χ2 tests were used to compare groups. Of the 403 patients, the median age was 7.8 years (interquartile range 5.2 to 12.5), and 270 (67%) were male. There were 14 confirmed cases of OI (3.5%). The OI (+) and OI (-) groups did not differ significantly by age or sex (P>0.05). OI (+) patients were more likely to sustain an injury from low-energy mechanisms (86% vs. 32%, P<0.001), sustain displaced fractures (86% vs. 21%, P<0.001) and undergo operative treatment (86% vs. 20%, P<0.001), and to report a history of previous fracture (79% vs. 16%, P<0.001) than OI (-) patients. 36% of OI (+) patients sustained a second olecranon fracture during the study period; there were no subsequent olecranon fractures in the OI (-) group. Isolated olecranon fractures may not be pathognomonic for OI. However, orthopaedists must be vigilant about the possibility of OI in patients who sustain displaced, isolated olecranon fractures under low-energy mechanisms with a history of previous fracture(s). Level III.