Background: Osteogenesis imperfecta (OI) is a hereditary disorder characterized by an abnormality of the quality or quantity of type I collagen, leading to bone fragility. Fractures in children with OI may result from minor trauma and have atypical patterns. Previous studies have found a strong relationship between olecranon fractures and OI in pediatric populations, but the characteristics of olecranon fractures within the OI patient population have not been fully described.
Methods: We reviewed the records of 358 children with a diagnosis of OI. Of those, 29 had at least 1 olecranon fracture. We collected general information relating to the patient's diagnosis of OI including OI type, fracture history, mobility, and bisphosphonate treatment. Information regarding the fracture, treatment, and the occurrence of bilateral fractures were recorded, as well as weight, height, and axial bone mineral density z-score from the time of the fracture.
Results: Within our OI population of 358 patients, we found an incidence of olecranon fracture of 8.1% (29 patients). The olecranon fractures occurred predominantly in the type I population (27 of 29). Within the population of patients specifically with OI type I (200 patients) the incidence is 13.5%, with 6% of OI type I patients sustaining bilateral olecranon fractures. The percentage of children with one olecranon fracture subsequently sustaining another on the contralateral side was 41.4%. The mean time to the second fracture was 5 months. The mean age at the time of the first olecranon fracture was 11.9 years old. The average axial bone mineral density z-score was -2.5 for primary fractures. All 12 patients who suffered a contralateral olecranon fracture had OI type I.
Conclusions: Olecranon fractures in the OI population occur most commonly in patients with type I OI and during early adolescence, a period of rapid growth. There is a high rate of bilateral olecranon fractures, with the contralateral fracture occurring quickly after the primary fracture. Further studies may elucidate risk factors to determine which patients are most likely to fracture the contralateral side and therefore drive treatment and potentially prevention.
Level of evidence: Level IV-retrospective cohort study.