Olecranon Fractures in Pediatric Patients With Osteogenesis Imperfecta

Abstract

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.

When Is an Isolated Olecranon Fracture Pathognomonic for Osteogenesis Imperfecta?

“…Previous literature has established that patients with OI tend to sustain olecranon fractures under low-energy mechanisms 4–7,12. Our study supports these findings and we report a significant difference in mechanism of injury between OI and non-OI patients.…”

“…It has been traditionally accepted that isolated fractures of the olecranon are pathognomonic for OI. 2,[4][5][6][7] A study by Zionts and Moon 4 found that only 5 of the 10 children who sustained an isolated olecranon fracture had received a diagnosis of OI before their first fracture, and therefore, recommended considering an OI diagnosis for any child presenting with an isolated, displaced olecranon fracture. However, Evans and Graham 11 reported only 6 of 57 patients with isolated olecranon fractures had a diagnosis of OI.…”

“…The median age of first olecranon fracture in our OI population was 11.5 years, which is similar to the average age reported for OI patients by Zionts and Moon, Tayne, Perisani, and Gwynne-Jones at 10, 12, 12, and 11.6 years, respectively, however it should be noted that we are comparing median age to average age across these studies. 4,6,7,12 Wilkins describes that the triceps expansion inserts on the metaphysis distal to the physis, making apophyseal fractures of the olecranon uncommon. 13 Decreased ossification and maturation of the apophysis combined with increased laxity of the triceps expansion in patients with OI would predispose these patients to isolated olecranon fractures.…”

“…Previous literature has reported contralateral olecranon fractures between 1 and 12 months following first olecranon fracture in a significant number of patients with OI. [4][5][6][7] We found 4 of 14 (29%) patients with OI sustained a contralateral olecranon fracture within 7 months, and an additional patient re-fractured the ipsilateral olecranon within 1 month of the initial injury. The exact etiology of this phenomena is unknown; however, during ages of rapid growth velocity the weak bone that predisposes an OI patient to an olecranon fracture, as we have described above, would be present bilaterally, predisposing them to an increased risk of a contralateral fracture.…”

“…As such, it is less prone to fracture relative to surrounding structures, accounting for only 4% of all elbow fractures in children 3. OI patients sustain olecranon fractures at a higher rate than non-OI patients, which has led some to conclude that isolated olecranon fractures are essentially pathognomonic for OI, specifically type-I 2,4–7. In addition, OI patients are significantly more likely to sustain a contralateral olecranon fracture, and within a relatively short period of time from their first fracture, compared with non-OI patients who sustain an olecranon fracture 3,4,6,7.…”