DISTAL ULNA PHYSEAL ARREST FOLLOWING DISTAL FOREARM FRACTURES IN CHILDREN

Abstract

Background: Pediatric forearm fractures are a common injury with only a small subset of these involving the distal physes of the radius and ulna. A common mechanism of injury in these fractures are from sports related injuries or fall on outstretch hand. Physeal fractures of the distal radius are well-studied, with varying rates of growth arrest and potential for deformity depending on the type of physeal fracture. The incidence and long-term complications of pediatric forearm fractures involving the distal ulna physis remains largely unknown. Distal ulnar physeal arrest can lead to the development of radioulnar length discrepancy and angular deformities. Two previous studies of limited sample size report a 50-55% of physeal arrest when the ulnar physiss was involved in the fractur, which seems higher than what is seen at our institution. The purpose of this study was to investigate the demographic distribution, as well as the incidence of physeal arrest following a physeal fracture of the distal ulna. Methods: After institutional review board approval, a retrospective study was performed of all patients with distal forearm fractures treated at our institution from January 2003 until December 2017. We included patients < 18 years of age who presented to our level-1 emergency department or to our orthopaedic department and excluded those with extra-physeal fracture and closed physis. Wrist x-rays of 1,618 patients with distal forearm fractures were reviewed revealing a total of 52 patients with distal ulna physeal fracture. Patient demographics including age, gender, height, weight, mechanism of injury, and age at follow up was recorded. Each injury x-ray was reviewed and the distal ulna physeal fracture was categorized using the Salter-Harris (SH) classification system. Concomitant injuries were also recorded and if there was a radial physeal injury the SH classification system was used again. All follow up radiographs > 6 months post-injury were reviewed to assess for physeal arrest. Results: There were a total of 11 patients (average age at injury 10 ± 2 years; 5 males, 6 females; average height 1.5 0.2 m, average weight 47 ± 23 kg) with at least 6 months follow up post injury (average follow up time 2.4 ± 2.2 years. Of these, the most common mechanism was fall on outstretch hand occurring 64% of the time (n = 7), followed by sports in 18% (1 football, 1 baseball), and 9% fall from bike (n = 1), and 9% from ATV accident (n = 1). The most frequent distal ulna physeal fracture was SH type 2 occurring 55% of the time (n = 6), while 36% had a SH type 3 (n = 4), and 9% had a SH type 1 (n = 1). Eight patients had an ipsilateral radius fracture with 45% having a metaphyseal fracture (n = 5) and 27% having a distal radius physeal fracture (n = 3; one SH type 1, and two SH type 2). One patient had an ipsilateral supracondylar fracture and another patient had a Galeazzi fracture. Casting was the most frequent treatment occurring 64% of the time (n = 7), followed by closed reduction and casting in 18% (n = 2). Closed reduction and percutaneous pinning was done in 9% (n = 1), and open reduction and internal fixation (ORIF) was done in 9% (n = 1). None of these patients developed distal ulna physeal arrest (while one of them developed a distal radius physeal arrest. The one patient with the Galezzi fracture did go on to develop a malunion with clicking of his wrist despite being treated with ORIF and required a revision osteotomy 7 months later. The remainder of patients had no complications. Conclusion/Significance: The most important finding of this study is that the rate of distal ulna physeal arrest following fracture was 0%. This is in contrast to previous studies of limited sample size that reported a rate of 50-55%. Our results demonstrate a much lower incidence of distal ulnar physeal arrest than previously thought in the pediatric population with distal forearm fractures. These findings suggest that the majority of patients with distal ulna physeal fractures do well with conservative management, and may only require routine clinical and radiographic follow up.