The importance of adequate diagnosis of pediatric forearm bowing fractures: A case report

Abstract

Introduction: Correct diagnosis of pediatric bowing fractures has proven to be challenging. Consequently, these entities are often underdiagnosed both at the initial presentation and at further follow-up. We present a case of an ulnar fracture with subsequent non-union and initially missed associated plastic deformity of the radius to highlight the importance of adequate diagnosis of bowing fractures and obtaining appropriate imaging in pediatric forearm trauma to prevent sequelae.

Case presentation: A 13-year old male sustained a diaphyseal fracture of the left ulna after a fall on the outstretched hand which was treated conservatively. A non-impact incident (push up on outstretched arm) 4.5 months after the initial trauma caused an ulnar fracture at the same location and was initially considered a simple refracture. Operative treatment was decided on due to significant clinical forearm valgus alignment. Intraoperatively however, a mobile non-union of the ulna was found and anatomic reduction was not possible due to radial bowing. Exploration of the radius showed a clear malalignment with periosteal callus reaction, indicative of a mal-union of the radial bone as a result of the initial injury. To correctly restore alignment, a closing wedge osteotomy of the radius was necessitated followed by plate and screw fixation of both the radius and the ulna.

Conclusion: In this patient, failure of recognizing the associated plastic deformity of the radius during the initial presentation led to radial malunion and non-union of the ulna. As a result of this complication, an osteotomy was necessary which probably could have been prevented if an adequate initial diagnosis had been made.

Keywords: Bowing fracture; Mal-union; Non-union; Pediatric trauma; Plastic deformity; Radius.

Fig. 1

Radiographic imaging after initial injury. Anteroposterior and lateral radiographs the day of the trauma (A); two weeks post-trauma (B) and at 6 weeks of follow-up (C).

Fig. 2

Radiographic imaging after second injury. Anteroposterior and lateral radiographs after non-impact incident show fracturing of the ulna at the same location of the initial injury (2); intraoperative imaging prior to and after the closing wedge osteotomy (B and C, respectively). Anatomic reduction of the ulna was not possible prior to the radial osteotomy (B); radiographic imaging at 3 months post-op shows healing of the ulna fracture and the osteotomy site (D).

Fig. 3

Radiographic and clinical imaging at 5 years postoperatively. AP and lateral radiographs at final follow-up. Clinical imaging shows symmetrical forearm rotation for both pro- and supination.

Fig. 4

Radial bowing measurement, method by Schemitsch and Richards on anteroposterior radiographic forearm imaging. (y) Line from bicipital tuberosity to distal radial epiphysis; (r) perpendicular line to the point of maximal radial bowing; (a) distance from point of maximal bowing to bicipital tuberosity. Radial bowing indicated as a percentage of radius length = r / y × 100 (>10% indicative of plastic deformity).