Pediatric pelvic ring injuries: How benign are they?

IntroductionWith an incidence of less than 0.2% of all pediatric fractures, pelvic ring injuries are rare. Historically they were conservatively treated, but because malunion and long-term morbidity are associated with unstable injuries, a trend towards operative treatment can be observed. The purpose was to determine clinical and radiographic outcomes following these complex pediatric pelvic ring injuries.Patients and methodsThis Level IV retrospective analysis was completed at a private orthopaedic practice in association with a Level One teaching trauma center. There were 33 children with pelvic ring injuries with a mean age of 12.6 years (4-16) and an average follow up of 28.6 months (range 6-101). Injuries were 2 A2, 3 B1, 16 B2, 10 B3, and 2 C2 according to OTA/AO classification. Group 1 had 16 unstable, operatively treated injuries and Group 2 had 17 stable, non-operatively treated injuries. Radiographic deformity, leg length discrepancy, low back, and SI joint pain were evaluated.ResultsFor Group 1, 10 of 15 patients (67%) had a permanent ischial height difference >5 mm compared to Group 2, in which 5 of 12 (42%) had an ischial height difference of >5 mm. Group 1 had more pelvic asymmetry (12.3 mm vs. 6.6 mm) and ring width difference (6.9 mm vs. 3.9 mm) on final X-rays as compared to Group 2. Children with 5-10 mm posterior sacral displacement had significantly more pain than children with 0-4 mm displacement (p = 0.034). Thirteen children (39%) had residual low back/SI joint pain; the rate was significantly higher in the Group 1 (3/17 vs. 10/16, p = 0.008). In three (9%) children with 2 B2 and 1 B3 injury, leg length discrepancy between 5 mm to 15 mm occurred.Discussion and conclusionIn pediatric patients with pelvic ring injuries, radiographic deformity persisted and did not remodel. Pelvic ring deformity occurred more commonly with complex unstable ring injuries. The complex displaced injuries have higher rates of operative intervention, residual deformity, and low back and SI joint pain.