Summary

Post-reduction advanced imaging following traumatic hip dislocations demonstrated posterior wall fractures in 78% and incarcerated fragments in 30%, and selective hip arthroscopy for the treatment of loose bodies and labral pathology was associated with excellent outcomes.

Abstract

Introduction

Traumatic hip dislocations are uncommon injuries in the pediatric population. Injury recognition and prompt closed reduction is standard of care. The purpose of this study is to describe injury patterns, treatment (including hip arthroscopy), and patient reported outcomes of traumatic hip dislocation in pediatric patients.

Methods

A retrospective review was performed of all patients less than 18 years of age treated for a traumatic hip dislocation between 2011 – 2017 at a single center. Chart and radiographic review were performed, and patients were contacted to obtain outcome scores, including the Harris hip score (HHS) and hip outcome score (HOS).

Results

23 patients, 18 males and 5 females, with a mean age of 11.3 years (range 4 – 16) were included. The most common mechanisms of injury were motor vehicle crashes (8), football (7), and falls (3). The direction of hip dislocation was posterior (21) and obturator (2). The majority of injuries (83%) were isolated orthopaedic injuries.

In addition to pelvis radiographs, 20 patients had a CT to assess the hip reduction and associated injuries. 15 of those patients (75%) had a posterior wall acetabular fracture and 6 (30%) had an incarcerated fragment within the joint. 5 patients had an MRI and all had an associated posterior wall fracture and posterior labral tear. In our series, posterior wall fractures and incarcerated fragments noted on axial imaging were not visualized on plain radiographs in 75% and 40% of cases respectively.

14 patients were treated non-operatively. Mean radiographic follow-up was 12 months. One patient developed avascular necrosis without collapse at 6 months. Patient-reported outcome scores were obtained in 10 patients (71%). Mean HOS-ADL, HOS-Sport, and mHHS were 75 (69 – 76), 32 (18 – 36), and 97 (85 – 100) respectively at a mean of 40 months (20 – 83) after injury.

9 patients were treated operatively, including 5 patients with hip arthroscopy. The indication for hip arthroscopy was an incarcerated fragment. These patients had loose body removal and 3 had a posterior labral repair. Mean radiographic follow-up was 14 months. One patient developed chondrolysis at 6 months post-op and one developed an anterior head-neck junction exostosis and underwent a second hip arthroscopy 29 months after his initial injury. Patient-reported outcome scores were obtained in 7 patients (78%). Mean HOS-ADL, HOS-Sport, and mHHS were 69 (50 – 76), 30 (14 – 36), and 86 (59 – 100) respectively at a mean of 34 months (5 – 63) after surgery.

Conclusions

Traumatic hip dislocations in the pediatric population occur most frequently as isolated orthopaedic injuries in association with posterior wall acetabular fractures. Incarcerated fragments occurred in 30% of the patients, yet were commonly not recognized on plain radiographs alone. Axial imaging, either MRI or CT, should be routinely obtained following reduction. Selective hip arthroscopy after traumatic hip dislocations is a viable less invasive method for treatment of incarcerated fragments and labral injury.