Traumatic, Posterior Pediatric Hip Dislocations With Associated Posterior Labrum Osteochondral Avulsion: Recognizing the Acetabular "Fleck" Sign.

BACKGROUND

Traumatic dislocation of the hip is uncommon in the pediatric population. Concentric reduction is usually achieved by closed means. Open reduction may be needed if there is femoral head fracture, incarcerated fragment, or incomplete reduction due to soft tissue entrapment. We present a series of 10 patients who sustained a posterior hip dislocation or subluxation with associated osteochondral avulsion of the posterior labrum. During surgery they were noted to have a labral injury pattern not previously recognized. Such treatment was dictated by postreduction advanced imaging, which revealed a consistent acetabular "fleck" sign indicative of this labral injury, which has not been previously described in literature.

METHODS

We performed a retrospective case review of patients with traumatic posterior hip dislocation/subluxation, treated operatively for a suspected associated labral tear and fractures.

RESULTS

Ten patients (2 girls and 8 boys) were identified. Average age was 12.7 years. Eight patients had postreduction computed tomography scans, which revealed a posterior acetabular wall "fleck" sign, suggestive of osteochondral injury. The small bony fragment was consistently displaced at least 2 to 3 mm in all patients with majority of the posterior wall remaining intact. Closed reduction was felt to be congruent in 7 of the 10 patients. All patients were treated operatively for exploration and stabilization of the suspected posterior labrum pathology and associated injuries using a surgical hip dislocation. A consistent pattern of labral pathology was seen in all patients, with disruption of the posterior labrum from the superior 12 o'clock attachment to detachment at the inferior 6 o'clock location. Reattachment of the osteochondral labral avulsion was performed with suture anchors along the posterior rim, and the associated femoral head fractures were also addressed with internal fixation. Two patients had inadequate follow-up and were excluded, the average follow-up for the remaining 8 patients was 9.8 months (range, 6 to 26 mo). There were no findings of avascular necrosis in any of the 8 patients.

CONCLUSIONS

Posterior hip dislocation in children may produce an acetabular "fleck" sign on advanced imaging, which in a stable, concentrically reduced hip has been treated without surgery in the past. Acetabular fleck sign may represent a near-complete avulsion of the posterior labrum as seen in our series. We recommend a high suspicion for this type of labral pathology and surgical repair when acetabular "fleck" sign is identified with hip subluxation or dislocation. Traumatic, posterior hip dislocations in young patients may be associated with significant labral pathology. Acetabular "fleck" sign on advanced imaging may predict such pathology.

LEVEL OF EVIDENCE: IV, retrospective study.