Bone Scintigraphy Prediction of Postoperative Femoral Head Avascular Necrosis in Children With Hip Trauma and Slipped Capital Femoral Epiphysis.

Background: Femoral head avascular necrosis (AVN) is a devastating complication that can occur in the setting of trauma to the pediatric hip. Bone scintigraphy (BoS) can be used to evaluate femoral head perfusion, but current evidence in support of its use in the pediatric population is lacking. The purpose of this study was to evaluate the sensitivity and specificity of BoS to diagnose femoral head AVN in children.

Methods: We retrospectively reviewed patients who underwent BoS to assess femoral head perfusion following treatment of traumatic femoral neck fracture, hip dislocation, or SCFE at a single pediatric hospital. All patients had a minimum radiographic follow-up of 1 year. Assessment of intraoperative femoral head perfusion was also recorded if performed. Results of BoS and intra-op assessments were compared with RAVN (radiographic findings of AVN) at final follow-up.

Results: Forty-eight hips were included, and 75% were male. The mean age at the time of surgery was 12.5±1.6 years. The mean age at BoS was 12.7±1.7 years. The mean follow-up was 23.3±13.1 months. RAVN developed in 15% (7/48) of hips. Nine hips had an abnormal BoS: 7 hips had absent perfusion and 2 hips had diminished perfusion. All 7 hips with absent perfusion on BoS went on to develop RAVN with collapse. Neither hip with diminished perfusion on BoS went on to femoral head collapse. No hip with normal BoS developed radiographic evidence of AVN at the final follow-up. BoS demonstrating absent perfusion had a sensitivity of 100% and a specificity of 95% in predicting RAVN. Evidence of femoral head perfusion at the time of surgery (drilling or IOP) had a sensitivity of 17% and a specificity of 80% in predicting RAVN.

Conclusions: BoS demonstrates high sensitivity and specificity for predicting postoperative RAVN. Clinicians should have increased suspicion of impending femoral head collapse if there is absent perfusion on BoS at 6 to 12 weeks post-op, even with evidence of preserved femoral head perfusion at the time of surgery.