Perfusion Magnetic Resonance Imaging is the Best Way to Predict the Occurrence of Avascular Necrosis in Slipped Capital Femoral Epiphysis.

Background: Avascular necrosis (AVN) is a known complication of slipped capital femoral epiphysis (SCFE) that can lead to poor long-term outcomes. Therefore, predicting the onset of AVN is crucial for effective management. While various preoperative methods have been proposed to predict AVN, none have demonstrated accurate prediction. This study aimed to assess the efficacy of preoperative perfusion magnetic resonance imaging (MRI) in accurately predicting the onset of AVN in patients with SCFE.

Methods: This study included 17 cases (18 hips) treated for SCFE at a single institution between January 2017 and April 2021. Preoperative factors such as stability (stable, unstable), gradual onset (acute, chronic, acute on chronic), slip severity (mild, moderate, severe), superior translation, bone scintigraphy results (HOT, COLD), and perfusion MRI findings were compared with the incidence of AVN. Perfusion MRI involved sequential imaging of the contrast-enhanced femoral head to generate time intensity curves, categorized as type A (similar enhancement on both sides), type B (delayed but stronger enhancement on the affected side), and type C (no enhancement on the affected side).

Results: AVN was observed in 4 out of 18 hips (22%). Among unstable hips, 4 out of 8 (50%) developed AVN, and superior translation averaged 20.8 ± 6.54 mm in 4 cases with AVN, and a statistically significant difference was observed in each factor. In terms of gradual onset, AVN occurred in 3 out of 7 acute cases (43%) and 1 out of 7 acute-on-chronic cases (14%). Regarding slip severity, AVN was found in 1 out of 7 moderate cases (14%) and 3 out of 9 severe cases (33%); there was no significant difference. AVN was observed in 4 out of 5 cases (80%) showing a COLD pattern on bone scintigraphy, and in all 4 cases (100%) classified as type C on perfusion MRI. Statistically significant differences were found for both imaging modalities.

Conclusions: Stability, superior translation, bone scintigraphy, and perfusion MRI in cases of SCFE may serve as effective predictors of future AVN.

Level of evidence: Level Ⅳ.