Half Moon Sign of Osteoid Osteoma 

Strong compressive and tensile trabecular patterns in the femoral neck inhibit the spread of edema from osteoid osteoma, resulting in the half moon sign.
#radiology #steoidosteoma #pediatrics #MSK #halfmoonsign
Reference:
Osteoid Osteoma of the Femoral Neck: Use of the Half-Moon Sign in MRI Diagnosis
Michail E. Klontzas, Aristeidis H. Zibis, and Apostolos H. Karantanas
American Journal of Roentgenology 2015 205:2, 353-357 www.ajronline.org/doi/10.2214...