Femoroacetabular Impingement: Preoperative Planning and Postoperative MR Imaging Evaluation.

Imaging plays a critical role in the preoperative and postoperative evaluation of patients with femoroacetabular impingement. Non-contrast MR imaging and direct magnetic resonance arthrography of the hip are the modalities of choice for the preoperative assessment of chondrolabral lesions. The MRI protocol should include radial images for detailed analysis of the cam deformity and fast sequences covering the pelvis and knee for measurement of femoral torsion. In patients with postoperative pain, a comprehensive analysis of residual deformities and signs of osseous overcorrection should be performed as they can cause residual impingement or iatrogenic instability.