Atypical hip impingement.

Abstract

This article summarizes how atypical forms of hip impingement can be assessed with radiographs, CT, and MRI. Subspine impingement, ischiofemoral impingement, and iliopsoas impingement are atypical forms of hip impingement and are less common than classic femoroacetabular impingement. Additional forms of atypical impingement, such as abnormal femoral antetorsion, abnormal pelvic and acetabular tilt, and extreme hip motion, can occur combined with classic femoroacetabular impingement or as separate entities.