Editorial Commentary: Subspine Hip Abnormalities: Exploring the Difference Between "Morphology" and "Impingement".

Subspine impingement has been increasingly recognized as a source of hip pain over the past 5 to 10 years. Some surgeons routinely perform subspine/anterior inferior iliac spine (AIIS) decompressions, whereas others rarely perform these procedures as part of an arthroscopic hip procedure. Subspine impingement has been implicated with high range-of-motion activities, various AIIS morphologies and deformities, and in the setting of persistent anterior hip pain after intra-articular anesthetic injections. Dynamic computed tomographic imaging has recently shown subspine impingement even with relatively normal AIIS morphology and in the setting of decreased femoral anteversion. These findings further emphasize the importance of understanding and defining relationships between morphology and impingement. Ultimately, subspine decompressions might be critical to achieve the best possible outcome after arthroscopic hip procedures in a subset of patients, but making the diagnosis remains challenging for clinicians.