Impingement around the hip: beyond cam and pincer.

In this review, we bring to the attention of the reader three relatively unknown types of hip impingement. We explain the concept of low anterior inferior iliac spine (AIIS) impingement, also known as sub-spine impingement, ischio-femoral impingement (IFI) and pelvi-trochanteric impingement. For each type of impingement, we performed a search of relevant literature.We searched the PubMed, Medline (Ovid) and Embase databases from 1960 to March 2016. For each different type of impingement, a different search strategy was conducted.In total, 19 studies were included and described. No data analysis was performed since there was not much comparable data between studies.An overview of symptoms, clinical tests and possible surgical treatment options for the three different types of extra-articular impingement is provided.Several disorders around the hip can cause similar complaints. Therefore, we plead for a standardized classification. In young and athletic patients, in particular, there is much to gain if hip impingement is diagnosed early. Cite this article: EFORT Open Rev 2018;3:30-38. DOI: 10.1302/2058-5241.3.160068.