Subspine Impingement Decompression

Subspine impingement is an extra-articular form of impingement around the hip joint. The word ‘impinge’ is a verb defined in Cambridge Dictionary as ‘to have an effect on something, often causing problems by limiting it in some way’. Femoroacetabular impingement (FAI) as a cause of hip pain was brought to academic attention by Ganz et al. [1]. Traditionally, two forms of FAI are described, namely Cam and Pincer [1, 2]. However, over the last 20 years not only extra-articular impingement variants have been identified but also their concomitant presence has been recognised. Various forms of impingement phenomena around the hip joint are recognised now including Cam, Pincer (focal and global), mixed, ischiofemoral and subspine in broad terms [1, 3–5]. Subspine impingement refers to a conflict of a bony prominence that exists between the anterior inferior iliac spine (AIIS) and acetabular rim with that of femoral neck in extreme flexion. This may or may not coexist with an underlying prominent acetabular rim (Pincer) or an abnormal AIIS (true AIIS impingement) or soft tissue damage including both intra- and extra-capsular structures. We have to understand the anatomy to appreciate these subtle differences. Treatment ranges from non-operative management to open surgery or arthroscopic intervention.