**Abstract**

Femoroacetabular impingement (FAI) is an often unrecognized hip disorder in young adults that can lead to early hip osteoarthritis and a decrease in sports performance. The diagnosis and treatment of this entity have rapidly evolved in recent years. Hip arthroscopy finds its place in the treatment of this conflict, and its indications are more and more frequent. The technical challenge of this operation involves a relatively long learning curve and a good knowledge of the hip anatomy in order to minimize the risk of complications and iatrogenic lesions. In addition to intra-articular structures of the hip joint, the anatomical structures that may be affected by the main and accessory arthroscopic approach are primarily the lateral femorocutaneous nerve, the lateral circumflex femoral artery, the medial circumflex femoral artery, and the circumflex superior iliac artery. A little further, 3–5 cm from the main portals, we must pay attention to the femoral nerve, the sciatic nerve, the superior gluteal nerve, the profunda femoris artery, the superficial femoral artery, and the common femoral artery. The pathogenesis of femoroacetabular impingement is not fully understood. The multifactorial origin is still relevant today. We have divided factors incriminated in the genesis of FAI into three groups.

**Keywords:** femoroacetabular, impingement, anatomy, pathogenesis, arthroscopy

## **1. Introduction**

Femoroacetabular impingement (FAI) is a common cause of early hip osteoarthritis. Often underdiagnosed, this entity deserves a particular interest in orthopedic surgeons.

In some cases of FAI, the underlying structural abnormality is secondary to residual childhood hip disorders, such as Legg-Calvé-Perthes disease, slipped capital femoral epiphysis, and others. In other cases, there is no obvious history of previous hip pathology, and the impingement is referred to as primary FAI [1]. The exact description of this morphological anomaly and how it causes early hip osteoarthritis has been studied by Ganz in 2001 [2]. However, Smith Petersen and Stulberg have talked about this pathology several years before [3, 4].

Diagnosis has become easier and easier with new imaging techniques, but clinical suspicion remains essential before any exploration.

Arthroscopy is the most common surgical procedure for FAI involving acetabuloplasty, labral repair/debridement, and/or femoroplasty [5].

#### *Essentials in Hip and Ankle*

Nakano [6], in a systematic review published in 2017, reported a complication rate of 3.3% after hip arthroscopy, and potential complications include neurovascular injuries, chondral and labral injuries, muscle pain, and avascular necrosis of femoral head and even femoral neck fracture [6–8].

This chapter reviews the bony, muscular, and neurovascular anatomies of the hip joint with specific attention to structures of greatest relevance to FAI and hip arthroscopy.
