**2. Epidemiology and classification**

It is considered that DDH occur 1 per 100 births as instability and 1 per 1000 births as subluxation or dislocation in the United States of America [8]. In Mexico, it is estimated that 1% of neonates have dysplasia and up to 75% of macrosomic neonates have hip alterations demonstrable by ultrasound, but only evolve to dislocation 1 for every 7000 live births [9].

There have been births of children with DDH, anomaly with pathological changes in the size, shape, and cellular organization of the hip that is manifested in the tissue components, soft or hard [10], which for their study are classified in CDD: typical and teratological.

The teratological is an alteration of the embryonic hip, it is called rigid, and the femoral head is outside the acetabulum and its treatment is surgical [11].

The typical or lax DDH is classified as physiological immaturity, subluxation, or dislocation, since it integrates anatomical abnormalities that affect the coxofemoral joint of children, including the abnormal edge of the acetabulum and the malposition of the femoral head causing subluxation or dislocation that affects the development of the hip before and after of birth [12–14].

This is how, within this spectrum, the defects vary from a slight difference between the articular surfaces of the iliac and femur, to the most severe case when the femoral head is outside the acetabulum; all accompanied by loss of mobility of the affected joint. So, these alterations in the hip cause disability in the infant of great social burden, especially if the child already wanders and the treatment has not been implemented properly [15].

It is important the early diagnosis, mainly before the children walk and ideally before 6 months old; if the children walk, can complicate the treatment of the DDH, and from a conservative treatment (Pavlik Harness or Fredjka Cushion), it should be surgical, with threatening prognosis for hip function.
