[1] Risk factors for hip dysplasia include female sex, family history, certain swaddling practices, and breech presentation whether an infant is delivered vaginally or by cesarean section.

[3] Hip instability of meaningful importance occurs in one to two percent of babies born at term.

[8] The cause of the condition is unknown; however, some factors of congenital hip dislocation are through heredity and racial background.

[11] A genetic factor is indicated since the trait runs in families and there is an increased occurrence in some ethnic populations (e.g., Native Americans,[12] Sami people[13][14]).

[15] Beukes familial dysplasia, on the other hand, was found to map to an 11-cM region on chromosome 4q35, with nonpenetrant carriers not affected.

[3] As an acquired condition it has been linked to traditions of swaddling infants,[20] use of overly restrictive baby seats, carriers and other methods of transporting babies,[21] or use of a cradle board which locks the hip joint in an "adducted" position (pulling the knees together tends to pull the heads of the femur bone out of the sockets or acetabulae) for extended periods.

[22] A narrow uterus also facilitates hip joint dislocation during fetal development and birth.

[27] However, new UK guidelines published in April 2021 have stated that isolated clicks are no longer considered clinically significant and therefore do not meet the screen positive criteria.

Overall, the latest evidence suggests that clinical screening tests are not sufficiently reliable for diagnosing developmental dysplasia of the hip.

[32][33] Most vexingly, many newborn hips show a certain ligamentous laxity, on the other hand severely malformed joints can appear stable.

This terminology introduces challenges, because the joint in a newborn is formed from cartilage and is still malleable, making the onset difficult to ascertain.

For adults it describes hips showing abnormal femur head or acetabular x-rays.

[46][notes 1] When universal with targeted ultrasound screening was compared, the former results in an insignificant reduction in the late diagnosis of hip dysplasia, which is why universal ultrasonographic screening of newborn infants is not recommended by the American Academy of Pediatrics.

[11] Despite the widespread use of ultrasound, pelvis X-ray is still frequently used to diagnose or monitor hip dysplasia or for assessing other congenital conditions or bone tumors.

[47] The most useful lines and angles that can be drawn in the pediatric pelvis assessing hip dysplasia are as follows:[47] Different measurements are used in adults.

[citation needed] However, given the very real possibility of a limp, constant and/or debilitating pain, complicated treatment and impaired mobility later in life, careful developmental monitoring is indicated and early intervention is often the best result.

[citation needed] Early hip dysplasia can often be treated using a Pavlik harness[48] (see photograph) or the Frejka pillow/splint[49] in the first year of life with usually normal results.

Complications arise mainly because the sheet of the iliopsoas muscle pushes the circumflex artery[specify] against the neck of the femur and decreases blood flow to the femoral head, so the Frejka pillow is not indicated in all the forms of the developmental dysplasia of the hip.

Traction is sometimes used in the weeks leading up to a surgery to help stretch ligaments in the hip joint, although its use is controversial and varies amongst physicians.

[53] In older children the adductor and iliopsoas muscles may have to be treated surgically because they adapt to the dislocated joint position (contracture).

On the other hand, it has often been documented that starting treatment late leads to complications and ends in poor results.

Dislocated load bearing surfaces lead to increased and unusual wear, although there are studies that contradict these findings (see[54][55]).

Peri-acetabular osteotomy (PAO) surgery can be used to realign the hip joint in some adolescents and adults.

[citation needed] In the television program ER, Kerry Weaver uses a crutch owing to congenital hip dysplasia.

In season 12, she undergoes a hip replacement to cure her dysplasia when her previously untreated joint worsens.