What is hip dysplasia?

Hip dysplasia
Hip dysplasia is a congenital condition that can lead to spinal problems, hip dislocation, a rolling gait, death of hip tissue, and severe arthritis before age 50.

Hip dysplasia, also known as developmental dysplasia of the hip (DDH), is an abnormal development of the hip joint that causes hip instability or dislocation. Hip dysplasia is usually a congenital condition, though, in some people, it may not manifest until later in life.

The hip joint is a ball and socket joint, in which the ball-like head of the thigh bone (femur) fits into a socket (acetabulum) in the hip bone. The femoral head and the acetabulum are lined with cartilage that prevents friction between the bones, and enclosed in a joint capsule, which also lubricates the joint.

Normally, the femoral head fits neatly into the acetabulum which completely encloses it and prevents dislocation while allowing mobility. In hip dysplasia, the socket is often shallow which makes the joint unstable and affects normal functioning.

Hip dysplasia may vary in degrees as follows:

  • Dislocation: Complete loss of contact between the femoral head and acetabulum
  • Subluxation: Incomplete contact between the femoral head and acetabulum
  • Instability: Loose joint that can dislocate or subluxate easily

What are the symptoms of hip dysplasia?

Symptoms of hip dysplasia depending on the severity of the condition. Newborn infants may not show any outward signs of hip dysplasia. Doctors usually examine newborn children for hip dysplasia using certain maneuvers.

The signs of unilateral hip dysplasia in infants include the following:

  • Unequal leg lengths
  • Asymmetrical skin folds on the thighs
  • Decreased mobility or flexibility on one side
  • Popping sensation when the affected hip is moved

As the child grows, symptoms may become more apparent, which include:

  • Pain in the groin or hip that worsens with activity
  • Loose and unstable hip joint
  • Walking with a limp

If both hips are affected, many of the above symptoms may be absent, instead, the child may develop a waddling gait with extra curvature (hyperlordosis) in the lower spine.

What is the cause of hip dysplasia?

The exact cause of hip dysplasia is not clear. A newborn’s hip socket is normally shallow and soft, and the ligaments are loose, to allow flexibility during the passage through the birth canal. The ligaments become firmer after birth and the socket hardens and continues to become deeper until skeletal growth is complete.

If the femoral head doesn’t fit properly in the socket when the baby is born, the socket may not deepen normally, leading to hip dysplasia. Hip dysplasia is far more common in the left hip, possibly because the baby’s left leg rests against the mother’s sacral bone in the normal fetal position, which may apply pressure on the baby’s hip.

The risk factors for developing hip dysplasia include the following:

  • Genetic factors may play a role. A child’s risk for hip dysplasia is higher when a parent and/or sibling has the condition.
  • Being the first-born child, because the uterus may not enlarge adequately.
  • Girl babies have a higher risk, likely because of a hormone (relaxin) that women produce to soften and expand the pelvis during pregnancy. An estimated 80% of hip dysplasia patients are female.
  • The baby is in the breech position, with the head up and rear towards the birth canal.
  • Low level of amniotic fluid (oligohydramnios) in the uterus.
  • Tight swaddling of the baby with the hips and knees kept straight.

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Can hip dysplasia be prevented?

In most cases, hip dysplasia cannot be prevented. But risks can be minimized by:

  • Regular check-ups in early childhood
  • Avoiding swaddling tightly with legs straightened. Leaving the baby’s legs in their natural position is healthier for normal hip development.

Can hip dysplasia be cured?

Hip dysplasia can be successfully treated in most children. Prognosis is good, especially if surgery is not required. Early diagnosis and treatment greatly improve the chances of normal hip development, with the child being able to lead a normal and active life, including participating in sports.

Treatment outcome also depends on the degree of hip dysplasia, and the damage to the joint before the detection of the condition. Bilateral hip dysplasia may have a relatively poorer prognosis because diagnosis is often delayed and both hips require treatment.

What happens if hip dysplasia is left untreated?

With appropriate treatment, some people may still develop osteoarthritis and/or hip deformity later in life, especially if treatment starts after age 2. Left untreated, hip dysplasia can cause complications which include:

How do you treat hip dysplasia?

Treatment for hip dysplasia depends on the age at which it is diagnosed. Nonsurgical treatments may help correct hip dysplasia if detected early, but children older than six, adolescents and adults usually require surgery.

Children

Typically, hip dysplasia treatments in children up to the age of six are performed incrementally, with periodic scans or X-rays to monitor improvement. Treatments for hip dysplasia include the following:

  • Pavlik harness: The Pavlik harness, a soft splint that keeps the hips and knees bent and the thighs apart, is the primary treatment for newborns and babies up to the age of six months. The harness restricts hip movements until the unstable or dislocated hip slips into place and becomes stable.
    • Usually, the baby needs to wear the Pavlik harness 24 hours a day for six to twelve weeks. If the hips become stable, it is worn part-time, at nights, for another four to six weeks. Pavlik harness is discontinued for alternate treatments, if not successful within four weeks. Continuing with the harness while the hip is dislocated can damage the wall of the socket.
  • Fixed abduction brace: A fixed abduction brace is another type of device used for children under six months. An abduction brace supports the pelvis and hips, restricts movement, and holds the joint in place. An abduction brace may have to be worn for eight to 12 weeks, 24 hours a day. 
  • Closed reduction: Closed reduction is the usual treatment for hip dysplasia detected in children from six months to two years. It is also used in children for whom harness and/or abduction brace have not been effective. Closed reduction is usually performed under general anesthesia.
  • Closed reduction is a procedure to manipulate the joint into position without cutting the skin open. The doctor uses an X-ray or MRI to guide the femoral head into its proper position in the socket. Doctors may also use traction to stretch the muscles, before closed reduction.
  • Spica cast: After a closed reduction, the child is placed in a plaster cast known as a spica cast, which prevents hip movement. The standard period for a spica cast is three months, but some children may need to wear it longer for the hip to stabilize.
  • Surgery: Surgery is the option for children for whom the above procedures don’t help, and for most children diagnosed from ages two to six years. The child has to be in a spica cast for six to eight weeks after surgery. Surgical procedures for children up to age six include the following:
  • Open reduction: Open reduction is open surgery to set the joint in place with possible additional bone surgeries and ligament realignment as required. Open reduction is rarely performed for children older than six because bone changes become permanent by then.
  • Pelvic osteotomy: Pelvic osteotomy is a procedure to surgically shape the hip socket for the femoral head to fit in.
  • Femoral osteotomy: Femoral osteotomy is a procedure to shape the femoral head so that it fits properly into the socket.

Adolescents and adults

Some adolescents and adults may have residual problems after childhood treatment for hip dysplasia, but the most common reason for adult hip dysplasia is because the socket does not become deep enough during skeletal maturity and remains shallow. For many adults, hip dysplasia isn’t found until their hip starts hurting.

Hip dysplasia is the most common cause of osteoarthritis that develops before the age of 50.  A shallow or misshapen socket makes the cartilage that cushions the bone ends wear out faster, leading to early arthritis.

Nonsurgical treatments

Nonsurgical treatments can delay surgery, but most people will eventually need surgery. Mild hip dysplasia may be treated with non-surgical treatments such as:

  • Weight loss
  • Physical therapy
  • Opting for activities such as swimming which do not put a lot of stress on the hips
  • Pain medications
  • Cortisone injections can help with reducing inflammation and pain from osteoarthritis
  • Hyaluronic acid injections may help improve joint lubrication

Surgical treatments

Depending on the severity of hip dysplasia, in addition to pelvic and femoral osteotomies, surgical options for adolescents and adults include:

  • Hip arthroscopy: A minimally invasive surgery performed with a miniature camera and special surgical tools inserted through tiny incisions. Hip arthroscopy is usually performed to repair torn cartilage (labral tear) in the hip joint. 
  • Periacetabular osteotomy: The surgeon makes cuts around the acetabular cup and repositions it to fit the femoral head better.
  • Hip joint replacement: Hip replacement is avoided as far as possible and performed only when dysplasia is too severe to correct with other types of surgeries.

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Medically Reviewed on 3/7/2021
References
https://emedicine.medscape.com/article/1248135-overview

https://www.webmd.com/children/what-is-hip-dysplasia#1

https://hipdysplasia.org/developmental-dysplasia-of-the-hip/

https://orthoinfo.aaos.org/en/diseases--conditions/developmental-dislocation-dysplasia-of-the-hip-ddh/

https://www.ortho.wustl.edu/content/Patient-Care/3205/Services/Hip-Knee/Adult-Reconstruction-and-Hip-Preservation-Overview/Hip-Dysplasia.aspx

https://my.clevelandclinic.org/health/diseases/17903-hip-dysplasia