Developmental Dysplasia of the Hip

Introduction:

Developmental dysplasia of the hip is more common in girls than in boys. One or both hips may be affected. It usually manifests at birth but can also develop during the first year of life. It is also called congenital hip dislocation (CHD), hip dysplasia, hip dislocation, acetabular dysplasia, and developmental dislocation of the hip. The American Family Physician estimates that 1 out of every 1000 infants is born with developmental dysplasia of the hip.

What Are the Causes of Developmental Dysplasia of the Hip?

The causes are as follows:

• The hip has a ball-and-socket type of joint. The top portion of the thigh bone (femur) is a ball that attaches to the pelvic or hip bone socket. This ball portion of the hip moves in all directions inside the socket (acetabulum) but does not come out in an average individual. This attachment of the ball and socket joint enables us to move our hips front, back, and side to side. It also bears the weight of the body while walking or running. In babies with developmental dysplasia of the hip, the ball part of the thigh bone is either partially or completely out of the socket since the socket is not fully developed and is shallow.

• The ligament is the strong band of tissue that holds the bone together. Newborns can be born with loose ligaments due to the extra stretchy nature of these ligaments. This condition is called hip laxity and causes the hip to move loosely. It usually resolves within four to six weeks; if not, treatment may be required.

What Are the Risk Factors for Developmental Dysplasia of the Hip?

The risk factors include the following:

• Swaddling the babies tightly during the first year with the knees and hips kept straight can cause hip dislocation. This does not mean that swaddling is wrong, but improper swaddling methods can cause a problem in the hip joint.

• Girl predisposition.

• During the first delivery, the uterus can be tight, and the baby might not get sufficient space to stretch.

• Babies in breech position (the baby’s position is such that its feet are towards the bottom of the uterus instead of the head).

• Previous family history of developmental dysplasia of the hip (DDH).

• Low levels of amniotic fluid (oligohydramnios).

• The large weight of the baby.

What Are the Signs and Symptoms of Developmental Dysplasia of the Hip?

Usually, no pain is involved in babies with developmental dysplasia of the hip. However, parents can watch out for the following signs and symptoms:

• Both legs of the babies might not be of the same length.

• Popping or clicking sounds in the hips can be distinctly heard or felt.

• The movement of one hip might not be the same as the other.

• The skin folds on the thighs or under the buttocks are not uniform.

• The child might limp and walk on their toes when they begin to walk.

• Duck-like walk (shifting the body weight from side to side while walking).

• A wide gap between both legs.

• The leg on the side of the affected hip may turn outward.

• Once the child starts to walk, the lower back may appear to be rounded inward.

• Delay in crawling, sitting, and walking.

How Is Developmental Dysplasia of the Hip Diagnosed?

Developmental dysplasia of the hip (DDH) may be difficult to identify at the time of birth and might take some time to be noticed until the child shows visible signs and symptoms. However, a doctor will initially examine the child physically and check for any popping, clicking, or clunking sounds when the hip is moved. The following are the diagnostic procedures for infants below three years of age:

• Ortolani Test: The movement away from the body is called abduction. In this, the doctor places the thumb on the medial surface of the thigh and the fingers on the lateral surface and applies mild upward stress while moving the child’s hip away from the body. If the hip dislocates at rest with a distinct ‘clunk,’ it is considered positive Ortolani and requires treatment.

• Barlow Test: The movement done towards the body is called adduction. The infant is made to lie with face upwards (supine), and light pressure is applied on the knee as it is moved inward with a gentle force directed posteriorly. The thigh bone’s ball part (femur) dislocates from the socket (acetabulum) with a distinct clunk in infants with developmental hip dysplasia.

• Galeazzi Test: It is also known as the Allis sign. The baby is placed in a supine or face-upward position, and the knees are bent (flexed) at 90° with the feet on the table. The knees’ height or position is evaluated from the table's end and side. If they are of unequal length, then it is a suspected case of developmental dysplasia of the hip.

• Ultrasound: The most recommended diagnostic test for infants under three months, as soundwaves capture the baby’s hip joint picture. X-rays cannot be taken as the hip in these infants is not developed and is composed of soft tissues.

• X-rays: X-rays are advised for infants more than six months of age and older children.

What Are the Treatments for Developmental Dysplasia of the Hip?

A pediatric orthopedic surgeon (expert in treating children’s bones, joints, and muscles) is involved in treating developmental dysplasia of the hip. The treatment is based on the child’s age. The treatment modalities include the following:

• Bracing or Harness: This is recommended for babies less than six months of age. The commonly used harness is called the 'Pavlik harness.' In this method, the harness is placed on the baby's shoulder and is attached to the feet, keeping the baby in a frog-like position. The doctor teaches the parents how to bathe, nurse, and handle the child with this harness. It is an effective and successful treatment, and the harness should be kept in place for 6 to 12 weeks. Review is advised every 1 to 3 weeks, and the progress is monitored through ultrasound and other examinations. The harness will be adjusted by the doctor if required.

• Closed Reduction Surgery and Casting: This type of surgery is advised if there is a failure in the bracing or harness technique or if the child is above six months of age.In this surgery, the child is given a general anesthetic (put to sleep using medicine so that the child does not feel any pain). A contrast dye is injected into the thigh to locate the cartilage (the strong, flexible connective tissue that protects the bones and joints) on the ball part of the thigh bone. The ball part is then guided into the socket and is held in place by a spica cast. The cast will be removed after 2 to 4 months. The orthopedic surgeon might loosen the tight muscles around the hip or lengthen the tendons (the fibrous connective tissue that attaches muscles to the bone) before closed reduction.

• Open Reduction Surgery and Casting: This type of surgery is recommended in kids with closed reduction surgery failure or in kids above 18 months of age. Open-reduction surgery is also done under general anesthesia. An incision (cut) is made on the child’s skin, and the muscles are moved to get a view of the hip joint. The ball part of the thigh bone is placed in the socket manually and held in place by a cast. The incision is closed with stitches. The cast is removed after 6 to 12 weeks. The surgeon might also deepen the shallow socket or the pelvic bone to keep the ball part in place.

• Osteotomy: In severe cases, a portion of the shallow socket may be cut off and repositioned with the ball part of the thigh bone.

What Are the Complications of Surgery?

The complications include the following:

• Delayed walk in children with spica cast, but they can walk normally after the cast is removed.

• Skin irritation in the area around the straps of the Pavlik harness. In rare cases, there can be nerve compression which can be rectified with strap adjustment or after the removal of the harness.

• The difference in the length of the leg may remain even after placing the Pavlik harness.

• Disturbance in blood supply to the thigh region can affect normal growth in these areas but is rare.

• Even after treatment, the hip socket may be shallow, requiring surgery in early childhood.

What Are the Outcomes of Developmental Dysplasia if the Hip Is Left Untreated?

If left untreated, the following can occur:

• Hip Labral Tear: Soft tissue that covers the socket (acetabulum) may be injured.

• Osteoarthritis: Hip pain and stiffness may be caused by damage to the cartilage.

• Dislocated Joint: The ball part moves out of the socket.

• Unstable Joint: The loose hip joint can cause pain and weakness.

Conclusion:

Early diagnosis and treatment can bring positive results in children with developmental dysplasia of the hip. If treatment is done at a later stage, a hip deformity or osteoarthritis can occur later in life if treatment is done at a later stage. The American Academy Of Pediatrics recommends that an ultrasound must be taken in babies, especially in female babies born in the breech position. It is advised not to wrap the babies too tight to prevent hip dysplasia after birth.