Developmental Dislocation (Dysplasia) of the Hip

Developmental Dislocation (Dysplasia) of the Hip

Introduction

Developmental dislocation of the hip, also known as hip dysplasia or developmental dysplasia of the hip, is a developmental abnormality of the hip joint in which the “ball and socket" joint of the hip does not form properly in infants and young children.

The hip is a ball and socket joint with the head of the femur or thighbone as the ball and the pelvic acetabulum forming the socket. In a normal hip, the head of the femur fits firmly into the cup-shaped socket of the pelvic acetabulum. However, in infants and children with hip dysplasia, the socket of the acetabulum is too shallow and the femoral head is not held firmly in place, resulting in a loose hip joint. In severe cases, the femur can partially or completely slip out of the socket causing dislocation at the hip joint.

The condition is most often noted at birth. However, it may also present during an infant’s first year of life. Recent research indicates that newborn infants whose legs are tightly wrapped with the knees and hips straight are at increased risk of developing developmental dislocation of the hip after birth. 

Causes

Developmental dislocation of the hip tends to run in families. It can occur in one or both hips and in any child. However, it is more common in the left hip and is predominant in:

• Firstborn child
• Females
• Infants born in the breech presentation
• Oligohydraminos or insufficient amniotic fluid during pregnancy
• Familial history

Signs and Symptoms

The common signs and symptoms of developmental dislocation of the hip include:

• Restricted movement on the side of the dislocated hip
• Leg length discrepancy
• Toe walking, limping, or a waddling gait
• Dislocated hip may cause leg on that side to turn outwards
• Skin folds on the thigh or buttock may appear uneven
• Popping or clicking sound on the affected side of the hip

Diagnosis

As developmental dislocation of the hip most often presents at birth, your child’s physician will check the condition of your baby’s hip as part of a newborn physical examination within 3 days of being born. The newborn examination involves moving your child’s hip joints gently to elicit any abnormal sounds, which may indicate problems in the hip joint. Your physician may also ask about your child’s birth history and whether there is any family history of this condition. If any hip abnormality is suspected during the newborn exam, your child’s physician will order an ultrasound scan for a detailed examination of the hip joint and to confirm the diagnosis. For older infants and toddlers, X-rays may be ordered to check out bone details of the hip joint. 

Treatment

The treatment for developmental dislocation of the hip depends on both the age of your child and severity of the condition. The aim of the treatment is to keep the femoral head in good contact with the acetabulum so that the hip can develop normally. The treatment methods may include:

Bracing

Bracing is employed for infants younger than 6 months of age. The brace most commonly used is a Pavlik harness. A Pavlik harness is a soft brace that holds the hip in position for 1 to 3 months while the soft tissue around the hip tightens. By holding the femoral head in the socket of the acetabulum, the brace helps the acetabulum to develop more naturally. 

Closed reduction and casting

This method of treatment may be employed if the infant is over 6 months of age or bracing has failed to hold the ball of the hip in the socket. During closed reduction and casting, your surgeon:

• Administers general anesthesia to put your child safely asleep.
• Injects contrast dye into the hip joint to view the cartilage portion of the ball.
• Moves the child’s femur so that the ball of the hip joint goes back into proper position in the socket.
• Places a hip spica cast to hold the hip in position. The child needs to wear this cast for 2 to 4 months.
• An MRI or CT scan may be ordered after the cast is placed to confirm that the hip has stayed in the joint.

Open Reduction (Surgery) and Casting

Surgery may be required if the child is older than 18 months of age or the closed reduction has failed to hold the ball of the hip in the socket. During open reduction surgery, your surgeon:

• Administers general anesthesia to put your child safely asleep.
• Makes a surgical cut through the skin.
• Moves the muscle tissue out of the way to view the hip joint directly.
• Carefully removes tissue that is hindering the femoral head from being in the acetabulum and places the ball back into place in the socket.
• Closes the surgical incision with absorbable sutures.
• Places a hip spica cast to hold the hip in position. The child needs to wear this cast for 6 to 12 weeks.

Summary

Worldwide, roughly 2-3% of children are born with developmental dislocation of the hip. Early diagnosis is crucial for a successful outcome and will enable your child to have a normal hip joint without any functional limitation. If left untreated, the condition can result in debilitating pain, joint instability, reduced agility, and eventually osteoarthritis.