Hip dysplasia is a group of disorders that affect the joint between the pelvis and the femur in newborn infants. In most cases there is only mild looseness of the hip joint. However some infants may be severely affected, having total dislocation of one or both of these joints. Hip dysplasia occurs in approximately 5 to 20 out of 1000 infants at birth.  All infants should be checked shortly after birth for instability of the hip joint. If the diagnosis is missed shortly after birth, it may be more difficult to treat the disorder later. Hip dysplasia can be discovered by a physical exam.  Ultrasound of the hip joints may be useful also. Treatment of the hip dysplasia involves the use of a harness for several weeks or longer.

What is hip dysplasia and who gets it? 

Congenital hip dysplasia is a group of disorders that involves the joints of the hip in newborn infants.   The hip joint involves the connection between the pelvis and at the femur. Malformation or looseness of this joint may lead to partial or complete hip dislocation.

• Hip dysplasia - 0.5% to 2% of newborns
• Hip dislocation - 0.1 - 0.2% of newborns
• 10% to 20% of infants with hip dysplasia have a family member who had the same. 

What causes hip dysplasia? 

The exact cause is unknown.  However it is likely that most cases are due to pressure within the womb that holds the head of the femur out of normal position. Hip dysplasia is much more common in a breech delivery.

 How is hip dysplasia diagnosed?

All newborn infants should be checked for looseness at the hip joint.  Two common maneuvers for verifying hip dysplasia include the Ortolani and Barlow tests. These maneuvers involved bending the hip joint in such a way that a "clunk" will be felt the joint is abnormally loose.  Evaluating an infant for hip dysplasia may be tricky.  Many infants have a normal "click" when the hip and knee joints are bent. Some infants with hip dysplasia may have a normal exam early in life.

Ortolani test

With the infant lying on her back, the knees are bent and spread outward as the hip joint is moved upward.  If the hip is dislocated, a " clunk" should be felt as the head of the femur pops back into normal position. 

Barlow test

 With the infant lying on her back, the knees are bent and held relatively close together.  Gentle downward force is applied.  If the hip joint is loose, a "clunk" will be felt when the head of the femur pops out of its normal position.

Galeazzi sign

With the infant lying on her back, the knees are bent and held relatively close together.  The height of the knees above the examining table are compared.  If one hip is dislocated, in these may appear to be at different heights above the table.

Ultrasound of the hip 

 Ultrasound of the hip is the best imaging study for hip dysplasia in infants less than six months of age. The above maneuvers can be performed while imaging the hip joint.

How is hip dysplasia treated?

Most infants with significant hip dysplasia are treated with a device called a "Pavlik harness."  This harness can be up to 95% effective when started early in life.  The harness is typically used 24 hours a day for several weeks.  The harness must be adjusted every few weeks as the infant grows. The hip joint should be evaluated on a regular basis. Treatment is usually successful after wearing a harness approximately six weeks.

Photo credit - Thiemo Schuff, 2008. WikiMedia Commons.

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