Introduction

This condition, also known as hip dysplasia or developmental dysplasia of the hip (DDH) has been diagnosed and treated for several hundred years. Developmental dysplasia of the hip ((DDH) describes a spectrum of conditions related to the development of the hip in infordsmWil young children. It encompasses abnormal development of the acetabulum and proximal femur and mechanical instability of the hip joint.

New born often have physiologic laxity of the hip and immaturity of the acetabulum during the first few weeks of life. In most cases, the laxity resolves, and the acetabulum proceeds to develop normally. With assessment of risk factors, serial physical examination of the hips, and appropriate use of imaging, most children with pathologic hips can be correctly diagnosed and treated without long- term sequel.

Definition:

Congenital dislocation of the hip generally includes subluxation of the femoral head, acetabular dysplasia and complete dislocation of the femoral head from the true acetabulum.

The incidence of DDH is higher in girls, perhaps because females are more susceptible than males to the maternal hormone relaxin, which may contribute to ligamentous laxity. The left hip is affected three times more often than the right hip, which may be related to the left occiput anterior position of most non breech infants.

Clinical features:

Asymmetry of the thigh or gluteal folds, limb length discrepancy and restricted motion (especially abduction) can be signs of a dislocated hip

Hip clicks or pops can sometimes suggest hip dysplasia but a snapping sound can occur in normal hip from developing ligaments in and around the hip joint.

Limited range of motion

Parents may have difficulty diapering because hips can't fully spread.

Pain is normally not present in infants and young children with hip dysplasia but is the most common symptom of hip dysplasia during adolescence and young adults.

A painless but exaggerated waddling limp or leg length discrepancy are the most common findings after learning to walk. If both hips are dislocated then limping with marked swayback may become noticeable after the child starts walking.

According to the AAP guideline, the most reliable sign in the three-month- old infant is limitation of abduction. Other features of DDH at this age include asymmetry of the thigh folds, relative shortness of the femur with the hips and knees flexed (called the Allis or Galeazzi sign) and a discrepancy of leg lengths.

Investigations:

One specific method, called the Ortolani test, begins with each of the examiner's hands around the infant's knees, with the second and third fingers pointing down the child's thigh. With the legs abducted (moved apart), the examiner may be able to hear a distinct clicking sound, called a hip click, with motion. If symptoms are present with a noted increase in abduction, the test is considered positive for hip joint instability. It is important to note this test is only valid a few weeks after birth.

The Barlow method is another test performed with the infant's hip brought together with knees in full bent position. The examiner's middle finger is placed over the outside of the hip bone while the thumb is placed on the inner side of the knee. The hip is abducted to where it can be felt if the hip is sliding out and then back in the joint. In older babies, if there is a lack of range of motion in one hip or even both hips, it is possible that the movement is blocked because the hip has dislocated and the muscles have contracted in that position. Also in older infants, hip dislocation may be present if one leg looks shorter than the other.

By eight to 12 weeks of age, the Ortolani and Barlow tests are no longer useful, regardless of the status of the femoral head. At this age, capsule laxity decreases and muscle tightness increases.

The Galeazzi sign is a classic identifier of unilateral hip dislocation. This is performed with the patient lying supine and the hips and knees flexed. The examination should demonstrate that one leg appears shorter than the other. Although this finding is usually due to hip dislocation, it is important to realize that any limb-length discrepancy results in a positive Galeazzi sign.

X-ray films can be helpful in detecting abnormal findings of the hip joint. X rays may also be helpful in finding the proper positioning of the hip joint for treatment. Ultrasound has been noted as a safe and effective tool for the diagnosis of congenital hip dysplasia.

Ultrasound has advantages over x rays, as several positions are noted during the ultrasound procedure. This is in contrast to only one position observed during the x ray.

Radiographs are of limited value during the first few months of life but are more reliable in infants four to six months of age, when the ossification center develops in the femoral head. According to the guideline, ultrasonography and radiography are equally effective imaging studies for detecting DDH in infants four to six months of age.

Treatment:

The objective of treatment is to replace the head of the femur into the acetabulum and, by applying constant pressure, to enlarge and deepen the socket. In the past, stabilization was achieved by placing rolled cotton diapers or a pillow between the thighs. The child may be dressed in two or three diapers called double or triple diapering. Both these techniques keep the knees in a frog-like position. In the early 2000s, the Pavlik harness and von Rosen splint were commonly used in infants up to the age of six months to spread the legs apart and force the head of the femur into the acetabulum. A stiff shell cast, called a splint, may be also used to achieve the same purpose. In some cases, older children between six to 18 months old may need surgery to reposition the joint. Also at this age, the use of closed manipulation may be applied successfully, by moving the leg around manually to replace the joint. Operations are performed to reduce the dislocation of the hip and to repair a defect in the acetabulum. A cast is applied after the operation to hold the head of the femur in the correct position. As of 2004 the use of a home traction program was more common. However, after the child is eight years of age, surgical procedures are primarily done for pain reduction measures only. Total hip surgeries may be inevitable later in adulthood.

Non surgical treatment methods:

These methods are most common when baby is less than 6 months of age. They typically consist of bracing a baby in such a way so that his/her hips are kept in a better position hip joint development. The goal is to influence the natural growth process so a more stable hip joint is developed.

Pavlik Harness

The Pavlik Harness is one type of brace used to treat DDH. It has straps that are fastened around the babys legs and held up by shoulder and chest straps. This holds the hips and knees up with the legs apart. This is the best position for the hip joint to be in. It allows contact between the thigh and hip bones and helps strengthen the muscles and ligaments of the hip while it is developing.

Hip abduction braces

A brace can be used for infants to hold their hips in a properly aligned position to

Encourage normal hip joint development. Also called fixed abduction braces that hold the legs apart and are flexible like pavik harness.

Traction

Sometimes a few weeks of traction are used to stretch the ligaments before attempting a surgical treatment like a closed reduction. Traction is commonly used in Europe and Asia. The reason and benefits of traction remain controversial.

If not treated by these methods, then surgical intervention is needed.