Ideally, DDH is detected by routine history and physical exam in the neonatal period. Questions to the parents regarding risk factors can be important. Clinical screening is the gold standard for diagnosis with dynamic hip examinations carried out at birth and at subsequent pediatrician visits throughout childhood. The Ortolani test and Barlow maneuver should be done at each exam.
The Ortolani Test: The examiner’s hands are placed over the child’s knees with his/her thumbs on the medial thigh and the fingers placing a gentle upward stress on the lateral thigh and greater trochanter area. With slow abduction, a dislocated and reducible hip will reduce with a described palpable “clunk.”
The Barlow Maneuver is done by guiding the hips into mild adduction and applying a slight forward pressure with the thumb. If the hip is unstable, the femoral head will slip over the posterior rim of the acetabulum, again producing a palpable sensation of subluxation or dislocation.
Children under 6 months of age: Beyond clinical screening exams, US (ultrasound) is the preferred technique. Though US screening of all infants is not advised, infants with identified risk factors or questionable exams should be routinely screened. With a normal exam, screening US should be delayed until at least 4-6 weeks, when hip maturation improves exam specificity. US is also used to document reduction and follow the improvement or maturity of a dysplastic hip following treatment.
Children 6 months of age or older: Plain radiographic evaluation is used. On an AP radiograph, lines which localize the femoral head in relationship to the acetabulum-- Hilgenreiner’s, Perkin’s, and the acetabular index--can be drawn and measured. The proximal femoral metaphysis should lie medial to Perkin’s line, within the inner and lower quadrant of the resulting grid. In the dysplastic hip, the normal acetabular index (around 25 to 27 degrees) is increased. Other findings include disruption of Shenton’s line, delay in epiphyseal ossification and/or a widened or delayed “teardrop” appearance. Plain radiographs and measurements are also used to follow hip development and maturation.
Once DDH is identified, prompt referral to a pediatric orthopedist is suggested.
Birth to 6 months: Immature, stable hips (Barlow negative) that become normal do not need treatment. Hips that are Barlow positive at birth may also become stable in the first 3 weeks of life; therefore, treatment may be delayed. In both cases, close follow-up and routine physical exams are required, plus a later US to document normal hip stability and development.
With an unstable, Ortolani positive hip, early treatment is required. Reduced hips are positioned in flexion and mild abduction to stimulate normal joint development, most commonly performed via the Pavlik harness, a dynamic brace which positions the thighs to allow and maintain hip reduction. Infants are followed bi-weekly for strap adjustment. Progress is monitored and reduction verified with subsequent US evaluations. Pavlik treatment continues until US parameters have normalized and the hip stabilized on exam, on average 2-3 months later. Follow-up through skeletal maturity is then emphasized.
6 months to 1-2 years: Children who present at this time or fail to stabilize with the Pavlik harness require genera anesthesia, followed by closed or open hip reduction and spica casting.
Over 2 years of age: Older children may require extensive open surgical reductions with possible femoral and pelvic osteotomies (cutting and realigning the bones), followed by a spica cast.
Treatment success depends on the child’s age and the success of repositioning. Many cases treated in the first 6 months of life with a Pavlik harness recover and develop normally with no long-term problems. The older the child or less successful the reduction, the greater the possible need for repeated surgeries or eventual hip arthritis and subsequent replacements later in life.