The Pavlik harness is an effective treatment up to 6 months ofage. It provides hip flexion to just over 90° and limits adduction tono more than neutral. This positioning redirects the femoral headtoward the acetabulum. The hip must be reduced within 1 to 2weeks of beginning the Pavlik harness, although the infant willneed more time in the device. The Pavlik harness is successful in treating approximately 95% of dysplastic or subluxated hips, and80% successful for treatment of true dislocations. Persistently dislocated hips should not remain in a Pavlik harness for more than2 weeks for fear of iatrogenic acetabular damage. Patients failingthe Pavlik harness warrant treatment with an abduction orthosis.
Children over 6 months or those who have failed nonoperative treatment should undergo closed reduction using a hip spica cast. This is done under general anesthesia; reduction is evaluated with an intraoperative arthrogram, then confirmed by postoperative computed tomography (CT) or magnetic resonance imaging (MRI). If closed reduction fails, open reduction is indicated. Patients over 18 months of age may require a pelvic and femoral osteotomy.
The most important and severe complication of DDH is iatrogenic avascular necrosis of the femoral head. This can occur from excessive flexion or abduction during positioning of the Pavlik harness or hip spica cast. Infants under 6 months of age are at highest risk. Pressure ulcers can occur with prolonged casting. Redislocation or subluxation of the femoral head and residual acetabular dysplasia can occur.
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Transient synovitis, also known as toxic synovitis, is a common cause of limping in children. It is a diagnosis of exclusion, because septic arthritis and osteomyelitis of the hip must be excluded (see Chapters 117 and 118).
The etiology of transient synovitis is uncertain, but possible causes are viral illness and hypersensitivity. Approximately 70% of children diagnosed with transient synovitis have an upper respiratory tract viral infection in the preceding 7 to 14 days. Biopsies have revealed nonspecific synovial hypertrophy. Hip joint aspirations, when necessary, are negative for bacterial culture or signs of bacterial infection.
The mean age at onset is 6 years, with a range of 3 to 8 years. It is twice as common in male children.
The patient or family will describe an acute onset of pain in the groin/hip, anterior thigh, or knee. Irritation of the obturator nerve can cause referred pain in the thigh and knee when the pathology is at the hip. Patients with transient synovitis are often afebrile, walk with a painful limp, and have normal to minimally elevated white blood cell count, C-reactive protein, and erythrocyte sedimentation rate compared with bacterial diseases of the hip (Table 199-1). Table 197-3 lists the differential diagnosis of a limping child.
Anteroposterior and frog-leg radiographs of the hip are usually normal. Ultrasonography may reveal a joint effusion. It is mandatory to rule out septic arthritis in the presence of effusion with a joint aspiration and cell count.
The mainstay of treatment is bed rest and minimal weight bearing until the pain resolves. Nonsteroidal anti-inflammatory medication is usually sufficient to decrease pain. Limiting strenuous activity and exercise for 1 to 2 weeks following recovery is helpful. Follow-up will help ensure that there is no deterioration. Lack of improvement necessitates further evaluation for more serious disorders.
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Elevated joint fluid cell count Afebrile Fever—temperature >38.5° C Leukocytosis Normal WBC count ESR >20 mm/hour Normal ESR and CRP
Refusal to walk Painful limp Hip held in external rotation, Hip held normally abduction, and flexion