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A rare disease of children appears in a young man

Pamela Phelan, MPAS, PA-C

Pamela Phelan practices in interventional radiology with Valley Radiologists, an affiliate of Southwest Diagnostic Imaging Ltd in Glendale, Arizona. She has indicated no relationships to disclose relating to the content of this article.

CASE

The patient is a 22-year-old white male referred to the radiology department for an initial hip injection. He was being managed by his primary care provider for a chief complaint of chronic right hip pain, and the primary care provider had referred the patient to an orthopedic surgeon. The patient reported to the surgeon that he had had right hip pain since he was a young child. Lately, he had experienced increased leg weakness, nocturnal pain, grinding, stiffening, and overall instability of his right leg. The surgeon presented the patient with various treatment options, including hip replacement, hip fusion, or pelvic osteotomy. Considering the patient’s young age, hip replacement would be reserved as a last resort. The surgeon recommended that the patient receive serial cortisone injections to alleviate the pain.

Initial scout films revealed obvious chronic abnormalities of the right hip (see Figure 1 and Figure 2). What classic findings are seen in these films that would cause this patient’s persistent hip pain?

DISCUSSION

Figure 1 and Figure 2 are pelvic radiographs obtained in anteroposterior (AP) and frog-leg views. The scout images reveal a flattened right femoral head with a foreshortened neck. These are classic diagnostic findings associated with Legg-Calvé-Perthes disease.

Pathophysiology The etiology of Legg-Calvé-Perthes disease is unknown. What is known about this disease is that it involves transient interruption of blood flow to the femoral head. The result is loss of bone mass secondary to osteonecrosis, which ultimately leads to deformity of the hip ball and socket. The disease has a 4:1 predilection for boys over girls and is seen primarily in children aged 3 to 12 years, with a mean age of 6 years. Legg-Calvé-Perthes disease typically manifests unilaterally, but it involves both hips in approximately 8% to 10% of cases.

Clinical presentation Children with Legg-Calvé-Perthes disease typically present with complaints of hip pain and a limp. Persistent hip/groin pain that may radiate to the thigh or knee is usually alleviated with rest. Patients will exhibit limited range of motion, particularly rotation of the affected hip. Although the etiology of this condition is unknown, some patients may have a history of related trauma.

The disease has four radiographic phases: 1) in the initial phase, there is cessation of growth at the capital femoral epiphysis, a smaller femoral head epiphysis, and widening of articular space on the affected side; 2) in the fragmentation phase, evidence of repair and new bone formation are represented by increased radiolucency within the femoral head epiphysis; 3) during reossification, normal bone density returns as the shape of the femoral head and neck are restored; 4) in the healed stage, there may be residual deformity from disease and the repair process, and gradual remodeling may take 2 to 4 years.

Imaging and other testing Plain pelvic radiographs in AP and frog-leg lateral views are used for initial evaluation of bony structures and surrounding tissues. Radiographs are also utilized to monitor the response of the disease to treatment. Radionuclide bone scanning can determine the extent of avascular changes. MRI can provide a precise evaluation of internal structures. Arthrography is used to evaluate the nonbony structures of joints and the spherical nature of the femoral head in relation to the acetabulum; this test is very useful in evaluating containability. Laboratory studies are not particularly useful in the treatment of Legg-Calvé-Perthes disease but can help to narrow the differential diagnosis. A CBC, thyroid testing, and ESR may be ordered to exclude an infectious process.

Prognostic factors Specific clinical and diagnostic findings of Legg-Calvé-Perthes disease are directly related to treatment outcomes. The most important prognostic indicator is the extent of femoral head deformity and hip joint incongruity. Various classification systems are used to determine the extent of disease and thus guide treatment options. Age at onset of disease is the second most important factor related to outcome. The most reliable indicators of prognosis and the potential for development of degenerative joint disease are the shape of the femoral head and congruency to the acetabulum.

Treatment Although the treatment of Legg-Calvé-Perthes disease is controversial, the most widely accepted principle of treatment pertains to methods of containment. Conservative methods are the standard of care for children. These include rest and activity modifications; physical therapy abduction stretching exercises (swimming is encouraged); NSAIDs; and casting, traction, and bracing to restore range of motion and mobility. The course of treatment is individualized based on the patient’s overall health, medical history, and extent of disease. The primary goals of treatment are to minimize hip irritation, preserve mobility, “contain” the femoral epiphysis within the confines of the acetabulum (ball and socket), and regain the natural spherical shape of the femoral head.

Surgical containment options include the tenotomy procedure, which may be performed to release shortened, atrophied muscles resulting from prolonged limping. Casting is applied for 6 to 8 weeks to allow the muscle to regrow at a more natural length. Femoral or pelvic osteotomy involves cutting into the bone and redirecting to optimize position of the femoral head within the acetabulum.

Prognosis Early diagnosis is crucial for an optimal outcome that minimizes the potential long-term effects associated with Legg-Calvé-Perthes disease. Children younger than 6 or 7 years are more likely to have optimal outcomes compared to those aged 10 years or older. Younger patients have the best potential for revascularization and remodeling of the hip. Symptoms are often misdiagnosed as “growing pains” or simply fatigue. As health care providers, PAs must perform a thorough history and physical examination and follow up with appropriate diagnostic tests. Treatment goals for patients with Legg-Calvé-Perthes disease are targeted toward pain control, preserving range of motion, promoting healing of bone structures, and ultimately preventing long-term complications of permanent deformity and the development of late degenerative osteoarthritis. JAAPA

Julie Vajnar, PA-C, RT, department editor