A 7-year-old boy is brought to the office for evaluation of chronic left thigh pain and a limp. The pain began 8 months ago as an intermittent ache, especially after soccer practice. The patient's family thought his symptoms were growing pains and have been giving him ibuprofen as needed for pain, with some improvement. Over the past month, however, the pain has been constant, and the patient recently developed a limp. He has had no fever, additional joint pain, or chronic medical problems and takes no daily medications. While walking to the examination table, the patient avoids bearing full weight on the left leg. Examination shows significantly limited range of motion of the left hip and atrophy of the left proximal thigh muscle. The remainder of the examination is unremarkable. X-ray of the pelvis is shown in the image. Which of the following is most likely responsible for this patient's condition?

Question

A 7-year-old boy is brought to the office for evaluation of chronic left thigh pain and a limp.  The pain began 8 months ago as an intermittent ache, especially after soccer practice.  The patient's family thought his symptoms were growing pains and have been giving him ibuprofen as needed for pain, with some improvement.  Over the past month, however, the pain has been constant, and the patient recently developed a limp.  He has had no fever, additional joint pain, or chronic medical problems and takes no daily medications.  While walking to the examination table, the patient avoids bearing full weight on the left leg.  Examination shows significantly limited range of motion of the left hip and atrophy of the left proximal thigh muscle.  The remainder of the examination is unremarkable.  X-ray of the pelvis is shown in the image.  Which of the following is most likely responsible for this patient's condition?

Quizplus · Accepted Answer

11ec25c8_d73f_eba4_bc81_5731cc2f4738_MD0003_00 This patient has Legg-Calvé-Perthes (LCP) disease, or idiopathic osteonecrosis (avascular necrosis) of the femoral epiphysis. This condition most commonly affects boys age 3-12, with a peak incidence between age 5 and 7. Typical presentation includes chronic, progressive leg pain and/or a limp. The pain is often worse with activity and may be localized to the hip or referred to the groin, thigh, or knee. Physical examination may reveal limited range of motion, particularly internal rotation and abduction, of the hip and atrophy of the proximal thigh muscle. Although x-rays early in LCP disease may be normal, subacute or chronic symptoms usually indicate a flattened and fragmented femoral head, such as in this patient. The alternating regions of lucency and density reflect replacement of necrotic bone by new bone. Patients are made non-weight bearing and are managed conservatively with bracing or splinting. Surgery may be indicated in cases in which the femoral head is not well contained within the acetabulum. (Choice A) Osteomyelitis is an infection that typically affects the metaphyses of long bones and presents acutely with fever, pain, and refusal to bear weight. This patient's chronic symptoms and epiphyseal involvement make osteomyelitis unlikely. (Choice B) Primary bony malignancies can present with chronic and progressive pain in the long bones but typically reveal "onion skinning" (eg, Ewing sarcoma) or a sunburst pattern (eg, osteosarcoma) on x-ray. This patient has a fragmented and flattened femoral head consistent with LCP disease. sunburst pattern (Choice C) Duchenne muscular dystrophy (DMD) is a progressive and fatal disease that presents with proximal muscle weakness and calf pseudohypertrophy. Joint x-rays are normal in DMD, making this diagnosis unlikely in this patient. (Choice E) Slipped capital femoral epiphysis classically presents in overweight adolescents, and x-ray shows a posteriorly displaced femoral epiphysis. This patient's age and x-ray findings make this condition unlikely. Slipped capital femoral epiphysis (Choice F) Stress fractures are uncommon in children and usually develop after repeated tensile stress. X-ray findings include periosteal elevation and cortical thickening, neither of which is present on this patient's imaging. (Choice G) Transient synovitis of the hip is a common cause of limp in young children. Symptoms typically develop after a viral infection and last <4 weeks. X-ray may be normal or show a joint effusion, making this diagnosis unlikely in this patient. Educational objective: Legg-Calvé-Perthes disease (idiopathic osteonecrosis of the femoral epiphysis) classically presents in young children with progressive leg pain and/or a limp. Decreased hip range of motion and thigh muscle atrophy may be present on examination, and x-ray shows a flattened and fragmented femoral head. References: Legg-Calvé-Perthes disease. (http://www.ncbi.nlm.nih.gov/pubmed/27064472)

A 7-Year-Old Boy Is Brought to the Office for Evaluation