A 4-year-old boy is brought to the emergency department by his mother due to refusing to walk since this morning. The patient started having right groin pain 2 days ago after T-ball practice, and his mother noticed him "walking funny" yesterday. She says, "I had to carry him here because he says it hurts too much to walk." The mother has witnessed no recent falls or injuries, and the symptoms have not improved with acetaminophen. The patient has had upper respiratory symptoms for the last 2 weeks and was diagnosed with viral pharyngitis a week ago. He has a history of atopic dermatitis that is controlled with low-dose topical corticosteroids. Immunizations are up to date. He takes no medications and has no known allergies. Temperature is 38.6 C (101.5 F). The patient appears tired but nontoxic. The posterior pharynx is clear and without exudates. The lungs are clear to auscultation. On examination of the right hip, the patient cries and resists passive movement. There is decreased range of motion of the right hip. Dry, erythematous patches are noted on the bilateral forearms. Laboratory findings show a white blood cell count of 14,000/mm³ and a C-reactive protein of 4.0 mg/L (normal:

Question

A 4-year-old boy is brought to the emergency department by his mother due to refusing to walk since this morning. The patient started having right groin pain 2 days ago after T-ball practice, and his mother noticed him "walking funny" yesterday. She says, "I had to carry him here because he says it hurts too much to walk." The mother has witnessed no recent falls or injuries, and the symptoms have not improved with acetaminophen. The patient has had upper respiratory symptoms for the last 2 weeks and was diagnosed with viral pharyngitis a week ago. He has a history of atopic dermatitis that is controlled with low-dose topical corticosteroids. Immunizations are up to date. He takes no medications and has no known allergies. Temperature is 38.6 C (101.5 F). The patient appears tired but nontoxic. The posterior pharynx is clear and without exudates. The lungs are clear to auscultation. On examination of the right hip, the patient cries and resists passive movement. There is decreased range of motion of the right hip. Dry, erythematous patches are noted on the bilateral forearms. Laboratory findings show a white blood cell count of 14,000/mm³ and a C-reactive protein of 4.0 mg/L (normal: <3.0 mg/L). Which of the following is the best next step in management of this patient's condition?

Quizplus · Accepted Answer

Explanation: 11ec2b69_c0c6_6367_8f63_236b567e4566_MD0005_00 Septic arthritis is a joint infection that frequently involves the hip or knee in young children. Most cases occur in healthy children, but patients with immunodeficiencies, prior joint surgery, hemoglobinopathies, juvenile idiopathic arthritis, and diabetes mellitus are at increased risk. Patients with septic arthritis of the hip usually have swelling and decreased range of motion around the joint. Children often keep the hip in a flexed, abducted, and externally rotated position. In children with unilateral hip pain, septic arthritis can be differentiated from other etiologies, such as transient synovitis (post-viral inflammatory reaction of the joint), based on the following criteria (ie, Kocher criteria): Non-weight-bearing Fever ≥38.5 C (101.3 F) Erythrocyte sedimentation rate >40 mm/hr OR C-reactive protein >2.0 mg/dL Leukocytosis Pediatric patients with ≥3 criteria have a high likelihood of septic arthritis (>93%), and immediate joint aspiration is performed to both establish the diagnosis and decompress the joint. Once the diagnosis is confirmed, empiric parenteral antibiotics as well as surgical drainage and debridement of the joint are required. A delay in diagnosis and treatment can result in joint damage, avascular necrosis, femoral head enlargement, and limb length discrepancy. (Choice A) Acute rheumatic fever (ie, positive antistreptococcal antibody titers) typically presents a few weeks after pharyngitis. Although patients often have fever and elevated inflammatory markers, they typically have a migratory polyarthritis that rarely involves the hip. (Choice C) MRI may be used to evaluate the extent of infection prior to surgical debridement. However, ordering an MRI prior to joint aspiration delays treatment as antibiotics are not administered until synovial fluid is obtained. (Choice D) Serum antinuclear antibodies may be positive in juvenile idiopathic arthritis, which presents with an inflammatory arthritis characterized by a chronic, waxing-and-waning course involving multiple joints (rarely the hip). (Choice E) Borrelia burgdorferi serology is positive in Lyme arthritis, which typically presents with erythema migrans after a previous tick bite, and the associated arthritis is more common in the knee than the hip. Patients are generally afebrile and able to bear weight despite the swollen, painful joint. erythema migrans Educational objective: Septic arthritis is a joint infection characterized by pain, fever, swelling, decreased range of motion, and refusal to bear weight. Laboratory evidence of infection (eg, leukocytosis, elevated inflammatory markers) is typically present, and joint aspiration confirms the diagnosis and decompresses the joint. References: Bone and joint infections in children: septic arthritis. (http://www.ncbi.nlm.nih.gov/pubmed/26189923)

A 4-Year-Old Boy Is Brought to the Emergency Department by His