A 3-year-old boy is brought to the emergency department due to refusal to walk. The patient's mother first noticed a mild limp 3 days ago after picking him up from day care. The patient tends to climb and jump on furniture, so she initially attributed the limp to rough play. The symptoms worsened today, and the patient now refuses to stand, falling when held up by his mother. He has no chronic medical conditions but has had a runny nose and fever intermittently for 2 months since starting day care. Temperature is 38 C (100.4 F), pulse is 90/min, and respirations are 24/min. Pulse oximetry is 100% on room air. The patient appears comfortable while lying supine on the examination table. He has clear rhinorrhea with several soft and mobile anterior cervical lymph nodes approximately 1 cm in diameter. The abdomen is nontender and the liver edge is palpable. The hips are held flexed bilaterally. During movement of the left hip, the patient wails and resists. Sensation is normal, and reflexes are intact. Babinski sign is negative bilaterally. Laboratory results are as follows: Which of the following is the best next step in management of this patient?

Question

A 3-year-old boy is brought to the emergency department due to refusal to walk.  The patient's mother first noticed a mild limp 3 days ago after picking him up from day care.  The patient tends to climb and jump on furniture, so she initially attributed the limp to rough play.  The symptoms worsened today, and the patient now refuses to stand, falling when held up by his mother.  He has no chronic medical conditions but has had a runny nose and fever intermittently for 2 months since starting day care.  Temperature is 38 C (100.4 F), pulse is 90/min, and respirations are 24/min.  Pulse oximetry is 100% on room air.  The patient appears comfortable while lying supine on the examination table.  He has clear rhinorrhea with several soft and mobile anterior cervical lymph nodes approximately 1 cm in diameter.  The abdomen is nontender and the liver edge is palpable.  The hips are held flexed bilaterally.  During movement of the left hip, the patient wails and resists.  Sensation is normal, and reflexes are intact.  Babinski sign is negative bilaterally.  Laboratory results are as follows:  Which of the following is the best next step in management of this patient?

Quizplus · Accepted Answer

Explanation: 11ec25c8_d748_2915_bc81_95085984935f_MD0003_00 The most common cause of atraumatic hip pain and limp in children is transient synovitis, a self-limiting, inflammatory condition often preceded by a viral illness. However, transient synovitis must be distinguished from septic arthritis, a potentially life-threatening infection requiring emergency treatment (eg, intravenous antibiotics). Clinical features help distinguish between the 2 conditions: Transient synovitis typically presents in children age 3-8 who are afebrile or have a low-grade fever. Patients have pain and limited mobility of the affected joint but can usually bear weight. Leukocyte count and inflammatory markers (eg, erythrocyte sedimentation rate [ESR], C-reactive protein [CRP]) are normal or slightly elevated. In contrast, septic arthritis findings include high fever, inability to ambulate (severe pain), and abnormal laboratory evaluation (eg, leukocytosis, elevated ESR/CRP). Sometimes patients can have overlapping clinical features, as in this child with a low-grade fever and mildly elevated ESR (suggestive of transient synovitis) but with severe pain, inability to ambulate, and leukocytosis with neutrophil predominance (suggestive of septic arthritis). When the diagnosis is unclear, bilateral hip ultrasound is performed. Joint effusion in septic arthritis is unilateral, whereas 25% of patients with transient synovitis have bilateral hip effusions (even with unilateral symptoms). If hip ultrasound shows a unilateral effusion, arthrocentesis is required to evaluate for septic arthritis. (Choice B) CT scan can identify a psoas abscess, which presents with fever and abdominal pain that may radiate to the hip. This patient's nontender abdomen makes psoas abscess unlikely. In addition, for initial evaluation of the hip, ultrasound is preferred over CT because it can detect and characterize a joint effusion while avoiding radiation exposure. (Choice C) Ibuprofen and close follow-up are the management of transient synovitis. However, this patient's inability to ambulate requires further evaluation. (Choice D) Lumbar puncture is indicated for suspected Guillain-Barré syndrome, which may present with refusal to walk (due to weakness) and neuropathic pain. This patient's normal strength and reflexes make this diagnosis unlikely. (Choice E) Lymph node biopsy may be performed for suspected leukemia, which can present with fever and bone pain. However, generalized lymphadenopathy or hematologic abnormalities would be expected. Educational objective: Acute, atraumatic hip pain in children is typically caused by transient synovitis, which presents in well-appearing children who are often afebrile and able to ambulate. However, patients with features concerning for septic arthritis (eg, inability to ambulate, leukocytosis) require bilateral hip ultrasound, with or without arthrocentesis, to distinguish between the conditions. References: Distinguishing pediatric Lyme arthritis of the hip from transient synovitis and acute bacterial septic arthritis: a systematic review and meta-analysis. (http://www.ncbi.nlm.nih.gov/pubmed/29581924)

A 3-Year-Old Boy Is Brought to the Emergency Department Due