A 5-year-old boy is brought to the office due to left hip pain. The patient awoke this morning with a limp and says that his left hip hurts, especially with movement or walking. He played soccer outside yesterday with no known injury. Two weeks ago, he had had an upper respiratory infection that has since resolved. He has had no fever, vomiting, diarrhea, or other joint pain. His grandmother has rheumatoid arthritis treated with methotrexate. Temperature is 37.2 C (99 F), blood pressure is 100/65 mm Hg, and pulse is 92/min. Physical examination shows an interactive and talkative child who walks with a limp. The left hip is slightly abducted and externally rotated with mildly decreased range of motion. The patient is able to stand and bear weight on the left lower extremity. The remainder of the examination is normal. Bilateral hip x-ray is normal. Laboratory results are as follows. Which of the following is the best next step in management of this patient?

Question

A 5-year-old boy is brought to the office due to left hip pain.  The patient awoke this morning with a limp and says that his left hip hurts, especially with movement or walking.  He played soccer outside yesterday with no known injury.  Two weeks ago, he had had an upper respiratory infection that has since resolved.  He has had no fever, vomiting, diarrhea, or other joint pain.  His grandmother has rheumatoid arthritis treated with methotrexate.  Temperature is 37.2 C (99 F), blood pressure is 100/65 mm Hg, and pulse is 92/min.  Physical examination shows an interactive and talkative child who walks with a limp.  The left hip is slightly abducted and externally rotated with mildly decreased range of motion.  The patient is able to stand and bear weight on the left lower extremity.  The remainder of the examination is normal.  Bilateral hip x-ray is normal.  Laboratory results are as follows.  Which of the following is the best next step in management of this patient?

Quizplus · Accepted Answer

11ec25c8_d2ca_1a68_bc81_fb3196d2b200_MD0003_00 Transient synovitis is a common cause of hip pain in children, usually occurring in boys age 3-8. The etiology is unknown, but symptoms typically develop days to weeks after a mild viral illness, such as in this patient. Synovial inflammation leads to pain, decreased range of motion, and a limp. On examination, patients are well-appearing and afebrile. The affected hip may be flexed, slightly abducted, and externally rotated. This position maximizes the joint space, thereby providing pain relief. Laboratory evaluation shows a normal white blood cell (WBC) count and inflammatory markers (eg, C-reactive protein [CRP], erythrocyte sedimentation rate) due to lack of infection or significant inflammation. X-rays often reveal normal hip joints; ultrasound may show small unilateral or bilateral effusions. Treatment consists of rest and nonsteroidal anti-inflammatory medications (NSAIDs) (eg, ibuprofen). Children usually recover within 1-4 weeks with no complications. (Choices A and E) Blood culture, joint aspiration, and intravenous antibiotics are the management for septic arthritis, which should be suspected in patients with hip pain who are ill-appearing, febrile, or have laboratory evidence of inflammation/infection (eg, elevated WBC, elevated CRP). This child is well-appearing and afebrile with normal laboratory results, making septic arthritis unlikely. (Choice C) MRI is indicated for chronic hip pain and limp that is concerning for Legg-Calvé-Perthes (LCP) disease because initial x-rays may appear normal. However, patients typically have a Trendelenburg gait and limited internal rotation and abduction, in contrast to this patient who prefers hip abduction. In addition, this child has had symptoms for <1 day with a recent viral illness, making transient synovitis more likely. Trendelenburg gait (Choice D) Antinuclear antibodies may be positive in certain subsets of juvenile idiopathic arthritis (JIA) (eg, oligoarticular, polyarticular). Although presentation may include a limp, oligoarticular and polyarticular JIA are more common in toddler girls and rarely involve the hip, making this diagnosis unlikely. Educational objective: Transient synovitis presents with hip pain and limp in young children following a mild viral illness. In contrast to septic arthritis, patients are typically well-appearing, weight-bearing, and afebrile with normal laboratory results (ie, white blood cell count, inflammatory markers). Treatment is rest and nonsteroidal anti-inflammatory medications (eg, ibuprofen). References: Differentiating transient synovitis of the hip from more urgent conditions. (http://www.ncbi.nlm.nih.gov/pubmed/27294495) Transient synovitis. (http://www.ncbi.nlm.nih.gov/pubmed/29083677)

A 5-Year-Old Boy Is Brought to the Office Due to Left