WBR0851

Author	[[PageAuthor::Mohamed Moubarak, M.D. [1]]]
Exam Type	ExamType::USMLE Step 3
Main Category	MainCategory::Emergency Room
Sub Category	SubCategory::Infectious Disease
Prompt	[[Prompt::An 11 year-old boy brought to the ED by his mother complaining of progressive severe pain, and swelling in his left foot. The mother said that she used some analgesic medications that were prescribed to him 2 weeks ago for fever after he injured himself during playing, but neither the pain nor the fever subsided. He is a diabetic on insulin, taking no other medications. On examination, the patient is feverish with temperature 39 C (102 F), heart rate 100/min, blood pressure 140/80 mmHg, and respiratory rate of 22/min. His left foot is severely tender, red, and hot, with decreased range of motion on examination. You ordered x-ray which turned back with no pathology. You ordered a blood culture and prescribed the proper antibiotics. What is the best next step in diagnosing this patient?]]
Answer A	AnswerA::Repeat the x-ray in 2 weeks
Answer A Explanation	[[AnswerAExp::Incorrect Repeat x-ray in 2 weeks will only serve to delay the diagnosis, and it is insensitive before 2-3 weeks]]
Answer B	AnswerB::Order an open bone biopsy to confirm the diagnosis
Answer B Explanation	[[AnswerBExp::Incorrect Although bone biopsy is the gold standard in diagnosis of Osteomyelitis, it should be done only when the non-invasive procedures are inconclusive]]
Answer C	AnswerC::Continue the antibiotic treatment with no further investigations
Answer C Explanation	[[AnswerCExp::Incorrect Continue the antibiotics without reaching a diagnosis is in appropriate, and can miss potential complications (e.g. abscess or gas formation) which may need further management]]
Answer D	AnswerD::Order a three phase technetium 99m bone scan
Answer D Explanation	[[AnswerDExp::Incorrect A three phase technetium bone scan is the diagnostic test of choice for suspected Osteomyelitis if the radiological results are negative.]]
Answer E	[[AnswerE::Order a MRI scan]]
Answer E Explanation	[[AnswerEExp::Correct MRI is very accurate in detecting the changes of Osteomyelitis in early stages, especially in spine and complicated foot Osteomyelitis.]]
Right Answer	RightAnswer::E
Explanation	[[Explanation::Osteomyelitis is an infection of bone or bone marrow, usually caused by pyogenic bacteria or mycobacteria. It can be usefully subclassifed on the basis of the causative organism, the route, duration and anatomic location of the infection . It usually present with fever, chills, erythema, and swelling over the involved bone. Diagnosis of osteomyelitis is often based on radiologic results showing a lytic center with a ring of sclerosis, though bone cultures are normally required to identify the specific pathogen. Conventional radiographic evaluation of acute osteomyelitis is insufficient because bone changes are not evident for 14–21 days after the onset of infection. C.T and MRI is the best way to non- invasively approach the diagnosis of Osteomyelitis. MRI gives more details of the soft tissue involvement as a complication of Osteomyelitis (e.g. abscess or gas formation). A three phase technetium bone scan is the diagnostic test of choice for suspected Osteomyelitis if the radiological results are negative. Educational Objective: References: ]]
Approved	Approved::No
Keyword	[[WBRKeyword::Osteomyelitis]]
Linked Question	Linked::
Order in Linked Questions	LinkedOrder::