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The JBJS Quiz of the Month is a collection of 10 relevant questions from each orthopaedic subspecialty. The questions are drawn from JBJS Clinical Classroom, which houses over 4,500 questions and 3,100 learning resources. Take the Quiz to see how you score against your peers!

NOTE: This quiz does not earn users CME credits. The questions must be answered within Clinical Classroom to earn CME credits.

A 12-year-old male patient with a poorly controlled seizure disorder has been on high-dose anticonvulsants for 7 years. The patient sustains a low-energy fracture, and his primary care provider orders a dual x-ray absorptiometry (DXA) scan, which indicates a bone mineral density (BMD) measurement of 1.4 standard deviations below normal. Which of the following makes the interpretation of these results challenging?
  • It is not clear what skeletal site was measured.
    • The most widely validated technique to evaluate bone loss is DXA applied to standardized sites of biological relevance, including the hip, spine, and forearm.

  • Anticonvulsant medications affect bone mineral composition that cannot be measured by DXA.
    • The most widely validated technique to measure BMD is DXA, regardless of the root cause of impacts on bone mineral composition.

  • DXA scans are not an appropriate test for children <18 years old.
    • The most widely validated technique to measure BMD is DXA, and diagnostic criteria based on the T-score for BMD are a recommended entry criterion for the development of pharmaceutical interventions in osteoporosis.

  • The normal comparator for bone mineral density measurements is a healthy young Caucasian female.
    • Osteoporosis is defined by the World Health Organization (WHO) as a BMD that lies 2.5 standard deviations or more below the average value for young healthy women (a T-score of <-2.5 SD).

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