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.

Which of the following factors increases the fracture risk in a patient with osteoporosis?
  • Progressive thickening of the trabeculae in cancellous bone
  • Increased bone resorption affects trabecular bone, causing the trabeculae to become progressively thinner, eventually leading to the loss of trabecular connectivity. These changes in trabecular microarchitecture have been shown to rapidly compromise bone strength in areas where trabecular bone predominates, such as the vertebral bodies.

  • Progressive increase in cortical bone porosity
  • Cortical porosity can serve as a site for fracture initiation, and also results in decreased bone mass, both of which can increase fracture risk.

  • Increased cortical perimeter of the long bones
  • Increasing the cortical perimeter of a bone results in an exponential increase in resistance to bending and torsion without a marked increase in bone mass.

  • Greater mineral hydroxyapatite crystal size heterogeneity
  • In addition to the degree of mineralization, the size and shape of the hydroxyapatite crystals also influence fracture risk. Increased bone strength seems to be associated with greater heterogeneity of mineral crystal size when compared with the presence of mostly large mineral crystals.