Basics of bones and joints

Question 1

Structure of the bone

Answer 1

Macroscopic: Epiphysis, physis, metaphysis and diaphysis.

Microscopic: Trabecular bone (osteons loosely arranged in struts, no havesian canals), cortical bone (osteos tighly packed, central havesian canal).

Question 2

Atraumatic fractures

Answer 2

• Underlying abnormal bone:
• Insufficiency fracture, atypical fracture or pathologic fracture.
• Normal bone: Fatigue fracture.
• Fragility fractures: Eldery patient with osteoporosis

Question 3

Stress fractures

Answer 3

• Fractures due to summation of repetitive forces, which overwhelm the bone remodeling pathway.
• Fatigue or stress fractures: Injury of normal bone caused by repetitive submaximal force.
• Insufficiencty fracture: Injury on abnormal bone by normal stress.

Question 4

Pathologic fracture

Answer 4

• Fracture through a focal lesion (Neoplasm or osteomyelitis).

Question 5

Femoral atypical fracture

Answer 5

• Special type of insufficiency fracture, only occurring in the lateral cortex of the proximal-to-mid femur.
• American Society for Bone and Mineral Research by the following criteria:
• no or minimal trauma.
• mainly transverse.
• must involve the lateral cortex; medially may have “medial spike”.
• No or minimal comminution.
• Endosteal or periosteal thickening