= DECOMPRESSION SICKNESS = THE BENDS

Etiology: during too rapid decompression (= reduction of surrounding pressure ← ascent from dive, exit from caisson / hyperbaric chamber, ascent to altitude) nitrogen bubbles form (nitrogen is more soluble in fat of panniculus adiposus, spinal cord, brain, bones containing fatty marrow)

• “the bends” = local pain in knee, elbow, shoulder, hip
• neurologic symptoms: paresthesia, major cerebral / spinal involvement
• “chokes” = substernal discomfort + coughing ← embolization of pulmonary vessels

Location: mostly in long tubular bones of lower extremity (distal end of shaft + epiphyseal portion); symmetrical lesions

• early: area of rarefaction
• healing phase: irregular new-bone formation with greater density
• peripheral zone of calcification / ossification
• ischemic necrosis of articular surface → secondary osteoarthritis