Proper oxygenation
Drugs when properly used and dosed
Androgen
Lack of proper oxygenation
Detrimental hereditary factors
Proper rest or proper immobilization
Poor health and nutrition
Favorable hereditary factors
Immunocompromised condition
Estrogen
Infections
Poor sleep or prolonged immobilization
Dystress
Venous sufficiency
Good health and nutrition
Eustress
Older age
Venous insufficiency
Younger age
ETOH and smoking
