• Infectious arthritis. Also called septic arthritis, infectious arthritis refers to arthritis that is caused by an infection within the joint. Infectious arthritis is often caused by bacteria, which spread through the bloodstream to the joint. Sometimes it is caused by viruses or fungi and can affect the joints of the feet.

Learn more about septic arthritis from the National Library of Medicine.

  • Raynaud's phenomenon. Raynaud’s phenomenon is a condition characterized by a narrowing of the blood vessels to the extremities, usually in the hands and feet, in response to cold temperatures or stress. When blood vessels close down, toes become cold and white, then blue, and numb or painful. When the vessels open up again, the toes become red or purple. Raynaud’s is often associated with connective tissue diseases, notably scleroderma.

Learn about the connection between Raynaud's and alcohol and smoking.

  • Osteoporosis. Osteoporosis is a condition in which the bones lose enough mass that they become brittle and prone to breaking with slight trauma. In people with osteoporosis in bones of the foot, just stepping off of a curb can cause a stress fracture. The condition can occur with aging, inflammatory disease (such as rheumatoid arthritis) inactivity, a low-calcium diet or use of corticosteroid medications.

Find out if you are at risk for osteoporosis. 

Find answers to your questions about osteoporosis.

  • Scleroderma. Literally translated &quothard skin,&quot scleroderma is an umbrella term for disorders that involve the abnormal growth of the connective tissue supporting the skin and internal organs. Although there are several different forms of scleroderma, all forms can cause thickening and tightening of the skin on the fingers called sclerodactyly. Skin thickening can also affect the backs of the feet, but it is usually less disabling than skin tightening on the hands.

Learn more about scleroderma from the National Institute of Arthritis and Musculoskeletal and Skin Diseases.