Collagen diseases affecting the foot.

This article classifies various forms of arthritis which may affect the foot. Osteoarthritis of the foot usually involves the first metatarsophalangeal joint or the ankle, the latter usually being secondary to prior trauma. Secondary osteoarthritis of the foot is frequently due to Charcot destruction which is usually secondary to diabetic neuropathy. Seronegative spondyloarthropathies include ankylosing spondylitis and Reiter's syndrome. The three variants of psoriatic arthritis of the foot are also discussed.