Toe deformities in adults are caused mainly by an imbalance of the tendons, causing them to stretch or tighten abnormally. People with abnormally long toes, flat feet, or high arches have a greater tendency to develop toe deformities.

Arthritis is another major cause of discomfort and deformity. Toe deformities also can be aggravated by poorly-fitting footwear, or if a fractured toe heals in a poor position.

The most common digital deformities are hammertoes, claw toes, mallet toes, bone spurs, overlapping and underlapping toes, and curled toes.