A hammertoe is a deformity of the second, third or fourth toes in which the main toe joint is bent upward like a claw. Initially, hammertoes are flexible and can be corrected with simple measures. Left untreated, they can become fixed and require surgery. Hammertoe results from shoes that don’t fit properly or a muscle imbalance, usually in combination with one or more other factors. Muscles work in pairs to straighten and bend the toes. If the toe is bent and held in one position long enough, the muscles tighten and can’t stretch out.