A hammer toe is a toe which has become deformed due to hyperextension (lifting up) at the MTP joint (base of the toe) but flexion (bending downwards) at the PIP joint (next joint down within the toe). This can result in the toe rubbing on footwear and developing painful corns. The second toe is the most commonly affected. Hammer toes can be caused by a variety of factors including abnormal length of the toe, poor footwear, or capsulitis of the MTP joint which can lead to rupture of the plantar plate. They are often seen in feet with hallux valgus (bunions).
Various strategies can be used to deal with hammer toes. Buying shoes with deep toe boxes may stop the toe from rubbing. Toe splints can be used to prop the toes into better positions. The only way to correct the deformity is by surgery, usually in the form of a release of the MTP joint and fusion of the PIP joint. The plantar plate can also be repaired if ruptured. If a bunion is also present it is usually advisable to correct this at the same time.