ESSENTIALS OF DIAGNOSIS
Toe is bent at middle joint resembling a hammer.
Corns or calluses on top of the middle joint of toe, between toes, or on tip of toe.
Pain or irritation to toe when wearing shoes.
Hammertoe is a painful contracture of the second, third, fourth, or fifth toes. It can result from improperly fitting shoes (ie, too short or narrow), trauma, or a muscle/tendon imbalance.
Muscle/tendon imbalance is the most common cause of hammertoe. Structural changes in the foot can lead to a muscle/tendon imbalance, leading to the contracture of the toes. More specifically, the muscle/tendon imbalance can fall into three major categories: flexor stabilization, flexor substitution, and extensor substitution. Flexor stabilization generally presents in a pronated foot type as the flexor muscles gain mechanical advantage over the interossei muscles. Flexor substitution is the least common cause but presents in the supinated foot type due to the weakness of the triceps surae, which leads to substitution from the deep posterior and lateral muscle groups. Extensor substitution generally presents in the supinated foot type and occurs during the swing phase of gait as the extensor digitorum longus tendon overpowers the lumbricales. A hammertoe can be found in conjunction with or worsened by a bunion.
Narrow or high-heel shoes can push toes into a bent position. If a toe remains bent for an extended period, the muscle tightens and cannot stretch back. Women are more likely to be affected with hammertoes due to improperly fitting shoes.
Hammertoe is a progressive deformity. It begins as flexible in the earlier stages and becomes worse over time, leading to a rigid deformity. In more severe presentations of hammertoe, ulcerations can develop.
The presenting symptoms of hammertoe include contracture of the toe at the proximal interphalangeal (PIP) joint that leads to pain and irritation with shoe gear. There can also be associated buildup of corns and calluses at the location of the contracture. The most common complaint is redness or burning sensation.
A hammertoe deformity can be categorized as either flexible, semi-rigid, or rigid. The flexible hammertoe deformity has mobility at the PIP joint. The rigid hammertoe deformity is immobile at the PIP joint.
Plain radiographs are used to determine the severity of the hammertoe. Weight-bearing anteroposterior and lateral views are the most useful images. The radiographic images demonstrate dorsiflexion of the proximal phalanx with plantar flexion of the intermediate phalanx. In more severe cases, the joint illustrates signs of adaptation that include degeneration of the PIP joint or even dislocation of the MTP joint.