Toe deformities are commonly caused by a muscle imbalance in the foot as a result of flat feet, traumatic injury or disease of the toe joints. The toes may seem small and relatively insignificant, but they are vital to walking and stability. There are at least six sets of muscles that control each toe. Two tendons (extensor digitorum longus and extensor digitorum brevis) join on the dorsal aspect (top) of the toes, and insert into the middle and distal phalanges of each toe. On the bottom (plantar aspect) of the toes are two more muscles that, instead of joining like the extensors, remain separate. Each muscle stabilizes one of the bones in the toe. The flexor digitorum longus muscle attaches to the bone at the end of the toe (distal phalanx) and the flexor digitorum brevis attaches to the middle phalanx. The proximal phalanx (inner toe bone) is stabilized by muscles called the lumbrical and interossei. If there is an imbalance in the foot, these smaller muscles can be overpowered by the larger flexor and extensor muscles.
If a foot is pronated (flat), the two flexor muscles can overpower the others because a flat foot is longer than a foot with a normal arch. When the foot flattens and lengthens, greater than normal tension is exerted. The toes are not very strong and they are overpowered, resulting in one of two possible deformities, depending on which muscle contracts first.
If the flexor digitorum brevis contracts first and overpowers the rest of the muscles in the toe, the middle phalanx is pulled downward, causing the joint between the proximal and middle phalanges to buckle upward. This is known as a claw toe.
If the flexor digitorum longus contracts first and overpowers the smaller muscles, it can pull on the proximal phalanx, causing the outer two joints of the toe to bend downward. This results in a hammertoe.
Hammertoes and claw toes may seem minor, but if left untreated, they become serious fixed deformities. In this unnatural position, the inside of the shoe rubs against the bent toe joints, gradually causing calluses to form, usually on the tops of the toes. The metatarsal heads support the body weight and pressure calluses and ulcers can develop on the sole of the foot. When deformities reach this stage, the toes are fixed in a bent position and cannot be easily straightened.
For this reason, it is important to obtain treatment for hammertoes and claw toes when they first begin to develop, before they become fixed. Treatment for hammertoes and claw toes depends on the severity of the deformity. When the toes first start to buckle, they can be straightened easily. If the problem is caused by flat feet, a podiatrist can fit the patient for custom-molded orthotics that provide a better arch for the foot and help the muscles work together. In these cases, the prognosis is good. Without treatment, the soft tissue structures that attach to hammertoes and claw toes begin to tighten. Adhesions gradually form from the tendons to the joint capsules and a rigid deformity results. In these cases, surgery is necessary.
Arthroplasty is a minor surgical procedure that lengthens a shortened toe muscle. In this procedure, the podiatrist or surgeon makes an incision along the toe and trims the head of the proximal phalanx. This usually allows the toe to straighten. If the affected toe does not straighten sufficiently after arthroplasty, the podiatrist or surgeon can use a variety of progressive procedures to achieve the desired result. If these fail, it is likely that the deformity has been present for so long that the joint can no longer function properly. In these cases, there is one final procedure that may restore normal mobility. This procedure is called an arthrodesis and involves fusing two bones together, typically the proximal and middle phalanges. The surgeon removes the cartilage from the base of the middle phalanx. The head of the proximal phalanx had already been removed during arthroplasty, so the two bones can be fixed together with a removable pin. They eventually fuse together. These procedures require the patient to stay off his or her feet for several weeks. This may be inconvenient for a time, but with proper post-operative care, the patient can obtain the desired relief.