The Hammered Digit Syndrome is a common malady of a muscle/tendon imbalance. The biggest myth associated with this condition is the cause. Hammered digits are formed due to an imbalance of the forces that influence the positioning of the joints of the toes, i.e. the metatarsal-phalangeal joint (MPJ), the proximal interphalangeal joint (PIPJ), and the distal interphalangeal joint (DIPJ). Patients, on the other hand, often indicate that "high heeled shoes or a pointed toe box caused my hammer toes". This is not always the case, as hammered digits are seen in those who do not wear shoes. (The aborigines are a prime example.) Shoe gear, however, may aggravate or assist in the development of this digital deformity.

The bone anatomy of the lesser digits of the foot includes metatarsals and three phalanges (proximal, middle, and distal). The proximal articulates, or joins, with the metatarsal to form the ball of the foot. The distal (furthest) lies beneath the nail plate. The motion of these joints are in the sagital plane (a plane which divides the body or foot into left or right sides).

Normal motion allows an up or down flexion that is referred to as dorsiflexion and plantarflexion, respectively. The function of the digits is a "rigid-beam-effect". This means the toe lies flat on the ground by plantar flexion at the PIPJ and DIPJ, and as the heel and midfoot lift off the ground, the motion occurs at the MPJ as dorsiflexion. When acting properly, the tendons and muscles allow the occurance. If there is an overpowering influence of the extensor tendon to the flexor tendons, however, hammering will occur. Should this occurrence continue with significance, then the joints will maladapt accordingly, resulting in rigid contraction. In turn, this will become a non-reducible joint or a joint "locked" into a hammered position.

A muscle tendon imbalance usually occurs in a foot that is either hypermobile, as seen in a pronated (flat) foot, or excessively limited, as in a pes cavus (high arched) foot. In either example, the tendons try to compensate. In the pronated foot, the flexor tendons try to substitute motion that is lost at the ankle and subtalar joints. Thus, flexor substitution, flexor stabilization and extensor substitution are the deforming focus of a hammered digit syndrome.

Dermal irritation from shoe gear may cause the development of a corn (clavus) on the digit, and/or a callus on the ball of the foot. Occasionally, the PIPJ of one digit may irritate the DIPJ of another digit, thus causing a corn between the two toes. These painful lesions are known as soft corns, and typically lead patients to seek help from a Podiatrist.

Conservative management of hammered digits includes periodic reduction of the resulting calluses or corns with sharp debridement (trimming). Accomadative padding may also be used as an adjunct. I do not, however, recommend use of corn "plasters" or "softeners". These medicated modalities cause secondary burns and infections. It is important to note that conservative care results only in temporary relief and does not correct the underlying problem.

Surgical treatment of hammered digits is corrective for most individuals. This approach depends mainly on the level of deformity. In the case of a rigid hammer digit, there will typically be a dorsiflexed position of the MPJ, a plantarflexed position of the PIPJ, and a rectus (straight) or dorsiflexed position of the DIPJ. To correct this deformity, the PIPJ must be fused (through arthrodesis). This brings the toe to a rectus position to function as a rigid beam once again. It takes six to eight weeks for the fusion to occur. In the meantime, a pin is used to hold the digit in position. If this procedure were the only to be performed, then the toe would "stick up in the air" due to the contracted MPJ. The next step, then, is to elongate the extensor tendon on top of the digit, cut open the top of the MPJ capsule, and release the flexor plate on the bottom of the joint. By doing this the proximal phalanx may now be manipulated into rectus alignment. This is just one example of digital correction that is utilized. There are other approaches for hammered digits of varying severity.

The factors that dictate surgical correction include severity, pain, limited activity, and difficulty wearing shoes. A patient experiencing any of these symptoms would be considered a candidate for surgical correction. Patients who have poor circulation or fail to comply with physician orders would be excluded as surgical candidates.

The most common coalition of the rearfoot is the calcaneal navicular, CN Bar. Along with other coalitions, this occurs developmentally. The restrictions it imposes on joints are often painful. Upon examination, the physician will put the STJ and the MTJ through range of motion exercises. If a coalition exists, the manipulation of the affected joint will cause the patient pain and produce little to no range of motion.

Although x-rays and examinations are necessary in diagnosing a tarsal coalition, patients who suffer from this condition typically experience pain on the outside and top of the foot (dorsolateral) while walking. The peronial tendons are taught in spasm, thus causing the foot to evert. Pain is palpable on the coalition. An injection of an anesthetic and a steroid into the painful area may give temporary relief. When the coalition becomes symptomatic, however, conservative measures usually fail. Surgery is then indicated.

Before surgery is performed, other joints must be examined to assess secondary arthritic changes. If these changes exist, then fusion of the STJ and MTJ is indicated. If no other arthritic changes are noticed, then resection of the union is performed. The muscle belly of the Extensor Digitorum Brevis is commonly transplanted into the area of resected tissue. Post-operatively, a posterior splint is applied to the foot and leg and range of motion exercises are encouraged. Walking as soon as possible after sufficient healing is encouraged. Doing so will result in an increased range of motion.

Other coalitions in the foot include talo calcaneal (mid facet), talo navicular (rare), and calcaneal cuboid (also rare). Resection of this union must be employed. Should this fail, then a triple arthrodesis or fusion of the rearfoot bones is needed. Patients need to be told of this in the pre-operative consult.

Dr. Graham has been in private practice in Effingham since 1989 and is on staff at St. Anthony's Memorial Hospital and Effingham Ambulatory Surgical Treatment Center. He is Board Certified by the American Board of Podiatric Surgery and American Board of Podiatric Orthopaedics and Primary Podiatric Medicine. Dr. Graham is a Fellow of the American College of Foot and Ankle Surgeons, the American College of Foot and Ankle Orthopaedics and Medicine, and American Professional Wound Care Association. He is also a member of the American Podiatric Medical Association and the Illinois Podiatric Medical Association.

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