Surgical Correction of Brachymetatarsia

Brachymetatarsia is a term used for a shortened metatarsal. The metatarsal may be significantly shorter than normal, which can cause cosmetic displeasure, functional limitations, and secondary callus formation to any areas of skin that may be rubbing against each other or against a pair of shoes. Those with brachymetatarsia and subsequent digital deformities may have difficulty finding shoes that fit them comfortably.

Most commonly, brachymetatarsia affects only one metatarsal. The most common metatarsal affected is the fourth metatarsal. Causes of brachymetatarsia may include trauma, post-surgical brachymetatarsia, or associated with a specific disease process such as Down’s Syndrome, Apert’s Syndrome, osteodystrophy, sickle cell anemia, or poliomyelitis. However, it is most frequently a congenital deformity with no specific underlying cause.

Clinically, it is common to see the digit attaching to the affected metatarsal cocking upwards, and often with an under-riding digit next to it. This is frequently seen with fourth metatarsal disease, where the fourth digit rides up in the air, and the fifth digits lies underneath the fourth. A callus on the plantar surface of the foot (bottom) is frequently seen in the area underneath the head of the fourth metatarsal, due to increased pressure in the area.

There are three categories of surgical correction of brachymetatarsia. All three methods involve lengthening the bone, but go about it in different ways.

One method is to use a bone graft to lengthen the bone. This method requires a single surgical intervention. A cut is made into the bone and a bone graft is placed between the two cut ends to lengthen the metatarsal. The bone graft used may come from the patient’s own bone, commonly the iliac crest (hip bone), or it may be a synthetic bone graft that is used. Complications of this type of surgery include damage to the soft tissues of the digits, particularly the nerves and arteries than run into each digit. With a single incident of elongation, these neurovascular structures can become damaged.

Another method is with the use of callus distraction. In this method, A cut is made through the metatarsal. However, instead of filling in this space with the desired length, an external fixator device is attached to each end of the cut bone. This device allows for a more gradual lengthening of the bone, typically at a rat of about 0.5mm per day. The external fixator device uses pins to go through the bone and come out through the skin, and rings attach to these pins. The device can then be lengthened daily to distract the healing bone, thus lengthening it in the process. The downside to this particular method is that the device must be worn for a period of time until the desired lengthening is achieved. This can be particularly cumbersome in a child.

The last main category of surgical intervention for brachymetatarsia is a single operation involving a cut in the bone in such a way that it can slide to lengthen. This osteotomy is then fixed with screws and/or pins. This technique is not as popular of an option as the first two, as the surgeries have shown to be less successful.

With any of these surgical procedures, the goal is to re-establish a normal parabola for both the tips of the toes and the metatarsal heads (the portion of the metatarsal that attaches to the digits). The parabola to the toes addresses the cosmetic appearance, while the parabola to the metatarsal heads addresses the functional outcome. Functionally, the joints at the metatarsal and the digits (the metatarsophalangeal joints, or MTP’s) aid in propulsion while walking. The parabola is determined by looking at an x-ray, which will aid the foot surgeon in planning the operation.

Many times, other procedures are combined with the lengthening of the affected digit. This may include shortening of the adjacent metatarsals, as they are often elongated in cases of brachymetatarsia. In other words, if the fourth metatarsal is too short, the third metatarsal may be too long. Thus, lengthening the fourth and shortening the third would be required to establish a normal foot.

When brachymetatarsia occurs in several metatarsals, they will all be addressed at once. This way, the surgeon can establish a foot that is more functional, alleviates any pain or discomfort associated with the deformity, and is aesthetically pleasing to the patient.

If you have symptoms similar to those of brachymetatarsia, discuss them with your doctor or foot and ankle surgeon. A proper examination is essential, including x-rays to evaluate the bone structure of the foot.

Central Florida Foot and Ankle Center101 6th St Nw Winter Haven, Fl 33881Phone: (863) 299-4551www.FLFootandAnkle.com