Striving For Optimal Cosmetic And Functional Results In Addressing Brachymetatarsia

Brachymetatarsia is defined as a congenital or, less commonly, traumatic condition in which a metatarsal bone is shorter than the other metatarsals. The condition typically occurs in the fourth metatarsal and is often associated with a shortened metacarpal bone as well. Initially, one identifies this hypoplastic condition by clinical examination and confirms it with radiographs. Although this condition is not common, most foot and ankle specialists have had patients present with the condition and questions. Of all of the patients I have seen with brachymetatarsia, none have had pain. Thus, one can classify this condition as a cosmetic entity.

What defines a condition as cosmetic? Is it whether or not a patient presents with pain associated with deformities, or is it defined by the reimbursement standards of insurance companies? In the case of brachymetatarsia, most patients do not have pain. Some patients may develop hyperkeratotic lesions due to adjacent increases in biomechanical pressures but most patients are just embarrassed by the condition. From an insurance perspective, there is an existing ICD-10 code and a corresponding CPT code based on the surgical approach.

The two common procedures that podiatrists use to provide an improved outcome include a callus distraction and a bone graft. A callotasis procedure is a gradual osteodistraction lengthening procedure of a long bone. It entails lengthening an osteotomy of the bone with an application of an external fixator to assist in the distraction process. Careful planning is critical.

I recommend positioning the external fixator and securing the pins in the bones prior to making the osteotomy. In the most common location for brachymetatarsia, the fourth metatarsal, place one proximal pin in the cuboid and one in the proximal metatarsal base. The distal pins can be in the metatarsal head and neck. Make the bone cut in the metatarsal at the metaphyseal/diaphyseal junction. Performing the cut in the diaphysis of the bone increases the chances of malposition due to a less stable osteotomy. Moreover, there is a decreased blood supply in the diaphyseal region of the bone, which can result in a callus distraction failure.

Once the pins for the external fixator are in place, perform the osteotomy. Typically, this is a transverse cut perpendicular to the weightbearing surface. One can perform the osteotomy with a small incision. Fluoroscopy is a great intraoperative tool to identify the best location and ensure that you are making the osteotomy in the correct bone. 

The first post-op visit is typically five to seven days after the procedure. After ensuring the stability of the external fixator, the lengthening process can start. In an adult, the callus distraction starts at approximately day seven post-op but in a child, one should start the callus distraction after four days. In a child, healing of the osteotomy will start by the first week, which can make distraction difficult. Lengthen the external fixator rail approximately 1 mm a day. After eight to ten days, stop the distraction process. There will be a noted gap on X-ray but the bone will fill in over time. The average bone lengthening after callus distraction is 1 cm. The procedure provides a more acceptable functional and cosmetic parabola and is the procedure of choice.

The other acceptable surgical procedure is to lengthen the bone by making an osteotomy and inserting a bone graft. Take care not to add too big of a graft. This can lead to angiospasm and nerve injury due to stretching of these soft tissues. This is a surgical option when less than 1 cm of bone length is necessary to achieve the desired result.

When the patient has completed care and one evaluates the outcome, there is the surgeon’s perspective and the patient’s perspective. From a surgeon’s point of view, evaluate the success of correction by the metatarsal length achieved and the parabola of the metatarsophalangeal joints. On the contrary, patients will measure the surgical success by the cosmetic improvement of the digital parabola and the appearance of their foot when they are barefoot or wearing open sandals.

This is just another example of a genetic condition considered to be a medical condition but the reality is that it is a cosmetic embarrassment that brings a patient to your facility. Offer all the options and allow your patients to walk with comfort and look great doing it.