Brachymetatarsia and Polydactyly

What is Brachymetatarsia?

Brachymetatarsia is a condition in which one of the bones in the front of the foot is significantly shorter than the others. This usually affects both feet and although it may affect any of the five metatarsals, it most commonly affects the fourth metatarsal. If it affects more than one metatarsal and toe in the foot it is termed brachymetapody. Looking at the foot, it might appear that the involved toe, often the fourth toe, itself is shorter than the adjacent toes. Sometimes it may even appear as if the fourth toe is raised up with the adjacent toes at times touching underneath. 

Brachymetatarsia & Polydactyly - Causes, Diagnosis, & Treatment

What causes brachymetatarsia?

The condition occurs when the affected metatarsal bone fails to develop fully, or its growth plate closes prematurely. The other metatarsals continue to grow around it, causing a short appearance of the toe. This can be a congenital condition or can be an acquired deformity following trauma, infection, tumor, radiation, or prior surgery. Brachymetatarsia has a much higher prevalence in women than men, at a ratio of 25:1. It is typically noticed in early childhood during bone development and the diagnosis is easily confirmed with an x-ray.

What can be done about brachymetatarsia?

Patient with brachymetatarsia often have associated pain and difficulty wearing shoes. Often the pain and deformity may impact there walking and activities not to mention the negative psychological impact many have about the foot’s appearance. Often these problems are progressive as the foot grows and develops. As for most foot deformities there are both conservative and surgical options. Conservative cares consists of accommodating the prominent and elevated toe with comfortable, wide and high toe box shoes. Patient may also avoid activities that aggravate the problem and exacerbate the symptoms.

When considering surgery there are two surgical approaches that we can utilize to correct the deformity/metatarsal length abnormality and contracture of the toe.

  1. Bone Graft
    This is a one-stage technique where a space in the metatarsal is created by cutting the metatarsal and distracting it to its proper length. Then a structural bone graft is inserted into the space. However, there is a limit to how large a graft can be used and thus how much length can be obtained with this method. Typically, a plate and screws are used to hold the metatarsal and graft in place while the bone heals. After the surgery the patient is often non-weight bearing for 8 weeks or until the bone graft incorporates/heals enough to begin protected weight bearing in a cam-walker type boot. We often utilize bone from the patient’s own foot (heel). This technique may be utilized when the involved metatarsal is not extremely short. 

One-stage bone graft

  1. External Fixation
    This surgical approach is where the involved bone is cut and then “stretched” out to length using a technique called bone callus distraction or distraction osteogenesis/callotasis and osteodistraction. The surgeon makes a small incision and cut of the involved metatarsal preserving the local blood supply. Next a mini-external fixator (pins and adjustable, external clamps) is applied. After the surgery in about 7 days the patient will gradually turn a nut on the device (daily), painlessly, to slowly lengthen the metatarsal. The lengthening occurs at about 1mm a day until the desired length is achieved. This usually takes about 4-6 weeks based on the amount of length required. Then the mini-external fixator is left in place while the newly created bone heals. The process is followed with X-rays in the office. The final step is removal of the mini-external fixator, which is often performed in the office and is also painless. Patient will often bear weight in a walking boot before the mini-external fixator is removed.

Distraction osteogenesis

External fixation applied

External fixation removed

What is Polydactyly?

Polydactyly is a condition in which a person has more than five toes per foot. It is the most common birth defect in the foot. Polydactyly can occur as an isolated finding or in conjunction with other birth defects and cognitive abnormalities. Polydactyly can also be found in conjunction with brachymetatarsia. In some cases the extra digits may be well-formed and functioning.

There are three types of polydactyly that are distinguished based on the location of the extra finger or toe:

  • Pre-axial polydactyly — the extra digit is located outside the big (1st) toe (tibial polydactyly)
  • Post-axial polydactyly — the extra digit is located outside the little (5th) toe (fibular polydactyly)
  • Central polydactyly — the extra digit is located in between other toes

How is polydactyly diagnosed?

Diagnosis of polydactyly involves the surgeon performing a physical examination and is confirmed by obtaining X-rays. The X-rays are used to see the abnormal bone structure of the foot and to help plan if surgery is needed. The patient may be sent to their physician for further work up for genetic conditions and obtain preoperative clearance when appropriate.

How is polydactyly treated?

When surgery is needed it may be complicated because the extra digit may have irregular internal structures. This may include deformed bones, angled joints, missing or extra tendons, and non-anatomic nerves and blood vessels. Surgery may be considered especially for poorly developed digits, very large extra digits, or extra digits that are painful or interfere with shoe wear and activity. The remaining digits themselves may need remodeling due to irregularities at the time of surgery as well. Surgical management depends greatly on the complexity of the deformity. After surgery the foot is protected in a bulky bandage or cast for several weeks. Surgery performed in childhood may need to be revised as the child grows in a few instances.

The knowledgeable and highly-trained staff at DFAC will work with each patient to determine the best treatment option as well as timing of the surgery if needed.


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