A coalition is the union of 2 bones in the foot. The two bones will be fused by boney, cartilaginous, or fibrous tissue. This union will prevent the normal range of motion that the foot requires.
Why does this happen?
There are two theories; the most accepted theory is that during development, for an unknown reason there is the failure for the embryonic tissue, which will eventually become bone (called mesenchyme) to divide properly. However, it has been found that pedal coalitions are inherited meaning if one of your parents has a coalition you have a high chance of having one too. The other theory is that the additional little bones in the foot called ossicles fuse into the joint spaces causing the bones that make up the joint to be “glued” together.
Who gets pedal coalitions?
Both adults and children can have pedal coalitions. However, the symptoms will not usually present until age 6. This is because this is when the bones start to harden (ossify) and the foot will become more rigid, so if the foot is rigid and the joints are not working properly, due to a coalition, it will be painful. Adults that begin having symptoms of coalitions usually get them due to arthritis, trauma that changed the coalition, and/or infection of the bone. On-the-other-hand, you may have a coalition and never know due to not ever having symptoms.
What are the symptoms of coalitions?
• A dull aching pain usually near the ankle
• The pain is worsened by activity, walking or running on uneven ground, and/or standing for many hours
• The pain is relieved by rest
• An inability to turn your foot to the outer edge (inversion)
• Your foot may appear flat when standing
• You may notice spasms in the peroneus brevis muscle; this muscle begins in the outer aspect of the leg and inserts on the outer aspect of the foot
How will the Boulder Foot and Ankle Clinic determine if you have a coalition?
The most common way to diagnose pedal coalitions is by using advanced imaging. First, a baseline x-ray will be taken. Only bone shows up on an x-ray, so this may not show if a coalition is present, since there are the cartilaginous and fibrous tissue coalitions as well as the boney tissue type. So, since x-ray does not show cartilage or fibrous tissue, imaging such as a Computed Tomography (CT) scan or MRI is needed in order to see the fused joint. In addition, the podiatrist will be able to measure your range of motion. If there is decreased range of motion, this may indicate coalition. The podiatrist will also be able to find the site where you have the most pain, which may also lead to the diagnosis.
What is the treatment for coalitions?
There is non-surgical treatment for coalitions, which is effective in about 20-30% of all cases of coalitions. These non-surgical treatments include:
• Shoe modifications and orthotics
• Physical therapy
• Non-steroidal Anti-inflammatory medications
• Immobilizing the foot with a cast
Non-surgical treatment will usually take anywhere for 1-3 months for you to have improvement of symptoms. If symptoms do not improve, you may need to have surgery to re-open the joint and get rid of the coalition. There are several procedures that can be done. For further evaluation, schedule an appointment at the Boulder County Foot and Ankle.
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American Academy of Podiatric Sports Medicine