Plantar Fibroma: A fibrous knot or nodule embedded in the plantar fascia, in the arch of the foot.
A plantar fibroma is a knot or nodule of fibrous tissue that develops in the medial longitudinal foot arch. This nodule grows within the plantar fascia—a strong band of connective tissue on the underside of the foot that runs from the heel to the toes. Plantar fibromas can develop in one or both feet, are noncancerous (i.e., benign), and typically will not resolve without appropriate treatment. Though a number of theories have been proposed, a definitive cause for this foot problem has not been identified or agreed upon by researchers or practitioners.
Plantar fibromas, unlike plantar warts (which grow on the skin), grow within the thick, fibrous connective tissue of the plantar fascia. Plantar fibromas are slow-growing masses and usually themselves do not cause pain. However, as they become larger, they may put pressure on sensitive structures (such as nerves and blood vessels) within the foot, which can make weight-bearing activities (e.g., walking, standing, running) for prolonged periods quite painful. They can also cause gait changes that put abnormal stress on the body’s joints and soft tissues.
This common growth is usually a solitary nodule, though multiple nodules are possible in the same foot. The mid-arch region of the foot is the most common location for plantar fibromas to develop, though they can appear anywhere along the underside of the foot. Plantar fibromas can occur in people of any age, though they are most common in children. Plantar fibromas, though not life-threatening tumors, can be profoundly uncomfortable, reduce mobility, and impair a person’s ability to wear shoes.
Signs & Symptoms
Plantar fibromas appear as one or more (painful or painless) lumps on the bottom of the foot and are firm to the touch. This lump can stay the same size or grow over time (sometimes to the size of a golf ball!), or more nodules may appear. Walking and wearing shoes can cause pain or discomfort. To help diagnose the problem, a foot care professional will often press on the lump, and this may generate pain that extends to the toes. An MRI or biopsy can also help confirm or rule out a plantar fibroma.
Researchers and physicians are still unsure about the underlying cause(s) of plantar fibromas, though many believe there is a genetic component to this problem, as some people are predisposed to fibrotic diseases and an overdevelopment of connective tissue. Other possible contributing factors include:
Improper Footwear: Footwear that contains heel elevation and toe spring stretches the plantar fascia and leads to weakness in this tissue. Fibromas may develop in response to a loss of plantar fascia integrity, foot structure imbalances, or point pressure caused by the above-mentioned shoe features.
Trauma: Damage to the plantar fascia may lead to a plantar fibroma, though this factor is contested by some. It’s thought that the formation of excess tissue may be a robust healing response after overuse or traumatic injuries, such as a puncture wound.
Certain Health Problems: Individuals who have certain pre-existing conditions (such as diabetes, epilepsy, liver disease, and thyroid problems) appear more likely to develop plantar fibromas.
Certain Medications: Some medications may increase the likelihood of a plantar fibroma, especially when taken after plantar fascia trauma. Such medications include beta-blockers and anti-seizure drugs.
Other Factors: Other factors that may play a role in the development of plantar fibromas include alcoholism, age, and gender.
Conservative (i.e, nonsurgical) care measures can help reduce the pain and discomfort of a plantar fibroma, though they will not make the lump disappear. Some of the most common non-surgical approaches to treating plantar fibromas include:
- Stretching exercises
- A change in footwear to help redistribute bodyweight more appropriately
- Physical therapy modalities that deliver anti-inflammatory substances directly into the fibroma
Surgery to remove the plantar fibroma is commonly performed, especially if non-surgical methods fail to manage the pain or discomfort, though possible problems associated with surgery include:
- The onset of hammertoes
- A high incidence of recurrence
- A flattening of the main foot arch