Chronic foot pain is very common and can be very debilitating for the person who suffers through it. Foot pain can be called chronic when it continues without significant relief for several months or longer. The difference between chronic foot pain and foot pain that is shorter in duration (called acute pain) is that the body has a harder time healing chronically injured tissue. There are many causes of chronic foot pain depending on where the pain is located. This article will discuss the most common causes of chronic foot pain in each part of the foot.
Chronic pain in the ankle is most often due to arthritis in the ankle joint. Arthritis can develop from normal wear of the joint, as well as from gradual damage formed during old fractures and even serious sprains. In arthritis, the cartilage of the joint wears down, allowing bone to rub on bone during movement. The joint tissue becomes inflamed, painful, and spurs can develop that restrict motion. Another cause of chronic ankle pain involves an abnormal enlargement of a bone behind the ankle joint that restricts motion of the joint and gets pinched during ankle motion. When pain is in front of the ankle on the outer side of the foot, the cause can often be due to inflammation of a small portal into the deeper joint below the ankle. This region is called the sinus tarsi, and the tissue inside this tunnel can become inflamed are irritated, causing pain to radiate in the front of the outside of the ankle.
After serious ankle sprains, the ankle ligaments can become weak, and the ankle may easily turn in, leading to chronic sprains and pain on either side of the ankle.
Top of the foot:
Chronic pain on the top of the foot, like the ankle, is often due to arthritis in the middle part of the foot, called the midfoot. This occurs especially in people with flat feet, who develop compression of the bone in this part of the foot as it flattens. The compression causes the top part of the joints across the foot to erode, and spurs can develop. This leads to pain when one walks, especially when barefoot. Additionally, the spurs can irritate nerves on top of the foot, causing numbness, burning, or tingling on top of the foot, radiating to the tops of the toes. People with high arches can also experience chronic foot pain, due to the fact that high arches do not absorb the shock generated during walking very well, which gets transmitted through the arch and to the top of the foot with every step, leading to eventual tissue inflammation.
Inner side of the foot:
When chronic pain develops on the inner side of the foot, the usual cause is inflammation and degeneration to an important tendon called the posterior tibial tendon. This tendon helps stabilize the foot and can become chronically damaged after injury or even with simply walking with flat feet. If allowed to continue untreated, the foot can flatten further, and walking can become very difficult due to the pain. In addition to tendon degeneration, an extra bone can form near where this tendon attaches to the side of the foot, and the bone itself can provide additional irritation to the tendon.
Outer side of the foot:
Like the inner side of the foot, chronic pain to the outer side of the foot is often due to a problem with a tendon. The peroneal tendons can become injured during walking on uneven surfaces, during athletic activity, or with the use of unstable shoes. One or both of these tendons can develop partial tears, which lead to chronic inflammation and pain.
Ball of the foot:
The ball of the foot, at the base of the toes, is a site where numerous conditions can cause chronic pain. Most often linked to flat feet or high arches where pressure increases in the ball of the foot foe different reasons, chronic pain in this location involves inflammation of the tissues in and around the joints that bend the toes upward and downward (the metatarsal phalangeal joint). The tissue around the joints can become inflamed (capsulitis), as can protective pads in between these joints call bursae (bursitis). Nerve tissue can become pinched and inflamed, leading to a condition called a neuroma that often causes a lumpy burning pain to the ball of the foot sometimes with numbness to two toes.
Skin problems can also cause chronic pain in the ball of the foot, including deep calluses as well as wart infections. While calluses represent areas of abnormal pressure due to an abnormality in one’s foot structure, a wart is due to a viral infection that has nothing to do with the foot structure.
Occasionally, when combined with a hammertoe deformity, the tissue under one of the joints can tear, leading to further pain and joint degeneration. While actual arthritis of these joints is uncommon, the stress to these bones can eventually lead to stress fractures in the part of the long metatarsal bone before the joints.
When the pain involves the big toe joint, a bunion deformity is responsible for pain on the side of the big toe joint, while arthritis is commonly the cause of pain on top of or deep in the big toe joint. When the pain is felt under the joint, the cause is often due to inflammation of a small egg-shaped bone called a sesamoid.
Toes and toenails:
Chronic pain in the toes most often forms directly as a result of a crooked toe deformity like hammertoes, in which the toe is bent upward at the first ‘knuckle’. This can allow for pain when the shoe contacts the prominent toe, and can also result in chronically painful corns on the top of the toe, in between the toes, or at the tip of the toe. Additionally, the 4th and 5th toe can often rotate inward, leading to a painful corn along the side of the nail.
Toenails can be chronically painful when there is an ingrown toenail, or when the toenail is thick due to damage or a fungus infection. The nail can also become humped and painful due to a benign mass in the toe bone directly underneath the nail, leading to pain with shoe pressure. This is more common in the big toe.
Heel and arch:
One of the most common areas people experience chronic pain in the foot is in the heel and arch. By far the most common cause of heel and arch pain on a chronic basis is inflammation to a ligament called the plantar fascia. This condition is known as plantar fasciitis, and is often mistakenly attributed to a heel spur that may or may not be present but is rarely the cause of actual pain under the heel. General arch pain and fatigue is usually due to the strain of walking with flat feet, although plantar fasciitis can also have some role in this pain.
When the pain is located on the back of the heel, the usual culprits are chronic inflammation of the Achilles tendon, possibly combined with the irritation of a spur behind the heel bone. Additionally, a rounded enlargement of the back of the heel bone called a Haglunds deformity, or ‘pump bump’ as it is popularly known, can cause chronic foot pain especially with rubbing from the back of the shoe.