It is an inflamed bursal sac. A bursal sac is a sac filled with fluid that acts to lubricate and reduce the friction between two surfaces in the body, usually muscles and tendons as they glide over bony prominences, however their purpose in not limited to just muscles and tendons. They may also be found in various pressure points in different parts of the body.
The body contains literally hundreds of bursal sacs but in the foot there is just one naturally occurring (non-adventitious) bursal sac. It is located between the Achilles tendon and the heel bone (calcaneaus), otherwise known as an Achilles tendon bursal sac. Note the yellow circle in the picture below. In this instance the Achilles tendon is protected from the pressure of the heel bone pressing against it when we walk.
In the foot we have a unique situation in that between the shoes that we wear, and the ground that we walk on various parts of the foot are constantly being “micro” traumatized, otherwise known as repetitive stress, meaning that every time we take a step we do a small amount of damage to a particular part of the foot and eventually that part of the foot begins to hurt.
The body’s response to this micro-trauma is to create a bursal sac to initially protect, by cushioning, the area, but if micro-traumatized enough the bursal sac itself becomes inflamed and we have a bursitis.
In the two pictures below, the red circles represent the most common, but not only, sites for inflamed bursal sacs.
BURSITIS SECONDARY TO HAMMERTOES- the top of the toes are so close to the irritating shoes that the constant rubbing of the toe on the shoe may form a bursal sac, (a corn may also occur). The top of the toe will typically be very tender, mildly swollen and red. Pressing on the swollen area will cause a fair amount of pain. If barefoot, the toe will generally not hurt, but even socks or stockings can cause pain. If the toe is rubbed too much by the shoe, the bursal sac can burst on its own and may become infected.
BURSITIS ADJACENT TO A BUNION OR TAILOR'S BUNION-In fact the true definition of a bunion is the enlargement of the metatarsal bone, deviation of the big toe towards the second toe, and the formation of a bursitis. Again, this is nothing more than too much pressure and friction occurring on the bony prominences of the foot.
BURSAL SAC ON THE BACK OF THE HEEL- between the Achilles tendon and back of the heel bone, that may become inflamed. As previously mentioned, this is the only naturally occurring bursal sac in the foot.
SUPERFICIAL BURSAL SAC ON THE BACK OF THE HEEL-many times there will develop a superficial area of mild redness, swelling and tenderness just off center to the back of the heel. This is referred to as a “pump bump”. Due to the enlargement of the calcaneus (heel bone) on its posterior aspect and the constant pressure of a shoe, usually a women’s dress shoe, the body will form a bursal sac that eventually becomes inflamed.
Patients will relate that the site hurts while in shoes but most times will feel better without shoes or be improved with very conservative shoes, but any outside pressure on the spot will cause pain, such as the heel hitting the mattress if you sleep on your back.
BALL OF FOOT-a bursal sac may form on the bottom of forefoot simply from excessive pressure of walking or running. These are usually not visible because they are below the level of fat on the ball of the foot.
When dealing with pain on the ball of the foot under the metatarsal heads, an inflamed bursal sac has to be a consideration along with capsulitis, neuroma , metatarsalgia , and sesamoiditis . Generally, when a patient complains of burning on the ball of the foot, neuroma and bursal sac are the first two things I explore.
BOTTOM OF THE HEEL-Unlike the bursitis we have already discussed these are usually not visible because they are deep to the fat layer on the bottom of the foot.
When diagnosing heel pain many times I include heel bursitis as one of the causes of heel pain. In the symptomatic heel if the patient complains that the more they walk, the more the heel hurts, then I have to consider a bursal sac in the heel as part of the problem. Over the years I have actually removed an inflamed bursal sacs from the heel during heel spur surgery.
Symptoms may vary depending of the particular location. Redness and swelling may be evident in a more superficial bursitis such as seen in a bunion or hammertoe, not so much in a deeper bursitis. When first removing your shoes the redness and swelling may be quite evident, but over the course of the next few hours the swelling and redness will subside to some extent, only to return when wearing shoes again. The pain may also have a burning component to it.
MODIFY YOUR SHOE SELECTION-If the bursitis pain is occurring on the toes, bunion or back of the heel area the smart money would be on eliminating the shoes that seem to aggravate the condition. This means wearing a more conservative shoe that reduces pressure points on your foot. Eliminating these shoes may not in itself clear up the problem but you can be sure that if you continue to wear the offending shoes nothing you or your doctor do will permanently “fix” the problem. A recurring theme that I use throughout this site that if you put an abnormally shaped foot in a dressy shoe it is literally the same as trying to put a square peg in a round hole; it will not fit.
ORAL ANTI-INFLAMMATORY MEDICATION- OK, so you threw away those dressy shoes and the foot still hurts, now what? Depending on the severity of the pain, over the counter anti-inflammatory medication may do the trick. The key here is to take the medication on an ongoing basis, according to the directions on the package to build up therapeutic blood levels. Assuming you can tolerate this type of medication, (see warnings about anti-inflammatory medication under my arthritis section, along with alternative treatments you can try). take the medication for 10-14 days. Stop if the symptoms have not dramatically improved. Keep in mind, this therapy should be considered a short term solution, not a long term solution.
TOPICAL PAIN RELIEVER-Over the counter pain relievers applied topically can be very helpful in reducing the pain. Keep in mind, this is not a cure, but just another option to reduce the discomfort.
ICING-The area during this period may also help reduce the symptoms.
ORTHOPEDIC PADDING-Applying padding around the area will reduce the pressure directly on the inflamed spot and that will help reduce the pain.
ORTHOTICS-If the bursitis is occurring on the bottom of the foot, trying an over the counter arch support may help in an effort to redistribute body weight and take pressure off the painful area, as well as cushion the affected area. If that only affords you some relief, you may have to consider orthotics.
DRAINING THE BURSITIS-We, as foot specialists, have a few things we can do to reduce the pain. If the bursal sac is very superficial we can usually drain the sac, which will should alleviate the problem, but with the warning that if the offending cause is not eliminated the problem may return.
CORTISONE INJECTIONS-May be very helpful in reducing the pain of the bursal sac. More than one injection may be necessary.
PRESCRIPTION MEDICATION-If over the counter medication does not work, then prescription medication including oral prednisone may be prescribed.
PHYSICAL THERAPY-Usually for the deeper type of bursitis is also helpful.
SURGICAL INTERVENTION-Correcting a bunion or fixing a hammertoe may be the only solution for some people to ultimately rid them of their pain. Be sensible in your problem and try all the conservative things first, if they do not help then surgery may make sense.
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