Pes anserine bursitis: causes, symptoms, diagnosis and treatment

Pes anserine bursitis is an inflammatory condition of pes anserine bursa of knee joint, involving the medial (the region facing the other knee) or inferio-medial aspect (same region but slightly below) of knee. But to understand the concept behind pes anserine bursitis, you should be having clear cut knowledge about the normal anatomy and physiology of pes anserine bursa.

What is a bursa? How does it get inflamed?

These questions might be troubling you but once you come to know about the structure of bursa in detail, it will be easier for you to understand pes anserine bursitis. Bursa is small sac like structure that is usually found between bones and muscles tendons.

Bursa is lined by a synovial membrane (lubricating membrane) that secretes synovial fluid (lubricating fluid). This synovial fluid is slippery in nature that protects the bones from rubbing effect of muscles and tendons.

When the joints move, the muscle tendons rub against the bony structures and friction is produced. This friction is deleterious for the health of joints and tendons as it can tear the tendons and can erode the bones.

Thus, the friction between muscle tendons and bones must be reduced to allow smooth, frictionless movements. In order to protect the joints and tendons associated with these joints from the harm of wear and tear, the nature has provided us with a structure called bursa.

Normally a bursa forms an intervening structure between tendons and bones. The chief purpose of this fluid filled space or sac is to protect our bones, joints and tendons from the harmful effects of friction. With the presence of slippery bursa between the muscle tendons and bones, it is easier for the muscle tendons to glide freely over the bones during movements.

This is how the bursa aids our joints in moving smoothly by reducing the friction between joint structures. That is why bursa are present between bones and tendons in almost all the major joints of body like hip joint, knee joint, shoulder joint and elbow joints. Till now, this was the talk about normal and healthy bursa.

What happens when the bursa gets inflamed?

When bursa gets inflamed, the condition is known as bursitis. The presence of constant stress or pressure on the joints or bursa makes them more vulnerable to inflammation. With too much friction or stress on the joint or tendons thickening of synovial membrane starts.

As a result, the site where tendon moves over bones get inflamed, swollen, painful and feels taut on movement. Now, here another question arises.

What is pes anserinus? What is the reason behind pes anserine bursitis?

Pes anserinus is the term used for the area on the media aspect of knee joint where tendons of three muscles join to form a common insertion point. These three muscles, in anterior to posterior order, include Sartorius, Gracilis and Semitendinosus. The tendons of these muscles combine to form a single webbed shaped tendon that is inserted on the medial surface of shinbone or tibia.

Pes anserinus is a Latin word which means “goose foot”. The name pes anserinus was given to this common muscle tendon due to its resemblance to the webbed shaped foot of goose. These three muscles are the main flexors of knee. They help in bending the knees and moving the legs and knees towards each other. They also limit the rotation of tibia, thus protecting it from rotatory stress.

But all these movements of pes anserine muscles are made possible due the presence of pes anserine bursa. The pes anserine bursa is located between the common tendon of above mentioned three muscles and tibia bone. The purpose of this bursa is to provide cushioning effect between muscles tendons ad tibia bone. Sometimes overuse, trauma or stress on the knee joint provokes the inflammation of pes anserine bursa.

Damage to pes anserine bursa triggers the release of inflammatory mediators (chemicals involved in inflammation). These inflammatory mediators increase the secretion of synovial fluid, leading to pain and swelling. Pes anserine bursitis, sometimes, presents along with other degenerative disorders of knee joint. It commonly occurs in athletes, obese individuals, females and in patients with arthritis.

Signs and symptoms of pes anserine bursitis

The patients of pes anserine bursitis present with following symptoms:

Mild to moderate pain on the medial aspect of knee

The patient complains of mild to moderate pain on the medial (area facing the other knee) aspect of knee. Pain may be localized to the region of pes anserine bursa or may be diffused along the medial side of knee and shinbone. But usually the patients point out the pain, approximately 2-3 inches below knee cap, along the inner side of knee. The pain develops gradually with the passage of time. It aggravates while climbing stairs and standing from sitting posture.

Disturbed sleep patterns

Patients with pes anserine bursitis often have disturbed sleep pattern. While sleeping, when the patient bends or move the knees, excruciating pain occurs that can disrupt the sleep of patient.

No pain on a level surface

Patients do not complain of pain while walking on a level surface. The pain usually exacerbates when the person attempts to ascend or descend the stairs.

Discomfort in doing exercise

There is difficulty and discomfort in doing exercise, bending and straightening of knee joint.

Swollen knee

The affected area becomes tender and swollen. The skin over the area of pes anserinus becomes warm and red.

Prolonged pain

The presence of prolonged pain and swelling in the affected joint limits the range of its motion. Patients find it difficult to perform daily routine activities.

Chronic refractory pain

Chronic refractory pain occurs in patients with arthritis and in obese females.

Causes of pes anserine bursitis

Here are some of the common causes of pes anserine bursitis:

Tight hamstring muscles

The main cause of pes anserine bursitis is the tightness of hamstring muscles. Normally, pes anserine bursa cushions the shin bone from the rubbing effect of hamstring muscles. But, in case of tight hamstrings muscles, the pressure on pes anserine bursa increases. When the knee joint moves, the tight hamstring muscles rub against pes anserine bursa and friction is produced.

This friction has the tendency to damage the pes anserine bursa and related structures including bones and muscle tendon. Eventually, an inflammatory reaction pops up due to wear and tear caused by friction. Various inflammatory mediators are produced at the site of inflammation that further causes damage to the synovial lining of pes anserine bursa, leading to its thickening. To compensate the effects of increased friction, the production of synovial fluid by bursa raises. This fluid begins to accumulate in the bursa, causing the joint to become swollen and painful.

Overuse of hamstring muscles

Another common cause of pes anserine bursitis is the overuse of hamstring muscles. This thing happens usually in athletes and runner having tight hamstring muscles. Sports activities require sudden and repetitive movements of knee joint.

Thus, the overuse of hamstrings muscles increases the friction between muscle tendons and pes anserine bursa. This elevates the risk of damage to pes anserine bursa. Tear or damage of pes anserine bursa kicks start the inflammatory reaction, leading to excess fluid buildup in the bursa.

This results in inflammation, swelling and tenderness of knee joint. Lack of proper training, avoiding stretching and warm up exercises, suddenly increasing the distance of run and uphill climbing or running increases the risk of pes anserine bursitis.

Stress or pressure on pes anserine bursa

Pes anserine bursa acts as a shock absorber between tendons of hamstring muscle and tibia. Bursa is a jelly like sac. When pressure is applied on it, it absorbs the pressure and prevents the surrounding structures from damage or tear. When the stress on pes anserine bursa goes beyond its shock absorbing capacity, the result is irritation or inflammation.

The bursa tends to absorb the raised pressure by increasing the secretion of synovial fluids. But the enhanced synthesis of fluids in bursa does more harm than good by initiating a viscous cycle of inflammatory reactions. This phenomenon commonly occurs in athletes. The athletes have to participate in sports activities that require a lot of knee and leg work. That is why they are more prone to pes anserine bursitis because their knee joint and pes anserine bursa constantly remain under pressure or stress.

Obesity

The whole body weight of an individual is supported on the load bearing joints of body including hip and knee joint. This means these joints are always under great pressure due to body weight. But, normally, these joints can withstand this pressure provided the weight remains in normal range. When you gain weight, the stress or pressure on the weight bearing joints increases more than normal.

Now the joints will have to do extra work in order to support this extra weight. This may cause the rupturing or tearing of bursa and muscle tendons, leading to their inflammation. The inflamed bursa becomes swollen, tender and painful which limits the joint mobility as well.

Gender difference

Pes anserine bursitis is predominant in females as compared to males because females have wider pelvis and greater leg knee angle that increases the stress on knee joint. Thus females are at higher risk of developing pes anserine bursitis. Increased body weight or obesity is another risk factor in females that contributes to pes anserine bursitis.

Injury or trauma to knee joint

Knee joint is more prone to get injured during exercises, running and sports activities. Direct injury or blow to pes anserine bursa can cause its damage. In response to damage or injury, the inflammatory changes begin to set up in bursa.

The synovial lining of bursa also gets inflamed, which in turn starts producing more and more synovial fluid in the bursa. Sometimes, along with synovial fluid, the blood begins to accumulate into the cavity of bursa due the damage of surrounding blood vessels and capillaries.

When the blood seeps in to the sac of bursa, it irritates the lining of bursa that further aggravates the inflammation. The inflammatory mediators like prostaglandins, histamine and leukotrienes are produced that are responsible for making the joint swollen, tender and painful.

Structural deformity

Any deformity in structure or alignment of knee joint increases the chances of pes anserine bursitis. People having problems like foot rolling, knocking knees, outturned knees and limping gait are vulnerable to develop pes anserine bursitis because in all these situations there is either structural deformity or misalignment of knee joints. Due to this reason stress on the pes anserine bursa or the medial aspect of thigh increases, making the bursa more prone to inflammation, injury or rupture.

Degenerative joint diseases

People suffering from degenerative joint diseases more often present with the symptoms of pes anserine bursitis too. Thus, presence of degenerative joint disease in a person increases the likelihood of pes anserine bursitis as well. Osteoarthritis is the most prevalent degenerative joint disease. Normally the bones in joint are covered with tough and slippery fibrous connective tissue called cartilages. These cartilage plates, surrounding the ends of bones, help in reducing the friction between bones while the joints move.

This protective role of cartilages is, more or less, same as the role of bursa. In osteoarthritis, there is increased production of inflammatory mediators and degradation or destructive enzymes which cause the damage or break down of these protective cartilage covering. When the cartilages are degraded, their cushioning effect is lost, leading to increased friction between the bony surfaces when the joints are moved.

Rubbing of bony surfaces against each other promotes their wear and tear. This wear and tear of joint may spread to the bursa, causing its inflammation and destruction. Thus, having knee osteoarthritis may increase your chance to get pes anserine bursitis.

Infected bursitis

The bacteria like staphylococcus aureus and streptococcus epidermidis can infect the pes anserine bursa. This results in infected pes anserine bursitis.

How is pes anserine bursitis diagnosed?

The doctor will diagnose pes anserine bursitis on the basis of medical history of patient and physical examination. The patients of pes anserine bursitis will present with the complaints of pain and swelling on medial side of knee.

This may give a rough clue to doctor about the condition of patient. But to confirm the diagnosis doctor will do complete examination of the knee and will also check the joint mobility as well.

If the doctor suspects pes anserine bursitis, he will assess the hamstring tightness as well. To check the tightness of hamstring muscle, the patient is made to lie in supine position.

Then he is asked to flex his hip at 90 degree. The knee of patient is extended or straightened to check the degree of tightness at knee joint. If the patient is unable to extend his knee properly or the knee remains flexed, it means the hamstring muscles of patient are tight.

However, history and physical examination are not enough to reach a final diagnosis because there are many other conditions of knee having symptoms similar to pes anserine bursitis.

To rule out the other diseases following investigations are carried out:

• X rays are done to rule out the possibility of fracture, trauma or tumors.
• MRI (magnetic resonance imaging) and ultra sounds are done to have better view of inflamed or damaged bursa. These tests also show the extent of damage to the tissues.
• Aspiration of bursal fluid is carried out to rule out infection.

Prognosis

The prognosis of pes anserine bursitis is good because it is a self limiting condition. Limiting physical activity along with taking analgesics can effectively cure the condition. Surgery is done rarely, only in cases of unresolved infected bursitis.

Treatment and management of pes anserine bursitis

Pes anserine bursitis is an inflammatory condition that needs time to get resolved. Usually the condition is self timing and heals on its own. There are a lot of treatment options available for curing the pes anserine bursitis but the natural treatment options are preferred over surgical procedures. Let’s have a look on the ways to treat the pes anserine bursitis.

Limit your physical activity

Rest is the first and foremost way to cure pes anserine bursitis. The major reason behind pes anserine bursitis is over activity or overuse of hamstring muscles during bicycling, climbing and other athletic activities that put strain on the pes anserine bursa. So, the initial step for getting rid of the symptoms of pes anserine bursitis is to avoid the stress on joints as much as possible. You cannot expect your inflamed bursa to heal own its own without taking proper rest.

By rest it does not mean complete bed rest. In fact complete rest will do more harm than good. You can continue your routine activities but you need to bring some changes in them according to the need of your condition. Avoid those physical activities that put strain on your knees like climbing stairs, running and vigorous exercises. You doctor will advise you to limit your physical activity for as long as possible, until the pain settles.

Ice packs

Using ice pack and ice compresses is one of the conventional and effective ways to heal the inflammation. Apply ice packs for 20 minutes, at least 3-4 times per day until pain and swelling subside. At the site of inflammation, the blood vessels get dilated. From these dilated blood vessels, fluid seeps out into tissue resulting in swelling. The purpose of using ice packs is to reduce this swelling.

When you apply ice pack to the affected inflamed and swollen area, the dilated vessels undergo constriction that stops the leakage of excess fluid into the surrounding tissues. Ice packs not only limit the leakage of fluids from vessels but they also help in regulating the blood flow to affected area which accelerates the process of healing.

Now, advanced cold compression therapies are also available in the market. They are easy to use, time saving and cheap as well. Cooling gel containing ice wraps are gaining popularity these days. These are flexible and easily adjustable knee wraps that you can wear safely. All you need to do is to cool these gel packs in fridge and wear them around your affected knee. The cooling gel in the wraps will provide you with cooling effect for all day long. Also the risks of frost bite and cold burns with these gel wraps are extremely rare.

Compression

Simply compressing the inflamed area with the help of compression wraps can significantly reduce the swelling and pain. Compressing the affected inflamed area will limit its movements. This helps in relieving the stress on the bursa and in promoting the healing of damaged tissue.

Keep your legs elevated

Patients having pes anserine bursitis are advised to keep their legs elevated during sleep. As the blood vessels at the site of inflammation are dilated, hanging down the legs will further promote the seeping of fluid and swelling. But, elevating the legs will prevent the leakage of fluid by preventing the stasis of blood in vessels. This will eventually result in reduced swelling and pain. So place a pillow under your legs while sleeping to keep your legs in elevated posture.

Non steroidal anti inflammatory drugs (NSAIDs)

Sometimes the home remedies are not enough to treat pes anserine bursitis. In order to treat the severe pain, not relived by any other remedy, over the counter pain killers are used.

Non steroidal anti inflammatory drugs like ibuprofen, naproxen and aspirin are of great value in relieving the symptoms of pain and inflammation. Pain and swelling during inflammation are caused by the release of certain inflammatory mediators like histamine, serotonin, prostaglandins and leukotrienes. The purpose of anti inflammatory drugs is to suppress the synthesis of these inflammatory mediators. These drugs inhibit enzyme, like Cox 1 and Cox 2, which are involved in the synthesis of these mediators.

Once these drugs block the pathway of production of these mediators, the pain and swelling resolves within no time. Use of anti inflammatory drugs along with other remedies can significantly reduce the swelling of pes anserine bursitis. But the patients with stomach pain or ulcer should take these drugs with great caution as they can aggravate the stomach ulcers.

Steroids injection

In certain cases, the anti-inflammatory drugs, alone, fail to relieve the symptoms of pes anserine bursitis. If the pain remains persistent even after taking the anti inflammatory and analgesic drugs, then it is recommend to give an injection of steroid along with local anesthetic into the site of inflamed bursa. Local anesthetic inhibits the pain sensations and provides prompt relief from pain.

On the other hand, steroids act in the same way as anti inflammatory drugs. They provide rapid relief from the swelling by inhibiting the synthesis of inflammatory mediators. But great care should be taken while giving steroid injection into the affected bursa. Injecting, mistakenly, into any of the muscle tendons surrounding the pes anserine bursa will not only weaken the muscle tendon but will also exacerbate the pain as well.

Antibiotics

If pes anserine bursitis does not resolve after taking the course of anti inflammatory drugs and steroids, there are chances that bursitis is due the infection. Thus, in cases of infected bursitis, the antibiotics are prescribed. Antibiotics reduce the risks of recurrent infection and inflammation.

Physical therapy exercises

Stretching exercises are highly beneficial for the patients of pes anserine bursitis because tightness of hamstring muscles is of one the factors responsible for pes anserine bursitis. Stretching exercises of hamstrings and quadriceps muscles release the muscle tension and make them relaxed.

Not only this, stretching exercises increase the range of motion of joint and improve the blood flow to the affected area, thus aiding in rapid healing of inflamed bursa. Your doctor may recommend you to consult a professional physiotherapist for taking proper training of stretching exercises.

The hamstring and quadriceps stretching exercises program usually last for 6-8 weeks. The patients of pes anserine bursitis are never advised to completely immobilize their joint for longer duration as it can cause muscle wasting. To avoid muscle wasting, light stretching exercises are recommended that help to maintain the joint mobility. The purpose of these physiotherapy sessions is to encourage the patients to gradually resume their routine activities.

Blood flow stimulation therapy

Blood supply acts as a source of fuel for tissues. The nutrients carried by blood are essential for the healing of injured tissues. But, in inflamed or injured tissues the blood flow becomes sluggish due to blood vessel dilation, promoting swelling and pain. The concept of blood flow stimulation therapy was introduced to improve the blood flow in injured tissues. In blood flow stimulation therapy, the affected knee joint is covered with an inferno knee wrap. This knee wrap generates electromagnetic radiations that penetrate into the affected tissues.

Once the electromagnetic radiations are absorbed by the tissues, their energy helps in stimulating the blood flow through vessels. These energy radiations bring fresh blood to the inflamed area and flush out the toxins present there, thus helping in rapid recovery and healing of inflammation.

Aspiration

In aspiration, a needle is inserted into bursa and extra fluid is sucked out. Needle aspiration is also done to detect the bacterial growth in fluid. It is a diagnostic test for ruling out the infection.

Surgical treatment

Surgical treatment is done only in refractory cases that are not resolved by any other method. Surgery is indicated when bursitis becomes chronic due the infection. During surgery, small incisions are given in the knee and then infected bursa is removed carefully. Postoperative recovery time is approximately 2-3 weeks.