Joint Knowledge: The Bursa

Unless you’re in the medical field or have had a recent visit with your physical therapist or orthopedic doctor, you probably weren’t aware that you even had little structures called bursae (plural of bursa).

Bursae…what the heck are they? Let’s dig in…

 

What is a bursa?

A bursa is a thin, lubricated cushion located between a bone and tissue formations such as skin, muscle, tendons, and ligaments. Filled with fluid, bursae allow for smooth gliding movements at the joint such as bending the elbow or rotating the shoulder.  Without bursae, more friction occurs at the joint.

The average adult human body contains roughly 160 bursae.

Healthy bursae are thin, often measuring just a few millimeters in thickness but can vary depending on the person and the location in the body. Some bursae, such as those in the elbow joint, are found just beneath the surface of the skin; others are nestled deep below soft tissue.

Image Source: WebMD 

The Three Types of Bursae

The three different types of bursae are mainly distinguished by where they’re found in the body and whether or not they are there naturally or as a result of trauma.

Most of the bursae in the human body are synovial.  That is, they are sacs present between bones, muscles, and tendons. The synovial fluid around a bursa forms a membrane that provides the lubrication necessary for movement. This fluid is viscous and similar to an egg white in appearance and texture. The synovial membrane is semi-permeable, allowing certain substances such as blood to enter and exit. Most synovial bursae are present within joints such as the shoulders, knees, and feet.

Subcutaneous bursae are found between the skin and bone such as within the elbow.

The third, often problematic type of bursae is the adventitious (accidental) variety. These develop in soft tissue above a bony region, often due to constant pressure or trauma. One type of adventitious bursae is a big toe bunion, usually caused by wearing shoes with inadequate toe space, compressing the big toe against the other toes.

Over time, this unnatural positioning leads to swelling and discomfort of the metatarsal joint and bone. Adventitious bursae can also develop from shearing or friction. This is a common occurrence in contact sports such as football, wrestling, and combat sports, and often presents as bursitis.

 

Bursitis

Bursitis is the inflammation of a bursa due to injury, overuse, or infection. Once inflamed, the bursa loses its gliding properties, making movements involving that joint or muscle uncomfortable. Bursitis can occur at any joint but most commonly affects the shoulders, elbows, hips, and knees.

Indications of bursitis include discomfort, tenderness, swelling, and loss of mobility.

Bursitis caused by injury or overuse is called aseptic bursitis, with some of the most common types being:
• Tennis elbow: This is caused by repetitive bending of the elbow, common in sports such as tennis, golf, and combat sports.
• Shoulder bursitis: Powerlifters, bodybuilders, and boxers often experience this type of bursitis due to the force and impact on the shoulders.
• Clergyman’s/Washmaid’s knee: Repeated kneeling or bending of the knees under pressure can lead to knee bursitis.
• Ankle bursitis: Sports that place a heavy demand on the ankles such as tennis, basketball, running, and ice skating can lead to ankle bursitis.

Septic bursitis is caused by bacterial infection. Indications include fever, redness, and hotness upon touch. Septic bursitis often occurs in bursae closer to the surface of the skin, such as those in the elbow or knee. Even a small cut or abrasion can allow bacteria to infect the site. Having a weakened immune system increases the risk of developing septic bursitis. Risk factors include heavy alcohol consumption, steroid use, and chemotherapy.

Caring for Your Bursae

Most cases of aseptic bursitis can be remedied through self-care and/or physical therapy.

Four Ways to Calm Bursitis

• Wrap and/or pad the affected site to protect the bursae from further trauma or pressure
• Minimize use of the joints where the bursa is located. Most cases of aseptic bursitis respond well to rest.
• Ice the affected area with a cloth-wrapped ice pack. Avoid placing ice directly on the skin.
• Elevate the affected site to limit blood flow and help reduce swelling.

When to See a Doctor

While most cases of aseptic bursitis can better with rest, persisting and extreme discomfort are good reasons to see your physical therapist or doctor.

Septic bursitis presents a more serious issue. Consult a doctor if you experience any of these joint issues:
• Discomfort that greatly limits movement
• Prolonged discomfort lasting longer than two weeks
• Sharp, intense discomfort
• Excess swelling, bruising, rash, or redness in the affected site
• Fever

In these cases, the doctor will often prescribe steroids or antibiotics. In rare situations, the bursa must be surgically drained.

Proper diet, exercise, and rest go a long way to reduce the risk of bursitis. Take breaks between repetitive tasks, and always warm up before intense physical activity. Stretching and strengthening the muscles around each joint can add additional protection.