Bursitis is commonly diagnosed as the cause of pain in many areas of the body; you may have heard of it when people discuss their shoulder or hip. However, the condition is often not well understood and so I will explain here what bursitis is and why your might get pain referring from the bursa.
A bursa is a sac of fluid often found close to joints in the body. It is thought that we have around 160 bursae within the body meaning there are often several around each major joint. Each bursa helps to minimise friction between moving tissues that may rub against each other and cause irritation. These (usually small) sacs are lined with a membrane of synovium, which produces a lubricating fluid found within the bursa (synovial fluid). This synovial fluid is the same liquid found within all major moving joints of the body and is often likened to raw egg white in its appearance and consistency. Many nerve endings are found going to each bursae, making bursitis a common source of pain.
There are many potential causes of bursitis including infection, autoimmune disorders, trauma, and crystal deposition (gout and pseudogout). However, the focus here will be overuse bursitis meaning bursitis caused by mechanical stress on the bursa.
Figure 1: An example of the location of a hip bursa
As bursae are designed to reduce friction, they are capable of withstanding a reasonable amount of pressure and stress. After activity, a bursa may swell a small amount in response to a greater load or stress than what this bursa is usually accustomed to – this is not a pathological reaction but rather a normal reaction to increased loads. This small amount of swelling may cause some post-activity soreness that will settle over a few days.
There are times, though, where this inflammation is larger and does not subside quickly. The typical causes of this include:
Excessive biomechanical stresses of the bursa; often the result of weakness or poor technique
Reduced rest between activity
Large increases in activity levels than the body cannot adapt to
At these times the bursae are typically compressed at the same time as friction is applied by a moving part (i.e. tendon, bone). This creates an inflammatory response within the bursa, increasing the permeability of its capillary membrane and allowing it to fill with high protein fluid. The synovial membrane of the bursa then becomes granulated and fibrous. Over time, the inflamed bursa becomes thicker and occupies more space, creating ongoing friction, pain and inflammation. Chronic (long-term) bursitis often leads to weakening of both ligaments and tendons surrounding the bursa, and the likelihood of tendon rupture is increased.
One of the most important components of treating bursitis is to alleviate ongoing irritation to the bursa. Biomechanical loads often need to be altered, weaknesses addressed, and exercise and training schedules modified. These changes may be enough to allow the bursitis to resolve, however sometimes anti-inflammatory medication is used to accelerate this process in the form of creams, tablets or injections. It is very important that any bursitis condition is well assessed by your physio. They will help you implement the appropriate changes the loading on that bursa, and help you understand the reasons for your condition. If this is not done, it’s likely your bursitis will return as soon as you return to the activity that first caused the irritation.
By Mark Fotheringham