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Tendonitis vs tendinosis

What is a tendon?

A tendon is a strong rope like structure that attaches a muscle to a bone. A common example of a tendon is the Achilles, which attaches your gastrocnemius and soleus muscles to your calcaneus or heel bone. Tendons are an essential part in allowing our bodies to move. They help transfer forces from our muscles (when contracted/tighten) to the bones they attach to, which leads to movement of that bone/body part. Often, they will attach from a large muscle such as your bicep to a small single point on a bone. Therefore, they must be made of strong material as they often undergo strong force transfers

(tendons are known to have one of the highest tensile strengths of any soft tissue in the body).

Anatomy of a tendon

Tendons are made of dense fibrous connective tissue that is made up of mostly collagen fibers (structural proteins). These fibers are found in very tightly wound bundles throughout the tendon. This collagen and bundling make them very strong and resistant to tears. Another important aspect of tendon anatomy is that they do not receive as much blood as the muscles and bones that they attach to. This is because they have a lower density of blood vessels (reason for their white color). This is an important factor when it comes to tendon injuries. While tendons are strong and resistant to injury they do occur and can be classified into 4 categories: tendinitis, tendinosis, tendon tear and tendon rupture.


The medical definition of the suffix “itis” is inflammation, so the term tendinitis translates to

“inflammation of a tendon.” This is often more of an acute injury (short-term) and is associated with swelling around the tendon and pain when that tendon is used (contracted by muscle). This inflammation and pain is caused by micro-tears in the tendon that occur when there is a force applied that is too heavy and or to sudden applied on that tendon. The treatment goal for tendinitis is to reduce inflammation. This can be done in a number of ways, starting with RICE (rest, ice, compression, and elevation), anti-inflammatory medications, and physical therapy techniques including soft tissue mobilization. Recovery time varies between days-6 weeks.