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).

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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.  

Tendinitis

​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.  

Tendinosis

​This term refers to degeneration of a tendons collagen fibers often caused by chronic overuse (longer 
periods of time). This degeneration of collagen fibers can lead to loss of fiber continuity, causing 
decreased overall tendon strength. These are often seen when a tendon is injured and not given the 
appropriate time to rest and recover. Because tendinosis is a chronic issue, there is no tendon 
inflammation/swelling present, so the treatment goals are different. Primary treatment goals are to 
inhibit the cycle of injury (or tendon overuse) and to optimize normal collagen production and 
maturation so that the tendon regains normal tensile strength. To do this we must determine what is 
causing the repetitive injury by looking at ergonomics, biomechanics, etc. Once this is determined we 
can use support (braces, tape, etc.) to help reduce forces on the tendon and allow for appropriate 
healing. Light stretching while minimizing pain is crucial to limit shortening of muscles and maintain 
flexibility. Eccentric strengthening and loading the tissue without pain is essential to help with collagen 
production and improve collagen alignment. Treatment time can vary from 6-10 weeks (if caught early) 
all the way up to 3-6 months.  

​If you are having any tendon pain (most commonly in heel, elbow, shoulder, knee) please give us a call. 
We can help evaluate this pain and determine the underlying cause then come up with a plan to get you 
back on track!

Author

David Simmons, PT, DPT