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Why the Difference Between Tendinitis and Tendinosis Matters

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It is important to distinguish between these disorders in order to apply the most appropriate treatment. But what is the difference?

Tendinitis is the inflammation of the tendon and results from micro-tears that happen when the musculotendinous unit is acutely overloaded with a tensile force that is too heavy and/or too sudden. Tendinitis is still a very common diagnosis, though research increasingly documents that what is thought to be tendinitis is usually tendinosis.

Tendinosis is a degeneration of the tendon’s collagen in response to chronic overuse; when

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overuse is continued without giving the tendon time to heal and rest, such as with repetitive strain injury, tendinosis results. Even tiny movements, such as clicking a mouse, can cause tendinosis, when done repeatedly.

A microscopic view of tendinosis reveals an increase of immature type III collagen fibers (mature type I fibers dominate in healthy tendon tissue); loss of collagen continuity so that collagen fibers are no longer aligned with each other and sometimes fail to link together to facilitate load-bearing; an increase in ground substance (the material between the body’s cells); and a haphazard increase of vascularization(2,3,5). These vascular structures “do not function as blood vessels” and “are not associated with increased healing(2).” The appearance of the tendon shifts from a reflective, “white, glistening and firm” surface to a “dull-appearing, slightly brown and soft” surface (mucoid degeneration)(2,3).

These changes result in a loss of strength in the tendon and increase the bulk of the tendon, both of which contribute to the cycle of injury and can set the stage for secondary conditions, such as tendinitis and nerve impingement. Studies lead to believe that, in the forearm and wrist, tendinosis can result in secondary carpal tunnel syndrome; this is because the thickening of the tendons with excess ground substance and the swelling of the surrounding tissue crowds and compresses the median nerve.

There is a prevalent supposition that tendinosis begins with tendinitis, which then instigates a healing process that changes the collagen and weakens the tendon, becoming tendinosis. Perhaps this supposition exists because the stages of soft-tissue healing are generally listed as, in short: inflammation response, regeneration (collagen production), and remodeling (strengthening the collagen in the direction of the forces placed upon it). In one article, tendinitis is cited as the first stage of a tendinopathy; tendinosis is cited as the second stage and rupture as the third stage. The fourth stage is described as a combination of stages 2 and 3, along with fibrosis and calcification(2).

The suggestion that tendinitis precedes tendinosis is at odds with the fact that a healthy tendon is up to twice as strong as the muscle, making the body of the tendon unlikely to tear before the muscle unless the tendon has already been weakened by degenerative changes(6).

The idea that tendinitis is the first stage of tendinosis seems to presume that micro-tears and inflammation are a precursor to collagen degeneration. Histopathologic analyses show that torn fibers, scar tissue, and calcification are only found in conjunction with tendinosis some of the time, and inflammatory cells are rarely found in conjunction with tendinosis, supporting the hypothesis that tendinitis occurs secondarily to tendinosis(1,2,3,5,7).


The most important reason to distinguish between tendinitis and tendinosis is the differing treatment goals and timelines.

The most prominent treatment goal for tendinitis is to reduce inflammation, a condition that isn’t present in tendinosis. In fact, some treatments to reduce inflammation are contraindicated with tendinosis. Ibuprofen, a nonsteroidal anti-inflammatory, is associated with inhibited collagen repair(9). Corticosteroid injections inhibited collagen repair in one study, and were found to be a predictor of later tendon tears(3,4,10).

The healing time for tendinitis is several days to 6 weeks, depending on whether treatment starts with early presentation or chronic presentation(3). Khan et al.(3) state that treatment for tendinosis recognized at an early stage can be as brief as 6–10 weeks; however, treatment once the tendinosis has become chronic can take 3–6 months. It is suggested by Rattray and Ludwig(10)that effective treatment might take up to 9 months once the tendinosis is chronic. Khan(3)reportedly suggests that tendons “require over 100 days to make new collagen.” Given this claim, treating chronic tendinosis for a matter of weeks would provide little benefit to the long-term repair of the tendon.

Some of treatment goals for tendinitis and tendinosis result in overlapping beneficial treatment methods. For example, deep-friction treatments are beneficial for both conditions, but for very different reasons. In the case of tendinitis, deep friction serves to reduce adhesions and create functional scar tissue once inflammation has subsided. In the case of tendinosis, deep-friction treatments serve to stimulate fibroblast activity and collagen production(11). Lucky concurrence of treatment recommendations is not to be substituted for a thorough understanding of which condition is being treated. Accurate assessment techniques and knowledge of the relevant condition will result in the most appropriate application of treatment.

The primary treatment goals for tendinosis are to: break the cycle of injury; reduce ground substance, pathologic vascularization, and subsequent tendon thickening; and optimize collagen production and maturation so that the tendon regains normal tensile strength(3).

Patients must avoid self-care. Refer to a physical therapist will be beneficial to the patient.

Treatment recommendations for tendinosis include:

- Rest. People with low-grade tendon injuries often find it difficult to rest as much as is necessary, especially as symptoms subside(3). With repetitive work tasks, the patient is recommended to take a break for one minute every 15 minutes and a five-minute break every 20–30 minutes(12). The patient should be advised to stay aware of their body as it heals. If the activity they are engaging in is causing pain, then they are probably doing too much.

- Adjust ergonomics and biomechanics. Small changes can make a big difference. With regard to ergonomics, for example, cashiers are encouraged to press the register keys as lightly as possible, and computer users should be sure their wrists are resting in a neutral position while typing. Physical therapists are experts at recognizing and adjusting improper biomechanics that might be causing injury.

- Use appropriate support. Physical therapists can also recommend appropriate support to reduce tensile stress on the tendon, such as bracing or taping(3). - Stretch and keep moving, though conservatively. Lightly stretching and moving the affected area through its natural range of motion while minimizing pain will prevent shortening of the related muscles (preserving active range of motion and flexibility). It can also increase circulation, thereby assisting the healing process. Stretching can also elongate the muscle-tendon unit, reducing the tension placed on the tendon during activity, thereby reducing the chemical changes that cause degeneration(8,13,14).

- Apply ice. Ice causes vasoconstriction and is thought to address the abnormal neovascularization of the tendon tissue(3). Use ice for 15–20 minutes several times a day, and after engaging in activities that utilize the tendon(7,15).

- Eccentric strengthening. An eccentric strengthening regimen done 1–2 times daily for 12 weeks has been clinically proven to be a very successful treatment for tendinosis, especially when the exercises are performed slowly(2,3,5,16). Eccentric strengthening is “lengthening a muscle while it is loaded and contracting(17).” For example, lengthening one’s bicep while holding a dumb-bell in one’s hand would stimulate eccentric contraction. Eccentric strengthening effectively stimulates collagen production, improves collagen alignment, and stimulates collagen cross-linkage formation, in turn improving tensile strength(5). Eccentric strengthening might also help to reduce ground substance and tendon volume (swelling/thickening)(2). It has also been proposed that part of the benefit of eccentric strengthening is the stretching involved, as described above. Consult with a physical therapist to maximize the benefit of strengthening exercises and to minimize the possibility of re-injury.

- Massage. Massage stimulates circulation and cell activity, especially when done at the appropriate depth. Deep-friction massage applied to the tendon serves to stimulate fibroblast activity and generate new collagen. Myofascial techniques and trigger-point therapy can reduce fascial restrictions, scar tissue, and trigger points in the muscle connected to the tendon, relieving tension on the tendon. Myofascial techniques, lengthening deep-tissue techniques, stretching and active-release techniques can reset muscle memory to a more lengthened position, reducing the tension placed on the tendon during activity. A variety of massage techniques can decrease overactive pain messages from sympathetic nervous system firing, increase circulation, and improve overall tissue health(10,11,19).

- Nutrition. Vitamin C, manganese, and zinc are all important for the synthesis of collagen production(20). Vitamin B6 and Vitamin E have also been linked to tendon health(21). Patients might benefit from talking with their primary health care provider or a nutrition specialist to be sure their intake of these nutrients is sufficient.

While the cellular damage is unlikely to be reversed completely, these treatments can increase the strength of the tendon by stopping the cycle of injury, introducing healthy collagen into the area, addressing unhealthy vascular changes, and decreasing the over-abundance of ground substance.

Tendinosis causes tissue changes that make the tendon more prone to injury, so it is important that the patient continue to take care of the compromised tendon once the initial phase of treatment is complete. Ongoing massage, stretching, strength training, and warming up before starting work or exercise can help to prevent re-injury and keep the tissue as healthy as possible.


1. Khan KM, Cook JL, Kannus P, et al. Time to abandon the “tendinitis” myth: Painful, overuse tendon conditions have a non-inflammatory pathology [editorial]BMJ. [Accessed 16 September 2011]. Published March 16, 2002.

2. Heber M. Tendinosis vs. Tendinitis. Elite Sports Therapy. [Accessed 16 September 2011].

3. Khan KM, Cook JL, Taunton JE, et al. Overuse tendinosis, not tendinitis—Part 1: A new paradigm for a difficult clinical problem. [Accessed 13 February 2012];Physician Sportsmed. 2000 28(5) [PubMed]4. Boyer MI, Hastings H. Lateral tennis elbow: Is there any science out there? J Shoulder Elbow Surg. 1999;8(5):481–491. doi: 10.1016/S1058-2746(99)90081-2. [PubMed]5. Kraushaar B, Hirschl RP. Current concepts review - tendinosis of the elbow (Tennis Elbow). Clinical features and findings of histological, immunohistochemical, and electron microscopy studies. [Accessed 28 January 2012];J Bone & Joint Surg. 1999 81(2):259–278. [PubMed]6. Lowe W. Types of tendon injury. [Accessed 16 September 2011];Massage Today. 2006 6(8) [Accessed 28 January 2012]. Murrell GA. Understanding tendinopathies. [Accessed 28 January 2012];Br J Sports Med. 2002 36(6):392–393. doi: 10.1136/bjsm.36.6.392. [PMC free article] [PubMed]]9. Tsai WC, Tang FT, Hsu CC, et al. Ibuprofen inhibition of tendon cell proliferation and upregulation of the cyclin kinase inhibitor p21CIP1 [abstract] [Accessed 28 January 2012];J Orthopedic Resear. 2004 22(3):586–591. doi: 10.1016/j.orthres.2003.10.014. [PubMed] [Cross Ref]10. Rattray F, Ludwig L. Clinical Massage Therapy: Understanding, Assessing and Treating Over 70 Conditions. Elora, Ontario: Talus Inc; 2001.11. Lowe W. Orthopedic Massage Theory and Technique. Philadelphia, PA: Mosby Elsevier; 2009.12. Repetitive Stress Injury. Tips for Preventing RSI. [Accessed 28 January 2012]. [no author] Alfredson H, Pietila T, Jonsson P, Lorentzon R. Heavy-load eccentric calf muscle training for the treatment of chronic Achilles tendinosis. [Accessed 10 February 2012];Am J Sports Med. 1998 26(3):360–366. [PubMed]14. Nicholas Institute of Sports Medicine and Athletic Trauma. Eccentric Training for Ttreatment of Achilles Tendinosis. [Accessed 10 February 2012]. Orthopedics. [Accessed 28 January 2012]. Mafi N, Lorentzon R, Alfredson H. Superior short-term results with eccentric calf muscle training compared to concentric training in a randomized prospective multicenter study on patients with chronic Achilles tendinosis. [Accessed 8 February 2012];Knee Surgery Sports Traumatology Arthroscopy. 2001 9(1):42–7. doi: 10.1007/s001670000148. [PubMed] [Cross Ref]17. Physical Therapy. Available from Stasinopoulos D, Johnson MI. Cyriax physiotherapy for tennis elbow/lateral epicondylitis. [Accessed 7 February 2012];Br J Sports Med. 2004 38:675–677. doi: 10.1136/bjsm.2004.013573. [PMC free article] [PubMed] 19. Lowe W. Orthopedic Assessment in Massage Therapy. Sisters, OR: Daviau Scott; 2006.20. Andrews J. Supplements That Rebuild Collagen. [Accessed 29 January 2012]. Published on January 16, 2011.21. News Medical. Tendinosis Treatments. [Accessed 10 February 2012].

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