PT Classroom - Tendinopathy – Itis vs. Osis ׀ by Ying Xiong, SPT

Tendinopathy is a common condition that affects people of all ages. From competitive athletes to recreational sports participants and working people, tendinopathy has created functional deficits across diverse populations (Khan, 2000). Achilles tendinopathy occurance is about 5.9% in sedendary people and 50% among elite endurance athletes (Fredberg, 2008) over the lifetime. In the athletic population, the prevalence of patellar tendinopathy is reported between 7-40% (Fredberg, 2008). Therefore while tendinopathies can occur in anyone, it is a major source of concern for recreational and competitive athletes where overuse injury is common and often tendon related (Reinking, 2011). Sports such as volleyball, basketball, long distance running, and jumping events in track and field also report high incidences of tendinopathy (Reinking, 2012).

Although its prevalence is well documented, the underlying pathology, etiology, pain mechanism, and even terminology are still debated today. For health care providers, this can cause misdiagnosis, mistreatment, and ultimately the lack of or delay in patient progress. Therefore, in this article I will define and differentiate between tendinosis, tendonitis, and paratenonitis, considering their pathology, and implications for clinical treatment.

Tendinopathy is an umbrella term that signifies the combination of tendon pain and impaired performance that may be associated with swelling of the tendon and/or intratendinous changes (Fredberg 2008). Its diagnosis can be made clinically without histopathologic examination (Fredberg 2008) and because of that, has been suggested as a better term for clinicians to use (Reinking 2012). The confusion usually occurs when tendinopathy is further broken down and classified as tendonitis, tendinosis, or paratenonitis.

Tendonitis, is described as a histopathologic term describing a condition in which the primary site of involvement is the tendon and with an inflammatory response being seen within the tendon (Fredberg 2008). This condition is rare, but may occur occasionally in the Achilles tendon in conjunction with a primary tendinosis (Kahn 2000).

Tendinosis, is used to describe a chronic degenerative state of a tendon where there is a conspicuous lack of inflammatory cells, disorganization and separation of the collagen bundles, increased proteoglycans in the extracellular matrix, hypercellularity, and neovascularization (Reinking 2012).

The third term, paratenonitis, also known as tenosynovitis, describes an inflammation of the paratenon, the outermost layer of the tendon. It is characterized by the presence of inflammatory cells, hypervascularity of the sheath, and development of a fibrinous exudate in the sheath space causing tendon crepitation (Reinking 2012).

Clinical Diagnosis:
While it is common to see clinical diagnosis such as lateral epicondylitis, achilles tendonitis, patellar tendonitis, and rotator cuff tendinitis, advances in the understanding of tendon pathology and an increasing body of evidence have supported the notion that these are mislabels (Khan 2000). Instead, they are in tendinosis, and involve no inflammation (Khan 2000). Many studies have argued that naming all tendon pathology tendonitis may lead to an incorrect line of reasoning in designing a plan of care (Reinking 2012) and that all conditions should instead, be treated initially as tendinosis (Khan 2000).

Although clinical differential diagnosis is difficult, there are some things to keep in mind when determining a plan of care for a pt treated between an -itis and -osis.

Table 3. Implications of the diagnosis of tendinosis compared to tendinitis. Adapted from: “Overuse tendinosis, not tendinitis: Part 1: A new paradigm for a difficult clinical problem,” by Khan KM; Cook JL, et. al, 2000. The physician and Sportsmedicine, 28 (5) pg.4.

While some traditional treatment protocols for tendonitis may still be appropriate for tendinosis, some may not, and clinicians should be aware of pathological differences to properly manage the condition. An article by Khan et al in 2000 suggest that anti-inflammatory modalities used to treat inflammation may still benefit the tendinosis patient if that treatment contains other effects, for example, such as vasoconstriction or collagen synthesis. They further suggest modalities that target only inflammation be discarded, and treatment such as corticosteroid injection be discontinued due to their deleterious effects on collagen repair and associations with further tendon ruptures. The authors also emphasize treatments such as load minimizing, to decrease collagen degeneration, proper evaluation for the root mechanism causing the injury in the specific patient, appropriate strengthening, and surgery as a last resort.

Although much evidence points to tendinopathy as a non inflammatory degenerative process described as tendinosis, some articles have found that an inflammatory process may be involved and that inflammation is a primary role ( Fredberg 2008). At best, much of the data point towards tendinosis, yet the conflicting evidence begs more research and conclusive evidence is needed.




Last revised: August 21, 2012
by Ying Xiong, SPT


Khan, K. M., Cook, J. L., Tauton, J. E., & Bonar, F. (2000). Overuse tendinosis, not tendinitis. The physician and sports medicine, 28(5), 38-48.

Fredberg, U., & Stengaard-Pedersen, K. (2008). Chronic tendinopathy tissue pathology, pain mechanisms, and etiology with a special focus on inflammation. Scandinavian journal of medicine and science in sports, 18, 3-15.

Reinking, M. (2012). Tendinopathy in athletes. Physical therapy in sport, (13), 3-10.

Terms & Conditions

Please review our terms and conditions carefully before utilization of the Site. The information on this Site is for informational purposes only and should in no way replace a conventional visit to an actual live physical therapist or other healthcare professional. It is recommended that you seek professional and medical advise from your physical therapist or physician prior to any form of self treatment.

..="font-size: 2pt">.