Time to abandon the “tendinitis” myth

Tendinitis such as that of the Achilles, lateral elbow, and rotator cuff tendons is a common presentation to family practitioners and various medical specialists.¹ Most currently practising general practitioners were taught, and many still believe, that patients who present with overuse tendinitis have a largely inflammatory condition and will benefit from anti-inflammatory medication. Unfortunately this dogma is deeply entrenched. Ten of 11 readily available sports medicine texts specifically recommend non-steroidal anti-inflammatory drugs for treating painful conditions like Achilles and patellar tendinitis despite the lack of a biological rationale or clinical evidence for this approach.²,³

Instead of adhering to the myths above, physicians should acknowledge that painful overuse tendon conditions have a non-inflammatory pathology. Light microscopy of patients operated on for tendon pain reveals collagen separation^4–6—thin, frayed, and fragile tendon fibrils, separated from each other lengthwise and disrupted in cross section. There is an apparent increase in tenocytes with myofibroblastic differentiation (tendon repair cells) and classic inflammatory cells are usually absent.⁴ This is tendinosis and it was first described 25 years ago,⁶ but this fundamental of musculoskeletal medicine has not yet replaced the tendinitis myth. Tendinosis is not merely a long term corollary of short term tendinitis. Animal studies show that within two to three weeks of tendon insult tendinosis is present and inflammatory cells are absent.⁷

A critical review of the role of various anti-inflammatory medications in soft tissue conditions found limited evidence of short term pain relief and no evidence of their effectiveness in providing even medium term clinical resolution of clearly diagnosed tendon disorders.² Laboratory studies have not shown a therapeutic role for these medications. Corticosteroid injections provide mixed results in relieving the pain of tendinopathy.⁸,⁹

If general practitioners, orthopaedic surgeons, and other members of the healthcare professions treating tendon disorders made a quantum shift from previous flawed teaching about overuse tendinitis and adopted these data there would be immediate ramifications. Nomenclature for the clinical presentation of tendon disorders would reflect the true histopathological basis underlying clinical presentation.¹⁰ The term tendinitis would rarely cross doctors' lips. Numerous authorities ²,¹⁰ recommend the term tendinopathy (for example, Achilles tendinopathy) as this acknowledges that the condition is not tendinitis. We favour this term for clinical diagnosis. Most importantly, we must acknowledge, at least till contrary data appear, that anti-inflammatory pharmacotherapy does not provide significant long term benefit in tendinopathy.²,¹¹ Nevertheless, high quality randomised controlled trials are urgently needed to examine the long term effects of these medications on tendinopathy.

If general practitioners treating musculoskeletal conditions embraced the tendinopathy paradigm, it would provide patients with an accurate description of their condition. It would avoid inappropriate pharmacotherapy with its attendant costs and comorbidity. Furthermore, by accepting need to allow time for collagen turnover and remodelling inherent in the pathology of tendinosis, doctors would be free to provide patients with a realistic prognosis that better reflects the finding of prospective clinical studies.¹² These conditions take months rather than weeks to resolve.

Some pockets of the sports medicine, orthopaedics, and rheumatology specialties have adopted this paradigm,^2–4,¹⁰ but it must no longer remain within that cabal. It is time for medical educators to accept the irrefutable evidence that the term tendonitis must be abandoned to highlight a new perspective on tendon disorders. Adopting the tendinopathy paradigm is essential if general practitioners are to practise evidence based medicine. However, there remain many unanswered questions, particularly with respect to treatment.