Deciphering the pathogenesis of tendinopathy: a three-stages process

Abstract

Our understanding of the pathogenesis of "tendinopathy" is based on fragmented evidences like pieces of a jigsaw puzzle. We propose a "failed healing theory" to knit these fragments together, which can explain previous observations. We also propose that albeit "overuse injury" and other insidious "micro trauma" may well be primary triggers of the process, "tendinopathy" is not an "overuse injury" per se. The typical clinical, histological and biochemical presentation relates to a localized chronic pain condition which may lead to tendon rupture, the latter attributed to mechanical weakness. Characterization of pathological "tendinotic" tissues revealed coexistence of collagenolytic injuries and an active healing process, focal hypervascularity and tissue metaplasia. These observations suggest a failed healing process as response to a triggering injury. The pathogenesis of tendinopathy can be described as a three stage process: injury, failed healing and clinical presentation. It is likely that some of these "initial injuries" heal well and we speculate that predisposing intrinsic or extrinsic factors may be involved. The injury stage involves a progressive collagenolytic tendon injury. The failed healing stage mainly refers to prolonged activation and failed resolution of the normal healing process. Finally, the matrix disturbances, increased focal vascularity and abnormal cytokine profiles contribute to the clinical presentations of chronic tendon pain or rupture. With this integrative pathogenesis theory, we can relate the known manifestations of tendinopathy and point to the "missing links". This model may guide future research on tendinopathy, until we could ultimately decipher the complete pathogenesis process and provide better treatments.

Achilles tendinopathy alters stretch shortening cycle behaviour during a sub-maximal hopping task

“…The pathoaetiology of AT is complex 3 and whilst multiple factors clearly interact in the development of AT, mechanical factors dominate where the cumulative load placed upon the tendon exceeds its mechanical capacity, resulting in a 'failed loading response' 4 . Given the central role that the Achilles tendon plays in the stretch-shortening cycle (SSC), it seems reasonable that aberrations in SSC behaviour and AT may be related.…”

The management of greater trochanteric pain syndrome: A systematic literature review

“…36 Other models hypothesis that tendinopathy pathogenesis is related to a 'failed healing' response and is non-inflammatory. 34,37 Chronic tendinopathies seen on imaging can be asymptomatic, therefore clinical assessment rather than imaging for initial diagnosis and treatment planning of tendinopathy is advocated. 34 Chronic tendinopathic appearances on imaging show disorganised collagen bundles, neovascularisation and an increase in proteoglycan.…”

Tendinopathy and Sports: Understanding the Problem and Options of Management-perspectives from Physiotherapy, Sports Medicine, and Orthopedics

“…The exact mechanisms underpinning tendinopathy have eluded medical professionals with some authors proposing an inflammatory component 4 and others opposing this notion and claiming that acute tendinopathy is a noninflammatory response. 43 This debate has resulted in experimentation with various physiotherapy and medical interventions, majority of which have been successful in determining an effective concrete solution to the most effective management of tendinopathies (Table 4).…”