The Pain of Tendinopathy: Physiological or Pathophysiological?

Abstract

Tendon pain remains an enigma. Many clinical features are consistent with tissue disruption-the pain is localised, persistent and specifically associated with tendon loading, whereas others are not-investigations do not always match symptoms and painless tendons can be catastrophically degenerated. As such, the question 'what causes a tendon to be painful?' remains unanswered. Without a proper understanding of the mechanism behind tendon pain, it is no surprise that treatments are often ineffective. Tendon pain certainly serves to protect the area-this is a defining characteristic of pain-and there is often a plausible nociceptive contributor. However, the problem of tendon pain is that the relation between pain and evidence of tissue disruption is variable. The investigation into mechanisms for tendon pain should extend beyond local tissue changes and include peripheral and central mechanisms of nociception modulation. This review integrates recent discoveries in diverse fields such as histology, physiology and neuroscience with clinical insight to present a current state of the art in tendon pain. New hypotheses for this condition are proposed, which focus on the potential role of tenocytes, mechanosensitive and chemosensitive receptors, the role of ion channels in nociception and pain and central mechanisms associated with load and threat monitoring.

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

“…Neovascular ingrowth following collagen disorganization is proposed to be locally responsible for tendon-related pain. 44 On the contrary, Rio et al 45 have proposed a more centrally mediated response with multiple potential contributors to pain.…”

Achilles Tendinopathy and the 100-Pound Punching Bag

“…Tendinopathy may be defined as the, "...clinical syndrome of pain and dysfunction in a tendon..., " [20] and AT is likely an overuse injury [21,22]. The main symptom is pain upon palpation and loading, but the etiology of AT pain remains elusive [20,22,23].…”

“…Tendinopathy may be defined as the, "...clinical syndrome of pain and dysfunction in a tendon..., " [20] and AT is likely an overuse injury [21,22]. The main symptom is pain upon palpation and loading, but the etiology of AT pain remains elusive [20,22,23]. Studies have shown the development of bilateral Achilles changes in unilateral tendinopathy [24,25] and improvements on the contralateral side with unilateral Achilles surgery for those with bilateral AT [26].…”

“…Studies have shown the development of bilateral Achilles changes in unilateral tendinopathy [24,25] and improvements on the contralateral side with unilateral Achilles surgery for those with bilateral AT [26]. This suggests that the development and healing of Achilles tendinopathy may involve the central nervous system [24,25] and mid-portion Achilles pain may involve altered central pain processing [20,23].…”

“…The clinician recommended eccentric stretching but it was ineffective, and the physical therapy, which did not involve eccentric stretches, worsened the symptoms. However, there is evidence to the efficacy of eccentric stretching [26][27][28] but Achilles tendinopathy is known to be refractory to treatment and become chronic [20,29].…”