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Overview of overuse (chronic) tendinopathy

Karim Khan, MD
Alex Scott, PhD, RPT
Section Editor
Karl B Fields, MD
Deputy Editor
Jonathan Grayzel, MD, FAAEM


Tendinopathy is a clinical syndrome characterized by tendon thickening and chronic, localized tendon pain. It may result from acute trauma (eg, tendon laceration or rupture) or more commonly, from overuse. Recovery from acute tendinopathy follows more or less well-established treatment protocols, which are discussed in reviews of specific injuries.

Historically, overuse tendinopathy was commonly referred to as tendinitis. The “-itis” suffix implicated inflammation as the primary cause of pain and swelling. In fact, a classic inflammatory reaction is minimally present with overuse tendinopathy [1,2]. The pathophysiology underlying most cases, as judged by tissue analysis from a variety of commonly affected tendons, is tendinosis. Tendinosis may be broadly characterized as a failed healing response within the tendon tissue [3]. This failed healing response is associated with characteristic findings on ultrasound and magnetic resonance imaging (MRI) [4].

This topic will review the clinically relevant aspects of the pathophysiology of overuse tendinopathy. The diagnosis and management of overuse tendinopathy generally and in specific tendons is discussed separately. (See "Achilles tendinopathy and tendon rupture" and "Rotator cuff tendinopathy" and "Epicondylitis (tennis and golf elbow)" and "Overview of the management of overuse (chronic) tendinopathy".)


Our knowledge of the pathophysiology of overuse tendinopathy stems mainly from surgical biopsies taken from athletes with chronic tendon pain who have failed conservative treatment and undergone open or arthroscopic tendon debridement. Numerous histopathology and gene array studies have been performed on these tissue specimens [2,5-20].

The histopathology of a wide variety of tendons examined in this manner consistently reveals a minimal presence, of inflammatory cells. This is true of the Achilles, posterior tibial, patellar, gluteal [21], adductor [22], extensor carpi radialis brevis and longus, flexor carpi ulnaris, flexor digitorum [23], and rotator cuff tendons [7,12,18,24,25]. Gene array studies generally confirm minimal inflammatory gene upregulation in tendinopathy [14,26]. However, the increased presence of iron-containing macrophages does indicate the likelihood of prior episodes of vascular disruption and the resulting activation of the innate immune response during the development of tendinopathy [2,20].

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Literature review current through: Nov 2017. | This topic last updated: Apr 04, 2017.
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  1. Khan KM, Cook JL, Bonar F, et al. Histopathology of common tendinopathies. Update and implications for clinical management. Sports Med 1999; 27:393.
  2. Kragsnaes MS, Fredberg U, Stribolt K, et al. Stereological quantification of immune-competent cells in baseline biopsy specimens from achilles tendons: results from patients with chronic tendinopathy followed for more than 4 years. Am J Sports Med 2014; 42:2435.
  3. Nirschl, RP. Patterns of failed hearing in tendon injury. In: Sports-Induced Inflammation: Clinical and Basic Science Concepts, Leadbetter, WB, Buckwalter, JA, Gordon, SL (Eds), American Academy of Orthopaedic Surgeons, Park Ridge 1990. p.577.
  4. Cook JL, Khan KM, Kiss ZS, Griffiths L. Patellar tendinopathy in junior basketball players: a controlled clinical and ultrasonographic study of 268 patellar tendons in players aged 14-18 years. Scand J Med Sci Sports 2000; 10:216.
  5. Khan KM, Bonar F, Desmond PM, et al. Patellar tendinosis (jumper's knee): findings at histopathologic examination, US, and MR imaging. Victorian Institute of Sport Tendon Study Group. Radiology 1996; 200:821.
  6. Chard MD, Cawston TE, Riley GP, et al. Rotator cuff degeneration and lateral epicondylitis: a comparative histological study. Ann Rheum Dis 1994; 53:30.
  7. Galliani I, Burattini S, Mariani AR, et al. Morpho-functional changes in human tendon tissue. Eur J Histochem 2002; 46:3.
  8. Järvinen M, Józsa L, Kannus P, et al. Histopathological findings in chronic tendon disorders. Scand J Med Sci Sports 1997; 7:86.
  9. Rolf CG, Fu BS, Pau A, et al. Increased cell proliferation and associated expression of PDGFRbeta causing hypercellularity in patellar tendinosis. Rheumatology (Oxford) 2001; 40:256.
  10. Kvist M, Józsa L, Järvinen MJ, Kvist H. Chronic Achilles paratenonitis in athletes: a histological and histochemical study. Pathology 1987; 19:1.
  11. Martens M, Wouters P, Burssens A, Mulier JC. Patellar tendinitis: pathology and results of treatment. Acta Orthop Scand 1982; 53:445.
  12. Mosier SM, Pomeroy G, Manoli A 2nd. Pathoanatomy and etiology of posterior tibial tendon dysfunction. Clin Orthop Relat Res 1999; :12.
  13. Popp JE, Yu JS, Kaeding CC. Recalcitrant patellar tendinitis. Magnetic resonance imaging, histologic evaluation, and surgical treatment. Am J Sports Med 1997; 25:218.
  14. Ireland D, Harrall R, Curry V, et al. Multiple changes in gene expression in chronic human Achilles tendinopathy. Matrix Biol 2001; 20:159.
  15. Riley GP, Harrall RL, Constant CR, et al. Glycosaminoglycans of human rotator cuff tendons: changes with age and in chronic rotator cuff tendinitis. Ann Rheum Dis 1994; 53:367.
  16. Movin T, Gad A, Reinholt FP, Rolf C. Tendon pathology in long-standing achillodynia. Biopsy findings in 40 patients. Acta Orthop Scand 1997; 68:170.
  17. Clarke MT, Lyall HA, Grant JW, Matthewson MH. The histopathology of de Quervain's disease. J Hand Surg Br 1998; 23:732.
  18. Sarkar K, Uhthoff HK. Ultrastructure of the common extensor tendon in tennis elbow. Virchows Arch A Pathol Anat Histol 1980; 386:317.
  19. Millar NL, Hueber AJ, Reilly JH, et al. Inflammation is present in early human tendinopathy. Am J Sports Med 2010; 38:2085.
  20. Schubert TE, Weidler C, Lerch K, et al. Achilles tendinosis is associated with sprouting of substance P positive nerve fibres. Ann Rheum Dis 2005; 64:1083.
  21. Fearon AM, Scarvell JM, Cook JL, Smith PN. Does ultrasound correlate with surgical or histologic findings in greater trochanteric pain syndrome? A pilot study. Clin Orthop Relat Res 2010; 468:1838.
  22. Weinstein RN, Kraushaar BS, Fulkerson JP. Adductor tendinosis in a professional hockey player. Orthopedics 1998; 21:809.
  23. Lundin A. "Trigger finger is a form of tendinosis". Presented at: International Scientific Tendinopathy Symposium. Umea, Sweden. 30 September 2010.
  24. Budoff JE, Kraushaar BS, Ayala G. Flexor carpi ulnaris tendinopathy. J Hand Surg Am 2005; 30:125.
  25. Maffulli N, Testa V, Capasso G, et al. Similar histopathological picture in males with Achilles and patellar tendinopathy. Med Sci Sports Exerc 2004; 36:1470.
  26. Alfredson H, Lorentzon M, Bäckman S, et al. cDNA-arrays and real-time quantitative PCR techniques in the investigation of chronic Achilles tendinosis. J Orthop Res 2003; 21:970.
  27. Premdas J, Tang JB, Warner JP, et al. The presence of smooth muscle actin in fibroblasts in the torn human rotator cuff. J Orthop Res 2001; 19:221.
  28. ARNER O, LINDHOLM A, ORELL SR. Histologic changes in subcutaneous rupture of the Achilles tendon; a study of 74 cases. Acta Chir Scand 1959; 116:484.
  29. Svensson M, Kartus J, Christensen LR, et al. A long-term serial histological evaluation of the patellar tendon in humans after harvesting its central third. Knee Surg Sports Traumatol Arthrosc 2005; 13:398.
  30. Legerlotz K, Jones ER, Screen HR, Riley GP. Increased expression of IL-6 family members in tendon pathology. Rheumatology (Oxford) 2012; 51:1161.
  31. Fu SC, Wang W, Pau HM, et al. Increased expression of transforming growth factor-beta1 in patellar tendinosis. Clin Orthop Relat Res 2002; :174.
  32. Scott A, Backman LJ, Speed C. Tendinopathy: Update on Pathophysiology. J Orthop Sports Phys Ther 2015; 45:833.
  33. Maffulli N, Wong J, Almekinders LC. Types and epidemiology of tendinopathy. Clin Sports Med 2003; 22:675.
  34. Woo SL, Ritter MA, Amiel D, et al. The biomechanical and biochemical properties of swine tendons--long term effects of exercise on the digital extensors. Connect Tissue Res 1980; 7:177.
  35. O'Brien M. Structure and metabolism of tendons. Scand J Med Sci Sports 1997; 7:55.
  36. Schechtman H, Bader DL. Fatigue damage of human tendons. J Biomech 2002; 35:347.
  37. Ferretti A. Epidemiology of jumper's knee. Sports Med 1986; 3:289.
  38. Titchener AG, Fakis A, Tambe AA, et al. Risk factors in lateral epicondylitis (tennis elbow): a case-control study. J Hand Surg Eur Vol 2013; 38:159.
  39. Titchener AG, White JJ, Hinchliffe SR, et al. Comorbidities in rotator cuff disease: a case-control study. J Shoulder Elbow Surg 2014; 23:1282.
  40. Kjaer M, Hansen M. The mystery of female connective tissue. J Appl Physiol (1985) 2008; 105:1026.
  41. Kaufman KR, Brodine SK, Shaffer RA, et al. The effect of foot structure and range of motion on musculoskeletal overuse injuries. Am J Sports Med 1999; 27:585.
  42. Kvist M. Achilles tendon injuries in athletes. Ann Chir Gynaecol 1991; 80:188.
  43. Witvrouw E, Bellemans J, Lysens R, et al. Intrinsic risk factors for the development of patellar tendinitis in an athletic population. A two-year prospective study. Am J Sports Med 2001; 29:190.
  44. Voorn R. Case report: can sacroiliac joint dysfunction cause chronic Achilles tendinitis? J Orthop Sports Phys Ther 1998; 27:436.
  45. Lewis JS, Green A, Wright C. Subacromial impingement syndrome: the role of posture and muscle imbalance. J Shoulder Elbow Surg 2005; 14:385.
  46. Khan KM, Cook JL, Kiss ZS, et al. Patellar tendon ultrasonography and jumper's knee in female basketball players: a longitudinal study. Clin J Sport Med 1997; 7:199.
  47. Cook JL, Khan KM, Kiss ZS, et al. Prospective imaging study of asymptomatic patellar tendinopathy in elite junior basketball players. J Ultrasound Med 2000; 19:473.
  48. Mokone GG, Schwellnus MP, Noakes TD, Collins M. The COL5A1 gene and Achilles tendon pathology. Scand J Med Sci Sports 2006; 16:19.
  49. Posthumus M, Collins M, Cook J, et al. Components of the transforming growth factor-beta family and the pathogenesis of human Achilles tendon pathology--a genetic association study. Rheumatology (Oxford) 2010; 49:2090.
  50. Werner RA, Franzblau A, Gell N, et al. Predictors of persistent elbow tendonitis among auto assembly workers. J Occup Rehabil 2005; 15:393.
  51. Järvinen TA, Kannus P, Maffulli N, Khan KM. Achilles tendon disorders: etiology and epidemiology. Foot Ankle Clin 2005; 10:255.
  52. Soslowsky LJ, Carpenter JE, DeBano CM, et al. Development and use of an animal model for investigations on rotator cuff disease. J Shoulder Elbow Surg 1996; 5:383.
  53. Renström P, Johnson RJ. Overuse injuries in sports. A review. Sports Med 1985; 2:316.
  54. Gajhede-Knudsen M, Ekstrand J, Magnusson H, Maffulli N. Recurrence of Achilles tendon injuries in elite male football players is more common after early return to play: an 11-year follow-up of the UEFA Champions League injury study. Br J Sports Med 2013; 47:763.
  55. Stahlmann R, Lode H. Fluoroquinolones in the elderly: safety considerations. Drugs Aging 2003; 20:289.
  56. Wilton LV, Pearce GL, Mann RD. A comparison of ciprofloxacin, norfloxacin, ofloxacin, azithromycin and cefixime examined by observational cohort studies. Br J Clin Pharmacol 1996; 41:277.
  57. Shakibaei M, Stahlmann R. Ultrastructure of Achilles tendon from rats after treatment with fleroxacin. Arch Toxicol 2001; 75:97.
  58. van der Linden PD, van Puijenbroek EP, Feenstra J, et al. Tendon disorders attributed to fluoroquinolones: a study on 42 spontaneous reports in the period 1988 to 1998. Arthritis Rheum 2001; 45:235.
  59. Fernández-Carnero J, Fernández-de-las-Peñas C, de la Llave-Rincón AI, et al. Bilateral myofascial trigger points in the forearm muscles in patients with chronic unilateral lateral epicondylalgia: a blinded, controlled study. Clin J Pain 2008; 24:802.
  60. Cook JL, Malliaras P, De Luca J, et al. Neovascularization and pain in abnormal patellar tendons of active jumping athletes. Clin J Sport Med 2004; 14:296.
  61. de Vos RJ, Weir A, Cobben LP, Tol JL. The value of power Doppler ultrasonography in Achilles tendinopathy: a prospective study. Am J Sports Med 2007; 35:1696.
  62. Kayser R, Mahlfeld K, Heyde CE. Partial rupture of the proximal Achilles tendon: a differential diagnostic problem in ultrasound imaging. Br J Sports Med 2005; 39:838.
  63. Rompe JD, Nafe B, Furia JP, Maffulli N. Eccentric loading, shock-wave treatment, or a wait-and-see policy for tendinopathy of the main body of tendo Achillis: a randomized controlled trial. Am J Sports Med 2007; 35:374.
  64. Smidt N, van der Windt DA, Assendelft WJ, et al. Corticosteroid injections, physiotherapy, or a wait-and-see policy for lateral epicondylitis: a randomised controlled trial. Lancet 2002; 359:657.
  65. Nørregaard J, Larsen CC, Bieler T, Langberg H. Eccentric exercise in treatment of Achilles tendinopathy. Scand J Med Sci Sports 2007; 17:133.
  66. Ohberg L, Lorentzon R, Alfredson H. Eccentric training in patients with chronic Achilles tendinosis: normalised tendon structure and decreased thickness at follow up. Br J Sports Med 2004; 38:8.