Histopathology of Common Tendinopathies

Abstract

Tendon disorders are a major problem for participants in competitive and recreational sports. To try to determine whether the histopathology underlying these conditions explains why they often prove recalcitrant to treatment, we reviewed studies of the histopathology of sports-related, symptomatic Achilles, patellar, extensor carpi radialis brevis and rotator cuff tendons. The literature indicates that healthy tendons appear glistening white to the naked eye and microscopy reveals a hierarchical arrangement of tightly packed, parallel bundles of collagen fibres that have a characteristic reflectivity under polarised light. Stainable ground substance (extracellular matrix) is absent and vasculature is inconspicuous. Tenocytes are generally inconspicuous and fibroblasts and myofibroblasts absent. In stark contrast, symptomatic tendons in athletes appear grey and amorphous to the naked eye and microscopy reveals discontinuous and disorganised collagen fibres that lack reflectivity under polarised light. This is associated with an increase in the amount of mucoid ground substance, which is confirmed with Alcian blue stain. At sites of maximal mucoid change, tenocytes, when present, are plump and chondroid in appearance (exaggerated fibrocartilaginous metaplasia). These changes are accompanied by the increasingly conspicuous presence of cells within the tendon tissue, most of which have a fibroblastic or myofibroblastic appearance (smooth muscle actin is demonstrated using an avidin biotin technique). Maximal cellular proliferation is accompanied by prominent capillary proliferation and a tendency for discontinuity of collagen fibres in this area. Often, there is an abrupt discontinuity of both vascular and myofibroblastic proliferation immediately adjacent to the area of greatest abnormality. The most significant feature is the absence of inflammatory cells. These observations confirm that the histopathological findings in athletes with overuse tendinopathies are consistent with those in tendinosis--a degenerative condition of unknown aetiology. This may have implications for the prognosis and timing of a return to sport after experiencing tendon symptoms. As the common overuse tendon conditions are rarely, if ever, caused by 'tendinitis', we suggest the term 'tendinopathy' be used to describe the common overuse tendon conditions. We conclude that effective treatment of athletes with tendinopathies must target the most common underlying histopathology, tendinosis, a noninflammatory condition.

Process of neovascularisation compared with pain intensity in tendinopathy of the long head of the biceps brachii tendon associated with concomitant shoulder disorders, after arthroscopic treatment. Microscopic evaluation supported by immunohistochemical

“…Presence of neovascularization is well documented in advanced tendinopathies and can be demonstrated using Doppler Ultrasound examination [20,22,23,24,25,26]. Similarly, in our study the presence of neovascularization of the LHBT was confirmed in 78% of specimens.…”

Deep Friction Massage to Treat Tendinopathy: A Systematic Review of a Classic Treatment in the Face of a New Paradigm of Understanding

“…Commonly affected areas include the Achilles, 1 posterior tibialis, [3][4][5][6] patellar, 7,8 lateral elbow, 10 and rotator-cuff tendons. 11,12 The Achilles tendon is the most commonly affected lower extremity structure, with a cumulative lifetime incidence of 5.9% 1 in an inactive population and 50% in elite endurance athletes. 1 The patellar tendon, involved in "jumper's knee," is affected 12% of elite athletes among an assortment of sports, and injury incidence may be as high as 40% in jumping sports such as basketball and volleyball.…”

Estudo comparativo da eficácia da fonoforese, do ultra-som terapêutico e da aplicação tópica de hidrocortisona no tratamento do tendão de rato em processo de reparo tecidual

“…Os tendões normais são brilhantes, brancos e possuem uma textura fibroelástica, o que demonstra uma grande resistência a cargas mecânicas (KHAN et al, 1999;JÓZSA & KANNUS, 1997; MCNEILLY et al, 1996;STOLINSKI, 1995; BIRK & TRELSTAD, 1986 PARIZOTTO, 1998; REDDY et al, 1998a, b; GUM et al, 1997; ENWEMEKA, 1991a, b;ENWEMEKA et al, 1990; ENWEMEKA, 1989b 2) Fase Neoangiogênica e Proliferativa;…”

“…Os tendões normais são brilhantes, brancos e possuem uma textura fibroelástica, o que demonstra uma grande resistência a cargas mecânicas (KHAN et al, 1999;JÓZSA & KANNUS, 1997;MCNEILLY et al, 1996;STOLINSKI, 1995;BIRK & TRELSTAD, 1986 A ruptura do tendão do calcâneo normalmente é precedida por alterações degenerativas onde há redução do fluxo sanguineo para o tendão com resultante hipóxia local. A alteração da nutrição e da atividade metabólica também predispõem a essas alterações (ALMEKINDERS & DEOL, 1999;SALOMÃO et al, 1993).…”

“…Na outra extremidade, as fibras do tendão sempre se aderem com o tecido fibroso da estrutura a que se unemcomumente ao osso, onde elas são contínuas ao mesmo tempo com uma cobertura fibrosa externa, o periósteo e com as fibras que formam a substância do osso. Sua função é transmitir a força criada no músculo para os ossos tornando possível o movimento articular.Os tendões normais são brilhantes, brancos e possuem uma textura fibroelástica, o que demonstra uma grande resistência a cargas mecânicas (KHAN et al, 1999;JÓZSA & KANNUS, 1997; MCNEILLY et al, 1996;STOLINSKI, 1995; BIRK & TRELSTAD, 1986 PARIZOTTO, 1998; REDDY et al, 1998a, b; GUM et al, 1997; ENWEMEKA, 1991a, b;ENWEMEKA et al, 1990; ENWEMEKA, 1989b 2) Fase Neoangiogênica e Proliferativa;3) Fase de Remodelamento.Para o tendão as duas últimas fases são essenciais para um adequado reparo tecidual onde haverá uma intensa proliferação celular (fibroblastos); síntese de fibrilas de colágeno e alinhamento das fibras no eixo longitudinal do tendão (ENWEMEKA, 1989a). …”