Achilles tendinopathy refers to a combination of pathological changes affecting the Achilles tendon usually due to overuse and excessive chronic stress upon the tendon. It can be seen both in athletes and non-athletes. It is hard to differentiate clinically from paratendinopathy (which is most common). It may or may not be associated with an Achilles tendon tear.
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Epidemiology
It can affect a range of people from athletes to recreational exercisers and even inactive people. It affects non-athletes in around one-third of cases.
Pathology
Macroscopically, tendinopathy results in enlargement, disruption of fibrillar pattern and an increase in tendon vascularity. Histopathologically, there is evidence of disorganised proliferation of tenocytes, disrupted organisation of collagen fibres, an increase in the non-collagenous matrix, and neovascularisation. Usually, there is no evidence of inflammation, but the cause is thought of as a failed healing response 1. Repetitive microtrauma from unusual or excessive mechanical loading is deemed to be a causative factor.
Location
Achilles tendinopathy can be classified as 6
midportion: >2 cm from its insertion
insertional: <2 cm from its insertion
Radiographic features
Ultrasound is the first-line imaging modality 6.
Ultrasound
Often shows thickening and rounding of the affected portion of the tendon. A cutoff value of 1 cm in anteroposterior diameter is usually used for diagnosis ref. There is also evidence of neovascularisation, which, if present, is usually indicative of a poorer outcome and more severe clinical symptoms ref. Additional signs include increased Kager fat pad echogenicity (especially with chronic tendinopathy) and thickening of a hypoechoic paratenon.
MRI
Can show increased intratendinous signal and tendon enlargement, with oedema in Kager fat pad in cases of tendinosis.
Radiology report
The following should be included as a minimum 6:
AP diameter of the Achilles tendon
altered structure (e.g. echotexture on ultrasound, signal on MRI)
peritendinous or intratendinous vascularisation
insertional calcifications