The Science of Achilles Tendinopathy / Tendinitis

Achilles tendinopathy is a failed healing response characterized by degenerative changes rather than acute inflammation. The condition involves disorganized collagen, increased ground substance, and neovascularization within the tendon. This represents a chronic overuse injury where the cumulative load on the tendon exceeds its adaptive capacity. Two distinct types require different treatment approaches: Mid-portion Achilles tendinopathy (MAT) occurs 2-7 cm from the heel insertion and is primarily a tensile overload condition. Insertional Achilles tendinopathy (IAT) affects the tendon's attachment to the calcaneus and involves both tensile and compressive forces, as the tendon can be compressed against the heel bone during dorsiflexion movements. The pathophysiology involves a breakdown in the normal collagen structure, leading to painful, thickened tissue with reduced mechanical properties. Unlike acute inflammation (tendinitis), this degenerative process (tendinosis) requires specific loading strategies to stimulate proper tissue remodeling rather than anti-inflammatory treatments.