Achilles tendonitis is the inflammation of the Achilles tendon, often resulting from intratendinous damage such as microtears or partial fiber ruptures. Inflammation may also arise if the surrounding tendon sheath (paratenon) is injured or if a nodule or other structural irregularity develops along the tendon.
Achilles tendonitis can be classified as either acute or chronic, depending on the duration and severity of the condition.
The causes of Achilles tendonitis are multifactorial and can be categorized into exogenous and endogenous factors:

• Exogenous factors include overuse, improper training techniques, inadequate footwear, and the use of medications such as corticosteroids (topical or systemic) or fluoroquinolone antibiotics.

• Endogenous factors involve internal predispositions such as increasing age, male sex, systemic illnesses (e.g., diabetes, rheumatoid arthritis), limb length discrepancies (anisomelia), lower limb deformities, and muscle weakness or imbalance.