Tendinitis, tendinosis & tenosynovitis
Tendinitis is usually caused by tendon trauma with associated vascular disruption and acute, subacute, or chronic inflammation. Crystal deposition into the tendon (especially basic calcium phosphate [apatite] crystals) can also cause inflammation (calcific tendinitis).
Tendinosis (tendinopathy) is noninflammatory, intratendinous atrophy and degeneration that is often associated with chronic tendinitis. Tendinosis can lead to partial or complete tendon rupture.
Tenosynovitis is inflammation of the paratendon, which is the outermost sheath that is lined in some tendons by a synovial membrane (e.g., extensor tendons of the thumb in De Quervain’s tenosynovitis).