[Pathogenesis of ruptures of the shoulder rotator cuff]

Rupture of the rotator cuff occurs exceptionally in a healthy cuff and almost always in a degenerated cuff. This degeneration may be either ischaemic and secondarily conflictual or primarily conflictual. There are two zones of conflict: anteromedial and superior, resulting in two clinical presentations: small anterosuperior ruptures which are initially very painful, but minimally disabling and large posterosuperior ruptures which are initially which are immediately disabling but minimally painful.