An arthroscope comprises a sleeve having an internally hollow, proximal portion and an internally hollow middle portion connected to the proximal portion so as to create a through axial cavity. The sleeve has, within the middle portion, an abutment area. The arthroscope also comprises an optical unit having an elongated portion and a coupling portion configured to be at least partially received inside the through axial cavity of the sleeve. The coupling portion has a matching area suitable to couple with the abutment area. The matching area and the abutment area are shaped so as to have at least one pilot element so as to determine a univocal predefined coupling position between the sleeve and the optical unit; the matching area and the abutment area are also shaped so as to guide and automatically place the optical unit in such a predefined position.