A prosthesis for primary artrodhesis can be used for artroplasty and a prosthesis for artro- plasty comprises members for artrodhesis. The prosthesis (1 b) for primary artrodhesis comprises a locking member (33b) with an attachment portion (16b) which is insertable into a hole (8b) in a first attachment member (4b) of the prosthesis for location of the locking member therein, and a lockable member (34b) integral with a second attachment member (5b) of the prosthesis. The lockable member (34b) is configured for adjustable setting thereof relative to the locking member (33b) and for fixation thereof, in set position, to the locking member. Alternatively, the lockable member comprises an attachment portion which is insertable into a hole in the second attachment member for location of the lockable member therein. At the prosthesis for artroplasty, the hole in the first screw-like attachment member is partly configured to define a press fit with an attachment pin of a socket member and partly threaded to permit, after removal of the socket member, during artrodhesis, securing by screwing in the hole of the locking member for cooperation with a lockable member which is configured for adjustable setting thereof relative to the locking member and for fixation thereof, in set position, to the locking member.Prothèse pour arthrodèse primaire, susceptible d'être utilisée pour une arthroplastie, et prothèse pour arthroplastie comportant des éléments pour arthrodèse. La prothèse (1b) pour arthrodèse primaire comporte un élément (33b) de blocage doté d'une partie (16b) de fixation susceptible d'être insérée dans un trou (8b) pratiqué dans un premier élément (4b) de fixation de la prothèse pour y positionner l'élément de blocage, et un élément blocable (34b) intégré à un deuxième élément (5b) de fixation de la prothèse. L'élément blocable (34b) est configuré pour être posé de façon réglable par rapport à l'élément (33b) de blocage et pour être fixé, en position posée, à l'élément
