The present application is directed to a facet joint prosthesis (1) comprising a first component (20) having a first disc (21) with a first outer face (22) for engagement of a first facet process bone (7). The first outer face (22) has an opposed first inner face (24), said first inner face (24) including a first post (25) connecting said first disc (21) to first engagement means being in the form of a substantially flat tongue (26) having a first maximal length (L1) and a first maximal width (W1). The facet joint prosthesis (1) further comprises a second component (40) having a second disc (41) with a second outer surface (42) for engagement with a second facet process bone (6). The second outer surface (42) has an opposed second inner face (44), said second inner face (44) includes at least one bridge (45) located near the periphery of said second disc (41), said at least one bridge (45) connects the second disc (41) with a third disc (46). The third disc (46) comprises a pocket (47) having a second maximal length (L2) and a second maximal width (W2). The second maximal length (L2) and the second maximal width (W2) of said pocket (27) are larger than said first maximal length (L1) and said second maximal width (W1) of said tongue (26), respectively. Further said first maximal length (L1) of said tongue (26) is larger than said second maximal width (W2) of said pocket (27), wherein insertion of said tongue (26) into said pocket (27) and rotation of said tongue (26) relative to said pocket (27) results in a locking of said tongue (26) between said second disc (41) and said third disc (46).La présente invention concerne une prothèse de facette articulaire (1) qui comprend un premier composant (20) comportant un premier disque (21) présentant une première face externe (22) pour se trouver en contact avec un premier os de processus de facette (7). La première face externe (22) a une première face interne opposée (24), ladite première face interne (24) comprenant un pre
