other details difficult to perceive may have been omitted turning now to the drawing and in particular to fig1 there is shown a front view onto a front side of a knee 10 in particular the lower end of the femur 12 the anterior cruciate ligament 14 and the posterior cruciate ligament 16 as well as the menisci 18 and the collateral ligament 20 are shown schematically beside the tibia 22 the fibula 24 can be seen a tibia implant 26 which has an approximately trapeze shaped cross section with a concavely shaped side can be seen in the knee proximal region of the tibia 22 this tibia implant 26 is located in an incision 28 of the tibia 22 which as can be seen in fig2 is introduced into the tibia 22 essentially vertically from above so that a tibia section 30 is formed whose lower end is still connected to the tibia 22 the tibia implant 26 is inserted into this v shaped incision 28 from the side by bracing the tibia section 30 the anterior ligament 32 is tightened fig3 shows a perspective view of the tibia implant 26 which has a circumferential support frame 34 and a sponge structure 36 located there between the tibia implant 26 is configured wedge.