A knee arthrodesis implant has a femur nail inserted in the bone marrow canal of the femur, and a tibia nail inserted in the bone marrow canal of the tibia, the nails being rigidly connected to each other by a connecting means. The problem of providing a knee arthrodesis implant having increased modularity as the result of increased length variability, having a reduced number of parts, and allowing simplified modification is addressed. The problem is addressed in that the connecting means has at least one collar-like module lying in the axis direction defined by the nail, the module having at least two half-shells which are connected to each other in a detachable manner and which are separated in the axis direction (LA) of the module, said half-shells together forming a passage which extends axially and through which a nail neck is inserted, and which have recesses corresponding to each other for receiving a tensioning means, said recesses being arranged coaxially in the longitudinal direction of the module and positioned perpendicular to the axis (LA). The tensioning means fixes the respective nail neck in the passage when in the tensioned state in the manner of a clamping jaw, exclusively by means of a friction fit producing a sufficient clamping torque to prevent axial displacement and rotation.
