PURPOSE: To insert the title part without cutting a cruciate ligamentum, by forming the rear surface part of a bridge part connecting the malleolus medialis and malleolus lateralis of a base plate into an escape surface part formed so as to extend along an anterior cruciate ligamentum and providing a fixing peg to the lower rear surface of the base plate.

CONSTITUTION: The insertion part of the tibia 2 is cut in such a state that the kneecap is shifted and a tibia part 10 is inserted in the tibia from the front and the fixing pegs 17 of the tibia part 10 is driven in the tibia. By this structure, the cruciate ligamentum passing part of the malleolus medialis 13 and malleolus lateralis 14 provided to a metal plate 11 is largely opened rearwardly by a curved cavity 12 and the insertion property of the tibia from the front at the time of operation becomes well. Since an oblique escape surface part along an anterior cruciate ligamentum is formed to the rear surface part of the bridge part 15 connecting the malleolus medialis and malleolus lateralis 13, 14 of the metal plate 11, it is unnecessary to process the anterioal cruciate ligamentum 4 at the time of operation and the anterior cruciate ligamentum can be certainly preserved and the fixability of a knee becomes well and operation also becomes simple.