A structure improvement of orthopaedic implant includes a tibial baseplate, a tibial insert, and a reinforcement. The tibial baseplate forms a recess having a bottom that has a central portion defining a through hole extending through the tibial baseplate. The through hole has a top circumference that defines a circumferential groove extending outward. The tibial insert has a bottom forming a projection corresponding to the recess of the tibial baseplate for press-fitting to the tibial baseplate. A support is formed on at a central portion of a top of the tibial insert and defines a bore that extends through the tibial insert. The tibial insert forms two curved surfaces on opposite sides of the support to support contact and rolling. The reinforcement is inset in the tibial insert and includes a sleeve and a bolt.