Identify the apex of the medial tibial spine with a diathermy (bovie) and make a mark just medial to the apex. Use the reciprocating saw designed for the OUKA with a stiff narrow blade, round end, and depth markings (Fig. 7.3) to make the vertical tibial saw cut. The saw cut should be just medial to the apex of the medial tibial spine. It will pass through the edge of the ACL insertion. Point the blade towards the ASIS, the position of which can be demonstrated by the assistant (Fig. 7.11(b)) or align the blade in the tibial flexion plane. The saw must reach the back of the tibial plateau and a little beyond. This is achieved by lining up the appropriate mark on the saw with the anterior tibial cortex (a series of marks appropriate to each size of tibial component exist on the saw blade). Advance the saw vertically down until it rests on the surface of the saw guide (Fig. 7.11(c)). The saw must remain parallel to the guide. Do not lift the saw handle as this will damage the posterior cortex and increase the risk of tibial plateau fracture.
