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Tibial Preparation
Extramedullary or intramedullary alignment guides may be used. First, a thin bent Hohmann is placed around the proximal medial tibia and also laterally to retract the patella. Osteophytes are removed from the anteromedial and medial tibia.
Extramedullary Tibial Alignment
- Assemble the extramedullary tibial alignment guide and place it onto the tibia. (Figure 14) Ensure that the correct left or right tibial cutting block is chosen and that the alignment guide is correctly set distally for the left or right leg. The distal portion of the guide is adjusted over the center of the ankle and the proximal portion is aligned with the tibial crest.
- Assess rotation of the alignment guide and slope of the cutting plane. Rotational alignment is critical due to the 3° posteriorly sloped cut. The goal is to align the extramedullary alignment assembly rotationally so that it aligns over the medial third of the tibial tubercle and over the second toe. The slope can be adjusted according to the patient’s anatomy.
Note: 4° of slope is built into the articular insert and 3° of slope is built into the tibial cutting block. Neutral alignment should be used.
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