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Step 2 of the Implant Planning section provides
the user the ability to dial in soft-tissue laxity
(gap/tightness) for the patient in extension and
flexion. The soft-tissue gap planning is predicated
on the stressed extension and flexion input from
Ligament Balancing Input (Section 5). During that
stage, the user applied varus and valgus stress
to the operative-leg collateral ligament in order
to map how much “space” the medial and lateral
compartments have based on ligament laxity.
The Gap Planning screen has four interactive
views (similar to the screens used in Step 1 of
Implant Planning) for translating and rotating
the components with respect to the patient’s
virtualized joint (Figure 48). Beneath these
viewscreens is a graph of Extension gap balance
on the bottom left, and Flexion gap balance on
the bottom right. The vertical axis represents (in
millimeters) the relative gap in ‘purple’ (laxity) or
overlap in ‘pink’ (tightness). Both graphs depict
medial and lateral condyle laxity or tightness
information.
Figure 48.
Figure 49.
To balance flexion gaps, manipulate the femur sizing and
position, keeping in mind that AP adjustments and component rota-
tion will require re-evaluation of notching criteria on the femur bone
surface. Use the rotate view button to toggle between sagittal and
frontal views in this stage.
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Implant Planning - Soft Tissue Balancing
