Plan the femoral cuts.
0°Extension limit
130°Flexion limit
Illustrative motion limits
Green: native surface. Orange: proposed cut. Each tick is 1 mm.
Compare extension and 90° flexion. Cut planes and the Persona component follow the settings; the tibial reconstruction stays fixed.
About this illustration
The contact check preserves the chosen implant orientation and moves the femur vertically to avoid sampled penetration of the bearing. One compartment can lift off; both compartments are not forced into contact. This is not a load, pressure, or ligament-force calculation.
This is an illustrative cut-planning and motion view. Valgus is measured from a plane perpendicular to the model shaft, not from a measured hip-to-knee mechanical axis. Native rotational zero uses the model’s cartilage-covered posterior condylar reference, not the transepicondylar axis. Internal/external directions apply to this right knee. The supplied Persona CR femoral CAD is visible by default. Turn it off to inspect the native femur and proposed cut planes. The cut-plane control also changes the illustrative extension limit: appropriate resection reaches 0°, the maximum under-resection setting stops at 10°, and maximum over-resection reaches −5° hyperextension. Intermediate settings interpolate between these endpoints. These are authored examples, not a clinical conversion from millimeters to degrees. Posterior resection independently controls the illustrative flexion limit: 125° with maximum under-resection, 130° at reference, and 135° with maximum over-resection. Intermediate settings interpolate between these endpoints; the millimeter-to-degree relationship is authored, not clinically calibrated. The supplied femoral component now translates and rotates relative to the femur with the cut settings. Bone preparation is recomputed against that placed CAD using the existing ray-based illustration. The registered 6° valgus setting retains the approved component placement; other settings apply the relative angular change. This is not a manufacturer cutting-block or cement-mantle simulation.
The illustrative reference is 9 mm proximal to the lowest native articular point. Patient-specific cartilage thickness, implant geometry, and individual condylar measurements remain necessary for surgical planning.
Changing distal resection primarily changes extension space. Posterior femoral resection controls flexion space in this comparison. Femoral joint-line changes can also affect mid-flexion stability; these effects are not calculated here.