Overview
Femur surgical planning defines the final surgical intent that will be translated into a patient-specific instrument (PSI).
At this stage, anatomy and landmarks are already approved, and the focus shifts to positioning, orientation, and validation of the surgical plan.
Every change made during planning directly affects the generated PSI.
Prerequisites
Before entering femur surgical planning, the following must be completed:
Segmentation approval
Femur landmarking confirmation
Planning is unavailable until these steps are finalized.
Planning Workspace
The planning environment includes:
3D femur model as the primary reference
Planning elements (e.g. reference planes, axes, cut definitions)
Side panel for showing/hiding elements
Parameter panel for controlled adjustments
Measurement panel for visual validation
Undo and pre/post comparison tools (when available)
All interactions update the plan in real time.
Core Planning Elements
During femur planning, you will work with:
Distal femoral reference plane
Defines the primary surgical reference surface.Femoral axes
Mechanical and/or anatomical axes derived from landmarks and used for alignment.Orientation references
Used to define varus/valgus, flexion/extension, and rotation.Planned cut or guide definition
Represents the intended surgical action that the PSI will enforce.
These elements are interdependent and update together.
Alignment Control
Planning alignment is defined in three planes:
Coronal (Varus / Valgus)
Controls medial–lateral alignment of the femur.Sagittal (Flexion / Extension)
Controls anterior–posterior tilt.Axial (Rotation)
Controls internal/external femoral rotation, typically based on condylar references.
Alignment values are displayed for reference and are recalculated automatically when planning elements are adjusted.
How Adjustments Work
Key principles during planning:
You adjust planning elements, not the PSI directly
Adjustments are made using controlled UI inputs (sliders, handles, or fields)
All changes are constrained to predefined safe ranges
Measurements update live to reflect changes
If something looks incorrect, adjust the underlying reference, not the measurement itself.
Measurements & Validation
Measurements are provided to help you:
Verify alignment consistency
Confirm spatial relationships
Compare pre- and post-adjustment states
Measurements are:
Visual validation tools
Not diagnostic
Not intended for standalone clinical decision-making
What Becomes Locked
Once planning is confirmed:
Planning parameters are locked
Alignment and orientation are fixed
PSI generation uses these exact definitions
Changes after confirmation require reopening the planning step.
Confirming the Plan
To proceed:
Review all planning elements and alignment
Use multiple viewing angles
Confirm the planning step
The system records:
User
Role
Timestamp
Only confirmed plans can be used for PSI design and export.
Why This Step Is Critical
Femur surgical planning directly determines:
PSI position and fit
Guide orientation during surgery
Accuracy of intraoperative execution
Errors at this stage will propagate to the physical device.
Important Notes
Planning assists surgical execution but does not replace clinical judgment
Displayed values are reference outputs
Final responsibility remains with the surgeon
Practical Tips
Always validate alignment in all three planes
Use undo liberally when testing adjustments
If alignment looks unexpected, recheck femur landmarks
Do not confirm planning unless the result matches surgical intent