What professional planning software should actually do
Hip planning must connect femoral and acetabular reconstruction. A plausible stem size alone is not a complete plan: cup center, hip center, neck length, offset, leg length and pelvic position interact and should be reviewed as one reconstructive concept.
The hip module reflects long-standing hands-on experience with THA templating, implant anatomy and the practical consequences of changing head length, offset, cup center and stem position.
Questions the workflow must answer
- Where is the native or intended center of rotation?
- How should leg length and femoral offset be reconstructed?
- Which cup and stem sizes fit the available bone and planned position?
- How does pelvic orientation influence radiographic cup assessment?
- Which values are image-derived and which depend on operative judgment?
A traceable planning workflow
- 01
Pelvic reference
Assess projection, pelvic rotation and the reliability of bilateral anatomical references.
- 02
Baseline geometry
Measure leg-length difference, offset and center-of-rotation relationships before templating.
- 03
Cup planning
Evaluate size, coverage, center and radiographic orientation.
- 04
Stem planning
Assess canal fill, stem alignment, shoulder level, neck length and the interaction with femoral anatomy.
- 05
Repositioned construct
Review planned leg length and offset after head/neck selection and component repositioning.
- 06
Functional context
Where appropriate, assess cup anteversion, pelvic tilt and standing/sitting differences in dedicated workflows.
Useful planning outputs
- Cup and stem size estimate
- Leg-length difference and planned change
- Femoral offset and COR reconstruction
- Cup inclination/anteversion assessment
- THA planning report
Typical quality limits
- Pelvic rotation or obliquity
- Calibration marker far from hip level
- Dysplasia, deformity or prior implants requiring additional imaging
- Assuming radiographic orientation equals functional orientation
- Ignoring soft-tissue and intraoperative stability
Frequently asked questions
Which parameters are central to THA planning?
Leg-length difference, femoral offset, center of rotation, cup size and position, stem size, neck length and the intended reconstruction of hip geometry.
What is COR reconstruction?
COR means center of rotation. Reconstruction determines the planned hip center from anatomical references and, where appropriate, the contralateral side.
Why does pelvic tilt matter?
Pelvic position can change functional cup orientation between standing and sitting. Separate functional assessment can make that relationship visible.
Can planning replace intraoperative assessment?
No. Preoperative planning is preparation. Intraoperative anatomy, stability, soft tissues and final component choice require surgical judgment.