Acetabular Cup Alignment Using Sagittal Spinopelvic Positioning
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Solution Overview
Problem
Current methods for positioning acetabular cups in hip replacement surgeries rely heavily on the frontal plane, which is not consistent across patients and does not account for functional movements, leading to potential mechanical risks and implant failure due to aberrant pelvic behavior and mobility.
Innovation Solution
The use of sagittal parameters such as Anteinclination (AI) and Sacroacetabular Angle (SAA) to individually target and track the acetabular cup, leveraging biomechanical properties of the spino-pelvic-femoral complex, allowing for accurate placement based on patient-specific measurements and mobility, using digital platforms for preoperative planning and intraoperative guidance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If frontal plane positioning (Lewinnek safe zone) is used for acetabular cup placement, then standardization is achieved, but patient-specific functional mobility and pelvic behavior are not accounted for leading to implant failure
Solution Approach 1:
The patent applies local quality by transitioning from a universal frontal plane reference (Lewinnek safe zone) to patient-specific local references in the sagittal plane. Each patient's unique spinopelvic morphology is captured through individualized measurements of pelvic incidence, sacral slope, and lumbar lordosis, allowing the cup position to be adapted to their specific functional characteristics rather than forcing them into a standardized coronal template.
Solution Approach 2:
The patent introduces another dimension by shifting the primary reference plane from the frontal (coronal) plane to the sagittal plane. This dimensional change enables visualization and measurement of pelvic tilt, sacral slope, and lumbar curvature relationships that are invisible in the traditional frontal view, thereby capturing the third dimension of spinopelvic function that correlates with implant stability.
2Measurement precision
If static tilt adjustment in supine position is performed, then APP leveling is achieved, but dynamic pelvic mobility during functional movements is not corrected
Solution Approach 1:
The patent applies dynamics by measuring pelvic parameters in multiple functional positions (standing, sitting, lateral bending, rotation) rather than a single static supine position. This dynamic approach captures the full range of pelvic mobility and spinopelvic coupling, allowing the surgical plan to account for how the pelvis moves through functional tasks. The system tracks changes in sacral slope, pelvic tilt, and lumbar lordosis across positions to establish safe zones that maintain stability throughout motion.
Solution Approach 2:
The patent applies preliminary action by performing comprehensive dynamic measurements and computational analysis during the preoperative planning phase. Patient-specific spinopelvic parameters are measured, modeled, and analyzed before surgery to determine optimal cup positioning that anticipates intraoperative and postoperative functional demands. This preliminary characterization of pelvic mobility allows surgeons to proactively plan for dynamic stability rather than reactively adjusting for it during surgery.
3Ease of manufacture
If conventional coronal targeting is used, then surgical simplicity is maintained, but sagittal plane parameters (Anteinclination and Sacroacetabular Angle) are not optimized
Solution Approach 1:
The patent replaces the simple mechanical act of coronal plane alignment with a computational modeling system that integrates multiple measurement modalities (radiographs, CT, motion analysis) and applies spinopelvic biomechanics principles. Instead of relying solely on mechanical alignment tools in the frontal plane, the system uses computer-based planning to calculate optimal sagittal parameters (Anteinclination and Sacroacetabular Angle) based on patient-specific morphology and functional characteristics.
Solution Approach 2:
The patent introduces an intermediary computational layer between measurement and execution. The system acts as an intermediary that processes preoperative imaging data, characterizes spinopelvic function, and generates personalized surgical guides or robotic pathways. This intermediary planning phase translates complex biomechanical relationships into actionable positioning targets, bridging the gap between theoretical optimization and surgical implementation while maintaining procedural feasibility.
Data Source
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Figure 3A~3B
AI summary
The disclosure provides example methods and.non-transitory computer-readable mediums for acetabular cup placement An example method includes a processor (a) determining for a first patient a sagittal acetabular cup position in the form of a standing AI a seated AI and a SAA based on (I) a standing SS relative to a normative SS, (It) a dSS between a standing position and an upright seated position, (iii) a femoral version corresponding to a femoral version outlier position. and (iv) a PFA-to correspond to a PFA outlier position in a standing position or an upright seated position, (k) determining a coronal acetabular cup position in the form of a supine coronal anteversion and at least one of a supine-or a standing coronal inclination based on the sagittal acetabular cup position, and (c) determining a post-operative standing AI and a post-operative seated AI based on the coronal acetabular cup position.