Hip Prosthesis Cup Positioning via Acetabular Landmarks
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Solution Overview
Problem
Current methods for positioning hip joint prostheses during surgery often disregard the complex biomechanical interactions between the implant, bone, and anatomical features, leading to suboptimal biomechanical stability and potential issues like psoas impingement and inadequate cup coverage.
Innovation Solution
A method that uses anterior alignment points on the acetabular rim and cup containment criteria to optimize cup positioning, incorporating parameters such as anteversion, inclination, and coverage to prevent impingements and ensure stable fixation, utilizing iterative algorithms for automatic optimization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If cup positioning is optimized based on classical Lewinnek safe zone, then surgical procedure is simplified, but biomechanical stability and range of motion are compromised
Solution Approach 1:
The patent transforms the cup positioning problem from using fixed angular parameters (Lewinnek zone: 40°±10° inclination, 15°±10° anteversion) to using anatomical landmark-based parameters (anterior rim points, TAL orientation). This parameter transformation allows the surgical procedure to remain straightforward while achieving optimized biomechanical outcomes specific to each patient's anatomy.
Solution Approach 2:
The patent divides the acetabular rim into multiple reference points (at least two anterior points superior and inferior to the psoas tendon crossing) and uses these segmented points to define the opening plane and orientation. This segmentation enables precise positioning that accounts for individual anatomical variations while maintaining surgical simplicity through systematic measurement procedures.
2Reliability
If cup positioning is optimized for range of motion using arithmetic formulae, then implant-implant impingement is reduced, but other biomechanical aspects such as bone-implant interaction are disregarded
Solution Approach 1:
The patent creates a multi-functional positioning method that simultaneously optimizes multiple biomechanical aspects: range of motion, bone-implant contact, prevention of psoas impingement, and cup stability. By using anatomical landmarks (anterior rim points, TAL) as a universal reference system, the method addresses all these functions through a single integrated approach rather than separate optimizations.
Solution Approach 2:
The patent introduces anatomical landmarks (anterior acetabular rim points and transverse acetabular ligament orientation) as intermediary references that mediate between the implant geometry and the patient's unique anatomy. These intermediaries enable the optimization to account for bone-implant interaction, soft tissue constraints, and individual anatomical variations without requiring complex patient-specific modeling.
3Reliability
If TAL-based positioning is used, then dislocation reduction is achieved, but comprehensive functional optimization according to multiple criteria is not provided
Solution Approach 1:
The patent merges the TAL-based dislocation prevention approach with anterior rim point positioning to create a comprehensive optimization system. By combining these anatomical references and integrating them with cup geometry constraints and bone contact requirements, the method provides multi-criteria optimization that includes dislocation prevention along with range of motion, stability, and soft tissue preservation.
4Reliability
If formula-based combined anteversion approach is used, then implant-to-implant impingement is addressed, but assumptions about implant position disregard other influences such as CCD angle, femoral tilt, or varus-valgus deviation
Solution Approach 1:
The patent applies local quality by using patient-specific anatomical measurements (anterior rim points, TAL orientation) rather than generic formulae. This allows the cup positioning to be locally adapted to each patient's unique anatomy, including their specific CCD angle, femoral tilt, and varus-valgus deviation, while still preventing impingement through systematic optimization.
Data Source
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AI summary
The present invention relates to a method for planning the positioning of a ball joint prosthesis, in particular a hip joint prosthesis, wherein the prosthesis includes a stem and a cup and the method comprises the following steps: - determining the position of at least one point lying on the rim of the joint socket, in particular the position of at lest two points lying in an anterior region of the acetabulum; - defining a requirement for the position and/or orientation of the cup on the basis of the determined positions of the at least one point. The present invention also relates to a method for optimising the positioning of a ball joint prosthesis, in particular a hip joint prosthesis, wherein the prosthesis includes a stem and a cup and the method comprises the following steps: - defining at least one requirement for the position and/or orientation of the cup; - calculating an optimum position and/or orientation of the cup on the basis of all the defined requirements being fulfilled.