Patient Specific Knee Implant Tolerance Volume Matching
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Solution Overview
Problem
Current implant sizing methods for procedures like Total Knee Arthroplasty (TKA) often require compromises due to limited available sizes, leading to mismatches between implants and bones, which can result in increased blood loss, soft tissue risk, and post-operative pain.
Innovation Solution
A system that uses three-dimensional modeling and tolerance volumes to optimize implant placement by accounting for variations in surgical technique, instrumentation, manufacturing, anatomy, and imaging, allowing for the creation of custom or more accurately fitting implants.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If standard implant sizes are used, then implant availability and ease of manufacture are improved, but implant-bone match precision deteriorates
Solution Approach 1:
The patent applies parameter changes by creating a tolerance volume that accounts for variations in resection cuts, anatomical variations, and manufacturing tolerances. This volume defines a range of acceptable implant positions and orientations, allowing standard implants to be used while achieving precise functional matching through adjusted placement parameters rather than custom implant geometries.
Solution Approach 2:
The patent transitions from two-dimensional implant size selection to three-dimensional tolerance volume analysis. By defining a volumetric region that incorporates all relevant tolerances and variations, the system enables precise implant positioning in three-dimensional space, resolving the contradiction between using standard implant sizes and achieving precise bone-implant matching.
2Manufacturing precision
If custom implants are manufactured to match bone precisely, then implant-bone match precision is improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent performs preliminary action by calculating the tolerance volume and determining the optimal implant position and orientation before the actual implantation surgery. This pre-surgical planning allows standard implants to be selected and positioned precisely, eliminating the need for complex custom implant manufacturing while achieving the benefits of precise fitting.
3Adaptability or versatility
If bone resection is increased to accommodate standard implants, then implant availability is improved, but patient harm increases due to blood loss and soft tissue risk
Solution Approach 1:
The patent applies dynamics by creating a flexible tolerance volume that can adapt to different bone geometries and resection scenarios. This dynamic approach allows the system to determine the minimal necessary resection for each patient's anatomy while still accommodating standard implant sizes, thereby reducing unnecessary bone and soft tissue removal while maintaining implant availability.
Data Source
AI summary
Patient specific implant technology, in which an outline representation of a portion of an outer surface of a periphery of a bone volume is determined and the outline representation is used in operations related to implant matching. In addition, an instrument may be made to match a perimeter shape of a Patient Specific Knee Implant with features for locating holes in a distal femur such that posts or lugs in a femoral implant locate the femoral implant centered medial-laterally within an acceptable degree of precision to prevent overhang of either the side of the femoral implant over the perimeter of the distal femur bone resections. Further, a two-dimensional outline representation may be segmented into segments that correspond to resection cuts used in fitting an implant on a portion of a bone and operations related to implant matching may be performed based on the segments.