Kinematic Alignment of Knee Prosthetics via 3D Modeling
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Solution Overview
Problem
Current Total Knee Arthroplasty (TKA) methods fail to consistently reproduce natural knee kinematics due to inadequate evaluation of underlying joint deformities and rotational deformities, leading to malalignment, instability, and premature component wear.
Innovation Solution
A tibial component placement guide and kinematic femoral component that align prosthetic components based on patient-specific kinematic axes, such as the helical axis and transverse axes, determined through fluoroscopic imaging and 3D modeling, to replicate natural knee motion and load distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If mechanically aligned TKA is used to restore normal anatomy, then anatomical restoration is improved, but rotational deformities are not accounted for leading to malalignment
Solution Approach 1:
The patent transitions from traditional two-dimensional mechanical axis alignment in the coronal plane to three-dimensional kinematic alignment that incorporates rotational deformities and helical axes. This multi-dimensional approach allows simultaneous correction of varus/valgus deformities and rotational malalignment, achieving both anatomical restoration and accurate rotational positioning of prosthetic components.
Solution Approach 2:
The invention changes the alignment parameters from mechanical neutral axis to patient-specific kinematic axes (helical axis, transverse axes) determined through fluoroscopic imaging and 3D modeling. This parameter transformation enables the prosthetic components to be aligned according to the patient's natural knee motion patterns rather than standardized mechanical references.
2Manufacturing precision
If balanced flexion gap technique is used to correct defective anatomy, then varus component position is improved, but natural kinematics are not restored
Solution Approach 1:
The patent performs preliminary determination of patient-specific kinematic axes through fluoroscopic imaging and 3D modeling before prosthetic implantation. These pre-calculated helical and transverse axes are used to guide component alignment, ensuring that natural kinematics are restored before final component positioning and balancing procedures.
Solution Approach 2:
The invention uses fluoroscopic imaging to capture actual knee kinematics during motion, providing feedback on the patient's natural movement patterns. This feedback is used to determine the appropriate kinematic axes for prosthetic alignment, creating a closed-loop system that ensures the implantation restores the patient's specific kinematic characteristics.
3Ease of operation
If traditional alignment methods are used, then surgical simplicity is maintained, but joint stability and component wear are worsened due to malalignment
Solution Approach 1:
The patent introduces fluoroscopic imaging and 3D modeling as intermediary tools that capture and analyze knee kinematics non-invasively. These imaging technologies serve as mediators between the patient's natural motion and the surgical alignment process, providing objective data on kinematic axes without adding significant surgical complexity.
Solution Approach 2:
The invention creates a digital 3D model and fluoroscopic copy of the patient's knee kinematics that can be analyzed and measured independently. This virtual model allows precise determination of kinematic axes before surgery, enabling accurate alignment planning without requiring complex intraoperative procedures.
Data Source
Figure 1A-1C~2A
Figure 2B~3B
Figure 4A~4D
AI summary
A tibial component placement guide for use in a knee arthroplasty procedure involving a knee joint comprising a tibia, a patella, and a femur, the guide comprising an overlay configured to be overlaid a resected tibia, the overlay including at least one of an indicia and an opening indicative of at least one of an orientation and a position of at least one of a first axis of the femur, a second axis of the femur, and a first axis of the patella.