Patient-Specific Knee Revision Guides for Precise Bone Remodeling
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Solution Overview
Problem
Existing methods for total knee arthroplasty revision lack precision in remodeling bone portions to accommodate new prostheses due to the loss of geometric references from pre-existing prostheses, leading to potential misalignment and complications.
Innovation Solution
A patient-specific surgical guide is used to remodelling bone portions by coupling with the distal end of the femur and proximal end of the tibia, utilizing alignment pins, cutting blocks, and drilling tools to ensure precise resections and canal preparation for new prostheses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional metal instruments are used for prosthesis removal and bone processing, then the procedure can be performed with standard equipment, but the geometric references from pre-existing prostheses are lost, leading to imprecise bone remodeling
Solution Approach 1:
The surgical guide is manufactured in advance based on pre-operative imaging data (CT or MRI) that captures the geometric references of existing prostheses. This preliminary action allows the guide to be custom-fitted to the patient's specific anatomy and prosthesis configuration, ensuring precise bone remodeling references are established before the actual surgery begins.
Solution Approach 2:
The patient-specific surgical guide acts as an intermediary tool between the existing prosthesis and the new bone remodeling process. The guide couples to the existing prosthesis through dedicated coupling elements, transferring the geometric references from the old prosthesis to the bone processing instruments, thereby maintaining precision throughout the revision procedure.
2Measurement precision
If pre-operative planning is performed with imaging techniques, then anatomical conformations can be detected, but the presence of existing prostheses prevents accurate detection of geometric references
Solution Approach 1:
The surgical guide creates a physical copy or replica of the geometric references from the existing prosthesis and surrounding anatomy. By manufacturing the guide based on pre-operative imaging data, the essential geometric information is captured and reproduced in a tangible form that can be directly used during surgery to guide bone processing and prosthesis positioning.
Solution Approach 2:
The geometric references are captured and stored in the surgical guide design before surgery begins. The pre-operative planning phase includes detecting the anatomical conformation and prosthesis geometry through imaging, then incorporating this information into the custom guide design, so that all necessary reference information is preserved and ready for use during the procedure.
3Adaptability or versatility
If manual definition of cut tilt and canal direction is performed during surgery, then the surgeon can adapt to patient-specific anatomy, but the precision and reliability are reduced
Solution Approach 1:
The surgical guide is designed to be self-aligning and self-positioning on the patient's anatomy and existing prosthesis. Through dedicated coupling elements and positioning features, the guide automatically establishes the correct orientation and position, eliminating the need for manual alignment by the surgeon while maintaining high precision in bone resection and canal preparation.
Solution Approach 2:
The surgical guide serves as an intermediary that translates the pre-planned geometric references into precise physical guidance during surgery. The guide incorporates reference features that couple to the existing prosthesis and transfer the planned cut angles and canal directions to the bone processing instruments, ensuring accurate reproduction of the pre-operative plan.
Data Source
AI summary
A femoral component and a tibial component are respectively configured to exclusively couple with the distal end of a femur bearing a femoral prosthesis and with the proximal end of a tibia bearing a tibial prosthesis. The femoral component has a distal portion configured to face the distal end of the femur, bearing distal positioning holes facing a distal region of the femoral prosthesis. A frontal portion extends on the continuation of the distal portion and has a first abutment area operating against the femur bone part and a second area facing a frontal region of the femoral prosthesis. The frontal portion has at least two guide holes at the first abutment area, and at least two frontal positioning holes at the second area.