Tibial Positioning Device for Kinematic Alignment in Knee Arthroplasty
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Solution Overview
Problem
Current kinematic alignment techniques in total knee arthroplasty procedures are prone to errors due to manual processes, making it difficult to accurately locate and read marker lines on the tibia and properly activate collateral ligaments, which can lead to non-planar tibial cuts and increased surgical complexity.
Innovation Solution
The use of a tibial positioning device that couples a femoral cutting guide to a tibial cutting guide, allowing for precise alignment of the tibia relative to the femur, reducing the likelihood of errors and complexity by ensuring parallel resections and proper ligament activation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If manual processes are used for kinematic alignment (spacer block or osteotome to mark varus resection), then the surgeon has flexibility in technique selection, but the precision of resection alignment deteriorates due to difficulty in locating and reading marker lines
Solution Approach 1:
A positioning device is introduced as an intermediary tool between the spacer block/osteotome and the tibial cutting guide. This device includes a positioning block that couples to the femoral cutting guide and a tibial coupling block that couples to the tibial cutting guide, with an extension connecting them. The positioning device serves as a mediator that transfers and maintains the alignment relationship, eliminating the need for manual marking and reading of marker lines while preserving surgical flexibility.
Solution Approach 2:
The manual process of marking and reading alignment lines is replaced with a mechanical coupling system. The positioning device uses physical couplings (positioning block coupling to femoral guide, tibial coupling block coupling to tibial guide) and a rigid extension to mechanically enforce parallel alignment between cutting guides, substituting the error-prone manual measurement and marking process with a mechanical alignment system.
2Device complexity
If free-hand approach is used to mark resection lines, then the surgical procedure is simpler, but the reliability of proper collateral ligament activation deteriorates
Solution Approach 1:
The positioning device acts as an intermediary that ensures proper ligament activation by maintaining the correct alignment relationship between femoral and tibial cutting guides. The device includes features such as a flat posterior face that mates with the femoral cutting guide and coupling mechanisms that ensure the tibial cutting guide is properly positioned relative to the femoral guide, thereby reliably activating collateral ligaments during the resection process.
3Reliability
If additional spacer block balancing is performed after manual marking, then knee balancing can be achieved, but the surgical complexity increases and the risk of non-planar tibial cuts increases
Solution Approach 1:
The positioning device performs the alignment function preliminarily, establishing the correct parallel relationship between femoral and tibial cutting guides before the resection process begins. By pre-establishing this alignment through the mechanical coupling system (positioning block, extension, and tibial coupling block), the need for additional spacer block balancing steps is eliminated, reducing surgical complexity while maintaining knee balancing accuracy.
Solution Approach 2:
The positioning device serves as an intermediary that integrates the alignment and balancing functions into a single tool system. The device includes a positioning block that couples to the femoral cutting guide, an extension, and a tibial coupling block that couples to the tibial cutting guide, creating a unified mechanical system that maintains proper alignment throughout the procedure and prevents non-planar tibial cuts.
Data Source
AI summary
Devices and methods for performing total knee arthroplasty procedures with kinematic alignment are described herein. A method of performing a total knee arthroplasty can comprise positioning a femoral cut guide adjacent a distal end of a femur, positioning a tibial cut guide proximate a proximal end of a tibia adjacent an anterior surface of the tibia, adjusting a position of the femoral cut guide and the tibial cut guide relative to each other using a tibial positioning device, fixing the position of the femoral cut guide relative to the tibial cut guide using the tibial positioning device, and resecting the femur and tibia with parallel resections using the femoral and tibial cut guides.