Modular Knee Spacer Block for Joint Gap Measurement
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Solution Overview
Problem
Current knee arthroplasty procedures face challenges in accurately determining the optimal joint gap and angle for prosthetic implant alignment, as they are influenced by bone resections, soft tissue tension, and varying surgical philosophies, leading to potential limitations in joint motion and stability.
Innovation Solution
A modular knee arthroplasty instrument system that includes a spacer tool with a tibial and femoral component, allowing for adjustable separation of the tibia and femur to measure joint gaps and angles, and accommodating different surgical philosophies through interchangeable spacer shims and accessories.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a fixed tibial component height is used, then the instrument structure is simple, but it cannot accommodate different surgical philosophies and patient-specific requirements for joint gap measurement
Solution Approach 1:
The tibial component is divided into multiple height segments (first height, second height greater than first) that can be selectively positioned. This segmentation allows the instrument to adapt to different surgical philosophies (measured resection vs. soft tissue balancing) by choosing appropriate height levels, while maintaining a relatively simple overall instrument structure.
Solution Approach 2:
The tibial component's height is made dynamic through the ability to select between different fixed height positions. The component can be positioned at a first height or a second height relative to the resection surface, allowing flexibility in accommodating various surgical approaches and patient anatomies without requiring a completely complex adjustable mechanism.
2Adaptability or versatility
If the tibial component has only one height position, then the manufacturing is simple, but it cannot provide flexibility for evaluating different joint gap scenarios
Solution Approach 1:
The tibial component incorporates multiple discrete height segments that can be selectively engaged. This segmentation provides flexibility in evaluating different joint gap scenarios (tight vs. loose soft tissue conditions) while keeping the manufacturing process relatively straightforward by using standardized height increments rather than continuous adjustment mechanisms.
3Measurement precision
If spacer shims are not used, then the instrument is simpler, but it cannot separately evaluate the effect of tibial component height on joint tension
Solution Approach 1:
Spacer shims are introduced as intermediary elements between the tibial component and the tibia. These shims allow for precise evaluation of the relationship between tibial component height and joint tension by providing incremental height adjustments. The shims act as a mediator that decouples the height adjustment function from the main tibial component, allowing independent optimization of each element.
4Measurement precision
If bone resections are performed before measurement, then the surgical procedure follows traditional sequence, but it limits the ability to evaluate and adjust soft tissue balance
Solution Approach 1:
The instrument enables preliminary measurement and evaluation of joint gaps and angles before final bone resections are completed. By allowing measurement at this early stage, surgeons can plan and adjust soft tissue balancing procedures beforehand, providing greater flexibility in the surgical sequence and improving overall measurement accuracy through iterative evaluation.
Data Source
AI summary
A knee arthroplasty system for use in a patient's knee joint comprises a spacer block instrument including a base portion, a tibial component extending from the base portion and configured for placement against a tibia, and a femoral component configured for placement against a femur. The femoral component is rotatably coupled to the tibial component. The system further includes one or more spacer block shims structured for removable attachment to the tibial component.