Sagittal Saw Blade Cartridge Guide Bar for Rigid Bone Cutting
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Solution Overview
Problem
Surgical sagittal blade cartridges flex undesirably when cutting through bone, leading to suboptimal cut surfaces and potential misfitting of artificial implants, due to the lack of rigidity in the guide bar, which cannot be increased without compromising cut smoothness.
Innovation Solution
A surgical sagittal blade cartridge with a guide bar composed of three plates, including a top, bottom, and inner plate with curved sections and tines, providing structural reinforcement to resist deformation and flexure, and outer tines extending forward to further stabilize the guide bar.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the guide bar is made more rigid to reduce flexure, then the likelihood of skiving and diving decreases, but the smoothness of the cut surface deteriorates
Solution Approach 1:
The guide bar is divided into three separate plates (top plate, bottom plate, and inner plate) that are positioned relative to each other to form a guide bar assembly. This segmentation allows each plate to contribute to overall rigidity while maintaining flexibility in the assembly structure, resolving the contradiction between guide bar strength and cut surface smoothness.
Solution Approach 2:
The guide bar assembly functions as a composite structure composed of three plates working together. The combination of multiple plates creates a composite system that provides enhanced rigidity and resistance to flexure while maintaining the smooth operational characteristics needed for precise cutting.
2Strength
If the guide bar thickness is increased to reduce flexure, then structural integrity improves, but the cut thickness increases and smoothness is compromised
Solution Approach 1:
Instead of increasing the thickness of a single guide bar, the structure is segmented into three thinner plates positioned relative to each other. This segmentation provides the structural integrity needed to resist flexure without increasing the overall thickness that would interfere with cut quality.
Solution Approach 2:
The solution moves from a single-dimension thickness increase to a multi-dimensional arrangement of three plates. The plates are positioned in space relative to each other, creating rigidity through spatial configuration rather than through increased thickness in one dimension, thus avoiding interference with cut surface quality.
3Productivity
If a conventional sagittal blade is used, then the blade can cut through tissue, but the oscillating movement causes significant wear on the cutting guide surfaces
Solution Approach 1:
Instead of having the entire blade assembly oscillate (conventional approach), this invention inverts the approach by keeping the guide bar static and only oscillating the blade head portion. This reversal of the oscillation strategy maintains cutting capability while minimizing contact and wear on the cutting guide surfaces.
Solution Approach 2:
The oscillating function is extracted from the entire blade assembly and isolated to only the blade head portion. This extraction allows the guide bar to remain stationary during cutting, thereby reducing wear on the cutting guide surfaces while maintaining the necessary cutting action.
Data Source
AI summary
A surgical sagittal saw blade cartridge that includes a guide bar formed from an inner layer and opposed outer plates. The inner layer comprising an outer tine extending distally from the proximal end of the guide bar. An outer surface of the outer tine forms a section of a side surface of the guide bar. A side weld may be formed along the side surface of the guide bar. The cartridge may include a blade coupled to the guide bar, the blade comprising a web disposed between the two outer plates. The blade may include a blade head integral with and located distal to the web, the head formed with teeth located distal to the guide bar, the teeth having a sufficient thickness to form a kerf able to receive the guide bar. A method of forming the cartridge is also contemplated, including welding the inner layer to the outer plates.