Cannulated Bone Screw with Axial Channel for Cement Delivery
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Solution Overview
Problem
Existing devices for stabilizing bone fractures and osteoporotic tissue face challenges in delivering high viscosity fluids like bone cement effectively, leading to inadequate stabilization and resistance to deformation and shear forces, with issues of fluid reflux and insufficient mechanical strength.
Innovation Solution
A cannulated screw with a stem and engagement means that transforms into a solid screw, featuring a tubular component with axial channels and transverse holes for fluid communication, along with a removable pin for enhanced stability and resistance, ensuring effective delivery of medicinal substances and preventing fluid reflux.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a cannulated screw with holes is used to deliver medicinal substances, then the ability to deliver bone cement and other substances is improved, but the mechanical strength and resistance to shear forces deteriorate
Solution Approach 1:
The screw transitions from a hollow cannulated structure to a solid structure by injecting liquid bone cement through the axial channel and transverse holes, which then hardens to provide mechanical strength. This dynamic transformation allows the screw to have both delivery capability and structural strength at different stages.
Solution Approach 2:
The bone cement is delivered locally through transverse holes at specific positions along the screw shaft, allowing medicinal substances to be applied where needed while the rest of the screw maintains its structural integrity. The local injection points enable targeted treatment without compromising overall screw strength.
2Productivity
If high viscosity fluids like bone cement are introduced through holes in a screw, then stabilization of fractures is achieved, but the fluids fail to reach the furthest holes due to physical laws governing their passage
Solution Approach 1:
The injection system transitions from lateral injection through transverse holes to axial injection through the longitudinal channel. This dimensional change in the injection path allows bone cement to be pushed through the entire length of the screw axially, ensuring all holes are filled even with high viscosity fluids.
Solution Approach 2:
The axial channel is pre-formed within the screw structure, allowing bone cement to be injected through the center of the screw before being distributed to transverse holes. This preliminary axial pathway ensures complete filling of all holes regardless of fluid viscosity.
3Adaptability or versatility
If a screw with transverse holes is used for substance delivery, then medicinal substances can be introduced, but fluid reflux into the cannulated screw occurs
Solution Approach 1:
Instead of having holes open to the external environment, the transverse holes are oriented to deliver substances away from the screw, and the axial channel is designed to prevent backward flow. The injection system pushes fluids in one direction (axially forward) rather than allowing bidirectional flow.
Solution Approach 2:
The axial channel acts as an intermediary pathway that controls and directs fluid flow. It serves as a controlled conduit that prevents uncontrolled reflux by channeling all fluid movement through a defined path with proper pressure management.
4Adaptability or versatility
If a hollow cannulated screw is used to allow fluid passage, then substance delivery is enabled, but stability to deformation and resistance to shear forces are insufficient
Solution Approach 1:
The screw's physical state changes from hollow to solid-filled by injecting bone cement into the axial channel and holes. This parameter change in the internal structure transforms the mechanical properties, providing both the original fluid passage capability (during injection) and the desired structural stability (after hardening).
Data Source
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AI summary
The present invention relates to a device for the selective biological synthesis of a bone tissue arranged to allow the stabilization of a fracture or an osteoporotic bone tissue and for the introduction of medicinal substances for bone diseases.