Bone Anchor Narrowing Member for Cement Containment
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Solution Overview
Problem
Existing bone anchors designed to prevent bone cement escape at the tip may not be suitable for applications where maintaining an open channel is necessary, such as in minimally invasive surgery for treating osteoporotic or weak bones.
Innovation Solution
A bone anchor with a narrowing member in the channel at the tip that allows passage of a guide wire and prevents bone cement from exiting through the tip, enabling modular assembly with varying narrowing effects based on the substance's viscosity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the channel at the tip of the bone anchor is closed to prevent bone cement escape, then bone cement containment is improved, but the ability to pass guide wire and allow substance injection is worsened
Solution Approach 1:
The narrowing member creates a localized restriction in the channel that selectively prevents bone cement escape at the tip while maintaining sufficient opening for guide wire passage and substance injection. The local modification of channel geometry achieves differential functionality along the channel length.
Solution Approach 2:
The narrowing member provides a dynamic balance between channel closure and openness based on the properties of the substance being injected. The restricted geometry adapts to different substance viscosities and injection pressures, allowing guide wires and cement to pass while preventing uncontrolled escape.
2Reliability
If a plug member is used to close the channel, then bone cement escape is prevented, but the device complexity and number of additional components increase
Solution Approach 1:
The narrowing member integrates the channel restriction function directly into the bone anchor structure, combining the containment function with the existing channel geometry. This eliminates the need for separate plug members and reduces the total number of components.
Solution Approach 2:
The invention extracts only the essential containment function from the complex plug member system, implementing a simplified narrowing geometry that achieves bone cement prevention without requiring additional removable or insertable components.
3Reliability
If the channel is completely closed to prevent cement escape, then containment is improved, but the adaptability for different surgical applications and substances is reduced
Solution Approach 1:
The narrowing member allows adjustment of containment effectiveness based on substance viscosity and injection parameters. The restricted geometry can accommodate different substance properties while maintaining prevention of uncontrolled escape, providing adaptability for various surgical applications.
Solution Approach 2:
The narrowing member design serves multiple functions: it prevents bone cement escape, allows guide wire passage, and accommodates different substance viscosities. This multi-functionality makes the bone anchor suitable for various surgical applications without requiring application-specific modifications.
Data Source
AI summary
A bone anchor includes a shank having a free end, a longitudinal axis, a channel extending axially through the shank to the free end, the channel having a first width, and at least one opening extending through a wall of the shank, and a narrowing member including an elastically deformable portion configured to extend into the channel at or near the free end. The narrowing member is adjustable from a first configuration where the deformable portion defines an opening with a width smaller than the first width to restrict a substance from exiting through the free end, to a second configuration where the deformable portion is deformed radially outwardly to define an opening with a width that is at least the first width, while at least a portion of the shank positioned at a same axial height as the deformable portion maintains a constant outer width.