Spinal Rod Connectors with Grip Grooves for Torsional Stability
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Solution Overview
Problem
Existing spinal fixation systems face challenges in maintaining stability and preventing motion between connected implants, particularly in limited spaces like the cervical spine, due to issues such as torsional slip and difficulty in handling and connecting multiple rods.
Innovation Solution
Implants with grip grooves and retaining members that enhance rotational and axial stability by engaging the rod with multiple edges, using grip grooves to resist rotational and longitudinal movement, and incorporating compression members for secure fixation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If multiple spinal rods are connected to each other to improve stability and strength, then the overall strength and stability of the implanted construct is improved, but the available space for the implanted construct becomes limited and manipulating and handling these relatively small implants in the surgical wound becomes challenging or cumbersome
Solution Approach 1:
The connector allows one rod to be nested within or alongside another rod through its rod-receiving recesses, enabling multiple rods to be connected in a compact configuration that improves construct stability while minimizing the space required in the limited cervical surgical field
2Stability of the object's composition
If polyaxial screw-heads, rod to rod, and screw-head to rod connectors are used to hold securely to the rod to provide stable fixation, then stability of the implanted construct is improved, but torsional slip between the implants on the rod or rods connecting them to each other becomes a serious risk
Solution Approach 1:
The grip grooves are strategically positioned at specific locations within the rod-receiving recess to provide localized engagement points that resist torsional forces. These grooves create specific zones of increased friction and mechanical interlocking that prevent rotational slip while maintaining overall connector flexibility
Solution Approach 2:
The grip grooves engage the rod not only in the axial direction but also in the radial and circumferential dimensions, creating multi-dimensional mechanical interlocking that effectively prevents torsional slip while maintaining the polyaxial adjustment capability
3Ease of operation
If the rod-receiving recess defines a circular cross-section to allow rod insertion, then ease of rod insertion is improved, but the rod can slide, rotate, or pull away from the connector
Solution Approach 1:
The grip grooves create localized engagement zones within the otherwise circular rod-receiving recess. These grooves provide specific points of mechanical interlocking that prevent rod slippage, rotation, and pull-away while maintaining the overall circular geometry that facilitates easy rod insertion
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The grip grooves and retaining members provide enhanced torsional and axial gripping capacity, preventing slip and improving the stability and strength of spinal fixation constructs, even in constrained surgical environments.
Implementation Method 1
The grip grooves and retaining members provide enhanced torsional and axial gripping capacity, preventing slip
Data Source
AI summary
Implants with grip grooves are disclosed herein. In some embodiments, an implant includes a rod-receiving recess defining a rod axis where an inner surface of the rod-receiving recess defines two grip grooves extending parallel to each other and the rod axis. Each grip groove defines two edges where the grip groove intersects the inner surface, the four edges of the two grip grooves together defining a circular radius about the rod axis. The implant includes a retaining member configured to move with respect to the body to apply a force against a rod that is perpendicular to the rod axis, the force engaging the rod against the four edges of the grip grooves, where the engagement of the four edges of the grip grooves against the rod restrains rotational movement of the rod about the rod axis.