Self-Locking Ratchet Spinal Pinching System
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Solution Overview
Problem
Current spinal stabilization systems for immobilizing vertebrae are complex to install, require external assistance, and lack a suitable area for bone graft visualization and placement, with risks of screw loss and difficulty in radiographic checks.
Innovation Solution
A self-locking thorn pinching system with a ratchet mechanism and a chamber for bone graft installation, allowing for one-handed operation and radiographic visibility, using plates with asperities and a tubular shaft forming an anti-return ratchet mechanism, and optionally made from radiotransparent materials like PEEK.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a screw and nut system is used to tighten and lock the plates (as in SPIRE Plate system), then the vertebrae can be immobilized, but the installation becomes complex and requires external assistance
Solution Approach 1:
The system employs a self-locking mechanism where the mobile plate automatically locks to the fixed plate through a ratchet and pawl system. The surgeon simply needs to push the mobile plate toward the fixed plate, and the ratchet mechanism automatically engages to maintain compression without requiring the surgeon to tighten screws or nuts, thereby eliminating the need for external assistance during installation
Solution Approach 2:
The invention removes the screw and nut components from the system entirely, replacing them with a direct ratchet-based self-locking mechanism. This extraction of unnecessary components simplifies the installation process while maintaining the reliability of vertebral immobilization
2Reliability
If a metallic cylinder is used to hold bone graft (as in ASPEN system), then the bone graft can be contained, but radiographic visualization of the graft is difficult
Solution Approach 1:
The shaft is constructed from composite materials including PEEK (polyether ether ketone) and titanium, where PEEK provides radiotransparency for imaging while titanium provides structural strength. This composite construction allows the bone graft to be contained securely while enabling clear radiographic visualization of the graft and its integration with the bone
Solution Approach 2:
The system utilizes materials with different radiographic properties - specifically radiotransparent PEEK material that allows X-rays to pass through, enabling clear visualization of the bone graft and surrounding structures on radiographic images, unlike opaque metallic materials
3Reliability
If a screwing instrument is used to install the implant (as in US 2008/183211), then the implant can be fixed in place, but the implementation becomes slow and complex
Solution Approach 1:
The system eliminates the need for screwing instruments by using a self-locking ratchet mechanism. The surgeon manually pushes the mobile plate toward the fixed plate, and the ratchet automatically engages to lock the position, dramatically simplifying the installation process and eliminating the need for specialized screwdrivers and bits
Solution Approach 2:
The invention removes the entire screwing instrument system from the installation process, replacing it with a direct manual pushing action that triggers automatic ratchet engagement. This extraction of complex tooling requirements accelerates installation while maintaining secure implant fixation
4Stability of the object's composition
If a ratchet mechanism with notches is used to lock the plates, then the pinching becomes irreversible without external help, but the mechanism complexity increases
Solution Approach 1:
The ratchet mechanism is integrated directly into the mobile plate structure itself, rather than being a separate component. The notches are formed as part of the plate's geometry, and the pawl is a simple feature of the same component, merging multiple functions into a single integrated element that provides stable locking without adding significant complexity
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
Facilitates easy and irreversible pinching of vertebrae without external help, stable over time, and allows for effective bone graft placement and monitoring, simplifying the installation process and reducing the risk of screw-related complications.
Implementation Method 1
the shaft and the second plate form an anti-return ratchet mechanism comprising a series of notches cooperating with the anti-return ratchet mechanism so that the rapprochement of the plates is irreversible without external help
Implementation Method 2
a surface of the internal face of the plates is provided with raised asperities
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
A system for gripping spinous processes, characterized in that it comprises a first plate (1) and a second plate (20), which are installed face to face, and a shaft (3), which is installed approximately perpendicularly with respect to the two plates (1, 20) and passes at least partially through one of them, the plates (1, 20) comprising an inner face and an outer face, in that a surface of the inner face of the plates (1, 20) is provided with raised roughening features (6), in that the first plate (1) is movable relative to the second plate (20), in that the first plate (1) is fixed in translation with respect to the shaft (3), and in that the shaft (3) and the second plate (20) form a non-return pawl mechanism comprising a series of notches that cooperate with the non-return pawl mechanism such that the movement of the plates (1, 20) toward each other is irreversible without external aid, as a consequence of which spinous processes can be effectively gripped between the two plates (1, 20).