Cannulated Anchoring Screw for Spinal Electrode Fixation
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Solution Overview
Problem
Current methods for implanting electrode arrays near the dorsal root ganglion for spinal nerve stimulation face challenges such as electrode migration, anatomical variability, and the need for precise placement, which affects efficacy and safety.
Innovation Solution
A minimally-invasive technique using a cannulated anchoring screw and a nickel-titanium alloy stylet to securely anchor the electrode array to the pars interarticularis, allowing for precise placement adjacent to the dorsal root ganglion and reducing migration risks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If percutaneous injection is used to place the electrode through the intervertebral foramen, then the electrode can be positioned adjacent to the spinal nerve root, but the electrode becomes suspended without firm fixation and is prone to migration
Solution Approach 1:
The anchor is inserted into the pars interarticularis bone before the electrode is placed. This preliminary anchoring action creates a fixed reference point that prevents subsequent electrode migration while maintaining precise positioning adjacent to the dorsal root ganglion.
Solution Approach 2:
The anchor acts as an intermediary element between the electrode and the bone. It provides firm fixation to the pars interarticularis while allowing the electrode to be positioned precisely adjacent to the spinal nerve root, resolving the contradiction between stability and precision.
2Ease of operation
If the electrode array is placed on the exterior of the vertebrae running parallel to the spinal column, then the placement is simpler, but increased energy is required to achieve desired stimulation and energy sources deplete quickly
Solution Approach 1:
The patent replaces the mechanical placement method (exterior vertebral placement) with a neuroanatomical-based placement method. By using fluoroscopic guidance and anatomical landmarks to position the electrode adjacent to the dorsal root ganglion, the system achieves more efficient energy delivery without requiring excessive energy consumption.
3Reliability
If surgery is performed to anchor the electrode, then firm fixation can be achieved, but the procedure carries surgical risks and time constraints and may not be suitable for certain patients
Solution Approach 1:
The patent extracts the anchoring function from complex surgical procedures and isolates it into a simple percutaneous insertion of an anchor into the pars interarticularis. This extraction allows firm fixation to be achieved through a minimally invasive approach that avoids the risks and complexities of traditional surgery.
Solution Approach 2:
The anchor is designed as a simple, inexpensive, single-use implant that can be inserted percutaneously. This disposable anchor provides sufficient fixation for the electrode without requiring complex, expensive, or reversible surgical anchoring systems.
4Reliability
If an anchoring hook is used to engage the fibrous fascia layer, then the electrode can be secured, but the hook must pierce the nerve fascia layer which presents risk of nerve damage
Solution Approach 1:
The patent introduces an intermediary structure (the anchor with collet and locking cap) that mediates between the electrode and the bone. This intermediary system secures the electrode through bone anchoring rather than directly engaging or piercing the nerve fascia, thereby eliminating the risk of nerve damage while maintaining anchoring reliability.
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
This method enables reliable and stable electrode placement near the dorsal root ganglion, reducing migration and improving the efficacy of spinal nerve stimulation while minimizing radiation exposure and surgical risks.
Implementation Method 1
a cannulated anchoring screw and a nickel-titanium alloy stylet to securely anchor the electrode array
Data Source
AI summary
A system and method for anchoring an electrode that stimulates a dorsal root ganglion. The anchoring device includes a screw, collet, and locking cap. The screw is inserted into bone of the pars interarticularis and the electrode is inserted through the screw and positioned next to the dorsal root ganglion for stimulation. The screw includes a recess that is shaped to fit the collet. The collet has flexible arms. When assembled, the locking cap forces the collet into the recess thereby moving the flexible arms inward radially, impinging on the electrode and holding the electrode in place adjacent the dorsal root ganglion.