Interspinous Spacer Actuator Locking for Weld-Free Arm Deployment
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Solution Overview
Problem
Existing interspinous spacers for treating spinal stenosis often require a weld between the body and actuator screw, which can lead to structural weaknesses and complications during deployment and retraction of the arms.
Innovation Solution
An interspinous spacer design utilizing an actuator screw with complementary threading in a channel, a wedge, and arms that rotate via longitudinal movement of the screw, with locking mechanisms to secure the arms in deployed or retracted positions, eliminating the need for a weld and enhancing stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a weld is used to join the actuator screw to the body, then structural strength is improved, but structural weaknesses and complications during deployment and retraction occur
Solution Approach 1:
The device is divided into separable components (actuator screw, body, arms) connected through threaded engagement rather than permanent welding. This segmentation allows independent movement and deployment of components while maintaining structural integrity through precision threading and locking mechanisms.
Solution Approach 2:
The welding process is replaced with a mechanical threading and locking system. The actuator screw threads into the body, and deployment is achieved through mechanical rotation and engagement of locking features, eliminating the need for thermal welding and its associated complications.
2Ease of operation
If the arms are made rotatable for deployment and retraction, then ease of operation is improved, but structural stability deteriorates
Solution Approach 1:
The arms are designed with dynamic characteristics, allowing rotation from a retracted to a deployed position through the actuator screw mechanism. The system transitions from a stable locked state during insertion to a dynamically adjustable deployed state for treatment, then back to a stable locked state for retraction.
Solution Approach 2:
The actuator screw serves as an intermediary mechanism between the operator's rotational input and the arms' deployment motion. It converts rotational movement into longitudinal movement that actuates the wedge, which in turn rotates the arms, providing controlled and stable deployment while maintaining structural integrity.
3Reliability
If locking mechanisms are added to secure arms in deployed position, then reliability is improved, but device complexity increases
Solution Approach 1:
The locking function is merged with the actuator screw mechanism itself. The actuator screw incorporates threading, wedge engagement, and locking features as integrated components rather than separate systems, achieving reliable position locking while minimizing overall device complexity.
Solution Approach 2:
The locking mechanism operates through self-engagement features that automatically secure the arms in their deployed position. The wedge and actuator screw design allows the system to lock itself through the natural forces applied during deployment, eliminating the need for additional active locking components or complex control systems.
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 design provides secure and reliable deployment and retraction of arms, ensuring proper spinal canal spacing and pain relief by avoiding nerve impingement, with improved structural integrity and ease of use.
Implementation Method 1
an actuator screw including a proximal end and a shaped cavity in the proximal end, wherein the shaped cavity is configured for receiving a bit of a driver tool having a complementary shape for rotating the actuator screw using the driver tool, wherein at least a portion of the actuator screw and the channel of the body include complementary threading
Implementation Method 2
a wedge coupled to the actuator screw, wherein, as the actuator screw is rotated using the driver tool, the actuator screw and the wedge move longitudinally relative to the body
Implementation Method 3
a first arm and a second arm, wherein the first and second arms are rotatably coupled to the distal portion of the body and configured for rotating in response to longitudinal movement of the wedge, wherein the actuator screw, wedge, first arm, and second arm are configured, upon rotation of the actuator screw in a first direction, to rotate the first and second arms from an implantation position
Data Source
AI summary
An interspinous spacer includes an actuator screw having a proximal end and a shaped cavity in the proximal end, where the shaped cavity is configured for receiving a bit of a driver tool having a complementary shape for rotating the actuator screw using the driver tool; a wedge coupled to the actuator screw, wherein, as the actuator screw is rotated using the driver tool, the actuator screw and the wedge move longitudinally relative to the body; and a first arm and a second arm, wherein the first and second arms are rotatably coupled to the distal portion of the body and configured for rotating in response to longitudinal movement of the wedge. The interspinous spacer may include locking inserts or a locking ring to resist rotation of the actuator screw absent the driver tool.