Spinal Stabilizing Collar with Anti-Torque Driver
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Solution Overview
Problem
Conventional spinal stabilizing systems face difficulties in screw alignment and removal due to the need for thin drivers, tissue growth over screw heads, and irregular seating of rods, leading to weak connections and unwanted stress on the spine.
Innovation Solution
The system features a collar with a polygonal exterior surface for easy engagement with drivers, a pin to facilitate rotation and pivotability, and an anti-torque device that minimizes stress on the spine by stabilizing the collar during rod insertion and tightening.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a polygonal socket on the screw head is used for driver engagement, then screw alignment and installation are improved, but the driver must be thin and elongated making it difficult and awkward to use
Solution Approach 1:
The driver is segmented into a handle portion and a working end portion connected by a flexible element, allowing the driver to bend and adapt to access constraints while maintaining engagement with the polygonal socket
Solution Approach 2:
The driver incorporates a flexible element that allows it to dynamically change its configuration from straight to bent, enabling the surgeon to navigate around obstacles and achieve proper screw alignment without requiring a perfectly straight access path
2Duration of action of stationary object
If the screw remains implanted for an extended period, then spinal stabilization is maintained, but tissue and bone grow over the screw head making removal difficult
Solution Approach 1:
The driver is designed as a removable, separate tool that can be reinserted through the same access path for removal operations, separating the installation and removal functions from the screw itself
Solution Approach 2:
The flexible driver acts as an intermediary tool that can access the screw head through tissue pathways, allowing removal without requiring direct exposure of the screw head that would be needed if tissue had grown over it
3Ease of operation
If the tubular body is pivoted to receive the rod in the transverse passage, then rod installation is enabled, but the rod seats irregularly on the flat head surface creating weak connections and unwanted stress
Solution Approach 1:
The screw head is changed from a flat surface to a rounded, spherical shape that provides a consistent curved seating surface for the rod, ensuring uniform contact and stable connection regardless of the tubular body's rotational position
Solution Approach 2:
The rounded head surface creates an asymmetric contact geometry that naturally guides the rod into a stable seating position, preventing the irregular seating that occurs with flat surfaces when the tubular body is rotated
4Reliability
If the anti-torque device is placed over the rod to stabilize the anchor during nut tightening, then undue stress on the spine is minimized, but the rod being adjacent to bone makes device placement difficult and time-consuming
Solution Approach 1:
The driver is designed to perform multiple functions: it engages the polygonal socket for screw installation, can be bent to access constrained pathways, and serves as the anti-torque stabilization device during nut tightening, eliminating the need for a separate anti-torque device
Solution Approach 2:
The installation driver and anti-torque device functions are merged into a single tool, where the driver's handle portion provides the necessary stabilization during nut tightening without requiring placement over the rod, simplifying the overall procedure
Data Source
AI summary
A spinal stabilizing system includes a collar having a tubular sidewall with an interior surface and an exterior surface, the interior surface at least partially bounding a longitudinal passage extending therethrough. A shoulder radially inwardly projects from a second end of the sidewall so as to at last partially encircle the longitudinal passage. A pair of spaced apart channels transversely extend through the sidewall at the first end thereof. The system further includes a screw having a threaded portion and an enlarged head mounted on the end thereof, the head of the screw resting against the shoulder of the collar so that the head can pivot on the shoulder, a locking slot being formed on the head of the screw. A pin is secured to the collar and projects into the locking slot on the head of the screw such rotation of the collar facilitates rotation of the screw.