Spinal Connection Assembly Side-Loading Rod Capture

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Solution Overview

Problem

Current spinal connection assemblies for posterior spinal fixation are limited by their geometry, which results in increased prominence, restricted motion, and torsional stresses due to the tulip design, and require preloading and torque to secure the rod, making them unsuitable for angled screw placements like facet or laminopedicle screws.

Innovation Solution

A low-profile spinal connection assembly with a housing that allows for significant pivotal motion in multiple planes, featuring a capture mechanism with arcuate guide surfaces and spring clips to secure posterior spinal connectors and rods without the need for preloading or excessive torque, enabling easy alignment and secure attachment without prominence.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a tulip design is used to couple the screw to the transverse rod, then the screw can be secured to the rod, but the distance between the screw head and the top of the mechanism increases causing prominence and the rod must be forced into place requiring preload and torque

Engineering Contradiction:

Improvesecurement of rod to screwVSAvoidprominence, preload, and torque on pedicle screw

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent transitions from a traditional tulip design where the rod connects to the top of the screw to a side-loading mechanism where the rod connects to the side of the screw. This dimensional change allows the rod to be loaded horizontally into a recess in the screw head rather than vertically into a tulip, eliminating the need for prominence and reducing preload and torque requirements

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The patent extracts the rod loading function from the tulip mechanism and places it directly in the screw head recess. By removing the intermediate tulip structure, the design eliminates the geometric constraints that cause prominence and the need for forcing the rod into place with preload and torque

Inventive Principle:

Principle #2Taking out (Extraction)

2Device complexity

If a rigid single structure with integral recess is used to secure the rod, then the structure is simplified, but the same problems of prominence and restricted motion remain

Engineering Contradiction:

Improvestructure simplificationVSAvoidprominence and restricted rotation

Core Design Contradiction:

Device complexityVSObject-affected harmful factors

Solution Approach 1:

The patent introduces dynamic capabilities to the screw head design by allowing the rod to pivot and rotate within the recess. The side-loading mechanism permits significant ranges of pivotal motion including pivotal motion in at least one plane of at least approximately 180°, in a second plane of at least approximately 120°, and permitting pivotal motion about the axis of the screw head, transforming the rigid structure into a dynamic, multi-axial system

Inventive Principle:

Principle #15Dynamics

3Reliability

If traditional tulip devices with thirty degree cone geometry are used, then the rod can be secured, but only limited rotation is permitted and the physician must use a persuader tool causing preload and torque

Engineering Contradiction:

Improverod captureVSAvoidrod insertion ease and surgical trauma

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The patent fundamentally changes the geometric parameters of the rod-screw interface. Instead of a thirty-degree conical tulip geometry that restricts motion, the design uses a side-loading recess that accommodates significant pivotal motion in multiple planes. This parameter change eliminates the need for persuader tools and reduces surgical trauma by allowing smooth rod insertion without forcing or torque

Inventive Principle:

Principle #35Parameter changes

4Adaptability or versatility

If facet screws or laminopedicle screws are placed at sharp angles, then angled screw placements are achieved, but traditional tulips cannot be used and the construct becomes incredibly prominent

Engineering Contradiction:

Improveangled screw placement capabilityVSAvoidprofile prominence

Core Design Contradiction:

Adaptability or versatilityVSShape

Solution Approach 1:

The patent creates a universal screw head design with side-loading capability that works for all screw types and angles. The recess in the screw head is configured to receive the rod regardless of the screw's orientation or angle of placement. This multi-functional design eliminates the prominence problem associated with traditional tulips while maintaining adaptability for facet screws, laminopedicle screws, and other angled placements

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS8951289B2Spinal connection assembly

Publication Date: 2015.02.10 TOTAL CONNECT SPINE

AI summary

A spinal connection assembly for use with a posterior spinal connector having a head and a groove adjacent the head for providing a neck and a connector element to treat a spine of a mammalian body is provided. The assembly includes a housing having first and second side portions and a top and a bottom. The first side portion is provided with a bottom-facing first opening adapted for receiving the posterior spinal connector. A capture mechanism is carried by the first side portion for engaging the head of the posterior spinal connector and extends at least partially into the groove so as to capture the head within the first opening. The second side portion is provided with a second opening. A securement mechanism is carried by the second side portion for capturing the connector element within the second opening.