Pivotal Bone Anchor With Pre-secured Insert for Spinal Fixation

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Solution Overview

Problem

Current spinal surgery systems lack advanced tools and techniques for further improving surgical spinal procedures, particularly in providing additional stability and flexibility in spinal fixation systems using bone anchors.

Innovation Solution

A pivotal bone anchor assembly featuring a shank sub-assembly with a coupler and a receiver sub-assembly that includes a snap-fit assembly, utilizing a positioner and retainer ring to secure the shank within the receiver, allowing for multi-planar or mono-planar pivoting motion, enhancing the stability and flexibility of spinal fixation systems.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a conventional top-loading screw design is used, then the structural simplicity is maintained, but the angular adjustment capability and flexibility are limited

Engineering Contradiction:

Improveangular adjustment capabilityVSAvoidreceiver sub-assembly complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The receiver sub-assembly is divided into separate functional components: a receiver body, a positioner, a retainer ring, and a coupler. This segmentation allows each component to perform its specific function while collectively enabling multi-planar angular adjustment capability without overwhelming complexity in a single monolithic structure.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The positioner is received within the receiver bore, the retainer ring is positioned within the expansion chamber of the receiver, and the coupler is uploaded through the receiver bottom opening. These nested arrangements allow compact integration of multiple adjustment mechanisms within the receiver structure, enabling angular adjustment capability while maintaining reasonable overall device complexity.

Inventive Principle:

Principle #7Nested doll (Nesting)

2Reliability

If multiple separate components are used for the receiver sub-assembly, then the angular adjustment and locking functionality is enhanced, but the assembly complexity increases

Engineering Contradiction:

Improvelocking reliabilityVSAvoidnumber of components

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The positioner is pre-positioned within the receiver bore and the retainer ring is pre-positioned within the expansion chamber before the shank sub-assembly is uploaded. This preliminary arrangement ensures that when the shank is inserted, the positioner and retainer ring are already in place to provide reliable locking engagement, reducing the need for additional locking steps or components.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The retainer ring automatically engages with the coupler's circumferential locking groove when the shank sub-assembly is uploaded through the receiver bottom opening. This self-locking mechanism provides reliable locking without requiring additional locking components or complex assembly steps, as the retainer ring and coupler work together to secure the shank in place.

Inventive Principle:

Principle #25Self-service

3Productivity

If a snap-fit connection is used to secure the shank, then the assembly speed is improved, but the precision of angular alignment may be compromised

Engineering Contradiction:

Improveassembly speedVSAvoidangular alignment precision

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The positioner acts as an intermediary element between the receiver and the shank sub-assembly. It is received within the receiver bore and provides a precise reference surface that guides the angular alignment of the shank while enabling quick snap-fit assembly. The positioner ensures accurate angular positioning without requiring complex precision fastening mechanisms.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The traditional precision mechanical alignment system is replaced with a snap-fit connection mechanism that uses elastic deformation and friction to achieve both speed and precision. The retainer ring and coupler engagement provides sufficient holding force while the positioner maintains angular alignment, eliminating the need for complex precision fastening mechanisms.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS20240423683A1Pivotal bone anchor assembly with pre-securement of an insert into a receiver

Publication Date: 2024.12.26 JACKSON CORP

AI summary

A medical implant assembly includes a shank having a head and an anchor portion, and a receiver having upright arms defining an open channel extending between front and back faces for receiving the rod, and a base defining the lower portion of a central bore for receiving the head of the shank upon its uploading through a bottom opening. The central bore further includes at least one non-resilient inwardly-protruding structure preformed therein and extending circumferentially around the central bore between vertical planar surfaces located adjacent the front and back faces of the receiver. The assembly also includes an insert having a saddle surfacing for receiving the rod, a lower surface for engaging the head of the shank, and outward-facing side surfaces disposed adjacent to and below the inwardly-protruding structures so as to limit vertical movement of the insert within the central bore prior to and during the uploading of the head of the shank into the lower portion of the central bore through the bottom opening.