Rotatable Interspinous Spacer With S-Shaped Members

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Solution Overview

Problem

Existing spinal implants for alleviating spinal stenosis, such as those disclosed in US Patents 6,068,630 and 5,645,599, face challenges in sizing, invasive surgical techniques, and lack of natural physiologic rotational movement and post-operative adjustment, with adhesive bonding issues leading to potential migration of components.

Innovation Solution

An expandable interspinous spacer with S-shaped members that can be laterally inserted and pivotally rotated to securely lock between adjacent spinous processes, allowing for minimally invasive insertion and adjustment, featuring central elements and concave arms to bear against spinous processes, with locking mechanisms for stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a Zuchermann implant with integral wings is used, then spinal distraction is achieved, but difficulty in sizing the central body independently and increased invasiveness occur

Engineering Contradiction:

Improvespinal distractionVSAvoidsizing independence

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The implant is divided into separate components: a central body and lateral wings that can be independently sized and assembled. This segmentation allows the central body to be sized independently of the lateral wings, resolving the contradiction between achieving spinal distraction and enabling independent sizing during manufacturing and surgical procedures.

Inventive Principle:

Principle #1Segmentation

2Reliability

If a Zuchermann implant with expansive geometry is used, then spinal distraction is achieved, but muscle mass and soft tissue conservation are compromised

Engineering Contradiction:

Improvespinal distractionVSAvoidmuscle mass

Core Design Contradiction:

ReliabilityVSLoss of substance

Solution Approach 1:

The implant incorporates flexible elements that allow dynamic adaptation to the patient's anatomy. The flexible body can conform to the interspinous space while maintaining spinal distraction, reducing the need for expansive rigid geometry that would compromise surrounding muscle mass and soft tissue.

Inventive Principle:

Principle #15Dynamics

3Stability of the object's composition

If a Samani flexible horseshoe-shaped device is used, then self-limiting flexibility is provided, but natural physiologic rotational movement and post-operative adjustment are not enabled

Engineering Contradiction:

ImproveflexibilityVSAvoidrotational movement

Core Design Contradiction:

Stability of the object's compositionVSAdaptability or versatility

Solution Approach 1:

Inventive Principle:

Principle #15Dynamics

4Device complexity

If adhesive bonding is used to attach the bearing cushion to the horseshoe element, then assembly is simplified, but component migration occurs

Engineering Contradiction:

ImproveassemblyVSAvoidcomponent stability

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent replaces adhesive bonding with a mechanical interference fit and friction-based retention system. The bearing cushion is retained through precise dimensional tolerances and friction between mating surfaces, eliminating the need for adhesives and preventing component migration while maintaining assembly simplicity.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentEP1968495B1Rotatable interspinous spacer

Publication Date: 2013.05.08 DEPUY SPINE INC

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AI summary

An interspinous spacer having opposed, pivotally connected s-shaped members that can enter the insterspinous space in an initial state state and then rotate to a final state to secure the implant to the adjacent interspinous processes.