Unilateral Inter-Spinous Spacer for Spinal Stenosis
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Solution Overview
Problem
Current treatments for spinal stenosis, such as laminectomy and inter-spinous spacers, either compromise spinal mechanics or limit flexion, and prior art spacers are made from materials that may not integrate well with the spinous processes, risking remodeling and loss of distraction.
Innovation Solution
An inter-spinous spacer affixed to only one spinous process, designed to fuse with it over time, using materials like allograft bone or PEEK, with fusion-promoting materials and mechanisms to allow spinal flexion while maintaining distraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an inter-spinous spacer is affixed to both superior and inferior spinous processes, then the spacer provides stable support and maintains distraction, but both flexion and extension of the spine are limited
Solution Approach 1:
The spacer system is segmented into two distinct attachment points: one end is affixed to the superior spinous process while the other end remains free or is affixed to the inferior spinous process. This segmentation allows the spacer to provide stable support at the affixed end while permitting spinal flexion at the unaffixed end, resolving the contradiction between stability and flexibility.
Solution Approach 2:
The spacer design transitions from a static, fully constrained structure to a dynamic system where one end can move relative to the spinous process. This dynamic configuration enables the spacer to maintain distraction and provide support while allowing the spine to flex naturally, addressing both reliability and ease of operation requirements.
2Strength
If prior art inter-spinous spacers are made from materials like metal, then the spacer provides structural strength, but the spinous processes may remodel around the spacer and lose their ability to distract
Solution Approach 1:
The spacer is constructed from materials that are substantially similar to the spinous processes themselves, such as cortical or cancellous bone or PEEK. This material homogeneity prevents the spinous processes from remodeling around the spacer, as the body does not recognize the spacer as a foreign object requiring encapsulation. The spacer maintains its structural strength while ensuring long-term reliability of distraction.
Solution Approach 2:
The spacer may utilize composite material structures combining cortical and cancellous bone or PEEK with porous structures. These composite materials provide both the necessary structural strength for load-bearing and biocompatibility to prevent remodeling, resolving the contradiction between strength and reliability.
3Object-affected harmful factors
If a laminectomy is performed to relieve pressure on the spinal cord, then the spinal canal is enlarged and pressure is reduced, but the mechanical integrity of the spine is compromised
Solution Approach 1:
Instead of removing the lamina (as in laminectomy), this invention extracts only the necessary portion of the inter-spinous ligament and places a spacer between the spinous processes. This approach relieves pressure on the spinal cord by distracting the spinous processes and enlarging the spinal canal, while preserving the lamina and maintaining the mechanical integrity of the spine.
Solution Approach 2:
The spacer acts as an intermediary device that maintains the distraction between spinous processes without requiring removal of structural bone elements. This mediator provides the necessary space relief while the intact lamina preserves spinal mechanical integrity, resolving the contradiction between pressure relief and structural strength.
Data Source
AI summary
This invention relates generally to spine surgery and, in particular, to methods and apparatus for treating spinal stenosis. The methods comprising gaining access to an interspinous space, abrading a portion of the superior spinous process, inserting an implant into the interspinous process space, verifying the position of the implant by observing the position of three radio-opaque markers embedded in the implant, and coupling the implant to the superior spinous process.