Intervertebral Spacer Offset Engagement for Brittle Material Insertion
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Solution Overview
Problem
Existing spinal implants and insertion tools face challenges during insertion, particularly when using materials that are prone to fracture under high stresses, as the forces applied during insertion can damage the implant or inhibit the use of certain materials, especially in procedures like transforaminal approaches where non-longitudinal forces are applied.
Innovation Solution
The design includes an implant with an offset tool engagement configuration and an insertion tool with a movable gripping end that can axially displace to securely engage and insert the implant between vertebrae, minimizing trauma and allowing for the use of materials that might otherwise fracture, such as bone or polymers, by distributing forces effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If high forces are applied during implant insertion, then the implant can be inserted into the disc space, but the implant may fracture or crumble especially when made from bone, polymers, or coral
Solution Approach 1:
The patent introduces an intermediary engagement surface between the insertion tool and the implant. This engagement surface acts as a mediator that distributes the insertion forces across a larger area of the implant, preventing stress concentration at single points. The tool engagement surface on the implant body provides a dedicated interface that allows the insertion tool to apply forces without directly transmitting them to weak areas of the implant structure.
Solution Approach 2:
The patent modifies the physical parameters of the implant by adding a specifically designed engagement surface with particular geometric characteristics. This engagement surface changes the way forces are applied to the implant during insertion, transforming the stress distribution pattern from concentrated to distributed. The offset axis configuration further modifies the force application parameters to avoid direct longitudinal loading that could cause fracture.
2Ease of operation
If non-longitudinal forces are applied to turn the implant in the disc space during transforaminal approach, then the implant can achieve desired alignment, but the forces may damage the implant or inhibit the use of certain materials
Solution Approach 1:
The engagement surface serves as an intermediary interface that enables the insertion tool to apply non-longitudinal forces for implant positioning and orientation. This mediator allows the surgeon to manipulate the implant into the desired alignment within the disc space without directly applying damaging forces to the implant body. The offset axis configuration provides a mechanical advantage that facilitates rotational and positioning maneuvers.
Solution Approach 2:
The patent segments the implant into distinct functional regions: the implant body that interfaces with bone tissue, and the engagement surface that interfaces with the insertion tool. This segmentation allows the implant body to be made from fragile materials like bone, coral, or polymers while the engagement surface provides a robust interface for tool manipulation. The separated functions enable independent optimization of each region for its specific purpose.
3Ease of operation
If the implant interface with the insertion tool concentrates forces on weak areas, then the implant can be grasped during insertion, but the implant may crack or break
Solution Approach 1:
The patent changes the geometric parameters of the implant by adding an engagement surface with specific dimensions and orientation. This engagement surface increases the contact area between the implant and insertion tool, fundamentally changing the stress distribution parameters from concentrated point loads to distributed surface loads. The offset axis configuration further modifies the force application parameters to eliminate stress concentration at critical implant locations.
Solution Approach 2:
The engagement surface is pre-formed on the implant body before insertion, creating a prepared interface that anticipates the force application during the insertion process. This preliminary action ensures that when the insertion tool grasps the implant, the forces are immediately distributed across the pre-configured engagement surface rather than concentrating on weak areas of the implant body.
Data Source
AI summary
An implant for placing in the spine is disclosed. The implant has a tool engaging surface on its trailing end configured for intimate engagement with an insertion tool. The insertion tool configuration is particularly suited for implants made of brittle materials including bone and bone substitutes. Also disclosed is an insertion tool having a gripping end adapted for intimate engagement with an implant. In one embodiment, the insertion tool is operable by axial movement of one gripping arm with respect to the other.