Spinal Bone Shim for Pedicle Screw Attachment
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Solution Overview
Problem
Current pedicle screws used in spinal fusion surgeries fail to provide a permanent attachment to the vertebral body, leading to loosening, pulling out, and vertebral fracture due to inadequate surface area interaction with cortical bone, and often result in complications such as vascular and neurological deficits, and require additional surgeries for correction.
Innovation Solution
A spinal bone shim attachment device with a partial shaft and asymmetric tip, featuring a concave surface and bone engaging ridges, is designed to enhance the surface area interaction between the pedicle screw and cortical bone, facilitating permanent attachment and accurate placement, even in cases of improperly formed receiving channels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a pedicle screw is inserted into the vertebral body, then the screw can provide spinal stabilization, but the screw fails to provide permanent attachment due to inadequate surface area interaction with cortical bone, leading to loosening and fracture
Solution Approach 1:
The patent introduces a receiving channel structure that extends in a third dimension (depth into the vertebral body) to increase the surface area for bone-screw interaction. The channel is formed at an angle that allows the screw to engage with cortical bone surfaces that would otherwise be inaccessible, transforming a two-dimensional surface contact problem into a three-dimensional engagement solution.
Solution Approach 2:
The receiving channel acts as an intermediary structure between the screw and the vertebral body. It provides a guided pathway that ensures proper screw positioning while creating a larger interaction surface area. The channel walls provide additional cortical bone contact points that mediate the force transmission between the screw and the vertebral body.
2Ease of operation
If a receiving channel is formed for screw insertion, then the screw placement can be guided, but improper channel formation leads to screw mispositioning and requires additional surgeries for correction
Solution Approach 1:
The receiving channel is formed as a preliminary structure before screw insertion. It is created at a specific angle and depth to pre-establish the optimal pathway for the screw. This preliminary action guides the subsequent screw placement, ensuring that the screw follows the correct trajectory and engages with the appropriate bone surfaces, thereby preventing mispositioning.
Solution Approach 2:
The patent replaces the traditional mechanical piercing tool approach with a controlled channel formation method. Instead of creating a narrow piercing hole that is difficult to control, the channel is formed with specific geometric parameters (angle, depth, diameter) that provide inherent guidance for screw insertion, reducing the skill requirement and improving placement accuracy.
3Productivity
If pedicle screws are used in spinal fusion surgeries, then spinal stabilization can be achieved, but screw failure occurs in approximately 2.5% of cases, resulting in vascular and neurological deficits
Solution Approach 1:
The receiving channel structure provides beforehand cushioning by creating a controlled pathway that protects the screw from mispositioning. The channel is designed with specific dimensions and angles that ensure the screw remains within safe boundaries, preventing it from encroaching on vascular or neurological structures. This protective structure is established before screw insertion, mitigating the risk of harmful effects.
Solution Approach 2:
The receiving channel provides immediate feedback during screw insertion through its geometric constraints. The channel's angle and depth specifications create physical feedback that guides the screw along the correct pathway, allowing the surgeon to verify proper positioning before final insertion. This feedback mechanism reduces the risk of vascular or neurological damage by ensuring the screw remains within safe anatomical boundaries.
Data Source
AI summary
Bone attachment shim device composed of a biomaterial compatible with bone and provides an enhanced surface area on the outer surface of the device for engaging the bone, an enhanced surface area within the device for engaging the bone screw, and is composed of a partial shaft design which is greater than 180 but less than 270 degrees around when viewed in cross section. The device preferably has a biased tip for facilitating placement into bone tissue.