Spinal Fixation Device with Dual-Pitch Thread and Locking Mechanism
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Solution Overview
Problem
Current spinal fixation methods face challenges in securely attaching spinal rods to vertebral bodies, especially in osteoporotic bone, where the cancellous bone's porosity compromises screw fixation, and in conditions like scoliosis, where posterior elements provide a stronger point for fixation but require innovative solutions to stabilize the spine effectively.
Innovation Solution
A spinal fixation device featuring a fastener with a threaded portion of varying pitch and a locking mechanism, including a pedicle screw and intralaminar or laminar hooks that engage both the pedicle and vertebral body, providing multiple fixation points and enhanced stability through a combination of pedicle screws and hooks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If screws are inserted through the pedicle and cortical shell into the cancellous center of the vertebral body, then spinal fixation is achieved, but the fixation strength is compromised in osteoporotic bone due to the porous nature of cancellous bone
Solution Approach 1:
The fixation system is divided into multiple independent components: a pedicle screw for cortical bone engagement, a separate bone anchor for cancellous bone engagement, and a connection element linking them. This segmentation allows each component to optimize its fixation strategy for different bone types, with the pedicle screw providing stable cortical fixation and the bone anchor providing distributed cancellous fixation through multiple smaller anchors.
Solution Approach 2:
The bone anchor is designed to be received within the pedicle screw structure, with the connection element nesting both components together. The bone anchor with its multiple smaller anchors is positioned within the broader pedicle screw fixation zone, creating a nested configuration that combines cortical and cancellous bone fixation in a compact integrated system.
2Strength
If posterior elements are used for fixation in scoliosis patients, then stronger fixation points are achieved, but innovative solutions are needed to effectively stabilize the spine
Solution Approach 1:
The combined pedicle screw and bone anchor system serves multiple functions: it provides fixation in both cortical and cancellous bone, accommodates different surgical scenarios (osteoporosis, scoliosis, trauma), and can be used with various connection elements and spinal rods. This multi-functionality allows the same basic fixation construct to address diverse clinical needs without requiring entirely different fixation systems.
Solution Approach 2:
The fixation system combines different material and structural approaches: the pedicle screw utilizes cortical bone engagement with threaded geometry, while the bone anchor employs multiple smaller anchors for cancellous bone distribution. This composite approach integrates two different fixation methodologies into a single system, leveraging the strengths of each approach for optimal overall fixation.
Data Source
AI summary
A spinal fixation device includes a fastener affixable to a vertebral body and an attachment member. The attachment member is adapted for receiving the fastener and engaging a portion of the vertebral body. The fastener includes a shank and a collet. The collet includes a channel for receiving a spinal rod and a locking member.