Distraction Screw Spinal Alignment and Disc Height Restoration
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Solution Overview
Problem
Current fixation devices for vertebrae fusion and distraction fail to effectively maintain natural spinal alignment and restore disc height while resisting shear forces and allowing for axial distraction without lateral translation.
Innovation Solution
A distraction screw with a proximal and distal portion secured to adjacent vertebrae and an intermediate portion positioned in the intervertebral space, featuring semi-rigid and pivoting segments with threaded designs and cannulated linkages to enable axial distraction and bone purchase, allowing for bone growth and fusion materials to be inserted.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a rigid fixation device is used to fuse vertebrae, then spinal stability is improved, but the ability to maintain natural spinal alignment and restore disc height is compromised
Solution Approach 1:
The fixation device is divided into multiple segments: a proximal screw portion, a distal screw portion, and an intermediate distraction portion. This segmentation allows each component to perform its specific function - the screw portions provide stable anchorage while the intermediate portion enables alignment restoration and distraction, resolving the contradiction between stability and shape maintenance.
Solution Approach 2:
The intermediate distraction portion incorporates dynamic elements such as threaded mechanisms that allow for controlled distraction and adjustment. This dynamic capability enables the device to restore disc height and maintain natural spinal alignment while still providing overall spinal stability through the anchored screw portions.
2Length of stationary object
If a distraction mechanism is added to the fixation device, then disc height restoration is improved, but device complexity increases
Solution Approach 1:
The distraction mechanism is merged with the fixation screw structure itself rather than being a separate component. The threaded distal portion and intermediate distraction portion are integrated into a single device, allowing disc height restoration functionality to be combined with the fixation function, thereby improving disc height without proportionally increasing overall device complexity.
3Length of stationary object
If the screw is designed to allow axial distraction, then disc height restoration is improved, but resistance to lateral translation is reduced
Solution Approach 1:
Different portions of the screw have different mechanical properties optimized for their specific functions. The proximal and distal screw portions have threaded designs optimized for bone purchase and lateral stability, while the intermediate portion has a distraction-optimized geometry that allows axial movement. This local differentiation enables axial distraction while maintaining resistance to lateral translation through the anchored screw portions.
Data Source
AI summary
A distraction screw includes a proximal portion secured to a first vertebra, a distal portion secured to a second vertebra and an intermediate portion. The intermediate portion is coupled to the proximal and distal portions and is positioned in an intervertebral space. The intermediate portion is configured and adapted to enable distraction of the first vertebra relative to the second vertebra.