Dynamic Interspinous Device Resolving Point Loading
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Solution Overview
Problem
Current interspinous process devices for treating lumbar spinal stenosis often cause point loading on spinous processes, leading to excessive subsidence or fracture, especially in osteoporotic bones, and restrict patient movement due to their rigid design.
Innovation Solution
An interspinous process device featuring a pair of superior and inferior plates connected by a joint that allows relative movement, such as channels, a universally directional capsule, spring joint, or ball joint, with spikes for fixation and an optional spacer to distribute stress, enabling natural spinal motion while maintaining decompression.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a hard material spacer is used in the interspinous process device, then the device can maintain separation between vertebral segments, but point loading occurs causing excessive subsidence or fracture of the spinous process
Solution Approach 1:
The device transitions from a uniform hard spacer to a composite structure with a resilient material body providing distributed contact surfaces, while maintaining structural integrity through the resilient material's inherent properties. This local quality change eliminates point loading while preserving separation function.
Solution Approach 2:
The device employs composite construction by integrating resilient material (such as polyethylene or rubber) with structural components, creating a hybrid spacer that combines the load-distributing properties of resilient materials with the structural support needed for vertebral separation.
2Stability of the object's composition
If a rigid interspinous process device is implanted, then stability between vertebral segments is achieved, but patient freedom of movement is unduly restricted
Solution Approach 1:
The device replaces rigid static structures with dynamic resilient components that can deform and adapt to physiological movements. The resilient material allows the device to flex and move with the spine during normal activities while maintaining vertebral separation and stability.
Solution Approach 2:
The device changes the mechanical parameters of the spacer from rigid to resilient, allowing controlled deformation under physiological loads. This parameter change enables the device to accommodate dynamic spinal movements while maintaining structural integrity and vertebral separation.
3Reliability
If the spinous process is osteoporotic, then the bone is more vulnerable to fracture, but the risk of fracture increases when the spine is in extension with a hard spacer
Solution Approach 1:
The resilient material spacer acts as a pre-positioned cushion that absorbs and distributes mechanical loads before they can concentrate on the osteoporotic spinous process. This beforehand cushioning protects vulnerable bone during extension movements when fracture risk is highest.
Solution Approach 2:
The device applies local quality change by using resilient material specifically at the contact surfaces with the spinous process, providing targeted protection to osteoporotic bone while maintaining overall device functionality for vertebral separation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The device minimizes point loading on spinous processes, reduces the risk of fracture, and allows greater freedom of movement by accommodating natural spinal biomechanics, ensuring effective pain relief and stability without relying on hard spacers.
Implementation Method 1
a spring joint, allowing relative movement between the superior plates and inferior plates
Implementation Method 2
a ball joint, allowing relative movement between the superior plates and inferior plates
Data Source
AI summary
Medical devices for the treatment of spinal conditions are described herein. The medical device includes a pair of superior plates with spikes adapted to be embedded in a superior spinous process and a pair of inferior plates with spikes adapted to be embedded in an adjacent inferior spinous process. The superior plates and inferior plates are connected to each other in such a way as to allow relative motion therebetween. A spacer may be disposed between the adjacent spinous processes.