Spine Disc Replacement Compliant Bag
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Solution Overview
Problem
Current intervertebral disc implants do not effectively provide varying resistance to rotation and translation between vertebral bodies, limiting natural motion and stability in the spine, and often require pre-filling with synthetic bone graft substitutes which may not fully restore anatomical height and mobility.
Innovation Solution
An intervertebral implant featuring a compliant bag with an expandable design, containing fill particles that increase in height and resistance to motion as more particles are added, allowing for adjustable resistance to rotation and translation, and potentially incorporating endplates and securement members for fixation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If traditional rigid intervertebral implants are used, then structural stability is provided, but natural spinal motion and varying resistance to rotation are limited
Solution Approach 1:
The patent applies parameter changes by using fill particles with varying physical properties (size, shape, material composition) within the compliant bag to dynamically adjust the resistance to rotation and translation. The particles can be arranged in different configurations and volumes to provide varying levels of resistance depending on the direction and magnitude of motion, thereby resolving the contradiction between stability and adaptability.
Solution Approach 2:
The patent employs composite materials by combining the compliant bag (flexible membrane) with fill particles (various materials such as bone graft substitutes, ceramics, or polymers) to create a hybrid structure. This composite system provides both the structural stability of the particles and the adaptability of the compliant bag, allowing varying resistance to rotation while maintaining spinal stability.
2Length of moving object
If vertebral bodies are distracted to insert implant, then clearance for insertion is achieved, but implant height may not fully restore anatomical disc height
Solution Approach 1:
The patent applies dynamics by using an expandable compliant bag that can be filled with particles to achieve the desired height. The bag can be expanded intraoperatively to precisely match the anatomical disc height, allowing for dynamic adjustment rather than relying solely on pre-set implant dimensions. This resolves the contradiction between insertion clearance and precise height restoration.
Solution Approach 2:
The patent applies preliminary action by pre-filling the compliant bag with bone graft substitutes or fill particles before implantation. This preliminary filling allows the implant to be prepared with appropriate height and volume, which can then be precisely adjusted during insertion to restore anatomical disc height accurately.
3Adaptability or versatility
If compliant bag with fill particles is used, then adjustable resistance to motion is provided, but device complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the implant into two functional components: the compliant bag (outer structure) and the fill particles (inner material). This segmentation allows each component to perform its specific function independently - the bag provides containment and compliance while the particles provide resistance to motion - thereby achieving adaptability without excessive overall complexity.
Solution Approach 2:
The patent uses the compliant bag as an intermediary between the fill particles and the vertebral bodies. The bag mediates the interaction by containing the particles while allowing controlled deformation, thereby simplifying the overall structure compared to directly exposing particles to mechanical loads. This intermediary approach reduces complexity while maintaining adjustable resistance to motion.
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 compliant bag design provides adjustable resistance to motion, restoring natural spinal motion and stability while allowing for customizable height and rigidity, potentially reducing the need for pre-filling with synthetic bone graft substitutes.
Implementation Method 1
a compliant bag that includes an outer wall that defines a superior surface configured to be disposed adjacent the superior vertebral body, and an inferior surface configured to be disposed adjacent the inferior vertebral body, and an internal void
Implementation Method 2
The fill particles touch each other in the internal void such that the compliant bag provides a first resistance to relative rotation of the superior and inferior surfaces when the internal void has a first volume of fill particles, and the fill particles engage each other such that the compliant bag provides a second resistance to relative rotation of the superior and inferior surfaces
Data Source
AI summary
An intervertebral implant can include a pair of endplates between which is coupled a bag that is filled or is fillable with small beads or particles having smooth exterior geometries. The bead sack implant allows for articulation about various centers of rotation without a predefined neutral position.