Coiled Bone Graft Cage With Nested Mesh Containment
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Solution Overview
Problem
Current methods for treating large bone defects with bone grafts often face challenges in maintaining the graft material in place, as it may fall away from the target site before incorporation into the healing bone, and existing devices may not effectively contain the graft material within the bone defect.
Innovation Solution
A graft containment device comprising an outer mesh member coiled about a longitudinal axis that contracts to engage separated bone portions and an inner mesh member that expands within the medullary canal to prevent graft material from passing through, both formed from biodegradable polymers like polycaprolactone, allowing for customization and effective containment of graft material between the outer and inner mesh members.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a mesh container is placed into the target area to contain bone graft material, then the graft material is contained at the location, but the device complexity increases due to the need for additional containment structures
Solution Approach 1:
The patent employs a nested structure where an inner mesh member is positioned within an outer mesh member, creating a containment system where the inner member is surrounded by the outer member. This nested configuration provides redundant containment to prevent graft material displacement while maintaining a relatively simple overall device structure that can be inserted as a unified assembly.
Solution Approach 2:
The containment device is divided into separate functional segments: an outer mesh member that provides primary containment and an inner mesh member that provides secondary containment. This segmentation allows each component to perform its specific containment function independently, improving reliability without requiring a single complex structure.
2Reliability
If PMMA spacers are placed in the target area to form a capsule for bone graft material, then the graft material is contained, but the device complexity increases and requires multiple surgical steps for insertion and removal
Solution Approach 1:
The patent removes the need for removable PMMA spacers by providing permanent mesh containment structures that remain in place during the bone healing process. The mesh members are designed to be biocompatible and can be resorbable, eliminating the need for a second surgical procedure to remove the containment device after graft incorporation.
Solution Approach 2:
The patent employs biodegradable or resorbable mesh materials that gradually degrade as the bone heals and the graft integrates. This eliminates the need for permanent implants or removable spacers, providing temporary containment exactly when needed without requiring future removal surgery.
3Ease of operation
If the outer member is uncoiled to position about separated portions of bone, then the device can be positioned, but the device complexity increases due to the coiled configuration mechanism
Solution Approach 1:
The outer mesh member is designed with a coiled configuration that allows it to dynamically change shape during insertion and positioning. The coil can be uncoiled to navigate through narrow access paths and then expanded to its functional configuration once positioned, providing ease of operation without requiring complex mechanical actuation systems.
Solution Approach 2:
The device utilizes changes in physical parameters, specifically the geometric configuration of the coiled mesh, to transition between a compact insertable state and an expanded functional state. This parameter change approach allows simple positioning without complex mechanisms.
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 effectively maintains graft material in place, promoting bone growth by containing it between the outer and inner mesh members, ensuring successful integration with the bone defect, and can be tailored to specific patient needs through customization.
Implementation Method 1
an outer member formed via an outer mesh sheet biased toward a coiled configuration in which the outer mesh sheet is coiled about a longitudinal axis thereof so that, when the outer member is positioned about separated portions of a target bone in an operative position, the outer member reverts to the coiled configuration and contracts about and engages the separated portions
Implementation Method 2
an inner member formed via an inner mesh sheet coiled about a longitudinal axis thereof, the inner member movable between a first biased coiled configuration and a second coiled configuration, a diameter of the inner member in the first coiled configuration being larger than a diameter of the inner member in the second coiled configuration
Data Source
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AI summary
A device for containing a graft material includes an outer member formed via an outer mesh sheet biased toward a coiled configuration in which the outer mesh sheet is coiled about a longitudinal axis thereof so that, when the outer member is positioned about separated portions of a target bone in an operative position, the outer member reverts to the coiled configuration and contracts about and engages the separated portions. The device also includes an inner member formed via an inner mesh sheet coiled about a longitudinal axis thereof. The inner member is movable between a first biased coiled configuration and a second coiled configuration. A diameter of the inner member in the first coiled configuration is larger than a diameter of the inner member in the second coiled configuration.