Post-Bone-Grafting Expandable Cage for Endoscopic Size Adjustment
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Solution Overview
Problem
Existing interbody cages are difficult to adjust in size continuously, making it challenging to place large cages endoscopically and often result in insufficient bone grafting due to the need for bone grafting within a fixed volume, affecting fusion efficacy.
Innovation Solution
A post-bone-grafting expandable cage with a height-adjustable design, featuring a main body, blade assembly, and pushing assembly, allowing for expansion and a large bone grafting chamber, facilitated by a threaded rod and U-shaped base mechanism, enabling easy filling of autologous and allogeneic bone post-implantation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conventional fixed-size cage is used, then the structure is simple and easy to manufacture, but it is difficult to achieve continuous adjustment of size and cannot accommodate large cages under endoscope channel
Solution Approach 1:
The cage employs an expandable structure with a pushing assembly that includes a threaded rod and U-shaped base mechanism, allowing the cage to dynamically change its size from a compressed state for endoscopic insertion to an expanded state for optimal bone grafting volume. The blade assembly can be pushed outward to expand the cage dimensions after implantation.
Solution Approach 2:
The cage is divided into functional modules including a main body, blade assembly, and pushing assembly. This segmentation allows independent optimization of each component - the main body provides structural integrity, the blade assembly enables expansion, and the pushing assembly facilitates size adjustment, thereby achieving adaptability without excessive overall complexity.
2Quantity of substance
If bone grafting is performed in a fixed-volume chamber, then the grafting process is simple, but the bone quantity implanted becomes insufficient and fusion effect is affected
Solution Approach 1:
The bone grafting chamber volume is made dynamic through the expandable cage structure. After implantation, the cage is expanded using the pushing assembly, which increases the chamber volume and allows sufficient bone grafting quantity to be implanted, directly addressing the insufficiency problem of fixed-volume chambers.
Solution Approach 2:
The cage expansion mechanism adds a dimensional aspect to the bone grafting chamber - transitioning from a fixed three-dimensional volume to an expandable volume with additional spatial capacity. This dimensional change enables sufficient bone quantity to be accommodated while maintaining ease of operation through the mechanical expansion mechanism.
3Volume of stationary object
If a large cage is placed endoscopically, then sufficient bone grafting space is achieved, but it is difficult to place large cages under endoscope channel
Solution Approach 1:
The cage utilizes a dynamic size transformation capability, being inserted in a compressed low-volume state through the endoscope channel, then expanded in situ to achieve the required large bone grafting chamber volume. This dynamic size change resolves the contradiction between large final volume and small insertion profile.
Solution Approach 2:
The blade assembly is nested within the main body in a compact configuration for endoscopic insertion, similar to a nested doll structure. After placement, the nested components are deployed outward to achieve the full expanded size, enabling large cage volume to be placed through small endoscope channels.
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 expandable cage ensures sufficient bone grafting, enhances fusion efficacy, and facilitates accurate endoscopic operation by providing a large opening for bone filling and a sealed chamber for confinement.
Implementation Method 1
a threaded section of the threaded rod extends out of an end face of the first U-shaped base, a square cylindrical section of the threaded rod penetrates the first U-shaped base
Implementation Method 2
the threaded section of the threaded rod being threadedly matched with the threaded through-hole, and the first U-shaped base being provided in a fitting manner with the blade assembly
Implementation Method 3
an elastic piece integrally connected to the arc-shaped plate, the elastic piece being interference-fitted with a fitting groove
Implementation Method 4
an end cover is interference-fitted on one end face of the main body
Data Source
AI summary
A post-bone-grafting expandable cage includes a main body, a blade assembly fitted to the main body, and a pushing assembly fitted to the blade assembly, wherein an end cover is interference-fitted on one end face of the main body. The main body comprising a screw section, a side section integrally connected to two ends of the screw section respectively, and an opening section integrally connected to the side section. The pushing assembly includes a first U-shaped base and a threaded rod fixedly connected to the first U-shaped base. The threaded section of the threaded rod extends out of an end face of the first U-shaped base, a square cylindrical section of the threaded rod penetrates the first U-shaped base. The threaded section of the threaded rod is threadedly matched with the threaded through-hole, and the first U-shaped base is provided in a fitting manner with the blade assembly.