Expandable Spinal Implant with Coupled Gear Mechanism
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Solution Overview
Problem
Existing expandable implants for the spine are prone to sinking into vertebral bodies, disrupting positional stability and statics, especially in cases of osteoporosis, and often have limited expansion capabilities and complex implantation procedures, making them unsuitable for various surgical techniques and bone growth.
Innovation Solution
An expandable implant with a dual adjustment mechanism using coupled gears and a bevel wheel gear system that allows for precise expansion and secure anchoring, enabling easy handling and minimally invasive implantation, and features a design that reduces surface pressure and allows bone growth through apertures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If expandable implants are used to correct positional relationships and restore lordosis, then the implant provides mechanical stability and structural integrity, but the implant is liable to sink into adjacent vertebrae disrupting position and statics
Solution Approach 1:
The implant is divided into an upper cage portion and a lower cage portion that can be independently adjusted and expanded. This segmentation allows for controlled expansion that distributes pressure evenly across the vertebral bodies, preventing sinking while maintaining mechanical stability and positional integrity.
Solution Approach 2:
The implant incorporates an adjustable expansion mechanism that allows dynamic adjustment of the implant's height and volume after implantation. This dynamic capability enables the implant to adapt to the patient's anatomy and correct positional relationships without excessive pressure that would cause sinking into the vertebrae.
2Strength
If cylindrical implants with screw threads are used to anchor in vertebral bodies, then the implant provides anchoring capability, but the bearing zone is small and the implant exhibits considerable sinking and becomes jammed
Solution Approach 1:
The implant transitions from a cylindrical design to a rectangular/cage structure with flat end plates. This dimensional change provides a significantly larger bearing surface area that distributes loads evenly across the vertebral bodies, eliminating the sinking and jamming problems associated with cylindrical implants while maintaining anchoring capability through the cage structure.
3Device complexity
If expandable implants with limited expansion capability are used, then the implant structure is simplified, but the correcting function is reduced and the implant cannot accommodate various surgical techniques
Solution Approach 1:
The implant features a dynamic expansion mechanism that allows for significant height adjustment between the upper and lower cage portions. This dynamic capability enables the implant to accommodate various surgical techniques including PLIF, TLIF, and ALIF, and provides sufficient correcting function for different pathological conditions without excessive structural complexity.
Solution Approach 2:
The implant design incorporates universal features that enable its use in multiple surgical approaches and indications. The adjustable expansion mechanism and cage structure allow the same implant to serve different correcting functions across various surgical techniques, enhancing adaptability without proportionally increasing complexity.
4Device complexity
If implants with punctiform loading are used, then the implant structure is simplified, but the implant sinks substantially into adjacent vertebrae and loses expanding or correcting function
Solution Approach 1:
The implant is segmented into upper and lower cage portions with distributed contact surfaces. This segmentation transforms punctiform loading into distributed loading across multiple contact points, preventing substantial sinking into the vertebrae while maintaining structural simplicity and expanding function.
Solution Approach 2:
The implant uses flat end plates with extended bearing surfaces instead of point contacts. This dimensional change from punctiform to planar contact distributes the load over a larger area, preventing sinking and preserving the expanding and correcting functions without significantly increasing structural complexity.
Data Source
AI summary
An expandable implant with an upper plate and a lower plate which serve for anchoring on/in the vertebral support surfaces, and at least two gears for the expansion of the implant, which are coupled to each other via toothed wheels. Each gear includes threaded spindles and threaded sleeves, the threaded spindles are connected rigidly to the upper plate, and the threaded sleeves are mounted rotatably in the lower plate, and on one gear a drive shaft is provided, which is connected rigidly to the one threaded sleeve, and wherein a force acting on the drive shaft of an operating instrument can be transferred to the gear by the drive shaft, and the implant includes a mechanism for rigidly securing, screwing or fixing the operating instrument on the implant. The invention also relates to an operating instrument for an implant.