Expandable Spinal Implant with Differential Thread Gears
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Solution Overview
Problem
Existing expandable spinal implants face challenges such as sinking into adjacent vertebrae due to limited bearing surface and design constraints, which disrupt vertebral positioning and statics, especially in cases of osteoporosis, and often hinder natural bone growth and stability.
Innovation Solution
An expandable implant with a triple adjustment mechanism featuring gears with different thread pitches, allowing for angular expansion and increased surface area, coupled with a secure operating instrument for minimally invasive implantation and pivoting capabilities to correct spinal geometry without sinking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If expandable implants with predefined expansion are used, then bearing surface is increased, but sinking into vertebrae still occurs due to punctiform loading
Solution Approach 1:
The implant uses a dynamic expansion mechanism with telescopic bodies that can be adjusted intraoperatively to achieve optimal expansion, transitioning from a static predefined expansion to a dynamic adjustable expansion that adapts to the specific anatomical conditions and bone quality of the patient
Solution Approach 2:
The implant allows changing the expansion parameter intraoperatively by adjusting the telescopic bodies to different positions, enabling the bearing surface and expansion angle to be optimized based on the actual anatomical conditions and bone quality observed during surgery
2Strength
If cylindrical implants with screwthread are used, then anchoring is improved, but bearing zone is small and sinking is considerable
Solution Approach 1:
The implant is divided into multiple telescopic bodies (inner and outer bodies) that can move relative to each other, allowing the bearing surface to be expanded segmentally across multiple vertebrae while maintaining strong anchoring through the screwthread mechanism on the outer body
3Ease of manufacture
If expandable implants with limited expansion design are used, then manufacturing is simplified, but expansion is restricted and sinking occurs
Solution Approach 1:
The implant employs a dynamic telescopic mechanism that allows continuous adjustment of expansion within a wide range (e.g., 4mm to 12mm or more), transforming a static limited expansion design into a dynamic adjustable system that maintains manufacturing simplicity while achieving versatile expansion capabilities
4Ease of manufacture
If implants are designed for dorsal or anterior implantation only, then manufacturing is simplified, but implantation versatility is limited
Solution Approach 1:
The implant is designed with a universal configuration that can be implanted through various approaches (dorsal, anterior, lateral) and can accommodate different implantation directions, making it a multi-functional device that serves multiple surgical approaches without requiring design modifications
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 implant provides stable anchoring, reduces the risk of sinking, allows for precise geometric correction, and facilitates natural bone growth, enhancing long-term stability and ease of operation.
Implementation Method 1
each gear has a threaded spindle and a threaded sleeve with inner thread, wherein the pitches of at least two gears, or of two threads each consisting of threaded sleeve and threaded spindle, are different
Data Source
AI summary
The invention relates to an expandable implant (11) with an upper plate (12) and a lower plate (16) which extend in the xy plane, which serve for anchoring on/in the vertebral support surfaces, and at least three gears (20, 25, 30) which are coupled to each other, wherein the gears (20, 25, 30) serve to expand the implant (11), and each gear (20, 25, 30) has a threaded spindle (21, 25, 31) and a threaded sleeve with corresponding inner thread (22, 27, 32), wherein the pitch of one thread (31, 32) is different from the pitch of the other threads (21, 22; 26, 27). The invention also relates to an operating instrument (80) for this implant.