Spinal Distraction Device with Rack and Pinion Mechanism
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Solution Overview
Problem
Current vertebral distraction methods during surgery, such as using screws for fixation, risk compromising anchorage and often result in uneven vertebral plateau alignment, leading to potential scoliosis and inadequate stabilization.
Innovation Solution
A spinal distraction device with parallel blades connected to a rack system, allowing controlled spacing and parallel alignment of vertebral plateaus, and an implant with slots for easy insertion and minimal over-distraction, facilitating parallel alignment and easy withdrawal without frictional interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If distraction is performed using screws for fixation, then vertebral stabilization can be achieved, but the distraction force adversely affects screw anchorage in bone
Solution Approach 1:
The distraction device is divided into two separate functional components: distraction blades for creating space and screws for fixation. The blades are inserted first to establish the distraction force, then the screws are inserted through the blade tips to secure the vertebral plateaus. This segmentation allows the distraction function and fixation function to be performed independently, preventing the distraction force from compromising screw anchorage.
Solution Approach 2:
The distraction blades are inserted and positioned before the screws are inserted. The blades create the necessary distraction and maintain the vertebral plateau alignment in advance, providing a stable foundation for subsequent screw insertion. This preliminary action ensures that the screws are inserted into properly positioned vertebral plateaus, optimizing their anchorage.
2Loss of time
If distraction is performed on just one side, then surgery duration is reduced, but local scoliosis is created and vertebral plateaus are not kept parallel
Solution Approach 1:
The device merges the distraction function with the fixation function into a single integrated assembly. The distraction blades are combined with the fixation screws in such a way that both functions are achieved simultaneously through one surgical approach. The blades maintain parallel orientation while the screws provide fixation, ensuring both distraction and alignment precision are achieved without requiring separate surgical steps.
3Device complexity
If manual posterior pressure is used to restore lordosis, then the procedure is simple, but it is dangerous and ineffective
Solution Approach 1:
The distraction blades act as intermediaries between the vertebral plateaus and the surgical instrument. Instead of applying direct manual pressure to the vertebral body, the blades are inserted to create the necessary distraction and maintain lordosis. The blades serve as a mechanical intermediary that safely transmits and distributes the distraction force, eliminating the need for dangerous manual pressure while achieving reliable lordosis restoration.
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
Enables precise, parallel alignment of vertebral plateaus for implant insertion with minimal surgical impact, ensuring stable fixation and reduced risk of scoliosis, while allowing for efficient withdrawal of the distraction device.
Implementation Method 1
a central part traversed by said racks and enclosing a pinion whose teeth are in contact with said racks in such a way that a rotation of said pinion causes said blades to move toward or away from each other
Data Source
AI summary
The invention relates to an assembly comprising: an implant (18b), the two ends of which are equipped with plates (19, 20) which are provided with slots (28); and a distraction tool consisting of blades (2) which are intended to co-operate with the slots (28). The widths of the slots (28) correspond to those of the blades (2), but the depth of the slots (28) is greater than that of the blades (2).