Height Adjustable Spinal Prosthesis with Screw Adjustment
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current spinal prostheses lack the ability to be dimensionally adjustable, particularly in height, which is essential for accommodating varying anatomical relationships and preventing subsidence due to spongy vertebral bone, leading to inadequate support and potential device failure.
Innovation Solution
The development of height adjustable spinal prostheses featuring first and second prosthetic portions with an adjustable coupling mechanism, such as a screw and gearing or rack and pinion assembly, allowing for axial displacement and infinite height adjustment from a minimum to a maximum height, facilitated by endplates for anchoring within the spine.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a fixed-height spinal prosthesis is used, then the device structure is simple, but it cannot accommodate varying anatomical relationships and may cause subsidence due to inadequate height adjustment
Solution Approach 1:
The prosthesis is divided into multiple segments including an upper body, lower body, and adjustment mechanism. The upper and lower bodies can be independently positioned relative to each other through the adjustment mechanism, allowing height customization while maintaining structural integrity. This segmentation enables adaptability without requiring a completely complex redesign of the entire prosthesis structure.
Solution Approach 2:
The prosthesis incorporates a dynamic adjustment mechanism that allows the height to be modified after implantation. The mechanism includes a threaded rod that can be rotated to adjust the axial distance between the upper and lower bodies, providing dynamic adaptability. This dynamic feature resolves the contradiction by allowing the structure to change from a fixed state to an adjustable state as needed.
2Manufacturing precision
If a height adjustable mechanism is added to the prosthesis, then anatomical variations can be accommodated, but the device complexity increases
Solution Approach 1:
The adjustment mechanism uses a threaded rod system where rotation of the rod translates to precise axial movement of the upper body relative to the lower body. This mechanical substitution provides precise height adjustment through a relatively simple threaded connection rather than requiring complex electronic or hydraulic systems. The precision is achieved through the thread pitch and rotational control.
Solution Approach 2:
The mechanism allows for continuous change in the height parameter by rotating the threaded rod. The thread pitch determines the precise increment of height change per rotation, enabling fine-tuned adjustment. This parameter change approach provides manufacturing precision through a straightforward mechanical relationship between rotation and axial displacement.
3Ease of operation
If the prosthesis height is fixed at maximum, then support surface area is increased, but the prosthesis cannot be adjusted for individual anatomical variations
Solution Approach 1:
The adjustment mechanism is designed to be self-contained within the prosthesis structure, with the threaded rod integrated into the coupling between upper and lower bodies. The surgeon or operator can directly rotate the rod to adjust height without requiring external tools or complex actuation systems. This self-service approach makes the adjustment easy to perform while keeping the mechanism relatively simple.
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 fitting and support to the vertebral bone, reducing the likelihood of subsidence and accommodating individual anatomical variations, thereby enhancing the stability and effectiveness of spinal prostheses.
Implementation Method 1
The adjustment mechanism is a screw and gearing assembly
Implementation Method 2
The adjustment mechanism is a screw and gearing assembly
Implementation Method 3
The adjustment mechanism is a rack and pinion assembly
Data Source
AI summary
Dimensionally adjustable spinal prostheses are adjustable in an axial or superior to inferior dimension such that spinal prostheses may assume variations in height. The height adjustable spinal prostheses are characterized by first and second portions that are configured for adjustable coupling with one another. Spatial adjustment between the first and second portions is provided by an adjustment assembly. The adjustment mechanism preferably, but not necessarily, provides infinite adjustment over a minimum prosthesis height to a maximum prosthesis height. In one form, first and second ends of the height adjustable spinal prostheses are configured to receive an endplate. The endplates aid in attachment and/or anchoring of the spinal prosthesis within the spine. The endplates may be fashioned in various configurations such as circular or anatomical. In one form, the adjustment assembly utilizes rotational motion for varying the axial position of one prosthetic portion relative to the other prosthetic portion. Rotational movement of an adjustment mechanism of the adjustment assembly is translated into axial movement of one prosthetic portion relative to the other prosthetic portion. In another form, the adjustment mechanism is a screw and gearing assembly. In yet another form, the adjustment mechanism is a rack and pinion assembly.