Expandable Spinal Implant With Independent Height Adjustment
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Solution Overview
Problem
Conventional spinal implants face challenges in achieving maximum contact with vertebral body endplates, maintaining intervertebral space, allowing bone growth, and resisting dislocation due to their concave design and limited ability to accommodate desired lordosis.
Innovation Solution
The spinal implant features a proximal and distal adjustment assembly allowing independent vertical height adjustment of its regions, with a set screw for locking, and a pivot linkage assembly with a double ramped inner surface expander to enhance contact and stability, along with tapered ridges for engagement with vertebral bodies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional prosthetic implants are inserted between adjacent vertebrae, then the intervertebral space can be maintained, but the implant may be dislodged or moved from its implantation location due to patient movement before sufficient bone growth or fusion occurs
Solution Approach 1:
The implant incorporates an expandable structure that transitions from a compressed insertion state to an expanded deployed state. The expandable cage body allows the implant to be inserted in a compact form and then expanded in situ to achieve maximum contact with the vertebral endplates, thereby maintaining stability while facilitating secure positioning
Solution Approach 2:
The implant utilizes changes in physical parameters including expansion ratio, contact surface area, and structural rigidity. The cage expands from a compact insertion configuration to a larger operational configuration, increasing the contact area with vertebral bodies and enhancing frictional resistance to dislocation while maintaining the ability to accommodate lordosis
2Adaptability or versatility
If conventional prosthetic implants are designed with limited adjustability, then the device complexity is reduced, but the ability to achieve maximum contact with vertebral body endplates and accommodate desired lordosis is compromised
Solution Approach 1:
The implant is divided into modular components including the cage body, expansion mechanism, and adjustment assemblies. This segmentation allows independent optimization of each component's function while maintaining overall system adaptability. The modular design enables adjustment of cage height and lordosis angle without requiring complete implant replacement
Solution Approach 2:
The implant integrates multiple functions within a single device: structural support, space maintenance, bone growth facilitation, and postoperative adjustment. The expandable cage body simultaneously achieves maximum endplate contact and accommodates lordosis, while the adjustment mechanism allows future modifications without requiring a different implant type
3Reliability
If conventional implants are designed to resist dislocation, then implant stability is improved, but the ability to allow bone growth between adjacent vertebrae may be compromised
Solution Approach 1:
The implant features differentiated surface properties: the internal surfaces of the cage body are designed with bone-promoting characteristics such as porosity or roughness to facilitate osteointegration, while the external surfaces provide smooth contact with the vertebral endplates to prevent dislocation. This local quality differentiation allows simultaneous achievement of dislocation resistance and bone growth facilitation
Data Source
AI summary
A spinal implant has proximal and distal regions, and includes upper and lower bodies. A proximal adjustment assembly is disposed between the upper and lower bodies in the proximal region of the spinal implant and is adjustably coupled to the upper and lower bodies, and a distal adjustment assembly is disposed between the upper and lower bodies in the distal region of the spinal implant and is adjustably coupled to the upper and lower bodies. The proximal and distal adjustment assemblies are independently movable with respect to each other, both concurrently and alternately, to change a vertical height of at least one of the proximal or distal regions of the spinal implant. A set screw is removably disposed within the proximal region of the spinal implant to lock the vertical height of the proximal and distal regions of the spinal implant.