Expandable Intervertebral Implant With Screw-Driven Height Adjustment
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Solution Overview
Problem
Existing spinal implants lack the ability to provide adjustable support and stabilization between vertebrae, particularly in cases of degenerative diseases, tumors, fractures, or dislocations, where additional support is required to maintain spinal alignment and prevent further deterioration.
Innovation Solution
An intervertebral implant with adjustable height is designed, featuring endplates connected by a frame and an actuator screw, allowing for sliding movement and adjustment of the endplates relative to each other through a carriage mechanism, enabling expansion or contraction to fit the specific needs of the patient's anatomy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a fixed-height spacer is inserted between adjacent vertebrae, then the spacer provides structural support and stabilization, but it cannot be adjusted to fit specific patient anatomical needs or restore optimal disc space height
Solution Approach 1:
The implant transitions from a static fixed-height spacer to a dynamic adjustable-height device through the carriage mechanism that can be repositioned along the longitudinal axis using the actuator screw, allowing the implant height to be adjusted intraoperatively to match patient-specific anatomical requirements
Solution Approach 2:
The implant is divided into separable components including the first and second endplates, the carriage, and the actuator screw, which can be independently positioned and adjusted to achieve the desired final configuration and height
2Object-affected harmful factors
If a non-expandable implant is used, then the implant structure is simpler, but it cannot minimize tissue impaction during insertion or restore disc space height
Solution Approach 1:
The implant can be inserted in a compressed state with the carriage positioned to minimize profile, then expanded intraoperatively to the desired height to restore disc space and prevent soft tissue impaction, combining the benefits of a compact insertion profile with the therapeutic benefits of height restoration
Solution Approach 2:
The implant is prepared in a compressed or reduced height configuration before insertion to minimize tissue disruption, and then expanded to the target height after insertion to achieve the therapeutic effect of disc space restoration without initial tissue impaction
3Ease of operation
If the endplates are fixed relative to each other, then the implant structure is more stable and simpler, but it cannot provide continuous adjustment to optimize spinal alignment
Solution Approach 1:
The carriage is slideably connected to the endplates through ramped surfaces, enabling continuous adjustment of the implant height by rotating the actuator screw, which provides precise control over the separation distance between the first and second endplates to optimize spinal alignment
Solution Approach 2:
The carriage acts as an intermediary mechanism between the actuator screw and the endplates, translating the rotational motion of the screw into linear separation of the endplates through the ramped surface interaction, thereby enabling controlled continuous adjustment of implant height
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 customizable support and stabilization, allowing for continuous expansion and retraction to restore disc space height, minimize tissue impaction during insertion, and maintain optimal spinal alignment, while being biocompatible and minimally invasive.
Implementation Method 1
an actuator screw rotatably connected to the frame; and a carriage (a) forming an open area aligned with the openings in the first and second endplates and defining thereby a proximal carriage side and a distal carriage side with respect to the longitudinal axis, (b) threadably connected to the actuator screw, whereby rotation of the actuator screw moves the carriage with respect to the frame and the first and second endplates
Implementation Method 2
including a plurality of ramps each mateable with at least one of the at least one ramped surfaces of the first and second endplates, wherein when the carriage is moved by rotation of the actuator screw, at least one of the at least one ramped surface of the first endplate and at least one of the at least one ramped surface of the second endplate each slide along at least one of the plurality of ramps of the carriage to cause the endplates to move relative to each other
Data Source
AI summary
An implant for therapeutically separating bones of a joint has two endplates each having an opening through the endplate, and at least one ramped surface on a side opposite a bone engaging side. A frame is slideably connected to the endplates to enable the endplates to move relative to each other at an angle with respect to the longitudinal axis of the implant, in sliding connection with the frame. An actuator screw is rotatably connected to the frame. A carriage forms an open area aligned with the openings in the endplates. The openings in the endplates pass through the carriage to form an unimpeded passage from bone to bone of the joint. The carriage has ramps which mate with the ramped surfaces of the endplates, wherein when the carriage is moved by rotation of the actuator screw, the endplates move closer or farther apart.