Spinal Implant Insertion Instrument With Worm Gear Actuation
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Solution Overview
Problem
Conventional prosthetic implants for spinal conditions often fail to maintain desired lordosis and resist dislocation, and are difficult to implant effectively between adjacent vertebrae, especially before sufficient bone growth occurs.
Innovation Solution
An insertion instrument with an elongate member, shuttle, and worm gear is used to position and lock expandable spinal implants, allowing for desired lordosis and bone growth between vertebrae, featuring a handle, end effector, and screws for secure engagement and articulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional prosthetic implants are inserted between adjacent vertebrae, then the implant can be placed to maintain disc spacing, but the implant may be dislodged or moved from its desired implantation location due to patient movement before sufficient bone growth occurs
Solution Approach 1:
The implant transitions from a static conventional design to a dynamic expandable design. The implant is inserted in a compressed state and then expanded in situ to achieve final positioning and stability. This dynamic transformation allows the implant to be inserted easily in a compact form while achieving stable fixation after expansion, resolving the contradiction between insertion ease and post-implantation stability.
Solution Approach 2:
The insertion instrument performs preliminary actions by pre-positioning the implant and securing it with locking mechanisms before the patient leaves the operating room. The instrument includes features like engagement protrusions and locking components that secure the implant in place during the procedure, ensuring stability is achieved before bone growth occurs, thereby preventing dislocation.
2Ease of operation
If conventional prosthetic implants are used, then the implant can be inserted between vertebrae, but achieving the desired lordosis is difficult given the limitations of typical prosthetic implants once implanted
Solution Approach 1:
The implant incorporates a dynamic adjustment mechanism that allows lordosis to be modified after implantation. The expandable structure enables change in the angle between upper and lower vertebral bodies, allowing physicians to achieve desired lordosis positioning post-implantation. This dynamic capability resolves the limitation of fixed-angle conventional implants.
Solution Approach 2:
The insertion instrument employs a nested structure where the shuttle is received within the end effector cavity, and the worm gear is rotatably disposed within the same cavity. This nested arrangement allows multiple functional components to be integrated in a compact manner, enabling complex adjustment capabilities without excessive external complexity.
3Reliability
If expandable spinal implants are used to provide desired lordosis and resist dislocation, then bone growth and space maintenance are improved, but effectively implanting such devices can be difficult
Solution Approach 1:
The implantation system is segmented into distinct functional components: the expandable implant itself, the insertion instrument with end effector, the shuttle for actuating expansion, and the worm gear for locking. This segmentation allows each component to be optimized for its specific function and simplifies the overall implantation procedure by allowing sequential activation of functions (insertion, expansion, locking) rather than requiring complex simultaneous operations.
Solution Approach 2:
The insertion instrument acts as an intermediary between the surgeon and the expandable implant. It provides controlled interfaces for expanding the implant (via the shuttle) and locking it in position (via the worm gear), translating simple surgical actions into precise implant manipulation. This intermediary device simplifies the implantation process while ensuring reliable bone growth support and dislocation resistance.
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 instrument enables precise placement and locking of expandable spinal implants, maintaining desired lordosis and preventing dislocation, facilitating bone growth and stable integration between vertebrae.
Implementation Method 1
The worm gear is rotatably disposed within the cavity defined in the end effector and is in mechanical communication with the shuttle such that rotation of the worm gear effectuates movement of the shuttle
Implementation Method 2
The shuttle includes a wedge shaped distal end configured to engage an expandable spinal implant. Distal movement of the shuttle effectuates articulation of an expandable spinal implant
Data Source
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AI summary
An insertion instrument for expandable spinal implants includes an elongate member, a shuttle, and a worm gear. The elongate member includes a handle portion of a proximal end and an end effector on a distal end, wherein the end effector is configured to be releasably engaged to an expandable spinal implant. The shuttle is slidably disposed within a cavity defined within the end effector and includes a wedged shaped distal end configured to engage an expandable spinal implant. The worm gear is rotatably disposed within the cavity defined in the end effector and is in mechanical communication with the shuttle, such that rotation of the worm gear effectuates movement of the shuttle. Distal movement of the shuttle effectuates articulation of an expandable spinal implant. A method of performing surgery is also disclosed.