Spinal Implant Midline Insertion with Toggle Fixation
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Solution Overview
Problem
Conventional spinal implants tend to subside after implantation, leading to loosening or damage of vertebral bodies due to lack of accommodation for subsidence and limited insertion pathways, especially in patients with prior surgeries or anatomical obstacles.
Innovation Solution
A spinal implant designed for midline insertion with apertures that allow predetermined nutation of fixation elements, featuring anti-migration and anti-backout mechanisms, along with tactile or visual feedback for secure seating, and instruments like angled screwdrivers and awls for minimally invasive placement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If rigid fixation is provided to secure the implant to vertebral bodies, then immediate stability is improved, but the implant is prone to subsidence and loosening of fixation elements
Solution Approach 1:
The aperture in the implant is designed with a non-circular cross-section that allows the fixation element to toggle between engaged and disengaged positions. This dynamic design enables the fixation element to move relative to the aperture, accommodating subsidence while maintaining stable engagement during normal use.
Solution Approach 2:
The fixation element is divided into distinct functional zones: an engagement portion that interfaces with the aperture and a fixation portion that anchors into the vertebral body. This segmentation allows the engagement portion to tolerate movement while the fixation portion maintains rigid anchoring.
2Ease of operation
If conventional insertion pathways are used, then access to the implant site is achieved, but intrusion into musculature and ligamentous tissue is excessive
Solution Approach 1:
The implant is designed for insertion through a midline approach, utilizing a different spatial dimension compared to conventional lateral approaches. The instrument shaft is configured to approach the implant site from the midline, allowing access while minimizing intrusion into surrounding musculature and ligamentous tissue.
3Stability of the object's composition
If fixation elements are rigidly fixed to prevent any movement, then stability is improved, but subsidence causes loosening or damage to vertebral bodies
Solution Approach 1:
The aperture allows the fixation element to dynamically adjust its position relative to the implant body. During subsidence, the fixation element can toggle within the aperture to maintain engagement, preventing loosening while accommodating the subsidence movement.
Solution Approach 2:
The toggle mechanism is designed beforehand to accommodate expected subsidence movements. The aperture geometry and engagement features are configured to absorb the effects of subsidence before they can cause harmful loosening or damage to the vertebral bodies.
Data Source
Figure 1A~1B
Figure 1C~1D
Figure 1E~2
AI summary
The embodiments provide a spinal implant that is configured for midline insertion into a patient's intervertebral disc space. The spinal implant may include structural guidance features to facilitate the angular approach of fixation elements into the apertures. The spinal implant may also be a configured with a tactile or visual feedback response feature to allow the user to know when the fixation elements are fully seated within the apertures.