Shape-Memory Nerve Shield for Minimally Invasive Spinal Surgery
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Solution Overview
Problem
Minimally invasive spinal surgery poses risks of nerve root injury, dural tears, bleeding, infection, and other complications due to the difficulty in protecting exposed nerve roots and surrounding tissues during procedures like disc space access between vertebrae.
Innovation Solution
A tissue protector or nerve shield with a thin web structure that can change shape from a constrained oval or round form to fit within a cannula to an unconstrained shape for shielding nerve roots, featuring parallel rails for guiding spinal implants and protecting tissues, allowing for safe insertion and positioning between vertebral bodies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a rigid protective shield is used to protect nerve roots, then protection effectiveness is improved, but the ability to navigate through narrow cannulae deteriorates
Solution Approach 1:
The shield transitions from a constrained compressed state during insertion to an unconstrained expanded state during protection. The body structure is configured to shrink about a longitudinal axis to a smaller constrained second shape sized to fit into a lumen of a cannula, and return to the first shape when the cannula is withdrawn, allowing the shield to adapt its form dynamically
Solution Approach 2:
The shield is nested within the cannula during insertion, with the constrained second shape fitting inside the cannula lumen. The shield is inserted through the cannula in a compressed state and then deployed outward once the cannula is removed, enabling the smaller shield to contain the larger protective structure
2Area of stationary object
If the shield is made large enough to effectively shield nerve roots, then protection coverage is improved, but the ability to insert through minimally invasive access deteriorates
Solution Approach 1:
The shield dynamically changes its dimensions from a small constrained second shape for insertion to a large unconstrained first shape for protection. The body structure shrinks to fit within the cannula lumen during insertion and expands to provide comprehensive nerve root protection after deployment
Solution Approach 2:
The shield transitions from a compressed configuration during insertion to an expanded three-dimensional protective barrier. The thin web structure with rails transforms from a compact form factor to a voluminous protective envelope that envelops the nerve roots and guides the implant
3Reliability
If the shield structure is made complex to provide comprehensive protection, then protection effectiveness is improved, but the device complexity increases
Solution Approach 1:
The shield is segmented into functional components: a thin web structure providing the protective barrier, parallel rails for implant guidance, and a body structure for shape transformation. Each component serves a specific protective or guidance function, with the rails spaced by the web to form channels that guide the implant while shielding nerves
Solution Approach 2:
The shield performs multiple functions simultaneously: it protects nerve roots from injury, guides the spinal implant through the formation of channels, and provides a barrier against tissue damage. The thin web with spaced rails creates both protective shielding and directional guidance for implant insertion
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 nerve shield effectively minimizes the risk of tissue and nerve injuries by providing a protective barrier for nerve roots during spinal surgery, ensuring safe implant placement and reducing the likelihood of complications like dural tears and pneumothorax.
Implementation Method 1
The body structure has an unconstrained first shape configured to form a nerve shield and is configured to shrink about a longitudinal axis to a smaller constrained second shape sized to fit into a lumen of a cannula
Implementation Method 2
The body structure is configured to return to the first shape when the cannula is withdrawn from between two adjacent vertebral bodies and the body structure is held in position between the vertebral bodies
Data Source
AI summary
A tissue protector has a body structure having a longitudinal extending thin web. The body structure has an unconstrained first shape configured to form a nerve shield and is configured to shrink about a longitudinal axis to a smaller constrained second shape sized to fit into a lumen of a cannula. Preferably, the second constrained shape is oval or round having a maximum diameter equal or less than an inside diameter of the lumen. The body structure is configured to return to the first shape when the cannula is withdrawn or returned to this shape as the implant advances.