Skull Anchor Bolt Controlled Break Point
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Solution Overview
Problem
Existing anchor bolts used in neurosurgery for depth electrode placement are susceptible to loosening and displacement due to lateral forces, such as those experienced during seizures, which can lead to complications like cerebrospinal fluid leakage and infection. Additionally, when these anchor bolts break or bend, they can be difficult and time-consuming to remove, often requiring surgical intervention.
Innovation Solution
The improved anchor bolt features a controlled break point and recovery means, including a secondary fitting, designed to facilitate removal if the anchor bolt is impacted and breaks or bends at the controlled break point. This design isolates excessive torque from the subdural stem, protecting the patient and ensuring the integrity of the depth electrode placement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If anchor bolts are made with thicker walls to withstand lateral forces, then strength and stability are improved, but the risk of loosening and displacement during seizures increases
Solution Approach 1:
The anchor bolt is divided into two distinct segments: a thick-walled proximal portion for withstanding lateral forces and a thin-walled distal portion for controlled breaking. This segmentation allows each portion to have optimized wall thickness for its specific function, resolving the contradiction between overall strength and stability during seizures.
Solution Approach 2:
Different portions of the anchor bolt have different wall thicknesses tailored to their specific functional requirements. The proximal portion has thicker walls for strength, while the distal portion has thinner walls for controlled breaking, creating local quality variations that resolve the contradiction between strength and stability.
2Reliability
If anchor bolts are made with thinner walls to prevent loosening during seizures, then stability is improved, but the anchor bolts become difficult and time-consuming to remove after breaking
Solution Approach 1:
The anchor bolt is segmented into a thin-walled distal portion that breaks during seizures and a proximal portion that remains. The controlled break point is positioned to separate these segments, allowing the thin-walled portion to break easily for stability while the proximal portion can be removed relatively easily after breaking, resolving the contradiction between stability and ease of removal.
Solution Approach 2:
The controlled break point is pre-positioned in the thin-walled distal portion during manufacturing. When a seizure occurs, the anchor bolt breaks at this predetermined location, separating the thin-walled portion from the proximal portion. This preliminary positioning of the break point enables easy removal of the broken portion without requiring surgical intervention, resolving the contradiction between stability and ease of removal.
3Adaptability or versatility
If anchor bolts are made longer to ensure proper depth electrode placement, then adaptability is improved, but the susceptibility to loosening when knocked increases
Solution Approach 1:
The anchor bolt is segmented into a long proximal portion for adaptability in depth electrode placement and a thin-walled distal portion for controlled breaking. This segmentation allows the anchor bolt to be long enough for proper placement while the thin-walled distal portion prevents loosening during seizures by breaking at a controlled point, resolving the contradiction between adaptability and stability.
Solution Approach 2:
The anchor bolt has non-uniform wall thickness along its length, with the proximal portion having thicker walls for strength and the distal portion having thinner walls for controlled breaking. This local quality variation allows the anchor bolt to be long for adaptability while maintaining stability through the thicker proximal portion, resolving the contradiction between adaptability and stability.
4Strength
If anchor bolts are made stronger to prevent displacement, then strength is improved, but the complexity of removal after breaking increases
Solution Approach 1:
The anchor bolt is segmented into a strong proximal portion and a thin-walled distal portion. The controlled break point is positioned to separate these portions, allowing the strong proximal portion to remain in place for strength while the thin-walled distal portion breaks easily for simple removal, resolving the contradiction between strength and complexity of removal.
Solution Approach 2:
The controlled break point is pre-positioned during manufacturing to separate the strong proximal portion from the thin-walled distal portion. When breaking occurs during a seizure, this preliminary positioning ensures that only the thin-walled distal portion breaks, allowing for simple removal without requiring complex surgical intervention, resolving the contradiction between strength and complexity of removal.
Data Source
AI summary
An improvement to anchor bolts adapted to be screwed into a patient's skull for the purpose of placing a depth electrode at a desired location within the patient's cranium. The improved anchor bolt includes an engineered controlled break point and recovery means such as a secondary fitting to facilitate removal if the anchor bolt is impacted and breaks or bends at the controlled break point. The anchor bolt is intended to be used in a similar manner to existing anchor bolts with the added benefits of protecting the patient from excessive harm from violent impact of anchor bolts which can occur during seizures for example, as well as facilitating removal of remaining parts of a damaged anchor bolt without the need for surgical intervention and in a relatively easy fashion.