Spinal Surgery Dilator With Eccentric Guide Hole and Nerve Shield
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Solution Overview
Problem
Existing dilator devices for percutaneous spinal surgery, such as those described in EP2911733A, limit the available space in Kambin's triangle due to the shield occupying a significant portion, making it difficult to perform operations like introducing an intervertebral box or cage, and risk nerve root damage from pressure or cutting during bone cutting.
Innovation Solution
A dilator design with an eccentric guide hole and a slender, laminar-shaped shield that allows the main body and shield to slide relative to each other, providing ample space for subsequent operations while protecting the nerve root, and includes a through-hole for a guide wire to facilitate bone cutting without moving the shield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a circular shield with 200° outer surface is used to protect the nerve root, then nerve root protection is improved, but the available space for subsequent operations is significantly reduced
Solution Approach 1:
The patent changes the shield geometry from a circular cross-section to an asymmetric design where the shield occupies only a portion of the available space. The shield has a specific angular coverage (less than 360°) that provides nerve root protection while deliberately leaving space in other directions for surgical instruments and cage insertion.
Solution Approach 2:
The patent repositions the guide hole from a central location to an eccentric position relative to the shield axis. This dimensional relocation allows the guide wire to pass through a region that does not interfere with the shield's protective function while maintaining adequate working space for bone cutting and cage placement operations.
2Reliability
If the shield occupies a significant portion of Kambin's triangle, then nerve root protection is improved, but the ability to introduce intervertebral box or cage is compromised
Solution Approach 1:
The asymmetric shield design creates an imbalance in space occupation that favors surgical access. By concentrating the protective function in specific angular regions while leaving other regions open, the shield enables both nerve protection and versatile surgical procedures including cage insertion.
Solution Approach 2:
The eccentrically positioned guide hole acts as an intermediary element that mediates between the shield's protective function and the need for surgical access. It provides a pathway for guide wires and instruments to reach the surgical site without requiring the shield to occupy the entire space.
3Area of stationary object
If bone cutting is performed to create more space, then available space is improved, but the risk of nerve root damage from involuntary cutting increases
Solution Approach 1:
The shield is positioned in advance before bone cutting operations. This preliminary placement creates a protective barrier that prevents involuntary cutting of the nerve root during subsequent bone removal procedures. The shield remains in place throughout the bone cutting process, allowing safe space creation.
Solution Approach 2:
The shield serves as a protective cushion or barrier positioned beforehand to absorb or prevent harmful effects. During bone cutting operations, the shield cushions the nerve root from potential damage caused by surgical instruments, allowing aggressive bone removal to create space without increasing nerve injury risk.
Data Source
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AI summary
Dilator for percutaneous spinal surgery which comprises a main elongate dilator body and an elongate shield for protecting the nerve root, the main dilator body and the shield each comprising mutually complementary contact surfaces and in which the main body and the shield define a transverse cross section of the dilator, it being possible for the main body and the shield to slide one relative to the other along an axial axis of the dilator, the dilator also comprising a through-hole for receiving a guide rod, characterised in that said hole is placed eccentrically with respect to a combined transverse cross section of the main body and of the shield.