Bone Access Instrument With Segmented Shaft For Cervical Pedicle Entry
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Solution Overview
Problem
Current spinal surgery techniques, particularly in the cervical spine, face challenges in accessing pedicles due to their narrow dimensions, leading to risks of pedicle breach, nerve, or blood vessel damage, especially when using K-wires or Jamshidi needles, which can bend and cause frictional resistance or misalignment.
Innovation Solution
A bone access instrument with a shaft having multiple diameters and tapered ends, including a handle for easier manipulation, facilitates safer pedicle access by providing tactile feedback and reducing the risk of pedicle damage through a cannula system that allows for precise placement and minimizes the risk of breaching the anterior cortical wall.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If K-wires or Jamshidi needles are used to access the pedicle, then initial access can be achieved, but the risk of pedicle breach, nerve damage, or blood vessel damage increases due to bending, frictional resistance, and misalignment
Solution Approach 1:
The instrument is divided into multiple segments: a stylet with cutting edges for initial bone penetration, a cannula for guiding subsequent instruments, and a shaft with multiple diameters for different functional requirements. This segmentation allows each component to perform its specific function optimally while working together to reduce overall risk.
Solution Approach 2:
The cannula serves as an intermediary structure that guides the stylet and subsequent instruments through the pedicle. It provides a stable pathway that prevents misalignment and reduces the risk of breaching the anterior cortical wall, while the stylet acts as an intermediary cutting tool that prepares the path without the bending issues of K-wires.
2Productivity
If the pedicle is accessed with narrow dimensions in the cervical spine, then minimally invasive surgery is achieved, but the risk of pedicle breach and damage to nerves or blood vessels increases
Solution Approach 1:
The shaft has different diameters at different locations: a first diameter for the proximal portion and a second, smaller diameter for the distal portion. This local variation in geometry allows the instrument to provide structural support where needed while fitting through the narrow pedicle dimensions required for minimally invasive cervical spine surgery.
Solution Approach 2:
The stylet with cutting edges performs preliminary action by cutting through the cortical bone of the pedicle before the cannula is fully inserted. This preliminary bone removal creates a safer pathway that reduces the risk of breaching the anterior cortical wall during subsequent instrument insertion.
3Measurement precision
If a shaft with multiple diameters is used, then precise placement and tactile feedback are improved, but device complexity increases
Solution Approach 1:
The shaft is segmented into distinct portions with different diameters, each optimized for specific functions. The proximal portion with the first diameter provides structural support and tactile feedback, while the distal portion with the second diameter enables precise navigation through the narrow pedicle. This segmentation achieves precision without requiring an overly complex overall structure.
Data Source
AI summary
A bone access instrument comprising a shaft having a first shaft portion and a second shaft portion. The first shaft portion has a first diameter, a proximal end, a tapered distal end including at least three straight cutting edges being equally spaced circumferentially about the tapered distal end, and at least three flutes extending from the tapered distal end toward the proximal end in a parallel relationship to one another. The second shaft portion has a second diameter and a tapered distal end. The second diameter is less than the first diameter, and the second shaft portion extends axially from the distal end of the first shaft portion.