Jamshidi Needle Depth Control via Rotatable Stop
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Solution Overview
Problem
Current medical instruments for percutaneous spinal surgery, such as Jamshidi needles, lack precision in depth control and simultaneous placement of dilation tubes, posing risks of neural damage and vascular injury due to inadequate depth adjustment and force application during cortical bone penetration.
Innovation Solution
A precision depth-guided instrument comprising an outer cannula with an adjustable inner cannula and a stylet, where the depth of penetration is controlled using a rotatable stop mechanism and radiography measurements, allowing for precise placement of the Jamshidi needle and optional dilation tubes within the vertebra.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a hammer or similar instrument is used to force the instrument through the cortical bone, then the penetration force is sufficient, but the danger of rapidly passing through the cancellous bone and out the other side of the vertebra increases
Solution Approach 1:
The patent introduces a depth control mechanism with a stop element that acts as an intermediary between the surgeon's force application and the needle penetration. The stop element physically limits the maximum penetration depth, serving as a mediator that allows forceful cortical bone penetration while preventing dangerous over-penetration through cancellous bone.
Solution Approach 2:
The depth control mechanism is pre-set before the procedure with the desired penetration depth determined by radiography. This preliminary action establishes the safe penetration limit in advance, allowing the surgeon to apply necessary force without needing to judge depth in real-time, thus preventing over-penetration.
2Force
If the force required to penetrate the cortical bone is greater than a surgeon can apply by hand, then penetration is achieved, but precision depth control is compromised
Solution Approach 1:
The depth control mechanism serves as a mechanical intermediary that translates the surgeon's manual force into controlled needle advancement. The stop element provides a physical reference point that ensures precise depth placement even when significant force is required for cortical bone penetration.
3Ease of operation
If no depth stop mechanism is used, then the instrument can be inserted freely, but the risk of neural damage and vascular injury increases
Solution Approach 1:
The depth control mechanism is pre-configured with the safe penetration depth determined by radiographic measurements before surgery begins. This preliminary determination of safe depth allows free insertion up to that point while automatically preventing penetration beyond the safe limit, thus protecting against neural and vascular damage.
4Loss of time
If the depth of penetration is not pre-determined by radiography, then the procedure can start immediately, but the accuracy of needle placement decreases
Solution Approach 1:
The patent requires pre-determination of the safe penetration depth through radiography before the procedure begins. This preliminary measurement is then transferred to the depth control mechanism, ensuring accurate needle placement while allowing the actual surgical procedure to proceed efficiently without repeated adjustments.
Data Source
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AI summary
A precision depth guided instrument, such as a Jamshidi needle, is provided for use in various surgeries related to the vertebrae. The instrument includes an outer cannula, an inner cannula and a stylet. After the cortical bone of a vertebra is penetrated by the outer cannula of the instrument, the depth of penetration of the inner cannula is adjusted by rotation of the inner cannula. The inner cannula is then moved further into the vertebrae, and a stop mounted on the outer cannula controls the depth of penetration of the inner cannula. The correct depth of penetration is determined by radiography prior to the procedure.