Depth-Controlled Needle Assembly with Adjustable Sheath
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Solution Overview
Problem
In orthopedic surgery, needle assemblies used for procedures like bone marrow biopsies and pedicle screw placement risk damaging nerves or blood vessels due to the inability to control the depth of needle insertion accurately, leading to potential complications such as nerve contact or bone cracking.
Innovation Solution
The development of needle assemblies with depth-stop mechanisms, including adjustable sheaths and cannula sub-assemblies, which limit further advancement of the needle into the bone, providing tactile feedback and radiopaque markers for precise depth control to prevent over-insertion and potential damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If needle assemblies are used for bone marrow biopsies and pedicle screw placement, then the ability to access target locations is improved, but the risk of damaging nerves or blood vessels increases due to inability to control insertion depth
Solution Approach 1:
The sheath is pre-configured with depth-stop features at specific distances from its proximal end. Before the procedure, the surgeon selects and attaches the appropriate sheath length based on the desired needle insertion depth, preventing over-insertion before it can occur.
Solution Approach 2:
The sheath acts as an intermediary component between the surgeon's control and the needle's penetration into bone. It provides a mechanical interface that limits how far the needle can advance, mediating the interaction between the surgeon's intent and the actual needle insertion depth.
2Manufacturing precision
If depth-stop mechanisms with adjustable sheaths are added to needle assemblies, then control over needle insertion depth is improved, but device complexity increases
Solution Approach 1:
The needle assembly is divided into separate functional components: the cannula sub-assembly and the sheath. The sheath can be detached and replaced with different lengths depending on the procedure requirements, allowing precision depth control without permanently complicating the base needle design.
Solution Approach 2:
The sheath is designed to be dynamically adjustable - it can be attached to the cannula sub-assembly before the procedure and detached afterward. This dynamic configuration allows the same basic needle assembly to adapt to different depth requirements without being permanently modified.
3Adaptability or versatility
If multiple sheaths with different lengths are provided in a kit, then adaptability to different procedure requirements is improved, but quantity of components and storage requirements increase
Solution Approach 1:
Each sheath is designed with universal features that allow it to work with the cannula sub-assembly through a standardized attachment mechanism. The sheaths can be stacked or nested when not in use, and the same attachment interface works for all sheath lengths, making the system versatile without requiring unique components for each length.
Data Source
AI summary
A target needle assembly can include a needle having a sharp tip, a cannula configured to receive the needle, and an outer sheath. The outer sheath is configured to receive the cannula. The target needle assembly includes a depth stop mechanism, and the outer sheath is configured to limit or inhibit further advancement of the needle into the bone once the needle has been advanced the desired distance to a target location.