Bone Screw Chisel Tip Geometry for Low-Torque Bone Insertion
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Solution Overview
Problem
Existing bone screws face challenges in achieving quick and accurate placement, particularly in pedicle screws, which can complicate spinal operations and require additional equipment for correct screw placement.
Innovation Solution
The bone screws feature a distal tip with cutting edges having a leading surface at an acute angle and a trailing surface angled oppositely, reducing drag and facilitating insertion, along with threads that terminate in cutting edges to efficiently advance into bone.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional bone screw designs are used, then the screw can be implanted into bone, but the insertion process requires excessive torque and downward force, making the operation difficult and time-consuming
Solution Approach 1:
The patent modifies the geometric parameters of the screw tip, specifically creating a chisel tip with a defined angle (e.g., 30-60 degrees) and specific dimensions. This parameter change allows the tip to act as a cutting tool that fractures bone along its path, dramatically reducing the insertion force required compared to conventional screw tips.
Solution Approach 2:
The screw design separates the insertion function from the anchoring function. The chisel tip is designed specifically for bone cutting and advancement, while the threads are designed for anchoring. This segmentation allows each component to be optimized for its specific function, with the tip requiring minimal force to advance through bone.
2Reliability
If conventional bone screw designs are used, then the screw can be implanted into bone, but additional equipment is required to ensure correct screw placement, increasing device complexity
Solution Approach 1:
The chisel tip design enables the screw to be self-guiding during insertion. As the chisel tip fractures bone along its path of insertion, it naturally follows the intended trajectory, providing self-correction and self-guidance capabilities. This eliminates the need for complex external guidance equipment while ensuring accurate placement.
Solution Approach 2:
The patent converts the potentially harmful aspect of bone cutting (which could be unpredictable and damaging) into a beneficial self-guiding mechanism. The controlled fracture pattern created by the chisel tip actually guides the screw along the correct path, turning a potential hazard into a feature that ensures accuracy.
3Productivity
If conventional bone screw designs are used, then the screw can be implanted into bone, but the operation takes longer to complete, reducing surgical efficiency
Solution Approach 1:
By optimizing the chisel tip geometry parameters (angle, dimensions, shape), the screw achieves rapid bone cutting and advancement. The specific parameter values are selected to maximize cutting efficiency while minimizing resistance, allowing the screw to be inserted quickly without requiring multiple attempts or adjustments.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The design minimizes torque and downward force required for screw insertion, enhancing operational efficiency and safety by ensuring precise and efficient screw placement.
Implementation Method 1
A distal-most end of the at least one thread can have a leading cutting edge extending transverse to the central longitudinal axis from an outer diameter of the screw toward the central longitudinal axis, and a leading surface can extend proximally from the leading cutting edge. The leading surface can extend at an acute angle relative to the central longitudinal axis of the elongate shank.
Implementation Method 2
A distal tip at the second end of the elongate body can have at least one cutting edge configured to cut bone
Data Source
AI summary
Various bone screws configured to be implanted into bone and methods of use are provided. In an exemplary embodiment, a bone screw is provided with an elongate shank and a head with a drive feature configured to couple with a driver tool for being advanced into bone and a threaded shank. The screw can have a distal end or tip that has one or more cutting edges thereon configured to cut bone as the bone screw is inserted into bone.