Bone Nail with Helical Ridges for Fracture Fixation
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Solution Overview
Problem
Bone pins used for fracture fixation often slip axially and rotationally, making them unsuitable for holding bone fragments aligned and providing compression, which is necessary for proper bone healing.
Innovation Solution
A bone nail with helical ridges of large pitch is developed, allowing axial force application for secure placement in bone, providing stability and compression by converting axial force into torque without stripping the bone, similar to bone screws.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a bone pin is driven into bone by applying axial force, then the installation process is simple and flexible, but the pin slips axially and rotationally, making it unsuitable for holding bone fragments aligned and providing compression
Solution Approach 1:
The invention merges the installation simplicity of bone pins with the stability of bone screws by combining a smooth cylindrical shaft (for easy axial insertion) with helical ridges (for rotational stability and compression). The helical ridges are formed on the shaft surface, integrating both functional characteristics into a single unified structure that exhibits both pin-like insertion ease and screw-like holding stability.
Solution Approach 2:
The helical ridges introduce a curved, spiral geometry to the otherwise cylindrical shaft. This helical curvature converts axial insertion force into rotational torque, enabling the nail to self-tap into the bone and achieve rotational stability. The curved helical path of the ridges allows the nail to screw into the bone while being driven axially, resolving the contradiction between simple axial installation and rotational stability.
2Object-affected harmful factors
If bone pins are smaller in diameter than bone screws, then they damage bone less and provide greater flexibility in selecting the site of implantation, but they are more likely to slip axially and rotationally
Solution Approach 1:
The invention combines the small diameter advantage of bone pins with the holding power of bone screws by adding helical ridges to the pin surface. The ridges provide thread-like engagement with the bone that prevents slippage, while the overall small diameter is maintained to minimize bone damage and allow flexible implantation site selection.
Solution Approach 2:
The nail structure can be considered a composite of a smooth cylindrical base (providing small diameter and flexibility) and helical ridge features (providing holding power). This composite geometry allows the device to exhibit both the advantages of pins and screws simultaneously, achieving high holding power in a compact form factor.
3Reliability
If bone screws are used to fasten orthopedic implants to bone, then they provide secure fixation, but they require threading into bone which can strip threads and complicate installation
Solution Approach 1:
The helical ridges convert the installation process by transforming axial force into rotational torque, allowing the nail to self-tap into the bone without requiring pre-threading or complex driving mechanisms. The curved helical geometry enables the nail to screw itself in during simple axial impact, eliminating the need for separate threading operations and reducing installation complexity while maintaining secure fixation.
Solution Approach 2:
The helical ridges enable the nail to create its own threading path as it is driven into the bone. The ridges act as self-forming threads that cut into the bone material during axial insertion, eliminating the need for pre-drilled threaded holes or complex installation procedures. The nail essentially creates its own fixation path as it is installed, simplifying the overall installation process.
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 bone nail achieves improved axial and rotational stability, reducing slippage and enhancing the effectiveness of bone fixation and repair by increasing contact and purchase with the bone, thus facilitating anatomic restoration and proper healing.
Implementation Method 1
at least one helical ridge having a large pitch. The large pitch permits the nail to be driven into bone by application of axial force to the nail
Data Source
AI summary
System, includes devices, methods, and kits, for fixing bone and/or repairing connective tissue associated with bone using a fastener constructed as a bone nail that includes at least one helical ridge having a large pitch. The large pitch permits the nail to be driven into bone by application of axial force to the nail, to secure the nail in the bone. In some embodiments, the bone nail may have a variable pitch that decreases toward the trailing end of the nail.