Intramedullary Device with Barbed Nitinol Ends for Bone Compression
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current intramedullary devices fail to consistently bring bone fragments into close proximity and maintain compressive load over time, leading to suboptimal healing outcomes due to rapid dissipation of compressive force as the bone relaxes and remodels, and lack of torsional stability.
Innovation Solution
The development of novel intramedullary devices featuring barbed ends that flare outward and can be elastically constrained to fit into bone holes, providing secure engagement and maintaining compression through shape memory materials like Nitinol, which also offer torsional stability by engaging the bone's circumference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If traditional intramedullary devices with co-planar legs are used, then the device can be inserted into the bone, but the compressive load dissipates rapidly as the bone relaxes and remodels
Solution Approach 1:
The device employs a dynamic mechanism where the legs are initially co-planar for insertion, then transition to a non-co-planar configuration after insertion. This dynamic reconfiguration allows the device to adapt to bone relaxation and remodeling, maintaining compressive load over time rather than dissipating it.
Solution Approach 2:
The legs are pre-configured in a co-planar state that enables easy insertion into the bone. After insertion, the legs are reconfigured to a non-co-planar state that provides superior compressive load maintenance. This preliminary action of preparing the device in an insertion-friendly configuration resolves the contradiction between ease of insertion and long-term load maintenance.
2Device complexity
If intramedullary devices with co-planar legs are used, then the device structure is simple, but torsional stability at the fusion site is insufficient
Solution Approach 1:
The device transitions from a symmetric co-planar leg configuration during insertion to an asymmetric non-co-planar configuration after insertion. This asymmetric arrangement of the legs provides superior torsional stability at the fusion site while maintaining relatively simple device structure.
3Reliability
If barbed ends that flare outward are used, then the device provides secure engagement with bone, but the device complexity increases
Solution Approach 1:
The barbed ends with flaring geometry are applied only at the insertion points of the legs, rather than throughout the entire device structure. This localized application of complex geometry provides secure engagement with the bone while minimizing overall device complexity.
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
These devices effectively bring and maintain bone fragments in close contact, enhancing healing by sustaining compressive load and providing improved torsional stability, thus accelerating the bone fusion process.
Implementation Method 1
The Nitinol devices typically have a pair of radially extending 'legs' at their opposing ends that expand outward when warmed to body temperature
Implementation Method 2
a first bone-engaging feature formed on the shaft at a first location, the first bone-engaging feature comprising at least one barb which, in its unbiased condition, flares outwardly from the longitudinal axis of the shaft and which is capable of being elastically constrained to a position substantially parallel to the longitudinal axis of the shaft
Data Source
AI summary
An intramedullary device includes a central bridge region having a first end and a second end. The intramedullary device also includes a bone engaging feature at both the first end and the second end. At least one of the bone engaging features includes a first barb and a second barb which, in an unbiased condition, flare outwardly from a longitudinal axis of the central bridge region and which are capable of being elastically constrained to a constrained condition such that the first end of the central bridge region may be advanced into a hole in a first bone fragment when the first barb and second barb are elastically constrained. The first barb and second barb are prevented from being withdrawn from the hole in the first bone fragment when the first barb and the second barb are not constrained. The intramedullary device i) is cannulated, ii) generates a compressive load, and iii) comprises nitinol.