DMLS Intramedullary Nail With Adjustable Stiffness for Fracture Healing
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Solution Overview
Problem
Current orthopedic intramedullary devices lack standardized guidelines for optimal performance, and existing materials like titanium and stainless steel may not provide the ideal axial bending and torsional stiffness for specific fracture types, which can impact fracture healing.
Innovation Solution
An orthopedic intramedullary nail manufactured via additive manufacturing using medical-grade powders, heat-treated, and machined to include a telescopic portion with a mechanical actuator for adjustable stiffness and an internalized sensor probe channel, optimizing mechanical properties and patient-specific design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If traditional isotropic materials like titanium or stainless steel are used for intramedullary nails, then the device has sufficient strength and durability, but the axial bending and torsional stiffness are too high for optimal fracture healing in specific fracture types
Solution Approach 1:
The patent applies local quality by creating anisotropic material properties within the intramedullary nail through additive manufacturing. Different regions of the nail have different material orientations and properties - the build direction provides higher strength while the infill pattern controls stiffness. This allows the nail to have high strength for durability while having reduced stiffness in specific directions to promote fracture healing, resolving the contradiction between strength and stiffness.
Solution Approach 2:
The patent uses composite materials by combining metal powder (titanium or stainless steel) with a binder material in an additive manufacturing process. The metal powder provides strength and durability, while the binder and infill pattern allow control over stiffness characteristics. This composite approach enables the nail to simultaneously achieve high strength for structural integrity and adjustable stiffness for optimal fracture healing performance.
2Reliability
If patient-specific custom designs are implemented for intramedullary nails, then optimal performance for specific fracture types is achieved, but manufacturing complexity and cost increase
Solution Approach 1:
The patent applies parameter changes by using additive manufacturing to easily modify design parameters such as infill density, pattern, and orientation without changing the fundamental manufacturing process. This allows rapid customization of intramedullary nails for different patient anatomies and fracture types by simply adjusting digital model parameters, achieving optimal performance while keeping manufacturing relatively simple and cost-effective.
Solution Approach 2:
The patent achieves universality by creating a single additive manufacturing process that can produce multiple variations of intramedullary nails for different applications. The same DMLS or FDM process can manufacture nails with different geometries, material compositions, and mechanical properties by changing digital parameters, providing a universal manufacturing solution that handles both standard and patient-specific designs efficiently.
3Adaptability or versatility
If additive manufacturing with medical grade powder is used, then manufacturing flexibility and design freedom are improved, but manufacturing time and process complexity increase
Solution Approach 1:
The patent applies preliminary action by preparing digital models and process parameters in advance before actual manufacturing. Complex geometries and patient-specific designs are fully designed and simulated in the digital domain before additive manufacturing begins, allowing the physical manufacturing process to proceed efficiently without interruptions for design modifications, thus reducing overall manufacturing time while maintaining design freedom.
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 solution provides improved mechanical properties and adjustable stiffness, enhancing fracture healing by accommodating individual patient needs and fracture types, while reducing manufacturing costs and time.
Implementation Method 1
forming from a medical grade powder, and via an additive manufacturing process, an additive manufactured orthopedic component
Implementation Method 2
heat treating the additive manufactured orthopedic component
Implementation Method 3
a wall comprising one or more laser sintered layers of a medical grade powder
Data Source
AI summary
An orthopedic device, such as an intramedullary nail for internal fixation of a bone and a method of manufacturing the same. The orthopedic device may be formed from a medical grade powder via an additive manufacturing process. The forming process may include heat treating the additive manufactured component and machining the heat treated additive manufactured component to form the orthopedic device. Further, the orthopedic device may be formed to include an internal sensor probe channel that extends within at least a portion of the wall of the device, but which does not protrude through an outer portion of the wall. Embodiments further include a dynamizing intramedullary nail that accommodate adjustments in the relative axial positions of one or more sections of the orthopedic device. The devise may include features in an inner region of the orthopedic device that may alter an elastic modulus of the orthopedic device.