Expansile Orthopaedic Implant Mesh for Bone Interface Fixation
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Solution Overview
Problem
Current orthopaedic implants suffer from micromotion at the bone-implant interface, leading to failure and the need for revision surgeries, particularly in cases involving obesity and anatomic variations, with limited contact area estimated at about 60% in femoral hip stems.
Innovation Solution
Expansile implants with a metal mesh structure made of NiTiNol or shape memory polymers that expand at body temperature, providing increased contact area and allowing bone ingrowth/on-growth, and optionally filled with osteoinductive/osteoconductive compounds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If traditional implants are used, then manufacturing and installation are simpler, but contact area with bone is limited to about 60% of available area leading to micromotion and fixation failure
Solution Approach 1:
The implant incorporates an expansile structure that transitions from a compressed state during implantation to an expanded state upon insertion into the bone cavity. This dynamic expansion allows the implant to achieve maximum contact area with the bone surface, improving fixation reliability by eliminating micromotion at the interface.
Solution Approach 2:
The implant utilizes shape memory alloys (such as NiTiNol) that undergo phase transformation when exposed to body temperature. This parameter change in material properties enables the implant to automatically expand to its final configuration, maximizing bone contact area and enhancing osseous integration without requiring additional surgical steps.
2Reliability
If expansile structures are added to increase contact area, then initial fixation improves, but device complexity increases
Solution Approach 1:
The expansile implant structure is designed to automatically expand and conform to the bone cavity using shape memory alloy properties. This self-expanding mechanism eliminates the need for complex mechanical expansion devices, surgical adjuncts, or multi-step insertion procedures, thereby improving initial fixation while keeping the overall device relatively simple.
Solution Approach 2:
The implant combines shape memory alloy materials with appropriate structural designs to create a unified expansile structure. This composite approach integrates the expansion function directly into the implant body, avoiding the need for separate expansion mechanisms and reducing overall device complexity while enhancing initial fixation reliability.
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
Enhances initial fixation, reduces micromotion, and improves osseous integration, offering better survivorship by aligning with native bone stress patterns and distributing stress more evenly.
Implementation Method 1
the expanding structure may be made of, for example a NiTiNol structure, which may further be designed for expansion at body temperatures
Implementation Method 2
the interstices of the fiber metal mesh may further be filled with a shape memory polymer and/or other elastic material which may also be programmed for expansion at body temperatures
Data Source
AI summary
In one or more embodiments orthopaedic implants may be provided. The implants may include an expansile structure which may allow for increased contact between an endosteal or periosteal surface for initial fixation and further allow for bone in-growth and/or on-growth. In some embodiments the expansile structure may be made of, for example a NiTiNol structure, which may further be programmed for expansion at body temperatures. In some embodiments the interstices of the expansile structure may further be filled with a shape memory polymer and/or other elastic material which may also be programmed for expansion at body temperatures.