Intramedullary Nail with Shape Memory Alloy Compression
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Solution Overview
Problem
Intramedullary medical devices face challenges in maintaining sustained compressive forces across bone fusion sites due to bone resorption, leading to potential unsuccessful fusion, pain, recurring surgery, infection, and limb amputation in procedures like tibio-talo-calcaneal ankle fusion.
Innovation Solution
Intramedullary medical devices made from pseudo-elastic shape memory alloys, such as nickel-titanium, are used, which undergo strain imparting and recovery to maintain compression across bone interfaces during the bone fusion process, utilizing an installation assembly with drill guide holders and compression structures to ensure precise placement and controlled strain application.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If conventional intramedullary devices are used, then initial compression is achieved, but compressive forces are lost due to bone resorption during fusion
Solution Approach 1:
The intramedullary device incorporates a dynamic contracting element that can change its length and force output over time. The contracting element transitions from an uncontracted state with greater length to a contracted state with lesser length, enabling the device to maintain compression despite bone resorption and length changes during the fusion process
Solution Approach 2:
The device utilizes shape memory alloy material that can change its physical properties (length and force generation) in response to temperature changes. The contracting element is heated to induce contraction, transforming from a longer uncontracted state to a shorter contracted state, thereby maintaining compressive force as bone resorption occurs
2Force
If strain is applied to the intramedullary device, then compression is maintained, but device complexity increases
Solution Approach 1:
The contracting element is integrated within the intramedullary device structure, merging the compression maintenance function with the structural support function. The contracting element works in conjunction with the proximal and distal anchors to provide both structural integrity and active compression maintenance
Solution Approach 2:
The shape memory alloy contracting element is self-actuating through temperature-induced phase transformation. Once heated (e.g., via electrical current or external heating), the material automatically contracts and maintains compression without requiring external mechanical adjustment or complex control systems
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 effectively limits the loss of compressive stress between bone interfaces, enhancing the chances of successful bone fusion by maintaining consistent compression despite bone resorption, thereby reducing complications and improving fusion outcomes.
Implementation Method 1
Intramedullary medical devices in accordance with this disclosure include pseudo-elastic shape memory alloys containing nickel and titanium
Implementation Method 2
Intramedullary medical devices in accordance with this disclosure include pseudo-elastic shape memory alloys containing nickel and titanium
Data Source
AI summary
Methods and apparatus for installing intramedullary medical devices (e.g., intramedullary nails) are described herein. Intramedullary medical devices in accordance with this disclosure provide sustained compressive forces across a bone fusion site despite bone resorption processes. Intramedullary medical devices in accordance with this disclosure include pseudo-elastic shape memory alloys containing nickel and titanium. Portions of intramedullary medical devices, including shape memory alloy elements in the intramedullary medical devices, may have strains imparted upon them through the methods and apparatus described herein. Further aspects of surgery techniques are also performed and controlled through the methods and apparatus described herein.