Shape-Locking Intramedullary Fixation for Curved Bone Pathways
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Solution Overview
Problem
Existing intramedullary fixation devices for curved bones, such as those found in the pelvic ring and acetabulum, face challenges in providing secure mechanical fixation due to their limited mechanical strength and the need for invasive surgery, which increases blood loss and healing time.
Innovation Solution
A convertible intramedullary fixation device with a proximal shape locking interface that can transition between flexible and rigid states, allowing insertion along curved pathways and providing adequate tensile and vertical shear mechanical support, utilizing a system of segments with fibers locked by a shape locking section to achieve rigidity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a straight intramedullary fixation device is used in curved bones, then the device can be inserted through minimal incision, but the mechanical strength of fixation is insufficient due to bone curvature limitations
Solution Approach 1:
The intramedullary fixation device transitions from a flexible state during insertion to a rigid state after deployment. The device includes a shape locking interface that converts the device from flexible to rigid, allowing it to adapt to curved bone pathways during insertion then provide strong mechanical fixation once positioned
Solution Approach 2:
The device changes its physical state from flexible to rigid through the shape locking interface mechanism. This parameter change enables the device to navigate curved intramedullary spaces when flexible, then lock into a rigid configuration to provide adequate tensile and vertical shear mechanical support for bone fixation
2Ease of operation
If a straight intramedullary screw is used in curved bones, then insertion is simpler, but the device penetrates bone and injures soft tissues when too long, or provides inadequate fixation when limited in length
Solution Approach 1:
The device dynamically changes from flexible to rigid state, allowing it to be inserted at appropriate lengths without penetrating through the bone, then locks into a rigid configuration to provide secure fixation. The shape locking interface ensures the device maintains its position and provides reliable mechanical support
3Strength
If invasive open surgery is performed to attach fixation plates to bone, then secure mechanical fixation is achieved, but blood loss increases and healing time extends
Solution Approach 1:
The device provides secure mechanical fixation equivalent to open surgery through its rigid locked state and shape locking interface, but achieves this through minimally invasive percutaneous insertion. The transition from flexible to rigid state ensures adequate mechanical support without requiring extensive surgical dissection
Solution Approach 2:
The device changes from flexible to rigid configuration after insertion, providing the mechanical strength needed for secure fixation while avoiding the need for invasive open surgery. This parameter change enables the device to deliver full mechanical support through a minimally invasive approach
Data Source
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AI summary
Implantable devices for fixation of curved bones such as the pelvic ring pubic symphysis and acetabulum, and methods for the use of the devices are disclosed. The implantable devices are convertible between a flexible state and a rigid state using a shape locking section. The implantable devices further include a main body and a distal bone interface. In a flexible state, the devices may be inserted along, and conform to a curved pathway, and in the rigid state, the devices may support the mechanical loads required to fixate a fracture.