Polymeric Braided Suture Fracture Fixation
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Solution Overview
Problem
Current surgical bone fixation technologies face issues such as mismatch in elasticity between metal devices and bone, leading to loss of compression, fatigue failure, stress-shielding effects, and complications like pathologic fractures, which hinder primary healing and increase the risk of non-union.
Innovation Solution
The use of polymeric cored braided sutures held in place by anchors on either side of the fracture, providing tension to compress and stabilize the bone fragments, with a deployment instrument that sets and maintains the necessary compressive force to facilitate primary healing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If metal fixation devices (screws, plates, nails) are used to stabilize fractures, then rigid fixation and compression are achieved, but mismatch in elasticity between device and bone causes loss of compression, fatigue failure, and stress-shielding effects
Solution Approach 1:
The patent changes the material parameter from metal to polymer, fundamentally altering the elastic modulus to match bone tissue. This parameter change allows the fixation device to maintain compression under physiological loads without the elasticity mismatch problems that cause loss of compression and fatigue failure in metal devices.
Solution Approach 2:
The patent employs composite material construction with a polymer core providing elasticity matching and a braided jacket providing tensile strength. This composite structure combines the beneficial properties of different materials to achieve both bone-compatible elasticity and sufficient mechanical strength for fracture fixation.
2Stability of the object's composition
If metal plates are used to span and compress fractures, then fixation stability is improved, but stress-shielding effect causes disuse-induced resorption and weakening of bone
Solution Approach 1:
By changing the material from metal to polymer with elastic modulus matching bone, the device allows physiological stress transmission to continue through the bone during healing. This prevents the stress-shielding effect where metal plates carry too much load, causing bone resorption and weakening.
3Force
If screw fixation is used to compress fractures, then initial compression is achieved, but screw holes act as stress risers increasing risk of pathologic fractures
Solution Approach 1:
The patent extracts the compression function from screw-based mechanical systems and implements it through a continuous polymer structure. This eliminates the need for screw holes that create stress concentration points and potential sites for pathologic fractures.
Solution Approach 2:
The patent uses a flexible polymer structure that distributes compressive forces continuously across the fracture site rather than through discrete screw holes. This flexible construction avoids stress concentration while maintaining effective compression.
4Force
If metal wires are used to apply compression to fractures, then initial compression is achieved, but devices are prone to fatigue failure requiring further surgical intervention
Solution Approach 1:
The patent uses a composite structure with polymer core and braided jacket that provides superior fatigue resistance compared to metal wires. The polymer material inherently resists fatigue failure while maintaining the ability to apply and sustain compressive forces throughout the healing process.
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
This method achieves rigid fixation and maintains compression under tensile and shear loads, promoting primary healing by minimizing complications and reducing the risk of non-union, while being flexible and fatigue-resistant.
Implementation Method 1
The polymeric cored braided sutures (110) is tensioned so as to compress the fracture and hold it in place... the tension preload provides compression which maintains fixation in the face of tensile and shear loads applied to the bone
Implementation Method 2
The anchor of the present invention is capable of distributing the suture load into the bone while holding up to 100 pounds in shear
Data Source
AI summary
The present invention is a new technology that addresses some of the deficiencies of current fracture fixation technology used in surgical procedures. It involves the use of a polymeric cored braided suture held in place by anchors implanted on each side of a fracture. The anchors must be secured into the bone while yet maintaining very high tensions in the suture during the deployment process. The polymeric cored braided suture is tensioned so as to compress the fracture and hold it in place, functioning as though it has sewn the bone fragment back together. This provides the rigid fixation of the fracture that is essential for primary healing to occur. Simultaneously, the tension preload provides compression which maintains fixation in the face of tensile and shear loads applied to the bone as a result of movement and weight bearing.