Vertebral Cement Containment Bag for Fracture Fixation
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Solution Overview
Problem
Current treatments for compression fractures of the vertebrae, such as vertebroplasty and kyphoplasty, face issues with cement migration, heat emission, toxicity, and mechanical property drops in polymethylmethacrylate (PMMA) materials, which can lead to further bone weakening and fractures.
Innovation Solution
The use of a biocompatible material that does not set to a hardened condition, injected into the bone to provide support and prevent retrograde motion, with options for additional cement to set and provide further structural support, utilizing materials with high viscosity or soft solid properties that can undergo plastic deformation without tearing, and incorporating additives like bone growth factors or radio-opaque materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If cement is injected into a fractured vertebra to fix the fracture and reduce pain, then the fracture is fixed and pain is reduced, but the cement may migrate out of the vertebra or through cracks in the vertebra causing bodily harm
Solution Approach 1:
A bag is introduced as an intermediary component between the injected cement and the surrounding bone tissue. The bag acts as a containment barrier that prevents cement from migrating out of the vertebra or through cracks, while still allowing the cement to perform its fracture fixation function. This mediator resolves the contradiction by isolating the harmful migration pathway while preserving the beneficial fixation effect.
Solution Approach 2:
The bag used in the invention functions as a flexible shell or thin film that can be inserted into the vertebra. This flexible barrier contains the cement within the vertebral body, preventing migration through cracks or outward displacement, while maintaining the structural integrity needed for fracture fixation. The flexible nature allows it to conform to the vertebral geometry.
2Reliability
If polymethylmethacrylate (PMMA) cement is used to fix the fracture, then the fracture is fixed, but the cement emits heat and possibly toxic materials while setting which may further weaken the bone and possibly cause the cement to loosen and/or the bone to fracture
Solution Approach 1:
The bag serves as a protective intermediary layer between the setting PMMA cement and the surrounding bone tissue. It contains the exothermic heat generation within a localized zone, preventing excessive heat from diffusing to and damaging the adjacent bone. Similarly, it contains toxic materials within the bag, preventing their release into the surrounding tissue while allowing the cement to set and provide fracture fixation.
Solution Approach 2:
The invention converts the harmful effects of PMMA (heat and toxicity) into localized, contained phenomena. By using the bag as a containment structure, the heat and toxic materials are confined to a specific region rather than spreading throughout the bone, effectively transforming these harmful factors into manageable, localized effects that do not compromise overall bone health.
3Reliability
If harder than bone materials are used to fix the fracture, then the fracture is fixed, but they induce fractures in nearby bones
Solution Approach 1:
The bag acts as a mediating layer between the hard cement and the surrounding bone. It isolates the high-stress, hard material from direct contact with adjacent bone structures, preventing stress concentration at the interface that would otherwise induce fractures in nearby bones. This intermediary allows the use of hard fixation materials while protecting surrounding tissue from their harmful mechanical effects.
4Object-affected harmful factors
If bone-like repair materials such as slurry of bone chips are used, then they do not induce fractures in nearby bones, but injecting such materials is difficult due to their viscosity
Solution Approach 1:
The bag serves as a delivery conduit and containment structure for viscous bone chip slurry. It facilitates the injection process by providing a controlled pathway through which the viscous material can be delivered into the vertebra, overcoming the difficulty of injecting high-viscosity materials. After injection, the bag contains the material to prevent migration, combining delivery and containment functions.
5Object-affected harmful factors
If more viscous cement is injected to reduce cement migration, then cement migration is reduced, but higher pressures are required for injection and the workability window is reduced
Solution Approach 1:
The bag acts as a pressure-regulating intermediary during injection. It accommodates the high-viscosity cement by providing a compliant containment structure that can expand as material is injected, reducing the peak pressures required compared to open injection systems. The bag's flexibility allows it to absorb some of the injection pressure, making the process more manageable while maintaining effective cement containment.
Solution Approach 2:
The bag modifies the physical parameters of the injection environment by providing a confined, flexible chamber. This changes the pressure-volume relationship during injection, allowing viscous materials to be injected at more manageable pressures while maintaining adequate workability time. The bag's elastic properties enable it to accommodate material injection without requiring excessively high pressures.
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 approach reduces the risk of cement migration, avoids exothermic reactions, and provides sustained support to the bone, allowing for more flexible injection methods and improved mechanical properties, while minimizing the risk of leakage and bone fracture induction.
Implementation Method 1
soft solid materials which can optionally undergo substantial plastic deformation without tearing
Implementation Method 2
the injected material moves the fractured pieces of the bone. The injected material remains in the bone to provide support and prevent retrograde motion
Data Source
AI summary
A method of treating a vertebra, comprising:(a) accessing an interior of a vertebra; and(b) introducing a sufficient amount of artificial biocompatible material which does not set to a hardened condition in storage, into said bone, with sufficient force to move apart fractured portions of said bone.