Composite Bone-Metal Orthopedic Fixation Devices
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Solution Overview
Problem
Current orthopedic fixation devices for spinal stabilization face challenges such as high pedicle perforation rates, dural tears, nerve root injuries, vascular injuries, non-union, pseudoarthrosis, and screw pullout, due to the rigidity of materials like titanium alloys and the mismatch between device alignment and bone anatomy.
Innovation Solution
Development of composite orthopedic fixation devices made from a combination of allograft/autograft bone and metal or metal alloys, with a multi-layered structure and cannulated portions featuring fenestrations for enhanced bio-integration and load-carrying capabilities, along with methods for applying a bone growth cocktail to promote integration with surrounding bone tissue.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If rigid materials like titanium alloys are used for orthopedic fixation devices, then strength and load-carrying capability are improved, but bio-integration with bone tissue deteriorates and rigidity mismatch causes stress shielding
Solution Approach 1:
The patent applies composite materials by combining metal components (for strength and load-bearing) with bone graft material (for bio-integration and osteconduction). The metal portion provides mechanical support while the bone graft portion promotes biological integration with surrounding bone tissue, resolving the contradiction between strength and bio-integration.
2Reliability
If devices are made fully from bone graft material, then bio-integration is improved, but strength and structural integrity deteriorate
Solution Approach 1:
The composite structure combines bone graft material with metal reinforcement. The bone graft material provides bio-integration and osteoconduction properties, while the metal portion supplies the necessary structural integrity and load-bearing capacity that bone graft alone cannot provide.
Solution Approach 2:
The device applies local quality by having different materials in different regions: bone graft material in areas requiring bio-integration and osteoconduction, and metal in areas requiring high strength and structural support. This spatial differentiation of material properties resolves the contradiction between bio-integration and strength.
3Adaptability or versatility
If polyaxial connectors are added to accommodate bone anatomy variations, then adaptability is improved, but device complexity increases
Solution Approach 1:
The polyaxial connector provides dynamic adaptability by allowing the rod to be inserted at multiple angles relative to the screw axis. This dynamic adjustment capability enables the device to accommodate variations in bone anatomy without requiring multiple different screw designs, thus improving adaptability while controlling complexity.
Data Source
AI summary
Composite orthopedic devices that facilitate spine stabilization, such as: bone screws, rods, plates, interbodies, and corpectomy cages are disclosed. They are designed to provide both strength and load carrying capabilities, while increasing bio-integration of the devices with the surrounding bone tissue. They are constructed of composite layers of allograft and/or autograft bone and a structural material, such as titanium alloy or carbon/graphite fiber composite. Cannulations within the device are loaded with a mixture of stem cells, particles of allograft and/or autograft bone, and bone growth factors, such as BMP-2. The cannulations are connected to the surface of the device via multiple fenestrations that provide pathways to supply the bone/stem cell mixture to the surface, allowing living bone tissue to grow and insure bio-integration. The devices can also have radiofrequency (RF) stimulation implantation within the structure of the implanted device, capable of responding to external RF stimulation of enhanced bone growth.