Spinous Process Fixation via Percutaneous Clamp and Rod Mechanism
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Solution Overview
Problem
Current bone fixation methods for spinal stabilization, particularly screw fixation into the pedicle portion of the vertebral body, are invasive and have significant shortcomings, necessitating a more effective and less invasive approach to rigidly fixate spinous processes between adjacent vertebral bones for spinal fusion.
Innovation Solution
A percutaneously deliverable orthopedic implant that forcibly clamps onto the spinous processes of vertebral bones, allowing for bone fusion material placement within the inter-spinous space and using a locking mechanism to immobilize the spinous processes between bone abutment surfaces, thereby stabilizing the spinal segment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If screw fixation into the pedicle portion of the vertebral body is used, then reliable spinal stabilization is achieved, but the surgical procedure becomes substantially more invasive and complex
Solution Approach 1:
The fixation system is divided into separate components: a rod member for longitudinal spanning, discrete clamps for vertical compression, and separate bone anchorages. This segmentation allows each component to be optimized independently and simplifies the surgical procedure by enabling modular assembly rather than requiring complex pre-assembled constructs like traditional screw-fixation systems.
Solution Approach 2:
The invention extracts the compression function from the fixation screws themselves and separates it into a dedicated vertical compression mechanism using the rod member and clamps. This extraction allows the bone anchorage elements to focus solely on securing the implant to bone, while the rod-clamp system provides adjustable compression, thereby simplifying the overall surgical procedure.
2Strength
If traditional screw fixation methods are used, then adequate fixation is achieved, but the operation becomes more invasive with multiple shortcomings
Solution Approach 1:
The bone anchorage elements are designed with localized features optimized for specific bone interaction mechanisms. The anchors incorporate features such as threads, fins, or expansion mechanisms that are specifically engineered to engage with bone tissue at the anchorage site, providing strong fixation without requiring extensive surgical exposure or damage to surrounding tissues.
Solution Approach 2:
The rod member is designed to receive and nest the clamps, which in turn receive and secure the bone anchorage elements. This nested configuration allows the entire fixation construct to be assembled in a compact manner and delivered through minimally invasive percutaneous approaches, reducing surgical invasiveness while maintaining strong fixation strength.
3Object-affected harmful factors
If percutaneous delivery of implant is used, then surgical invasiveness is reduced, but the ability to rigidly fixate spinous processes becomes more challenging
Solution Approach 1:
The rod member is designed with dynamic adjustment capabilities, allowing the vertical compression force to be adjusted and optimized after implantation. This dynamic feature enables the surgeon to achieve optimal fixation reliability through percutaneous adjustments without requiring open surgical exposure, thereby maintaining both minimally invasive delivery and reliable fixation.
Solution Approach 2:
The clamps serve as intermediary elements between the rod member and the bone anchorage elements. These clamps provide a mechanical interface that translates the longitudinal force from the rod into vertical compression on the spinous processes, enabling reliable fixation to be achieved through percutaneous delivery by mediating the force transmission between components.
4Reliability
If bone fusion material is placed in inter-spinous space, then bone fusion between vertebral bones is promoted, but the device complexity increases
Solution Approach 1:
The rod member serves multiple functions: it provides longitudinal spanning, delivers vertical compression through the clamps, and creates a containment structure for the bone fusion material. This multi-functionality reduces the need for separate containment structures or delivery systems, thereby promoting bone fusion without proportionally increasing device complexity.
Solution Approach 2:
The bone fusion material is contained within the nested structure formed by the rod member and clamps. This nesting configuration naturally creates a containment environment for the bone graft material without requiring additional complex containment structures, thereby promoting bone fusion while maintaining relatively simple device architecture.
Data Source
AI summary
Devices and methods for the treatment of abnormal spinal stability and stenosis of the spinal canal by the implantation of orthopedic devices between skeletal segments. In one embodiment, a device is disclosed to rigidly fixate the spinous processes of two vertebral bones relative one another. A first member of the device is advanced across an interspinous space, rotated, and/or advanced onto the contralateral side of the spinous processes. A second member of the device is also advanced onto the ipsilateral side of the spinous processes and forcibly captures the spinous processes between the first and second members. A protrusion extends from the first and/or second devices configured to embed into the bone of the spinous processes thereby increasing the immobilization strength of the device. The implant may be further configured to contain a bone forming material to form a fusion between the first and the second vertebral bones.