Lumbar Fusion Device Internal Threaded Tang Extension
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Solution Overview
Problem
Existing spinal fusion devices face challenges in securely affixing adjacent vertebrae during the bone growth period, with a risk of the stabilizing device dislodging before fusion is complete.
Innovation Solution
A lumbar vertebrae fusion device with an internal expansion mechanism, featuring recesses for bone graft material and a threaded actuator that allows for the extension of tangs into the vertebrae, providing secure anchoring and facilitating bone growth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a stabilizing device is implanted to prevent vertebrae movement during bone growth, then spinal stabilization is improved, but the device may dislodge before fusion is complete
Solution Approach 1:
The device incorporates a dynamic expansion mechanism where the body expands from an initial diameter to a larger final diameter after implantation. This dynamic change allows the device to initially fit within the intervertebral space and then expand to lock into place, preventing dislodgement during the bone growth period.
Solution Approach 2:
The device utilizes parameter changes by altering its physical dimension (diameter) after implantation. The expandable body changes from a smaller implantable size to a larger stabilized size, creating mechanical interlocking with the vertebrae and bone graft material, thereby ensuring long-term positional stability.
2Strength
If tangs are extended into vertebrae to secure the device, then anchoring strength is improved, but device complexity increases
Solution Approach 1:
The patent combines multiple functions into a single integrated mechanism. The threaded actuator simultaneously controls the expansion of the body and the extension of the tangs into the vertebrae. This merging of functions reduces the number of separate components and simplifies the overall device structure while maintaining strong anchoring capability.
Solution Approach 2:
The tangs are nested within the device body in a retracted state during implantation. After the body expands, the tangs are extended outward through controlled movement from the threaded actuator. This nested configuration allows the device to be implanted in a compact form and then deploy anchoring elements as needed.
3Ease of operation
If an external tool is used to extend tangs during surgery, then ease of operation is improved, but forces are exerted on the patient's spine
Solution Approach 1:
The actuating mechanism is extracted from a separate external tool and integrated directly into the device body. The threaded actuator is positioned within the device, allowing the tangs to be extended from within the implant itself rather than from an external instrument, thereby eliminating harmful forces on the spine during the procedure.
Solution Approach 2:
The device performs its own actuation function through the integrated threaded actuator mechanism. By rotating the actuator, the device self-regulates the extension of its tangs without requiring external surgical tools to apply force, making the system self-sufficient and eliminating harmful external forces on the patient's spine.
4Ease of repair
If the actuator is integrated into the device, then device removal is simplified, but manufacturing complexity increases
Solution Approach 1:
The actuator and device body are merged into a single integrated unit with common structural elements. The threaded actuator is positioned within the device body and shares manufacturing processes with the main structure, reducing the need for separate assembly steps and simplifying both manufacturing and removal procedures.
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
The device effectively secures the vertebrae in place, allowing for stable bone growth and fusion, while the integrated threaded actuator simplifies the process of retracting the tangs during device removal, minimizing forces exerted on the spine.
Implementation Method 1
Movement of the anchoring element with respect to the body is caused by rotation of a threaded actuator
Implementation Method 2
The bone graft material encourages the growth of the patient's bone through the device, affixing the device in place with respect to the spine
Data Source
AI summary
The spinal stabilization device is implanted using a surgical procedure referred to as an anterior lumbar interbody fusion (AILF). The body of the device includes upper and lower surfaces that are placed in direct contact with the adjacent vertebrae. After placement of the device between the vertebrae, a threaded member is rotated to cause the anchoring element to push into the body of the device, causing the extension of tangs through the upper and lower surfaces and into the adjacent vertebrae of the patient. Movement of the anchoring element with respect to the body is caused by rotation of a threaded actuator. The threaded actuator is a permanent element of the spinal stabilization device, rather than being integrated into a temporary tool.