Vertebral Body Replacement Footplate Orientation and Locking
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Solution Overview
Problem
Current spinal implants lack adjustability, leading to potential neurologic injury from torsional forces, improper sizing, limited access for height manipulation, and inadequate endplate angulation, which can result in improper spinal alignment and long-term neurological impairment.
Innovation Solution
A vertebral body replacement device with a modular design featuring a body member, central rod, and end members, allowing 360-degree adjustment and secure locking, eliminating torsional forces by converting rotational motion into axial movement, and enabling precise alignment and angulation to match unique bone contours.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a fixed length spinal implant is used, then the device structure is simple, but the implant cannot be adjusted to match the clinical space, leading to improper sizing
Solution Approach 1:
The patent implements a dynamic length adjustment mechanism where the spinal implant can be extended or compressed in vivo through rotational movement of an adjustment tool. The central rod with threaded sections and nuts allows the implant length to be modified after implantation, transforming a static structure into a dynamic one that adapts to the actual clinical space requirements.
Solution Approach 2:
The implant is divided into modular components including a body member, central rod with threaded portions, and nuts that can be independently adjusted. This segmentation allows for precise length control by rotating individual nuts along the threaded rod, enabling the implant to be customized to match the specific clinical space without requiring multiple pre-fabricated sizes.
2Adaptability or versatility
If a rotary lengthening mechanism is used, then the implant can be adjusted in vivo, but torsional forces are applied during lengthening risking neurologic injury
Solution Approach 1:
The patent introduces a central rod as an intermediary element that translates rotational movement into axial length adjustment. Instead of directly rotating the end members against the vertebral bodies, the threaded rod mechanism converts rotation into controlled axial extension, with the nuts serving as intermediaries that move along the threaded rod to lengthen the implant without applying torsional forces to the bone-implant interface.
Solution Approach 2:
The patent replaces the direct rotary lengthening mechanism with a threaded rod and nut system. Instead of rotating the entire implant structure, the adjustment is achieved by rotating nuts along the threaded central rod, which converts rotational motion into precise axial displacement. This mechanical substitution eliminates torsional stresses on the vertebral bodies while maintaining the ability to adjust length in vivo.
3Adaptability or versatility
If limited access ports are used, then the device structure is simplified, but height manipulation is restricted
Solution Approach 1:
The central rod serves multiple functions: it provides the structural core of the implant, enables length adjustment through threaded portions, and allows height manipulation through nuts that can be positioned at various locations along the rod. This multi-functional design eliminates the need for separate access ports for different adjustment operations, as the same central rod structure facilitates both length and height control.
4Adaptability or versatility
If the implant lacks endplate angulation capability, then the device structure is simple, but proper spinal alignment cannot be achieved
Solution Approach 1:
The patent incorporates asymmetric features in the footplate design, including non-circular engagement surfaces and oriented attachment mechanisms that allow the footplate to be secured at specific angular orientations relative to the vertebral endplate. This asymmetric configuration enables precise angulation control to match the natural spinal curvature and alignment requirements without requiring complex active adjustment mechanisms.
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 provides in vivo adjustability, ensuring optimal spinal alignment, reducing the risk of neurologic injury, and allowing for precise lengthening and shortening, thereby maintaining proper spinal spacing and preventing long-term neurological impairment.
Implementation Method 1
a central rod (40) for placement within the body member (30), the central rod (40) having a first threaded portion (41) and a second threaded portion (42)
Implementation Method 2
a locking mechanism (84) that is configured to securely couple the at least one footplate member (80) to the first end member (20) and/or the second end member (20)
Implementation Method 3
a sidewall (83) that is attached to the end surface (82) and that is configured to include an orientation mechanism (93) that functions to align the footplate member (80) in a certain position relative to each of the at least two end members (20)
Data Source
Figure 1
Figure 2A~3
Figure 4~5
AI summary
The footplate member (80) includes an end surface (82), a sidewall (83) that is attached to the end surface, and an orientation mechanism (93) that is designed to align the footplate member in a certain position relative to at least one of the two end members (90) of the vertebral body replacement device. The orientation mechanism includes a plurality of tabs (91) located on an end wall of each end member and corresponding slots (88) located along the edge of the sidewall, with the tabs and slots being sized and positioned to mate. The footplate member also includes a locking mechanism (85) designed to couple the footplate member to an end member prior to the implantation of the vertebral body replacement device within a space within a spinal column. A method for assembling a vertebral body replacement device and a method for using a footplate member in a vertebral body replacement device is also disclosed.