Vertebral Body Replacement With Resilient Support Member
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Solution Overview
Problem
Existing vertebral body replacement (VBR) apparatuses are rigid and static, leading to point-loading on bone-contacting surfaces, which can cause adjacent vertebral body subsidence and increased failure risk, and fail to efficiently distribute forces or stimulate bone graft growth.
Innovation Solution
A VBR apparatus with a telescoping design and a resilient support member that allows for axial and lateral flexibility, incorporating a spring portion with struts and hanging beams to maintain elasticity and distribute forces effectively, promoting bone graft growth and reducing the risk of subsidence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a rigid VBR apparatus is used, then structural support and stability are provided, but point-loading on bone-contacting surfaces occurs causing adjacent vertebral body subsidence and increased failure risk
Solution Approach 1:
The VBR apparatus transitions from a rigid static structure to a dynamic resilient structure through the incorporation of a spring portion with struts and hanging beams. This resilient support member allows controlled deformation and elastic recovery, enabling the apparatus to adapt to physiological movements while maintaining structural integrity and distributing loads dynamically to prevent subsidence and failure.
Solution Approach 2:
The patent changes the mechanical parameters of the VBR apparatus by introducing elasticity through the spring portion. The resilient support member exhibits variable stiffness and controlled compliance, allowing the apparatus to transition between rigid support and flexible adaptation modes, thereby optimizing both strength and reliability under different loading conditions.
2Stability of the object's composition
If a rigid VBR apparatus is used, then implant stability is achieved, but forces are not efficiently distributed leading to increased stress on adjacent vertebrae
Solution Approach 1:
The resilient support member with spring portion enables dynamic force distribution by deforming under load and returning to original shape. This dynamic behavior allows the apparatus to distribute forces evenly across the bone-contacting surfaces and adjacent vertebrae, preventing stress concentration while maintaining implant stability through elastic recovery.
3Ease of manufacture
If a static VBR apparatus is used, then surgical implantation is simplified, but bone graft growth stimulation is insufficient due to lack of mechanical signaling
Solution Approach 1:
The spring portion with struts and hanging beams creates controlled micromotions and mechanical signaling that stimulate bone graft growth. The resilient support member's elastic deformation under physiological loads provides mechanical stimuli that enhance osteogenesis and fusion, while the overall apparatus remains sufficiently stable to facilitate straightforward surgical implantation.
4Reliability
If a resilient support member with spring portion is incorporated, then force distribution and bone graft growth stimulation are improved, but device complexity increases
Solution Approach 1:
The resilient support member is segmented into discrete functional components: struts providing structural framework and spring portion providing elasticity. This segmentation allows each component to perform its specific function efficiently while maintaining overall apparatus simplicity and manufacturability, balancing improved force distribution with controlled device complexity.
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 dynamic VBR apparatus effectively distributes forces, stimulates bone graft growth, and reduces the risk of subsidence by maintaining elasticity and constant contact with adjacent vertebrae, enhancing the fusion process and implant stability.
Implementation Method 1
a spring portion (164) configured to deflect when a force is applied to the VBR apparatus (100, 100a)
Data Source
AI summary
A vertebral body replacement apparatus includes an outer body member having a first end, a second end, and an opening, and an inner body member having a first end, a second end, and an inner surface defining an opening. The first end of the inner body member is received in the opening of the outer body member such that the inner body member and the outer body member are movable relative to one another. A support member has a first end secured within the inner body member and a second end extending a distance beyond the inner body member. The second end of the support member deflects relative to the first end of the outer body member in response to a force applied thereto and returns to a substantially non-deflected condition upon release of the force.