Rotatable Bone Fastener Crown for Spinal Stress Distribution
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Solution Overview
Problem
Current spinal implant systems for treating disorders such as scoliosis and degenerative disc disease often fail to adequately distribute stress across spinal elements, leading to continued pain and mobility issues due to the lack of effective stabilization methods.
Innovation Solution
A two-piece crown bone fastener system with a keyed fit and spring relief mechanism that securely engages a spinal rod, allowing for adjustable angulation and reduced stress on spinal elements, facilitating better distribution of forces and enhanced stability during healing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional spinal implant systems are used, then spinal stabilization is provided, but stress distribution across spinal elements is inadequate leading to continued pain and mobility issues
Solution Approach 1:
The bone fastener is divided into three distinct portions: a first portion defining an implant cavity, an intermediate portion with rotatable parts, and a second portion for tissue penetration. This segmentation allows each portion to perform its specific function optimally while distributing mechanical stresses across different structural elements, preventing stress concentration at any single point.
Solution Approach 2:
The intermediate portion includes a second part that is rotatable relative to the first part, introducing dynamic capability to the otherwise rigid fastener structure. This rotational freedom allows the implant to accommodate physiological movements and adjust to varying stress conditions, improving stress distribution while maintaining stabilization.
2Stability of the object's composition
If spinal rods and bone fasteners are used to provide stability, then proper alignment is restored, but the system lacks adaptability for adjustable angulation to accommodate various spinal conditions
Solution Approach 1:
The rotatable second part in the intermediate portion enables adjustable angulation of the bone fastener relative to the spinal rod. This dynamic feature allows surgeons to optimize the orientation and angle of the fastener to match specific anatomical requirements and spinal conditions, enhancing the system's versatility while maintaining stable alignment.
Solution Approach 2:
By separating the intermediate portion into rotatable segments, the design enables independent adjustment of angular orientation without compromising the overall structural integrity or alignment stability. Each segment can be positioned independently to achieve optimal configuration.
3Ease of manufacture
If a monolithic bone fastener design is used, then manufacturing is simplified, but the system cannot provide enhanced stress distribution and stabilization
Solution Approach 1:
The bone fastener is manufactured as separate portions (first portion, intermediate portion with rotatable parts, and second portion) that are subsequently assembled. This segmentation enables each component to be optimized and manufactured using appropriate processes for its specific functional requirements, then combined to achieve superior overall performance in stress distribution and stabilization.
Data Source
AI summary
A bone fastener includes a first portion that defines a longitudinal axis and includes an inner surface defining an implant cavity. An intermediate portion includes a first part having a wall including a first end surface that defines at least a portion of the implant cavity and a second end surface. The intermediate portion further includes a second part having a wall including an end surface connected with the second end surface of the first part and an inner surface. The second part is rotatable relative to the first part. A second portion includes a first end engageable with the inner surface of the second part and a second end configured to penetrate tissue. Systems and methods are disclosed.