Spinal Bone Fastener Angulation and Distraction Control
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Solution Overview
Problem
Current spinal implant systems for treating disorders such as scoliosis and degenerative disc disease face challenges in providing adequate stability and alignment, particularly in achieving precise angulation and distraction, which can lead to suboptimal surgical outcomes.
Innovation Solution
A bone fastener system with a crown and anchor configuration that allows for sagittal and transverse angulation, featuring a tool-engagable receiver with lateral and vertical slots for precise rod alignment and a snap ring mechanism for secure fixation, enabling controlled distraction and lordosis correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional spinal implant systems are used, then basic fixation is achieved, but precise angulation and alignment are difficult to achieve
Solution Approach 1:
The bone fastener is divided into distinct functional components: a head for tissue penetration and anchoring, a crown for rod engagement and angulation adjustment, and a receiver for tool interaction. This segmentation allows each component to be optimized for its specific function, enabling precise angulation control without requiring complex integrated mechanisms.
Solution Approach 2:
The crown is designed to be rotatable relative to the head, allowing dynamic adjustment of the angulation during surgery. This dynamic capability enables precise control over the rod alignment and distraction forces while maintaining a relatively simple overall structure, as the adjustment mechanism is inherent in the relative motion capability of the components.
2Ease of operation
If multi-axial adjustment capability is added to achieve precise rod alignment, then alignment precision improves, but device complexity increases
Solution Approach 1:
The bone fastener provides adjustment capabilities in multiple dimensions: the crown can rotate relative to the head for angulation adjustment, and the receiver interacts with tools for positional adjustment. This multi-dimensional adjustment capability enables precise rod alignment in complex spatial orientations without requiring an overly complex mechanism, as each degree of freedom is provided by a simple relative motion between components.
3Measurement precision
If a tool-engagable receiver with slots is implemented, then precise distraction and lordosis correction are enabled, but manufacturing complexity increases
Solution Approach 1:
The receiver acts as an intermediary component that translates tool forces into precise distraction and lordosis correction. The lateral and vertical slots provide guided motion paths that ensure precise control during distraction while simplifying manufacturing, as the slots can be machined as simple linear features rather than complex three-dimensional contours.
4Reliability
If a snap ring mechanism is added for secure fixation, then fixation reliability improves, but device assembly complexity increases
Solution Approach 1:
The snap ring provides pre-engineered secure fixation by engaging with the receiver and crown components before final assembly. This beforehand prepared fixation mechanism ensures reliable locking of the bone fastener in place, reducing the need for complex post-assembly adjustment steps and simplifying the overall assembly process while maintaining high fixation reliability.
Data Source
AI summary
A bone fastener includes a first member having an inner surface defining an implant cavity. A second member is disposed with the first member. The second member is configured to penetrate tissue. The second member includes a head defining a socket. A part is disposed at an angle relative to the head. The part includes a top surface configured for disposal of an implant and an opposite bottom surface configured to rotatably engage the head to selectively adjust the angle. The part includes an opening that is in communication with the socket. The opening has a diameter that is less than that of the socket. Implants, systems, constructs, instruments and methods are disclosed.