Bone Anchoring Element With Spherical Holding Element
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Solution Overview
Problem
Existing bone anchoring elements in spinal surgery lack flexibility and reliable guidance for screw positioning, leading to suboptimal fixation and potential instability.
Innovation Solution
A bone anchoring element with a partially hollow-spherical holding element that engages around the screw head, combined with a conical outer surface and undercut design, allows for flexible positioning and secure axial fixation, along with a cylindrical section for precise alignment and a rib for rotation lock, and a half-shell recess for enhanced force transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a cylindrical bushing with holding ring is used to secure the screw head, then the screw can be fixed in the rod receiving element, but the positioning flexibility and guidance reliability are insufficient
Solution Approach 1:
The holding element features a hollow-spherical inner surface that receives the spherical screw head, replacing the cylindrical bushing design. This spherical geometry provides reliable guidance and positioning flexibility, allowing the screw head to be securely held while enabling flexible positioning during spinal surgery operations
2Adaptability or versatility
If the holding element has a hollow-spherical inner surface, then positioning flexibility and guidance reliability are improved, but the structural complexity increases
Solution Approach 1:
The hollow-spherical inner surface is integrated directly into the holding element as a single continuous structure, eliminating the need for separate spherical components. This unified design achieves positioning flexibility without proportionally increasing overall structural complexity
Solution Approach 2:
The holding element serves multiple functions simultaneously: it provides axial fixation through its conical outer surface, enables flexible positioning through the hollow-spherical inner surface, and maintains structural integrity as a single integrated component. This multi-functionality reduces the need for additional separate elements
3Reliability
If the outer surface of the holding element is conical, then positioning reliability in the rod receiving element is improved, but manufacturing precision requirements increase
Solution Approach 1:
The conical outer surface is designed with specific geometric parameters (angle, taper rate) that balance positioning reliability with manufacturability. The conical geometry provides reliable positioning through tapered fit while the parameter optimization ensures that standard manufacturing capabilities can achieve the required precision without excessive complexity
Data Source
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AI summary
The anchoring element (10) has a screw (20) including a shaft (22) and a ball head (26). A bar retaining element (30) has a longitudinal axis for connecting the screw with a bar-like element (60). The shaft has a bone thread section and the head has a head thread section (28). The retaining element has a holding element (40) and a channel (31) perpendicular to a longitudinal axis for receiving the bar like element. The holding element has an inner surface that has a spherical shape and partially holds the head.