Bone Anchor Receiving Part Rod Retention Mechanism
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Solution Overview
Problem
In spinal stabilization procedures, rods inserted into bone anchors often slip out before fixation, making the process difficult and time-consuming due to the lack of effective temporary retention mechanisms in existing receiving parts.
Innovation Solution
A receiving part with a recess for the rod and a resilient retention element on its sidewall, which temporarily holds the rod in place by exerting a frictional force, compatible with various bone anchoring device designs without altering their existing structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If no retention element is provided in the receiving part, then the structure remains simple, but the rod slips out before fixation making the procedure difficult and time-consuming
Solution Approach 1:
The receiving part is segmented into functional zones: a recess for rod insertion and a retention element protruding from the sidewall. This segmentation allows the retention function to be added without redesigning the entire receiving part structure, thus improving productivity while minimizing complexity increase.
Solution Approach 2:
The retention element is designed to automatically engage with the rod upon insertion, providing self-retention without requiring additional active components or complex mechanisms. The resilient nature of the retention element allows it to self-adjust and maintain holding force, improving surgical efficiency without proportionally increasing device complexity.
2Reliability
If a retention element is added to the receiving part, then rod slippage is prevented, but the receiving part design must be modified
Solution Approach 1:
The retention element is localized to a specific region on the sidewall of the recess, rather than modifying the entire receiving part. This localized addition provides the necessary rod retention stability while minimizing changes to the overall receiving part structure, thus improving reliability without substantially increasing device complexity.
Solution Approach 2:
The retention element is designed with resilient properties, allowing it to dynamically adjust its position and force application based on rod insertion depth and diameter. This dynamic characteristic enables reliable rod retention while maintaining a relatively simple structure that adapts to different conditions without requiring complex mechanical systems.
3Reliability
If the retention element is placed within the bore, then it can directly retain the rod, but it interferes with the fixation device insertion
Solution Approach 1:
The retention element is positioned on the sidewall of the recess rather than within the bore, utilizing a different spatial dimension. This dimensional relocation allows the retention element to effectively retain the rod while avoiding interference with the fixation device insertion path through the bore, thus maintaining both rod retention reliability and compatibility with various fixation devices.
Solution Approach 2:
The sidewall-retained element acts as an intermediary retention mechanism that indirectly holds the rod without directly obstructing the bore. This intermediary positioning allows simultaneous access for both rod retention and fixation device insertion, maintaining adaptability with different fixation device designs while ensuring reliable rod retention.
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
Prevents rod slippage during insertion and adjustment, allowing for secure temporary holding of rods of different diameters, enhancing the efficiency and reliability of spinal stabilization surgeries.
Implementation Method 1
The retention element prevents the rod from slipping out of the recess, in particular, from inadvertently slipping-out of the recess during steps of inserting the rod into a plurality of bone anchoring devices or adjustment of the position of a bone anchoring device relative to the rod.
Implementation Method 2
a resilient retention element protruding from at least one of the opposing sidewalls. When the rod is inserted into the recess, the rod can be held temporarily in the recess by the at least one retention element.
Data Source
AI summary
A receiving part for coupling a bone anchor to a rod is provided, where the bone anchor includes a shank for anchoring to a bone or a vertebra. The receiving part includes a first end and a second end, the second end being connected to the shank, a bore extending from the first end into the receiving part for receiving a fixation device, the bore having a bore axis, and a recess for receiving a rod, the recess being open at the first end of the receiving part for allowing insertion of the rod and having opposing sidewalls on at least one side of the bore. When a rod is inserted into the recess, a longitudinal axis of the rod extends substantially perpendicular to the bore axis. A resilient retention element is provided on at least one of the opposing sidewalls, where the resilient retention element is deflectable toward the at least one sidewall when the rod is inserted.