Modular Bone Anchor Assembly for Better Spinal Visualization
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Solution Overview
Problem
Challenges in spinal surgery include spatial anatomical awareness and visualization issues due to disruptive implant and instrument geometry, which obscure visualization and require smaller working channels, necessitating improved bone anchor assemblies and instrumentation.
Innovation Solution
A bone anchor assembly comprising a receiver member, insert, collet, and shank with a compression cap that allows longitudinal translation while limiting rotation, facilitating easier insertion and locking without deforming the collet, and enabling modular assembly for various surgical procedures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If traditional bone anchor assemblies are used, then fixation function is provided, but spatial anatomical awareness and visualization are disrupted due to implant and instrument geometry
Solution Approach 1:
The bone anchor assembly is divided into separate modular components: a receiver member, a collet, and a shank. This segmentation allows each component to be optimized independently and assembled in a lower-profile configuration that reduces geometric disruption during surgery while maintaining the necessary fixation function.
Solution Approach 2:
The collet is nested within the receiver member, with the shank extending through both components. This nested arrangement creates a compact, lower-profile assembly that minimizes the geometric footprint and improves surgical visualization while preserving the bone anchor's structural integrity and fixation capability.
2Object-affected harmful factors
If working channels are made smaller for less-invasive surgery, then tissue damage is reduced, but spatial anatomical awareness and visualization become more challenging
Solution Approach 1:
The design transitions from a monolithic structure to a multi-dimensional modular assembly where the receiver member, collet, and shank are arranged in specific spatial relationships. This dimensional reconfiguration enables a lower profile that fits within smaller working channels while maintaining operational effectiveness and surgical visualization.
3Reliability
If the collet is deformed during insertion, then it can be retained within the receiver member, but manufacturing complexity and cost increase
Solution Approach 1:
The collet is designed with flexible fingers that can dynamically deform during insertion to engage with the receiver member, then return to their original shape to provide reliable retention. This dynamic behavior achieves secure retention without requiring permanent deformation or complex manufacturing processes.
Solution Approach 2:
The collet's retention mechanism relies on changing the physical state of its fingers from a compressed insertion state to an expanded retention state. This parameter change allows the collet to be inserted without permanent deformation while still achieving reliable retention within the receiver member.
4Ease of operation
If the compression cap allows rotation, then assembly is easier, but longitudinal translation is restricted
Solution Approach 1:
The compression cap incorporates asymmetric features including a single flat surface that engages with a corresponding flat on the receiver member to prevent rotation, while maintaining a cylindrical outer shape that allows longitudinal translation. This asymmetric design enables both rotational constraint and longitudinal movement capability.
Solution Approach 2:
The compression cap is segmented into functional features: a flat engagement surface for rotational constraint, a cylindrical body for longitudinal translation, and a distal opening for tool engagement. This segmentation allows each feature to perform its specific function independently, combining rotational limitation with translational freedom.
Data Source
Figure 1A~1C
Figure 1D~1G
Figure 1H
AI summary
Bone anchor assemblies and related instrumentation are disclosed herein. In some embodiments, a modular bone anchor assembly allows for a bone anchor to be driven into bone and a head or receiver member to be attached thereto at some later point in time. The bone anchor can have a smaller footprint than the complete assembly, which can improve visualization and anatomical spatial awareness during insertion of the bone anchor and during other surgical steps performed prior to attaching the head or receiver member to the bone anchor. A variety of modular head types are disclosed, as are various instruments for driving a bone anchor, attaching a head to a bone anchor, removing a head from a bone anchor, and making a unilateral attachment to a head of a bone anchor assembly. Drive interfaces for driving a bone anchor are disclosed, as are features that allow a bone anchor to act as a fixation point for soft tissue retraction, disc space distraction, derotation, and the like.