Spinal Fixation Device Angulation Mechanism
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Solution Overview
Problem
Current spinal fixation devices have limited angulation capabilities, making it difficult to effectively correct spinal deformities such as scoliosis, which requires more precise manipulation and alignment of the spine.
Innovation Solution
A spinal fixation device with a bone screw member that can pivot up to 95° relative to its housing, incorporating a locking ring and crush ring mechanism to securely attach a spinal rod, allowing for greater angulation and adjustment during surgical procedures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a spinal fixation device with limited angulation (45 degrees) is used, then the device structure can be simpler, but the ability to correct spinal deformities is insufficient
Solution Approach 1:
The patent implements a dynamic angulation mechanism where the bone screw member can pivot relative to the housing within a cone of up to 95 degrees. The locking ring and crush ring allow the system to transition from a fixed to a locked angular position, enabling the device to adapt to various spinal deformity corrections while maintaining structural integrity.
Solution Approach 2:
The device is divided into separable components including the housing, bone screw member, locking ring, and crush ring. This segmentation allows independent optimization of each component's function while enabling the overall system to achieve greater angulation capability without proportionally increasing overall complexity.
2Adaptability or versatility
If a larger degree of angulation (up to 95 degrees) is provided, then the correction of spinal deformities is more effective, but the positioning precision requirement increases
Solution Approach 1:
The bone screw member is pre-configured with a head that can be selectively secured within the housing at various angles. The locking ring is pre-positioned to engage with the housing and bone screw member, establishing the angular relationship before final tightening, which simplifies the positioning process despite the large range of motion.
Solution Approach 2:
The locking ring acts as an intermediary component between the housing and bone screw member, facilitating the angular adjustment and locking function. This intermediary mechanism allows for smooth transitions between angles and maintains positioning precision through mechanical engagement features.
3Reliability
If a locking mechanism is added to secure the bone screw member, then the stability of the fixation is improved, but the device complexity increases
Solution Approach 1:
The locking ring and crush ring are combined into a single integrated component that performs both locking and securing functions. This merging of functions into one element provides reliable fixation stability while minimizing the increase in device complexity compared to having separate locking and securing mechanisms.
Solution Approach 2:
The crush ring is designed to deform under compression to lock the bone screw member in place, utilizing the insertion force itself to create the locking action. This self-locking mechanism provides reliable fixation without requiring additional active locking components, thereby maintaining relative simplicity.
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
Enables more precise and effective correction of spinal deformities by providing a larger degree of angulation, facilitating better alignment and stabilization of the spine during surgical procedures.
Implementation Method 1
The crush ring has an initial state and a deformed state when a force is applied thereto. The crush ring pushes against the head of the bone screw member when it transitions from the initial state to the deformed state
Data Source
AI summary
A spinal fixation device includes a housing defining a longitudinal axis, a bone screw member, a locking ring, and a crush ring. The bone screw member includes a head that is selectively securable within the housing and a threaded shaft. The locking ring is disposed within the housing and is radially expandable to a partially expanded position when the head of the bone screw member is positioned therein to retain the head within the housing. The crush ring is disposed within the housing proximal to the locking ring and adjacent the head of the bone screw member. The crush ring pushes against the head of the bone screw member when it transitions from an initial state to a deformed state when a force is applied thereto, which expands the locking ring to a fully expanded position to fix the bone screw member to the housing.