Spinal Plate Split Ring Locking Mechanism
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Solution Overview
Problem
Conventional spinal plate locking mechanisms are cumbersome, complicated, and expensive, making them inefficient for securing bone screws during surgery and difficult to remove or readjust, especially during revision surgery, which increases the risk of infection and prolongs operating room time.
Innovation Solution
A spinal plate assembly with a split ring locking mechanism that is radially deformable between locked and unlocked conditions, allowing for easy screw fixation and removal without complex instrumentation, using a rotating member with notches to drive the split rings into an unlocked position for quick removal of bone screws.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional locking mechanisms (securing caps, cover plates, bearings) are used to prevent screw disengagement, then screw security is improved, but device complexity and cost increase
Solution Approach 1:
The locking mechanism is merged with the aperture structure itself. The annular groove is formed as an integral part of the aperture, and the split ring locking element is contained within this groove, eliminating the need for separate securing caps or cover plates. This integration reduces device complexity while maintaining screw security through the split ring's engagement with the bone screw head.
2Reliability
If traditional locking mechanisms are used to secure screws, then screw fixation is achieved, but ease of operation for removal and readjustment deteriorates
Solution Approach 1:
The locking mechanism transitions from a static, permanently locked state to a dynamic system that can easily switch between locked and unlocked states. The split ring can be radially deformed by applying force through the driving tool engagement surface, allowing it to move between blocking the aperture (locked) and retracting into the annular groove (unlocked). This dynamic behavior enables easy screw removal and readjustment while maintaining secure fixation when locked.
3Reliability
If conventional locking mechanisms are employed, then screw security is improved, but loss of time during surgery increases
Solution Approach 1:
The locking mechanism is designed to be self-contained and self-operating. The split ring automatically engages with the bone screw head when the screw is inserted into the aperture, providing immediate locking without requiring separate locking steps or additional instrumentation. For unlocking, a simple driving tool engagement surface allows the split ring to retract into the annular groove, enabling quick screw removal. This self-service design eliminates time-consuming manual locking procedures and complex instrumentation requirements.
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
The solution provides a secure and efficient locking mechanism that simplifies the process of fixing and removing bone screws, reducing the risk of infection and operating time, while eliminating the need for cumbersome hardware and complicated techniques.
Implementation Method 1
The split rings are radially deformable within their respective annular grooves between the locked condition partially blocking the aperture for retaining the bone screws in the seat and the unlocked condition radially deformable into the annular groove for permitting the bone screws to be removed from the apertures
Data Source
AI summary
A spinal plate assembly comprising a base plate defining an opening adjacent at least one aperture for receiving a bone screw which attaches to spinal vertebrae. The aperture includes a seat and an annular groove having an end wall. The assembly comprises a locking mechanism having a split ring partially recessed within the annular groove and moveable between a locked condition partially blocking the aperture for retaining the screw in the seat and an unlocked condition radially deformable into the annular groove for permitting screw removal. The split ring has a proximal end and a distal end. The distal end is configured to engage the end wall of the annular groove. The locking mechanism comprises a rotating member retained within the opening of the base plate and having a notch configured to engage the proximal end of the ring to drive the ring toward the unlocked condition.