Acetabular Cup Locking Screw Assembly with Movable Insert
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Solution Overview
Problem
Existing acetabular cup fixation methods often result in misalignment and undesired movement, requiring additional surgery to correct, due to inadequate securement in deteriorated acetabulums, especially when press-fitting is not possible.
Innovation Solution
An acetabular implant design featuring an acetabular cup with an elongated slot and a movable insert that allows a bone fastener to be positioned at a selected angle, ensuring secure engagement with the acetabulum through sloping sidewalls and tapered surfaces, preventing movement and backout.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If press-fitting is used to secure the acetabular cup, then fixation strength is improved, but this method cannot be used when the acetabulum is deteriorated
Solution Approach 1:
The fixation system is segmented into multiple independent bone fasteners that can be inserted through the acetabular cup at different locations and angles, allowing adaptation to deteriorated bone structures where press-fitting is not feasible
Solution Approach 2:
The bone fasteners are designed with movable inserts and elongated slots that allow dynamic adjustment of insertion angles and positions, enabling secure fixation in deteriorated acetabulums where fixed-angle press-fitting cannot be applied
2Ease of manufacture
If the acetabular cup is secured with fixed alignment methods, then manufacturing is simplified, but misalignment and undesired movement occur
Solution Approach 1:
The insert is designed to be movable within the elongated slot, allowing dynamic adjustment of the bone fastener angle and position during surgery to achieve precise alignment, while the overall securing method remains simple and straightforward
Solution Approach 2:
The system allows change of geometric parameters (angle, position) of the bone fastener relative to the acetabular cup through the movable insert mechanism, enabling precise alignment adjustment without complicating the manufacturing process
3Manufacturing precision
If additional surgery is performed to correct misalignment, then alignment precision is improved, but loss of time and increased complexity occur
Solution Approach 1:
The movable insert mechanism is pre-configured in the acetabular cup to enable angle adjustment during surgery, allowing alignment corrections to be made in the same surgical procedure without requiring additional corrective surgeries
4Adaptability or versatility
If the bone fastener is allowed to move freely, then adaptability to different angles is improved, but unwanted movement and backout occur
Solution Approach 1:
The insert is designed to be movable during the positioning phase to allow angle adjustment, but becomes stable and fixed once the bone fastener is inserted and secured, providing both positioning flexibility and final stability
Solution Approach 2:
The system separates the positioning function (movable insert) from the securing function (fixed bone fastener), allowing the fastener to be adaptable during positioning while maintaining stability once secured in place
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 design provides secure fixation and alignment of the acetabular cup, minimizing movement and the need for additional surgery by allowing optimal positioning of the fastener within the acetabulum, even in cases where press-fitting is not feasible.
Implementation Method 1
slidably received in the first elongated slot and movable relative to the slot
Data Source
AI summary
An acetabular implant including an acetabular cup having a wall with a first elongated slot defining a passage through the wall, and an insert slidably received in the first elongated slot and movable relative to the slot in a first direction. The insert can include a second elongated slot that extends in a second direction different than the first direction. The second elongated slot can be configured to slidably receive a bone fastener and guide the bone fastener through the passage of the acetabular cup at a selected angle.