Constrained Liner Locking Ring with Resilient Tab for Secure Fixation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional prosthetic systems, such as those used in total hip arthroplasty, face challenges in easily implanting, confirming proper mating, and removing constrained liner locking rings without damaging the acetabular cup, especially when femoral head dislocation occurs.
Innovation Solution
A constrained liner locking ring design featuring a tab and undercut mechanism that allows for easy assembly and disassembly, with a resilient leg structure for secure fixation and tactile feedback, enabling clockwise or counter-clockwise removal without damaging the acetabular cup, and an interference fit feature for optimal congruency between the polyethylene liner and acetabular cup.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a conventional locking ring design is used, then secure fixation is achieved, but removal is difficult and may damage the acetabular cup
Solution Approach 1:
The locking ring incorporates segmented resilient legs with tabs that can be independently deflected. This segmentation allows the locking mechanism to be engaged by simple radial compression while enabling removal through rotational motion that sequentially deflects each segment, resolving the contradiction between secure fixation and easy removal.
Solution Approach 2:
The resilient legs transition from a static locking structure to a dynamic one where the legs can deflect radially during engagement and rotate during removal. This dynamic behavior allows the same structure to provide strong fixation during use while enabling easy removal through controlled deflection and rotation.
2Loss of information
If a conventional locking ring design is used, then fixation is achieved, but proper mating confirmation is difficult
Solution Approach 1:
The locking ring incorporates audible click feedback mechanisms where the resilient legs engage with corresponding features on the acetabular cup, producing distinct auditory signals. This feedback provides immediate confirmation of proper mating without requiring complex verification procedures or increasing overall device complexity.
3Strength
If the locking ring is tightly secured to the acetabular cup, then stable fixation is achieved, but removal may damage the cup
Solution Approach 1:
The resilient legs act as intermediaries between the locking ring and the acetabular cup. During removal, these compliant intermediaries can be radially deflected to disengage from the cup features before the locking ring is fully removed, preventing direct mechanical damage to the cup while maintaining strong fixation during normal use.
4Ease of manufacture
If a simple locking mechanism is used, then ease of implantation is achieved, but secure fixation is compromised
Solution Approach 1:
The locking ring features nested resilient legs where smaller legs are positioned within the structure of larger legs. This nested configuration allows multiple locking interactions to occur simultaneously through a single implantation motion, achieving secure fixation without complicating the implantation procedure.
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
Facilitates secure and easy implantation, confirmation of proper mating, and removal of the locking ring, minimizing micro-motion and ensuring secure fixation without damaging the acetabular cup, while maintaining optimal fit at both room and body temperatures.
Implementation Method 1
at least one of the legs is resilient such that upon engagement with the locking ring, the leg deflects radially inward and springs back to deflect radially outward
Implementation Method 2
an interference fit feature for optimal congruency between the polyethylene liner and acetabular cup
Data Source
AI summary
One embodiment of the present invention relates to a prosthesis, comprising: an acetabular cup, wherein the cup has an open end and a closed end, wherein the open end of the cup is defined by a rim and wherein the rim has an outer facing surface; at least one cavity disposed in the rim, wherein the cavity extends from a first end of the cavity at the outer facing surface to a second end of the cavity that is towards the closed end of the cup, and wherein the cavity comprises an undercut at the second end of the cavity; a locking ring; and at least one tab extending from the locking ring, wherein the tab comprises a first leg and a second leg having a separation therebetween, wherein each leg has a first end and a second end, wherein the first end of each leg is at the locking ring, wherein the second end of the first leg comprises a tab protrusion, and wherein at least the second leg is resilient such that the separation between the first leg and the second leg is reduced when the second leg is deflected towards the first leg; wherein the locking ring is removably locked to the cup by placement of the locking ring adjacent the rim and insertion of the tab into the cavity such that the second leg presses against a sidewall of the cavity to initially deflect the second leg towards the first leg as the tab enters the cavity and the tab protrusion of the first leg is urged into the undercut by the second leg subsequently deflecting back away from the first leg.