Acetabular Cup Holding Device for Damage-Free Ceramic Implantation
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Solution Overview
Problem
Resurfacing and large diameter total hip replacement acetabular cup implants face challenges during implantation due to the lack of holding features on the cup, particularly with non-metal bearing materials like zirconia toughened alumina ceramic and cross-linked ultra-high molecular weight polyethylene, which are difficult to manufacture with holding features and require protection from damage during forcible insertion.
Innovation Solution
A cup holding solution using a sealed cavity with low-pressure fluid, achieved through an impaction device, cover assembly, and cup implant interaction, where a non-return valve and resilient features allow for a tight fit without damaging the bearing surface, utilizing freely available sterile liquids like water to maintain a rigid assembly during implantation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If holding features are added to the cup for impaction, then the cup can be securely held during implantation, but the bearing surface is damaged and soft tissue structures are aggravated
Solution Approach 1:
The patent introduces a holding device as an intermediary component between the surgeon's tools and the cup implant. This holding device features a bearing-protecting surface that interfaces with the cup's bearing surface, allowing secure gripping and impaction forces to be applied through the holding device rather than directly to the cup's bearing surface, thus preventing damage while enabling controlled implantation
Solution Approach 2:
The system is divided into separate functional components: the cup implant, the holding device, and the introducer assembly. The holding device can be released from the cup after implantation, separating the temporary holding function from the permanent implant, allowing the cup to function without the holding device's interference
2Stability of the object's composition
If the outer surface of the cup is fully embedded in the bone socket, then the implant is stable, but the cup rim is the only accessible area for holding features
Solution Approach 1:
The holding device acts as an intermediary that extends the surgeon's reach and control to the cup rim area. The introducer assembly with its shaft and distal region provides a mechanical interface that can apply forces and control orientation through the holding device, enabling precise manipulation of the cup even when most of it is embedded in the bone socket
3Ease of operation
If holding features are added to non-metal bearing materials like ZTA or UHMWPE, then the cup can be held during implantation, but the material strength is compromised or manufacturing becomes prohibitively expensive
Solution Approach 1:
The holding device serves as a protective intermediary that interfaces with the cup through a bearing-protecting surface. This allows gripping forces to be applied to the holding device rather than directly to the fragile bearing surface of non-metal materials like ZTA or UHMWPE, enabling secure manipulation without compromising material integrity or requiring expensive manufacturing modifications
Solution Approach 2:
The bearing-protecting surface on the holding device provides beforehand protection for the cup's bearing surface during the impaction process. This cushioning effect prevents direct contact between potentially damaging holding features and the vulnerable non-metal bearing surface, preserving material strength and wear characteristics
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
This method provides a secure and damage-free implantation process by maintaining a tight fit between the cup, cover, and impaction device, ensuring correct orientation and alignment without compromising the bearing surface, even with challenging materials like zirconia toughened alumina ceramic and cross-linked UHMWPE, and can be released once positioned correctly.
Implementation Method 1
The low pressure in the fluid is achieved by means of a resilient feature on the cover adjacent to a flange on the introducer attachment which flexes down and in so doing reduces the volume of the sealed cavity. Low pressure is maintained because the resilient feature is flexed within its elastic limits and tries to forcefully return to its un-flexed state thereby holding the fluid at low pressure. The low pressure state of the fluid pulls together all three elements forming a tight fit between them
Implementation Method 2
The low pressure in the fluid is achieved by means of a resilient feature on the cover adjacent to a flange on the introducer attachment which flexes down and in so doing reduces the volume of the sealed cavity. Low pressure is maintained because the resilient feature is flexed within its elastic limits and tries to forcefully return to its un-flexed state thereby holding the fluid at low pressure
Implementation Method 3
The non-return valve is incorporated in the introducer and forms an outlet for air and surplus fluid to escape from the sealed cavity as the three elements are pressed together (whilst preventing fluid or air re-entering the cavity)
Data Source
AI summary
The present invention is directed to a system comprising a medical instrument (e.g. cup implant, 3) and a holding device (2) that interacts with said medical instrument to form a sealable cavity within the combined arrangement of components. An impaction device (1) is also provided, preferably which provides means to allow fluid to be expelled from the cavity but which prevents further fluid from entering the cavity.