Eccentric Acetabular Cup With Anterior Relief
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Solution Overview
Problem
Current jumbo acetabular cups, used in revision total hip arthroplasty and for patients with peri-acetabular bone defects, are larger than the anatomic acetabulum, leading to impingement with surrounding soft tissue and suboptimal biomechanical center of rotation, causing groin pain and instability.
Innovation Solution
An acetabular cup design featuring an eccentric socket and a first relief on one end, with multiple apertures for screw placement, allowing for secure fixation while reducing soft tissue impingement by positioning the center of rotation more anatomically and maintaining contact surface area for fixation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a jumbo acetabular cup is used to provide larger surface area for fixation, then implant stability is improved, but soft tissue impingement occurs causing groove pain
Solution Approach 1:
The patent applies asymmetry by creating a beveled anterior rim that is lower than the posterior rim, and by positioning the socket eccentrically within the cup. This asymmetric geometry allows the cup to achieve adequate bone contact area for stability while reducing impingement on anterior soft tissues such as the iliopsoas tendon, thereby resolving the contradiction between implant stability and soft tissue impingement.
Solution Approach 2:
The patent introduces a dimensional change by creating a beveled anterior rim that extends in a different spatial orientation compared to a uniform rim. This beveling creates a stepped configuration where the anterior portion is lowered, allowing the cup to maintain sufficient bone contact area while reducing soft tissue impingement in the anterior direction, thus resolving the contradiction.
2Strength
If the cup is made larger than anatomic size to provide greater fixation surface area, then fixation is improved, but the center of rotation is positioned higher than ideal biomechanically
Solution Approach 1:
The patent uses asymmetric socket positioning within the cup, where the socket is deliberately offset from the geometric center of the cup. This eccentric placement allows the cup to maintain a large overall size for adequate fixation surface area while positioning the functional center of rotation at an optimal biomechanical location, thereby resolving the contradiction between fixation strength and center of rotation positioning.
Solution Approach 2:
The patent applies local quality by creating different rim heights at different locations - specifically lowering the anterior rim while maintaining the posterior rim at a higher position. This localized variation in rim geometry allows the cup to achieve adequate bone contact for fixation while enabling proper positioning of the center of rotation, thus resolving the contradiction between fixation and center of rotation positioning.
3Adaptability or versatility
If multiple screw holes are placed in the peripheral portion of the cup for variable placement, then adaptability is improved, but the screws may be directed peripheral to the remaining bone stock
Solution Approach 1:
The patent applies local quality by creating non-uniform aperture distribution around the cup perimeter. By strategically positioning apertures at specific locations where bone stock is available, the design ensures that screws can be placed in multiple orientations while maintaining reliable fixation. This localized optimization of aperture placement resolves the contradiction between adaptability and fixation reliability.
Data Source
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AI summary
A system and method for placing a prosthetic acetabular cup within an acetabulum are disclosed. The system may comprise an acetabular cup with an eccentric socket. The acetabular cup may be substantially hemispherical with a cup rim and a portion of the cup rim removed defining a relief. The cup may accommodate a concentric liner in an eccentric position. Screw apertures may be present on the periphery of the cup and the screw trajectories may converge toward the dome of the cup. The cup is attached to a tool which is offset relative to the cup because of the substantially eccentric socket. The relief, when the cup is secured to the acetabulum, is positioned substantially anterior and the socket is positioned more posterior to provide a more natural center of rotation of a femoral head within the socket. The first relief reduces impingement of the acetabular cup on soft tissue.