Femoral Stem Lateral Post System for Hip Prosthesis Subsidence
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The press fit method for anchoring femoral stems in hip prostheses often results in subsidence, leading to decreased bone integration, increased dislocation risk, and potential fracturing, particularly in active patients or animals with thinner bone cortical walls.
Innovation Solution
A femoral stem design featuring a lateral post and port system, where a lateral post is secured within a lateral port on the stem, extending beyond the femur bone cortex to provide additional support and prevent subsidence, utilizing a guide hole and guide rod for precise alignment and implantation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If press fit method is used to anchor femoral stem, then bone integration is achieved, but subsidence occurs leading to decreased stability
Solution Approach 1:
The patent introduces a lateral post extending from the lateral surface of the femoral stem, adding a third dimension of anchorage. This lateral post projects through the lateral cortex of the femur into the soft tissue, creating stability not only in the mediolateral direction but also in the anteroposterior direction, effectively preventing subsidence while maintaining bone integration.
Solution Approach 2:
The femoral stem is segmented into multiple functional components: the main stem body for medullary anchorage and the lateral post for cortical and soft tissue anchorage. This segmentation allows each component to fulfill specific stabilization functions, with the lateral post specifically addressing the subsidence problem by providing independent lateral support.
2Strength
If press fit method is used to anchor femoral stem, then initial fixation is achieved, but repeated impacts from activity cause further impaction and subsidence
Solution Approach 1:
The lateral post acts as a pre-installed cushioning element that absorbs and distributes impact forces before they can cause further impaction of the stem. By extending into the soft tissue, the lateral post creates a buffer zone that protects the bone-implant interface from the full force of repeated impacts during patient activity.
Solution Approach 2:
The lateral post provides localized reinforcement at the critical lateral cortex region where subsidence typically initiates. This local quality enhancement creates a reinforced zone that resists impact forces specifically at the vulnerable interface between the stem and lateral cortical bone, without requiring modification of the entire stem structure.
3Stability of the object's composition
If lateral post system is added to prevent subsidence, then stem stability is improved, but device complexity increases
Solution Approach 1:
The lateral post is merged with the femoral stem as an integrated structure, eliminating the need for separate components or additional fixation elements. The post is formed as a continuous extension of the stem, sharing the same material and manufacturing process, which simplifies the overall device while providing enhanced stability.
Solution Approach 2:
The lateral post serves multiple functions simultaneously: it acts as a mechanical anchor in the lateral cortex, provides a lever arm for soft tissue attachment, creates a seal against lateral bone ingress, and distributes loads across multiple bone structures. This multi-functionality reduces the need for additional specialized components.
Data Source
Figure 1A
Figure 1B
Figure 2
AI summary
A femoral stem for use in hip replacement surgery, specifically hip replacement surgery in dogs and similar animals but also inclusive to implants used in humans. More particularly, the invention is directed to a femoral stem that includes a lateral bolt or post that protrudes through the cortex or wall of bone opposite the neck of the femoral stem. The lateral bolt or post reduces the occurrence of subsidence in implanted femoral stems. The lateral bolt or post provides an anchor point on the cortex or wall of bone as opposed to relying solely on the compression of the femoral stem against the wall of the bony canal of the femur being implanted.