Femur Prosthetic Stem Back Hollow Portion
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional short femur prosthetic stems with reduced anchorage are prone to tilting and shearing forces due to torque, risking mobilization and complications like aseptic loosening, and lack effective osseointegration and bone preservation.
Innovation Solution
A short femur prosthetic stem with a back hollow portion and divergent side wings, made from a single titanium alloy block, providing a constant radius of curvature and a longitudinal profile perpendicular to the femur axis, enhancing bone-prosthesis contact and osseointegration, and redistributing thrust forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If a short femur prosthetic stem with reduced anchorage is used, then bone capital is saved and metaphyseal conservation is improved, but the stem becomes prone to tilting and shearing forces due to torque
Solution Approach 1:
The stem is segmented into distinct functional zones: a proximal metaphyseal anchorage portion with optimized geometry for bone engagement, and a distal portion for load transmission. This segmentation allows each zone to be optimized independently - the proximal portion maximizes bone contact while the distal portion handles mechanical loads, resolving the contradiction between bone conservation and mechanical reliability.
Solution Approach 2:
The stem employs local quality variations through its geometry - the proximal portion features a larger diameter and specific surface characteristics for optimal metaphyseal engagement, while the distal portion has reduced dimensions. This localized optimization allows the stem to achieve both bone conservation (by limiting interference to the metaphysis) and mechanical reliability (through appropriate load-bearing geometry in critical zones).
2Ease of operation
If a short stem with metaphyseal anchorage only is used, then surgical invasiveness is reduced, but the stem is subject to mobilization forces that can turn into shearing forces
Solution Approach 1:
The stem incorporates curved and rounded geometric features in the proximal portion that conform to the natural metaphyseal anatomy. This curvature optimization enhances the stem's ability to distribute loads evenly across the metaphyseal bone, increasing resistance to shearing forces while maintaining the minimally invasive nature of the implantation procedure.
3Strength
If conventional stem designs are used, then mechanical strength is achieved, but bone-prosthesis contact surface is reduced and osseointegration is compromised
Solution Approach 1:
The stem design transitions from traditional cylindrical geometries to a more complex three-dimensional form with optimized surface area in the proximal portion. By utilizing dimensional optimization and surface area maximization within the metaphyseal region, the design achieves both mechanical strength and enhanced bone contact for improved osseointegration.
Data Source
Figure 1~3
Figure 4
AI summary
The invention relates to a femur prosthetic stem (1) having a front portion and a back portion, said stem being characterized in that it has a back hollow portion (2).