Eccentric Hip Implant Stem Offset Biomechanics
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Solution Overview
Problem
Conventional femoral head resurfacing designs with co-linear stem and femoral head axes fail to accurately reproduce natural biomechanics and stability due to anatomical variations, leading to discomfort, pain, and potential failure, with limited intra-operative flexibility to correct mismatches.
Innovation Solution
An eccentric resurfacing hip implant design where the stem axis is offset from the head bearing surface centre, allowing for greater flexibility in positioning and potentially improving biomechanical alignment, with the option of a monobloc single-part construction to reduce wear and include bone ingrowth surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional co-linear resurfacing design is used, then manufacturing is simple, but biomechanical alignment is inaccurate
Solution Approach 1:
The patent applies asymmetry by designing the implant with non-co-linear stem and head axes. The stem axis and femoral head axis are deliberately offset from each other, creating an asymmetric geometry that matches the natural anatomical variation between the femoral neck center and femoral head center. This asymmetric design allows accurate reproduction of patient-specific biomechanics while maintaining manufacturing feasibility through standardized offset measurements.
2Adaptability or versatility
If co-linear stem and head axes are used, then device structure is simple, but intra-operative flexibility is limited
Solution Approach 1:
The patent implements dynamics by making the implant system adjustable rather than fixed. The stem and head can be positioned with variable offsets along their respective axes, allowing the surgeon to dynamically adjust the positioning during surgery to achieve optimal biomechanical alignment for each patient's unique anatomy, rather than being constrained to a fixed co-linear configuration.
3Stability of the object's composition
If conventional resurfacing design is used, then implant construction is simple, but biomechanical stability is reduced
Solution Approach 1:
The patent applies local quality by optimizing specific regions of the implant independently. The offset between stem and head axes is localized to match the specific anatomical relationship in each patient, allowing the bearing surface geometry and stem positioning to be independently optimized for their respective functional requirements while maintaining overall structural integrity.
Data Source
Figure 1A~1B
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AI summary
An implant, comprising: a head having a central axis; and a stem having a stem axis, wherein the head central axis and the stem axis are not co-linear. A method for resurfacing a femoral head, comprising the steps of: providing an implant according to the present invention; and implanting the implant with reference to the centre of the femoral neck.