Femoral Stem Assembly Collar for Hip Prosthesis Fixation
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Solution Overview
Problem
Existing orthopaedic surgical instruments face challenges in efficiently securing and aligning femoral head components to implanted femoral stem components during hip replacement surgery, leading to suboptimal fixation strength and potential micromotion and fretting corrosion.
Innovation Solution
An orthopaedic surgical instrument assembly featuring an assembly collar with a cavity and bore configuration, a fastener, and an impaction guide to secure and align the femoral head component with the femoral stem, increasing the mass and inertia of the implant for enhanced fixation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If an assembly collar is added to secure the femoral head component to the femoral stem, then the pull-off force and fixation strength are improved, but the device complexity increases
Solution Approach 1:
The assembly collar acts as an intermediary component between the femoral head component and the femoral stem. It includes a cavity that receives the tapered trunnion of the femoral stem and a bore that aligns with the implant bore to receive a fastener. This intermediary structure enhances the pull-off force by 58% while providing a systematic approach to securing the components together.
Solution Approach 2:
The assembly collar features a cavity that nests the tapered trunnion of the femoral stem within its structure. The fastener is positioned in the bore of the assembly collar and extends through to engage with the implant bore, creating a nested arrangement where multiple components are housed within the collar structure.
2Reliability
If the assembly collar is secured to the implanted femoral stem component, then the stability and fixation strength are improved, but the surgical procedure complexity increases
Solution Approach 1:
The assembly collar is designed with pre-configured cavities and bores that align with corresponding features on the femoral stem and head component. The fastener is pre-positioned in the bore, allowing the surgeon to simply insert and secure the collar to the stem before assembling the head component, thereby simplifying the surgical procedure while enhancing stability.
3Manufacturing precision
If the cavity and bore configuration is used in the assembly collar, then the alignment precision and fixation strength are improved, but the manufacturing complexity increases
Solution Approach 1:
The assembly collar incorporates a tapered cavity that receives the tapered trunnion of the femoral stem, creating an asymmetric fit that provides precise alignment. The bore is positioned to align with the implant bore, creating a coordinated asymmetric design that ensures accurate positioning of the fastener and components while maintaining manufacturability through standard machining operations.
Data Source
AI summary
An orthopaedic surgical instrument includes an assembly collar having a cavity extending between a superior opening and an inferior opening. The cavity is sized to receive a tapered trunnion of an implanted femoral stem. A bore extends between an inferior end and a superior end of the assembly collar and is configured to align with an implant bore formed in the implanted femoral stem. The bore and the implant bore are configured to receive a fastener to secure the assembly collar to the implanted femoral stem. A method of utilizing the orthopaedic surgical instrument is also contemplated.