Cementless Knee Implants With Trabecular Fixation Pegs
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Solution Overview
Problem
Existing knee arthroplasty procedures face challenges with bone cement failures, such as weak bonding, cement fracture, and surgical complications, necessitating a need for improved cementless femoral and tibial implants and instruments.
Innovation Solution
Development of cementless femoral and tibial implants with trabecular structures and fixation pegs that promote bone healing and interdigitation, along with specialized instrumentation for secure implantation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If bone cement is used to adhere implants to bone, then initial fixation is achieved, but cement may fail by not producing a strong enough bond, may weaken over time causing cement fracture, or may result in insufficient cement application
Solution Approach 1:
The patent removes bone cement from the implantation system entirely, replacing it with a cementless design where the implant achieves fixation through mechanical interlocking via fixation pegs and trabecular bone ingrowth, eliminating cement-related failures
Solution Approach 2:
The implant design includes pre-formed fixation pegs with bulbous ends that are inserted into pre-drilled holes in the bone before final implant placement, creating initial mechanical anchorage without requiring cement
2Stability of the object's composition
If bone cement is used for implant fixation, then implant stability is achieved, but cement carries surgical challenges such as improper mixing techniques, proper timing of cement mixing and application, and cement impingement
Solution Approach 1:
The patent eliminates bone cement from the surgical procedure, removing all associated challenges including mixing techniques, timing constraints, and impingement risks, while maintaining implant stability through mechanical fixation
Solution Approach 2:
The fixation pegs are designed to be self-retaining through their bulbous ends that expand within the bone, and the trabecular structure provides self-anchoring through bone ingrowth, eliminating the need for cement to maintain stability
3Ease of manufacture
If traditional implants are used without specialized trabecular structures, then implantation is simpler, but bone healing and integration are compromised
Solution Approach 1:
The patent incorporates a trabecular structure with porous geometry into the implant, providing a scaffold that promotes bone ingrowth and accelerates integration, while modern manufacturing techniques like 3D printing make production feasible
Solution Approach 2:
The fixation pegs feature a bulbous end geometry that transitions from a narrow shaft to an expanded terminal region, creating mechanical interlocking in the radial dimension that enhances initial fixation while maintaining manufacturing capability
4Strength
If fixation pegs with bulbous ends are used, then initial fixation and surface area for bone ingrowth are increased, but implant structure becomes more complex
Solution Approach 1:
The patent divides the implant into distinct functional segments including fixation pegs with bulbous ends and a trabecular structure, where each segment performs a specific function (mechanical anchorage and bone ingrowth promotion) that can be manufactured separately or as an integrated unit
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The implants provide stable fixation without cement, reducing procedural time and complications, while enhancing bone integration and long-term stability through trabecular scaffolds and pegs.
Implementation Method 1
The inner surface of the femoral implant and the distal surface of the tibial tray define a trabecular structure, which provides a scaffold for bone healing and interdigitation
Implementation Method 2
The implants may include fixation pegs with bulleted profiles to provide initial fixation and increase the surface area for bone ingrowth
Data Source
Figure 1
Figure 2A~2B
Figure 3A~3B
AI summary
Knee arthroplasty implants, instruments, systems, and methods of implanting the same. The knee arthroplasty implants may include a femoral implant (10) and a tibial tray implant (110), each with trabecular surfaces (44, 144) configured to contact bone to provide a scaffold for bone healing and interdigitation. The implants may also include fixation pegs (60, 160) with bulleted profiles to increase the surface area for bone ingrowth. An inserter instrument (200) may include a sliding rack (234), which is incrementally extended with a rotatable shaft (216), thereby allowing for quick lock and release of various tibia trays.