Tibial Tray Suture Fixation for Ankle Replacement
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Solution Overview
Problem
Current total ankle replacement (TAR) fixation methods face challenges with initial fixation (time zero fixation) to bone, particularly with vertical pegs that are difficult to prepare due to limited exposure in the ankle joint space, and anterior approaches that weaken the weight-bearing anterior cortical bone.
Innovation Solution
The described prosthetic implant system includes a tibial tray with adjustable fixation components, such as sutures or Nitinol wires, that provide increased retention force and reduced bone resection, allowing for easier revision and minimizing the risk of stress shielding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If vertical pegs are used for fixation, then fixation strength is improved, but surgical exposure difficulty increases due to lack of exposure in the ankle joint space
Solution Approach 1:
The patent transitions from vertical pegs (one-dimensional insertion) to angled pegs inserted at oblique angles (two-dimensional trajectory), allowing the fixation components to be introduced through the anterior approach while achieving adequate engagement with the posterior tibial cortex. This angular transformation resolves the contradiction by enabling both surgical accessibility and fixation strength.
2Strength
If anterior approach with large drills is used, then fixation is achieved, but bone stock is weakened due to large bone voids requiring back filling
Solution Approach 1:
The patent employs multiple small angled pegs distributed across the tibial tray rather than single large vertical pegs. This distributes the fixation function across multiple localized points, each requiring minimal bone removal, thereby preserving overall bone stock while achieving adequate fixation through cumulative effect of the smaller insertion sites.
3Device complexity
If static fixation methods are used, then implant placement is simplified, but hardware loosening occurs during bone resorption or implant settling
Solution Approach 1:
The patent incorporates adjustable tensioning mechanisms in the fixation components, allowing the system to transition from a static fixed-state to a dynamically adjustable state. This enables the fixation system to adapt to bone resorption and implant settling processes, maintaining reliable fixation while preventing hardware loosening through controlled dynamic adjustment.
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
This solution enhances initial fixation and reduces the risk of hardware loosening or subsidence, preserving bone stock for potential revisions and minimizing stress shielding, thereby improving the long-term survival of the prosthetic implant.
Implementation Method 1
a button configured to rotate from a first position while traveling through the tibia of the patient to a second position
Implementation Method 2
A tension of the at least one fixation component is adjustable to thereby adjust a force applied by the body to the tibia of the patient
Data Source
AI summary
The present disclosure provides prosthetic implants for tibial fixation in a total ankle replacement device. Methods including the devices are also disclosed.