Angled Posterior Tibial Baseplate for BCR Knee Stability
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Solution Overview
Problem
Current bicruciate retaining (BCR) implants face challenges such as avulsion of the tibial eminence and suboptimal instrumentation and surgical techniques, which complicate surgery and limit the restoration of natural knee kinematics and stability after total knee replacement.
Innovation Solution
A bicruciate retaining tibial baseplate with an angled posterior wall and spring-loaded inserts that securely lock into place, designed to better engage the tibial eminence and provide enhanced stability and fixation, along with a method for preparing the tibia that includes angled cuts and a tibial eminence punch system to minimize bone removal and maximize stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional BCR baseplate design is used, then the ACL and PCL can be preserved, but avulsion of the tibial eminence occurs and surgical instrumentation is suboptimal
Solution Approach 1:
The baseplate features an asymmetric posterior wall configuration where the lateral posterior wall extends farther posteriorly than the medial posterior wall. This local differentiation in geometry allows the baseplate to engage the tibial eminence more effectively without causing avulsion, while preserving both cruciate ligaments. The asymmetric design distributes stresses differently across the tibial eminence interface.
Solution Approach 2:
The posterior wall of the baseplate is angled between approximately 5-45 degrees (preferably 15-25 degrees) with respect to the resected surface of the tibia. This angular parameter change optimizes the engagement between the baseplate and tibial eminence, providing stable fixation while preventing avulsion forces during implantation and subsequent knee movement.
2Reliability
If a traditional BCR baseplate design is used, then cruciate ligaments can be preserved, but surgical techniques become more challenging
Solution Approach 1:
The baseplate includes distinct medial and lateral condylar portions with differentiated posterior wall configurations. The lateral condylar portion has a posterior wall extending farther posteriorly than the medial condylar portion, creating segmented engagement zones that simplify surgical alignment and instrumentation while maintaining ligament preservation.
Solution Approach 2:
The asymmetric posterior wall design, with the lateral side extending farther posteriorly than the medial side, provides natural alignment cues during surgery. This asymmetry simplifies the surgical procedure by guiding proper baseplate orientation and engagement with the asymmetric tibial eminence anatomy, making the operation easier while preserving both cruciates.
3Strength
If the posterior wall is extended farther posteriorly, then engagement with tibial eminence improves, but the angle with resected surface increases
Solution Approach 1:
The posterior wall is configured at a specific angle range (5-45 degrees, preferably 15-25 degrees) relative to the resected tibial surface. This parameter optimization ensures sufficient posterior extension to engage the tibial eminence effectively while limiting the overall posterior projection of the baseplate to avoid interference with soft tissue structures and maintain appropriate knee kinematics.
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 solution improves the stability and fixation of the tibial baseplate, reducing the risk of avulsion and enhancing the restoration of natural knee kinematics, allowing for more effective preservation of both cruciate ligaments and improved surgical outcomes.
Implementation Method 1
At least one of the medial and lateral inserts may include a spring connected to a pin, the spring biasing the pin.
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3A~3B
AI summary
A bicruciate retaining tibial implant baseplate includes a tibial baseplate with medial and lateral condylar portions configured to receive bearing inserts. The baseplate includes an anterior bridge connecting the medial and lateral portions. A posterior wall of the anterior bridge may be angled to provide downward force on a correspondingly angled anterior portion of the tibial eminence when the baseplate is implanted. A method of preparing the tibia for implant includes a punch tower and punch guide configured to both cut the anterior tibial eminence and provide protection to the tibial eminence during resection of the proximal tibia.