Adjustable Posterior Stabilizing Post for Knee Implant Rollback Control
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Solution Overview
Problem
Current total knee replacement surgeries lack the ability to selectively position the posterior stabilizing post of tibial inserts, leading to variable rollback and potential over-stretching of soft tissues, which can restrict movement and necessitate additional surgeries like lateral patella release.
Innovation Solution
Development of trial and permanent tibial inserts with an adjustably positioned posterior stabilizing post that can be locked in place, allowing surgeons to customize the post's location along the anterior/posterior axis to optimize rollback and reduce soft tissue tension, using mechanisms such as troughs, rails, screws, and detents for precise positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a fixed posterior stabilizing post position is used in tibial inserts, then the device structure is simple, but the rollback is variable and soft tissues may be over-stretched
Solution Approach 1:
The patent applies the dynamics principle by making the posterior stabilizing post movable rather than fixed. The post can be positioned at different locations along the anterior/posterior axis of the insert base and locked in place, allowing the rollback characteristics of the knee replacement to be customized for each patient's soft tissue conditions.
Solution Approach 2:
The patent changes the positional parameter of the posterior stabilizing post along the anterior/posterior axis to control rollback. By adjusting the post position (anterior or posterior placement), the surgeon can modify the rollback distance and thereby adapt the implant to different patient anatomies and soft tissue tensions.
2Adaptability or versatility
If the posterior stabilizing post is positioned posteriorly to increase rollback, then rollback is improved, but soft tissue tension increases causing over-stretching
Solution Approach 1:
The patent uses parameter changes by adjusting the post position along the anterior/posterior axis to optimize rollback while avoiding excessive soft tissue tension. The surgeon can select an intermediate position that provides sufficient rollback without over-stretching the patellar tendon and quadriceps.
Solution Approach 2:
The patent incorporates feedback by allowing the surgeon to test different post positions intraoperatively and observe the resulting rollback and soft tissue tension, then adjust the post position accordingly to achieve the optimal balance between rollback and soft tissue comfort.
3Adaptability or versatility
If multiple trial inserts with different post positions are used, then the optimal post position can be selected, but the number of components and surgery time increase
Solution Approach 1:
The patent applies dynamics by providing a single trial insert with a movable post that can be repositioned during surgery, eliminating the need for multiple separate trial inserts. The surgeon can test different post positions by simply moving and locking the post at different locations on the same insert base.
Solution Approach 2:
The patent uses universality by designing a single trial insert that can serve multiple testing functions. The same insert base can accommodate the post at various positions, allowing the surgeon to evaluate different rollback scenarios without changing the entire insert component.
Data Source
AI summary
Trial joint inserts have posts at different positions relative to the base. During joint replacement surgery, a surgeon can test different positions for a post using a trial insert, identify a suitable position for the post, and then select a permanent insert with a post in the desired position. The devices and methods in this application allow a surgeon to provide an individualized joint replacement for a patient. Joint inserts may be configured so the post moves relative to the base. The post may be adjustably positionable, may lock in place, or may be actuated by a resistance member such as a spring.