Soft Tissue Tension Guided Bone Resection Instruments
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Solution Overview
Problem
Conventional total knee arthroplasty (TKA) techniques often require arbitrary bone cuts and subsequent soft tissue releases to achieve proper ligament balancing and stable joint alignment, as they focus on mechanical alignment rather than natural ligament tension, leading to non-parallel bone cuts and the need for extensive soft tissue balancing.
Innovation Solution
A tensioner device that utilizes the native length and tension of the medial and lateral collateral ligaments to link tibial and femoral bone cuts, allowing for the preparation of both extension and flexion gaps, thereby reducing the need for soft tissue balancing and ensuring optimal kinematic function by maintaining natural ligament tension.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional measured resection techniques are used to make femoral and tibial cuts independently based on mechanical alignment, then mechanical alignment of the limb is achieved, but the bone cuts are not parallel and extensive soft tissue balancing is required
Solution Approach 1:
The tensioner device acts as an intermediary between the femoral and tibial cuts, using the collateral ligaments as a mediator to link the two bone surfaces. By tensioning the ligaments, the device ensures that the femoral and tibial cuts are parallel, eliminating the need for soft tissue balancing procedures.
Solution Approach 2:
The collateral ligaments serve as a self-service mechanism that naturally indicates when the femoral and tibial cuts are parallel. When the ligaments are tensioned and show equal length on both sides, it self- confirms that the bone cuts are correctly aligned, eliminating the need for external soft tissue balancing interventions.
2Reliability
If soft tissue releases are performed to achieve ligament balancing after independent bone cuts, then ligament balancing is achieved, but the natural ligament tension is altered and extensive additional procedures are required
Solution Approach 1:
The tensioner device is applied before making the femoral and tibial cuts to establish parallelism between the bone surfaces. By performing this alignment action preliminarily, the need for subsequent soft tissue releases is eliminated, as the ligament balancing is achieved through the initial bone cut alignment rather than through corrective soft tissue procedures.
3Manufacturing precision
If the femoral cut is made first based on a desired angle using alignment guides, then the distal femoral cut is established, but the tibial cut cannot be linked to the femoral cut and soft tissue balancing is still required
Solution Approach 1:
The tensioner device serves as an intermediary that links the previously independent femoral and tibial cuts. After the femoral cut is made with precise angular control, the tensioner is applied to the knee joint, tensioning the collateral ligaments to ensure that the subsequent tibial cut will be parallel to the femoral cut, thereby establishing a linkage between the two cuts.
4Reliability
If multiple soft tissue balancing procedures are performed on MCL, LCL and other structures, then ligament balancing is achieved, but the surgical time is extended and the procedure complexity increases
Solution Approach 1:
The tensioner device is applied in the preliminary stage before bone cuts are made, establishing the parallelism between femoral and tibial cuts. This preliminary action ensures that ligament balancing is achieved through proper bone cut alignment, eliminating the need for multiple time-consuming soft tissue balancing procedures performed later in the surgery.
Data Source
AI summary
A device for preparing a femur of a patient for receipt of a knee implant in both extension and flexion relative to a resected tibia plateau based on applying tension to medial and lateral collateral ligaments of said patient, comprising a tibial baseplate, a tensioner, the tensioner comprising a tensioner body having a tensioner portion, the tensioner portion affixed to the tibial baseplate, and an expander arm comprising an elongated body portion, a superior side of the elongated body portion having a spiked tip adjacent a posterior end thereof. The spiked tip interacts with an intracondylar notch under tension. The expander arm is operatively connected to the tensioner body via the tensioner portion, the tensioner portion configured for use in selectively raising and lowering the expander arm relative to the tibial baseplate to apply tension to the medial and lateral collateral ligaments in extension or flexion.