Ligament Balancer for Knee Surgery
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional methods for positioning femoral cuts in knee surgery face challenges in balancing ligaments due to the presence of the patella, which complicates the alignment of surgical jigs and makes it difficult to achieve equal tension in ligaments throughout the knee's range of motion.
Innovation Solution
A ligament balancer with moveable guide portions and a tibial location plate, along with an intramedullary rod, allows for precise alignment and balancing of knee ligaments by drilling marker holes with the patella in its anatomical position, followed by using a drill guide to accurately position cutting block mounting holes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the patella is everted or subluxed to provide space for the surgical jig, then sufficient space for the surgical jig is achieved, but the quadriceps mechanism force acts out of normal alignment causing lateral or medial skewing of the joint
Solution Approach 1:
The surgical jig is designed with moveable guide portions that can adjust their position relative to each other along a movement axis. This dynamic structure allows the jig to adapt to the anatomical constraints while maintaining proper alignment, eliminating the need to dislocate the patella and preserving normal quadriceps force vector.
Solution Approach 2:
The surgical jig is divided into separate guide portions (first guide portion and second guide portion) that can move independently relative to each other. This segmentation allows each portion to be positioned optimally for its specific function while maintaining overall system coherence and proper force alignment.
2Ease of operation
If conventional surgical jigs are used with the patella in anatomical position, then normal quadriceps force alignment is maintained, but sufficient space for the surgical jig is not achieved
Solution Approach 1:
The guide portions are arranged in a configuration that utilizes three-dimensional space efficiently. By positioning guide portions at different locations and orientations, the jig achieves sufficient operational space while keeping the patella in its anatomical position and maintaining proper force alignment.
3Manufacturing precision
If the femoral cuts are positioned incorrectly, then the bearing surfaces are misaligned, but equal tension in the ligaments after surgery cannot be ensured
Solution Approach 1:
The surgical jig incorporates a ligament balancer mechanism that provides real-time feedback on ligament tension during the cutting process. The moveable guide portions can be adjusted based on this feedback to ensure that the femoral cuts are positioned correctly for achieving equal ligament tension throughout the knee's range of motion.
Solution Approach 2:
The invention replaces conventional rigid mechanical jigs with a more sophisticated system that incorporates the ligament balancer mechanism. This system uses the movement of guide portions along the movement axis to mechanically sense and compensate for positioning errors, ensuring accurate femoral cut placement and proper ligament tension balance.
Data Source
AI summary
A ligament balancer for a knee is disclosed that includes a first guide portion having a first guide hole extending there through, and a second guide portion having a second guide hole extending there through, the first and second guide portions being moveable with respect to each other along a movement axis, the balancer being adapted such that, in use, the movement axis is substantially parallel to the anterior/posterior axis of a distal femoral surface. Also disclosed is a kit of parts that includes the ligament balancer and a drill guide for a knee, the drill guide includes first and second connected arms, each arm comprising at least two guide openings extending there through, the guide openings being spaced longitudinally along each arm, longitudinal axes of the first and second arms intersecting at a predetermined angle. Also disclosed is a method of attaching a cutting block to a distal femoral surface as part of a knee replacement procedure.