External Knee Load Bearing Distracting Device
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Solution Overview
Problem
Current treatments for knee joint injuries and conditions, such as osteoarthritis and fractures, often result in reduced joint motion due to immobilization or inadequate approximation of the knee's complex motion requirements, and existing external load-bearing devices do not effectively unload the knee joint cartilage while allowing natural motion.
Innovation Solution
An external load-bearing distracting device comprising translational and rotatable components that can be attached to the femur and tibia, allowing six degrees of motion and enabling natural knee movement by distracting the joint, thereby reducing weight and mechanical stress on the cartilage, with adjustable nuts and retainers for precise positioning and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If external linkages are used to support the knee joint, then the joint can bear load, but the motion is only approximate and not compatible with the exacting motion requirements of the internal structures
Solution Approach 1:
The device employs a dynamic linkage mechanism with multiple degrees of freedom that can adapt to the complex physiological motion of the knee joint. The linkage includes rotational joints and translational components that allow the structure to dynamically adjust to the varying motion requirements during different phases of knee movement, thereby achieving both load bearing and motion compatibility.
Solution Approach 2:
The external linkage device incorporates adjustable parameters including the position of the femoral and tibial attachment points, the length of the linkage components, and the range of motion constraints. These parameters can be modified to match the specific anatomical and functional requirements of different patients, enabling precise replication of physiological knee motion while maintaining load bearing capacity.
2Reliability
If immobilization is used to treat knee joint injuries, then soft tissue repairs are protected, but subsequent joint motion is reduced, sometimes permanently
Solution Approach 1:
The device transitions from a static immobilization approach to a dynamic support system that allows controlled motion. The linkage mechanism provides stability when needed while permitting physiological movement, enabling soft tissue healing without the adverse effects of prolonged immobilization on joint mobility.
Solution Approach 2:
The external linkage device maintains continuous support and stabilization of the knee joint throughout the range of motion, rather than providing intermittent or fixed support. This continuous dynamic support protects soft tissue repairs while simultaneously maintaining joint mobility and preventing motion loss.
3Reliability
If the knee joint is distracted to unload cartilage, then cartilage regeneration is promoted, but the device complexity increases
Solution Approach 1:
The device is divided into separate functional modules including femoral attachment components, tibial attachment components, linkage elements, and adjustment mechanisms. This segmentation allows each component to be optimized for its specific function while simplifying manufacturing, assembly, and adjustment procedures.
Solution Approach 2:
The external linkage device is designed to perform multiple functions: providing load bearing support, enabling physiological motion, allowing joint distraction for cartilage unloading, and offering adjustable positioning. This multi-functionality reduces the need for multiple separate devices while maintaining manageable complexity through integrated design.
Data Source
AI summary
An external load bearing distracting device, which can be positioned to fully unload a knee joint cartilage while providing the knee joint normal motion, for an articulating anatomical joint. The device includes first and second rotatable extensions arranged longitudinally on opposite sides of the joint, and first and second translational inserts slidably arranged inside the first and second rotatable extensions, respectively. The joint may comprise a ball-and-ring-joint or a cardan joint. The first and second translational inserts include a threaded portion and a pair of threaded nuts thereon, which abut a retainer on each of the first and second rotatable extensions to limit longitudinal translation. The external load-bearing distracting device is temporarily attached to the patient, preferably for a period of 6 to 8 weeks, and is intended for use to treat osteoarthritis, focal cartilage defects, and fractures inside the knee joint, among other conditions of articulating anatomical joints.