Knee Joint Distractor With Polycentric Motion and Cartilage Unloading
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Solution Overview
Problem
Current treatments for traumatic injuries and pathological conditions of the knee joint, such as osteoarthritis and fractures, often immobilize the joint, leading to reduced motion and adverse effects on soft tissues, while existing external devices fail to accurately mimic the complex physiological motions of the knee joint.
Innovation Solution
An external load-bearing distracting device for the knee joint that allows natural motion and unloads the cartilage by distracting the joint, featuring adjustable components made of biocompatible materials, enabling six degrees of freedom of motion and temporary attachment for 6 to 8 weeks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If external linkages are used to support the knee joint, then joint stability is improved, but motion accuracy deteriorates because they provide only approximate motion and are not compatible with the exacting motion requirements of internal structures
Solution Approach 1:
The external linkage is designed with multiple degrees of freedom including rotational joints and translational capabilities, allowing the device to dynamically adapt to the complex polycentric motion of the knee joint. The linkage can rotate about multiple axes and accommodate varying instantaneous centers of rotation, transforming a static approximate support into a dynamic precise motion system that mirrors internal knee structures.
2Reliability
If immobilization is used to treat joint injuries, then soft tissue repair is improved, but subsequent joint motion deteriorates as it can reduce motion permanently
Solution Approach 1:
The device transitions from static immobilization to dynamic controlled support, allowing progressive motion as tissues heal. The adjustable linkage provides stability when needed while permitting controlled movement, enabling the joint to maintain motion capability throughout the healing process rather than losing motion permanently.
Solution Approach 2:
The device allows for periodic adjustment of motion constraints during the healing process. Initially providing greater stability for early tissue repair, then progressively allowing increased motion as healing progresses, creating a time-dependent treatment protocol that addresses both repair and motion preservation.
3Reliability
If the knee joint is distracted to unload cartilage, then cartilage regeneration is improved, but joint stability deteriorates
Solution Approach 1:
The external linkage provides dynamic stabilization that adapts to the distracted joint configuration. Even with the joint space increased for cartilage regeneration, the linkage maintains stability through its rotational and translational capabilities, allowing the distracted joint to remain stable while enabling the therapeutic unloading needed for cartilage healing.
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
Enables natural motion of the knee joint, reduces stress on bones, and facilitates cartilage regeneration by distracting the joint to a healthy distance, promoting recovery from osteoarthritis and fractures without long-term motion reduction.
Implementation Method 1
a first rotatable threaded rod; a second rotatable threaded rod
Implementation Method 2
a rotating joint joining the first and second rotatable threaded rods; the rotating joint being configured to enable natural motion present in the articulating anatomical joint
Data Source
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AI summary
An external load bearing distracting device (100), 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 (100) includes a first and second rotatable threaded rods (107; 108) arranged longitudinally on opposite sides of a rotating joint (117), and first and second translational tubes (106; 103) slidably arranged around the first and second rotatable threaded rods (107; 108), respectively. The rotating joint (117) may comprise a ball-and-ring-joint configured for accommodating a two mutually complementary brake elements (132A; 132B). The first and second rotatable threaded rods (107; 108) each include a first and second clamping nuts (115; 115') thereon, which contact a proximal end of the first and second translational tube (106; 103) to limit longitudinal translation thereof towards the rotating joint (117). The distracting device (100) is intended for temporary implantation to treat osteoarthritis, focal cartilage defects, and fractures inside the knee joint.