Segmented Joint Surface Replacement with Spherical Fixation
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Solution Overview
Problem
Existing joint replacement devices often suffer from breakage, bulk, excessive weight, and destructive lateral shearing forces leading to complete implant failure, and require modifications to the sub-chondral bone, use of materials like silicone, and cause detritic synovitis.
Innovation Solution
A joint surface replacement system with two implanted elements, each having a partially spherical member with integral screw means for solid fixation by compression press fit, eliminating lateral stress forces and providing full range of motion in three planes, formed from low-mass components to prevent breakage and bulk, and anchored firmly to bone.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional joint replacement devices are used, then joint surfaces can be replaced, but the devices suffer from breakage, bulk, excessive weight, and destructive lateral shearing forces leading to implant failure
Solution Approach 1:
The joint replacement device is divided into two separate components: a first component implanted in the first bone and a second component implanted in the second bone. Each component has a partially spherical member with articular surface, allowing independent optimization of each component's weight and structural integrity while maintaining reliable joint function
Solution Approach 2:
Both components feature partially spherical members with articular surfaces that provide smooth, curved contact surfaces. This spherical geometry eliminates lateral shearing forces by distributing loads through the center of rotation, preventing the destructive lateral forces that cause conventional implant failure
2Reliability
If conventional joint replacement devices are used, then joint surfaces can be replaced, but the devices suffer from breakage, bulk, and excessive weight
Solution Approach 1:
By segmenting the device into two compact components implanted in separate bones, the overall bulk is reduced while maintaining structural integrity. Each component can be minimized in size since it only needs to provide articular surface coverage for its specific bone, eliminating the need for a single large bulky implant
Solution Approach 2:
The partially spherical members provide efficient load-bearing geometry with minimal material volume. The curved articular surfaces achieve high structural strength-to-volume ratios, eliminating the bulk required by conventional flat or angular joint replacement designs
3Reliability
If conventional joint replacement devices are used, then joint surfaces can be replaced, but destructive lateral shearing forces cause complete implant failure
Solution Approach 1:
The partially spherical members with articular surfaces create a ball-and-socket type joint geometry where loads are transmitted through the center of rotation. This spherical configuration eliminates lateral shearing forces by ensuring all forces pass through the rotational axis, preventing the destructive lateral forces that cause conventional implant failure
Solution Approach 2:
Separating the joint replacement into two independently implanted components allows each to be optimally positioned and oriented in its respective bone. This segmentation enables precise alignment that eliminates misalignment-induced lateral shearing forces while maintaining implant stability
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
The system eliminates breakage, bulk, and excessive weight, providing a full range of motion and complete elimination of detritic synovitis, with solid fixation and reduced risk of implant failure, while being cost-effective and simple to install.
Implementation Method 1
solid fixation by compression press fit
Implementation Method 2
compression press fit
Data Source
AI summary
The present invention relates to an articular joint replacement system. The system has first and second components. Each component has a tapered head piece for covering the end of a bone and for acting as an articular surface, an integrally formed screw stem having a length sufficient to extend into the medullary canal, and inwardly angled bone grips affixed to the underside of the head piece to allow solid fixation to the bone by compression press fit. The head piece of the first component is provided with a shaped exterior surface which complements the shaped exterior surface of the head piece of the second component and which allows motion in three planes.