Bone Connector with Pivotable Joint for Scapholunate Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current treatments for scapholunate instability, such as the Herbert screw, often restrict bone movement for an extended period, leading to scar tissue formation and long-term loss of wrist function, and do not allow for the full anatomical range of joint articulation due to limited pivotal motion.
Innovation Solution
A bone connector with a pivotable joint, comprising a pair of anchor elements with a cylindrical head trapped in a cylindrical cavity, allowing relative pivotal motion about at least two nonparallel axes, enabling flexible accommodation of anatomical axes and promoting natural joint movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a Herbert screw is used to fix scaphoid and lunate bones, then bone separation is restricted and stability is improved, but bone movement is restricted for approximately six weeks leading to scar tissue formation and long term loss of wrist function
Solution Approach 1:
The invention transitions from a static fixed-position screw to a dynamic system where the distal portion can pivot relative to the proximal portion about the screw axis. This dynamic capability allows the bone connector to maintain stability while permitting natural bone movement and articulation, preventing scar tissue formation and preserving wrist function.
2Stability of the object's composition
If a Herbert screw is used to stabilize the scapholunate joint, then bone separation is prevented, but joint movement is restricted substantially to a pivotal motion about a single axis defined by the screw
Solution Approach 1:
The pivotable joint mechanism enables the distal portion to rotate relative to the proximal portion about the screw's long axis, transforming the single-axis constraint into multi-axis movement capability. This allows the scapholunate joint to achieve its full anatomical range of articulation while maintaining stability through the screw engagement.
Solution Approach 2:
The invention changes the degree of freedom parameter from one (single-axis pivotal motion) to multiple (pivotal motion about screw axis plus transverse axes), enabling the joint to accommodate varying anatomical configurations and achieve complete range of motion while maintaining stabilizing force.
3Stability of the object's composition
If the Herbert screw is installed at an unsuitable angle, then bone separation is restricted, but joint movement becomes even more limited and anatomical articulation is compromised
Solution Approach 1:
The pivotable joint provides dynamic adjustment capability that compensates for variations in screw installation angle. The distal portion can pivot relative to the proximal portion to accommodate the anatomical axis of the scapholunate joint regardless of the initial screw angle, ensuring both stable fixation and full range of motion.
Solution Approach 2:
The invention introduces rotational degree of freedom that allows the joint to adapt to different anatomical orientations and screw angles, transforming a rigid angle-dependent system into a flexible angle-independent system that maintains both stability and physiological function.
Data Source
Figure 1~2
Figure 3~5
Figure 6~8
AI summary
System, including methods, apparatus, and kits, for connecting bones and/or bone portions using a bone connector with a pivotable joint.