Intra-medullary Implant with Dynamic Compression Mechanism
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Solution Overview
Problem
Current intramedullary rod implants provide rigid, inflexible fixation for fractures, which does not allow for sustained, controlled, and dynamic compression necessary for rapid bone healing, and cannot accommodate bony contraction.
Innovation Solution
An orthopedic implant with a movable slide and tensioning mechanism that applies elastic tension across the fracture using an elastomeric tensile member and transfixing cross-pins to promote healing, allowing for dynamic compression and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a rigid intra-medullary rod is used for fracture fixation, then structural stability and support are provided, but the ability to accommodate bony contraction and provide sustained compression is lost
Solution Approach 1:
The patent applies the dynamics principle by replacing the static rigid rod with a dynamic telescoping mechanism comprising an inner rod and outer tube that can move relative to each other. This allows the implant to adapt to bone resorption and contraction during healing while maintaining structural stability through controlled mechanical interaction between the telescoping components
2Force
If interlocking screws are threaded through elongated holes to allow bone ends to be pressed together, then limited compression is achieved, but sustained and controlled compression cannot be maintained
Solution Approach 1:
The patent applies self-service through the spring mechanism that automatically generates and maintains compression force without external intervention. The spring continuously exerts force on the bone fragments, providing sustained compression throughout the healing process without requiring repeated surgical adjustments or patient compliance with weight-bearing protocols
3Reliability
If a rigid intra-medullary rod is used, then immediate fracture stabilization is achieved, but dynamic compression necessary for rapid healing cannot be provided
Solution Approach 1:
The patent applies dynamics by incorporating a spring mechanism within the telescoping rod structure that provides continuous dynamic compression at the fracture site. This dynamic force stimulation promotes osteogenesis and accelerates bone healing while the telescoping mechanism maintains reliable fracture stabilization throughout the healing process
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 implant achieves consistent, predetermined elastic force across the fracture, promoting bone healing by applying compression within a specific strain range (1500 to 4000 microstrains) and maintaining tension for an extended period.
Implementation Method 1
at least one elastomeric tensile member included in the intra-medullary implant... capable of exerting a working tension... to generate a compression force... capable of extension by a substantial percentage, preferably at least 100 percent
Data Source
AI summary
An Intra-Medullary implant includes: an elongated rigid body having a first end and a second end, adapted to be inserted longitudinally into a bony canal, the body having a generally axial passage through at least a portion of said body; at least one movable slide, movably received in said passage and adapted to be transfixed by engagement with a transverse member penetrated through the bone, said slide also adapted to receive tension from an elongated tensile member disposed longitudinally within said passage; and an anchor, adapted for fixation to the body near its first end and to said tensile member, to hold the elongated tensile member under tension between the anchor and the movable slide.