Flexible Composite Iliac Connector for Sacroiliac Joint Stabilization
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Solution Overview
Problem
Current spinal fixation techniques, particularly at the sacral-iliac joint, restrict natural movement, leading to energy absorption issues and potential degeneration of surrounding joints due to the loss of subtle flexion and nodding motions, causing discomfort and increased risk of osteoporosis.
Innovation Solution
An iliac connector system with a flexible connecting rod made of composite material, such as carbon filaments in a polymer matrix, allowing for low deformation and rotational movement while providing stabilization, mimicking the function of posterior sacral-iliac ligaments, and a connector head design enabling independent fixation of spinal and connecting rods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If rigid fixation elements (titanium rods/plates) are used to stabilize the sacrum and ilium, then mechanical strength and stability are improved, but natural movement between sacrum and ilium is restricted, leading to energy absorption issues and potential joint degeneration
Solution Approach 1:
The patent changes the material parameter from rigid titanium to flexible composite material (carbon fiber reinforced polymer), altering the mechanical properties to allow controlled flexibility while maintaining sufficient strength. This enables the fixation element to deform elastically under physiological loads, preserving natural sacro-iliac joint movement patterns.
Solution Approach 2:
The patent employs composite materials consisting of carbon fiber reinforcement embedded in a polymer matrix. This composite structure provides both the strength needed for mechanical fixation and the flexibility required to accommodate physiological movements, resolving the contradiction between strength and adaptability.
2Reliability
If multiple screws are used in the sacrum to prevent screw pull-out, then fixation reliability is improved, but device complexity and surgical procedure complexity increase
Solution Approach 1:
The use of composite material with high strength-to-weight ratio and superior bone bonding characteristics allows achieving reliable fixation with fewer screws. The material properties compensate for the reduced number of fixation points, maintaining reliability while simplifying the device.
3Stability of the object's composition
If the sacral-iliac joint is blocked to prevent screw pull-out, then fixation stability is improved, but patient comfort deteriorates due to loss of energy absorption mechanism
Solution Approach 1:
The patent changes the mechanical parameter of the fixation element from rigid to flexible, allowing controlled deformation under physiological loads. This flexibility preserves the energy absorption mechanism of the sacro-iliac joint, maintaining patient comfort while ensuring fixation stability through the material's inherent properties.
4Strength
If rigid fixation is applied to the soft sacral bone, then initial fixation strength is improved, but long-term reliability deteriorates due to screw pull-out risk
Solution Approach 1:
The composite material provides both immediate mechanical strength for initial fixation and long-term reliability through its flexibility and bone bonding properties. The material deforms elastically to accommodate physiological movements, preventing stress concentration and screw pull-out, thereby ensuring long-term fixation reliability in soft sacral bone.
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 maintains natural movement between the ilium and sacrum, absorbs shocks effectively, reduces stress on adjacent joints, and prevents screw pull-out, thereby enhancing patient comfort and preventing construct failure.
Implementation Method 1
the flexible connecting member (2) is made of a material being more flexible than titanium... allowing for low deformation and rotational movement
Implementation Method 2
absorbs shocks effectively... The longitudinal implant is a carbon filament composite material
Data Source
Figure 1
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AI summary
An inventive iliac connector comprises a connector head (1) and a connecting rod (2) for connecting a sacrum (S) or a spine (SP) to an ilium (I). The connector head (1) has a first hole (15) for holding a spinal rod (3) and a second hole (16) for holding the connecting rod (2), wherein the connecting rod (2) is made of a material being more flexible than titanium. This iliac connector enables a stabilization of ilium, sacrum and spine and enables at the same time movement between ilium and sacrum.