Cross Pin Fixator with Spherical Cavities for Proximal Humerus Fractures
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Solution Overview
Problem
Current methods for immobilizing proximal humerus fractures, such as casts and internal fixation devices, are either ineffective or cause significant trauma and infection, and there is a need for a lightweight, non-bridging external fixation device that allows for direct fixation and early mobilization of the shoulder joint.
Innovation Solution
A cross pin fixator device featuring a plate with spherical cavities and collapsible pin holders, where bone pins are inserted in a multi-angle and multi-planar configuration to secure fractured segments, and set screws immobilize the pin holders, allowing for secure fixation without bridging the joint.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If internal fixation devices (surgical nails, screws, plates) are used to treat proximal humerus fractures, then the fracture can be immobilized and healed, but the patient experiences extensive trauma, increased infection risk, and requires second surgery for removal
Solution Approach 1:
The patent introduces an external fixation device as an intermediary solution between the bone and the environment. The device uses pins inserted into the bone that extend through the skin to connect to an external frame, allowing fracture stabilization without internal implants. This intermediary approach avoids the trauma and infection risks associated with internal fixation while maintaining reliable immobilization.
Solution Approach 2:
The fixation mechanism is extracted from the interior of the body and placed externally. Instead of embedding screws, plates, or nails inside the bone and soft tissue, the patent uses an external frame that connects to the bone through pins passing through the skin. This extraction eliminates the need for second surgery to remove internal devices and reduces the risk of deep tissue infection.
2Reliability
If casts are used to immobilize proximal humerus fractures, then the bone can be held in position, but the shoulder joint cannot be mobilized early and the cast becomes ineffective due to swelling
Solution Approach 1:
The patent segments the immobilization function from the joint mobilization function. The external fixation device provides targeted immobilization of the fracture site through rigid pin connections, while allowing the shoulder joint to move freely. This segmentation enables simultaneous fracture stabilization and early joint rehabilitation, unlike casts that immobilize the entire limb.
Solution Approach 2:
The device transitions from static immobilization (like casts) to dynamic stabilization. The external frame maintains rigid fixation at the fracture site while allowing dynamic movement of the shoulder joint. This dynamic approach enables early mobilization without compromising fracture healing.
3Reliability
If external fixation devices with pins are used to treat proximal humerus fractures, then the bone fragments can be repositioned and immobilized, but the device is typically heavy and bridges the joint preventing early mobilization
Solution Approach 1:
The patent applies local quality by providing fixation only where needed - at the fracture site - rather than using a heavy bridging structure. The external frame connects directly to bone fragments near the fracture through pins, providing localized stabilization. This eliminates the need for heavy bars that span across the shoulder joint, reducing overall device weight and enabling joint mobilization.
4Reliability
If pins are inserted in a multi-angle and multi-planar configuration, then fractured bone segments are secured against rotation and axial movement, but the device complexity increases
Solution Approach 1:
The patent utilizes another dimension by arranging pins in multi-angle and multi-planar configurations. Instead of simple single-plane pin placement, the device incorporates pins oriented in multiple dimensions (anterior-posterior, lateral-medial, and cranial-caudal planes). This multi-dimensional arrangement provides comprehensive stabilization against rotation and axial movement while maintaining a relatively simple external frame structure.
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 cross pin fixator effectively immobilizes proximal humerus fractures, facilitating early shoulder mobilization and reducing the risk of infection and trauma, while maintaining radiological parameters and promoting callus formation.
Implementation Method 1
each collapsible pin holder member is press-fit into one of the spherical cavities
Implementation Method 2
threaded holes in the plate comprising set screws that immobilize or deform the pin holder members in the cavities
Data Source
AI summary
The present application relates to a cross pin fixator device comprising a plate member with spherical cavities that are open to the front and to the back of the plate, collapsible pin holder members having a central channel for insertion of a bone pin, the collapsible pin holder member being press-fit into the spherical cavities, and bone pins individually inserted into the central channel of a pin holder. The application also relates to a method for treating a fracture of the proximal humerus using the proximal humerus cross pin fixator and to a kit for treating a fracture of a bone.