Elastic Tri-Wire Hip Screw for Rotational Stability
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Solution Overview
Problem
Current devices for fixing femoral neck and trochanteric fractures lack rotational stability and are difficult to remove without damaging surrounding bone, especially for intracapsular fractures, and existing intermedullary nailing systems are not suitable for closed intermedullary treatment.
Innovation Solution
An intermedullary implant with a smoothly curved rod, a longitudinally slotted hip screw, and three elastic proximally curved wires (tri-wire) that provide improved rotational stability and can be easily inserted and removed, allowing for operative compression and sliding under weight-bearing forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If cement is used to augment the hip screw, then rotational stability is improved, but the hip screw cannot be removed without damaging the hip
Solution Approach 1:
The fixation system is divided into separate components: the intramedullary nail, the hip screw, and the elastic wires. This segmentation allows each component to be independently adjusted or removed without affecting the others, enabling removal of the hip screw without damaging the bone or other fixation elements.
Solution Approach 2:
The elastic wires are inserted through the intramedullary nail and then through the hip screw, creating a nested configuration. This allows the wires to provide rotational stability through the bone while passing through the removable hip screw, enabling stability during healing and subsequent removal of the screw without bone damage.
2Device complexity
If traditional intermedullary nailing systems are used, then they are simple in design, but they cannot be used for intracapsular fractures by the closed intermedullary method
Solution Approach 1:
The intramedullary nail is designed with multiple functions: it serves as the primary structural support, provides a channel for the hip screw, and acts as a guide for the elastic wires. This multi-functionality allows the same simple intramedullary nail design to be used for both extracapsular and intracapsular fractures through the closed intermedullary method.
Solution Approach 2:
The elastic wires act as intermediaries that connect the intramedullary nail to the hip screw and provide additional rotational stability. This intermediary element enables the system to handle intracapsular fractures by providing the necessary rotational control without requiring a completely different nail design.
3Ease of operation
If existing hip screw designs are used, then they are easy to implant, but they do not provide sufficient rotational stability of the fracture fragment
Solution Approach 1:
The system merges the traditional hip screw with elastic wires that pass through both the nail and the screw. This combination maintains the ease of implantation of the hip screw while adding rotational stability through the wire configuration, achieving both simplicity and effectiveness.
Solution Approach 2:
The elastic wires provide dynamic rotational stability that adapts to the healing process. The wires allow controlled movement during early healing while providing rotational control, and can be removed or adjusted as healing progresses, maintaining both ease of operation and reliability.
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 solution enhances rotational stability of fracture fragments, facilitates easy removal without damaging bone, and is suitable for intracapsular fractures, improving healing outcomes while maintaining dynamization of the fracture.
Implementation Method 1
an elongate device that consist of a three 'elastic' proximally curved wires, that can be inserted into the hip screw
Implementation Method 2
the leading end of said elongate fixing device having a plurality of projections which can be extended out of the rod to engage with bone surrounding the leading end of the rod
Data Source
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AI summary
A bone support fixating device with a longitudinally slotted hip screw which permits operative compression of the fracture and holds this compression yet allows sliding as further compression of the fracture occurs under forces of weight bearing; comprising a hollow cylindrical shaft with a screw portion at its upper proximal end and four equally spaced longitudinal grooves at its lower distal end, having three equally distant angled holes between the ends, through which three wires can be inserted, the three 'elastic' proximally curved wires, welded, glued or crimped distally, can be inserted into the hip screw collectively called the 'tri-wire'; The proximal end has the wires curved outward, with all three wires equally spaced; upon pushing the tri-wire into the hip screw, the wires goes through the angle holes in the hip screw and provides three projections equally spaced; which improves the rotational stability of the proximal fracture fragment.