Locking Spring Screw Orthopedic Implant Orientation
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Solution Overview
Problem
In orthopedic implantation procedures, ensuring proper screw orientation and simplifying the implantation process for medical professionals is challenging, particularly when securing implants to hard tissue like bone.
Innovation Solution
A locking spring screw system is introduced, featuring a spring member that locks the screw into place while allowing rotation, utilizing a flange and flange slot mechanism to provide movement in only one degree of freedom, facilitating secure attachment of implants to the implantation site.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a screw is used to secure the implant to hard tissue, then the implant can be firmly attached to the bone, but it becomes difficult to ensure proper screw orientation and simplify the implantation process
Solution Approach 1:
The spring member transitions from a compressed state during insertion to an expanded locked state after insertion, dynamically changing its configuration to provide both ease of insertion and secure locking. This dynamic behavior allows the screw to be easily inserted while ensuring proper orientation and firm attachment.
Solution Approach 2:
The spring member acts as an intermediary between the screw head and the implant bore, mediating the locking action. It engages with the ramp surface and flange to provide both guidance for proper orientation and mechanical locking for secure attachment.
2Reliability
If the spring member is made rigid to provide strong locking, then the screw can be securely locked into place, but it cannot be inserted into the screw hole which requires flexibility
Solution Approach 1:
The spring member dynamically changes its stiffness characteristics - flexible during insertion to navigate the screw hole, then rigid when locked to provide reliable attachment. The transition from compressed to expanded state provides both required flexibility and subsequent reliability.
Solution Approach 2:
The physical parameters of the spring member (compression ratio, expansion force) are specifically designed to provide flexibility during insertion and rigidity during locking. The spring constant and geometric parameters are optimized to exhibit different mechanical properties at different stages of the implantation process.
3Ease of manufacture
If the spring member is compressed to fit into the tool slot, then it can be inserted into the screw head, but it requires precise control to prevent slipping out
Solution Approach 1:
The spring member is designed to be self-retaining through its elastic properties. Once compressed into the tool slot and subsequently into the screw head, the spring's expansion force automatically secures it in place without requiring additional retention mechanisms or precise external control during the final positioning.
Solution Approach 2:
The potential harm of the spring slipping out during insertion is converted into a benefit through the elastic retention force. The same elasticity that allows compression for insertion also provides the retention force that prevents slipping out, turning a potential problem into a self-securing mechanism.
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 locking spring screw system ensures secure attachment of implants to the bone while allowing for easy rotation, simplifying the implantation process and reducing the complexity of screw placement, thereby enhancing the efficiency of orthopedic procedures.
Implementation Method 1
a flexible spring member; the spring member is inserted into a tool slot provided to the head of the spring screw in a flexed state and upon insertion into the tool slot, the spring member assumes an expanded state
Data Source
AI summary
Disclosed is a locking spring screw formed from a cylindrical screw body having a screw head that includes a tool slot adapted for receipt of a flexible spring member. The tool slot includes at least one outlet formed adjacent to the tool slot which is adapted for passage therethrough of a tongue extending outwardly from the spring member. A ridge is located opposite the outlet from the cylindrical screw body and formed at least partially around the circumference of the screw head wherein the spring member is retracted during installation and, upon the ridge engaging a flange, the spring member is released preventing screw head removal by entrapping the flange between the ridge and the tongue of the spring member.