Intramedullary Nail Coupling Unit for Bone Fixation
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Solution Overview
Problem
Conventional intramedullary nails face challenges such as cumbersome set screw insertion, potential uncontrolled medial deviation of the lag screw, and limited mechanical load stability due to the need for intraoperative assembly and modification of the lag screw design.
Innovation Solution
An implant system featuring an intramedullary nail with a coupling unit and bone fastener engagement members at the lateral and medial sides, allowing preassembly and facilitating the surgical procedure by guiding the coupling unit to engage with the bone fastener, preventing rotation and providing enhanced mechanical stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a set screw is inserted into a bore of the intramedullary nail to prevent rotation and uncontrolled medial deviation of the lag screw, then the stability of the bone fastener is improved, but the ease of operation deteriorates due to cumbersome intraoperative assembly
Solution Approach 1:
The coupling unit is preassembled within the intramedullary nail before surgery, with the set screw already positioned in the bore. This preliminary assembly eliminates the need for intraoperative set screw insertion, reducing surgical complexity and time while maintaining the rotational stability function.
Solution Approach 2:
The coupling unit integrates multiple functions into a single preassembled component: the set screw for preventing rotation, the guide wire for surgical guidance, and the structural support for the intramedullary nail. This merging transforms multiple separate operations into a single streamlined procedure.
2Adaptability or versatility
If the lag screw is allowed to slide in the intramedullary nail in accordance with the sintering of the femoral fracture, then the adaptability to fracture healing is improved, but the control over lag screw position deteriorates due to potential uncontrolled medial deviation
Solution Approach 1:
The coupling unit acts as an intermediary mechanism between the intramedullary nail and the lag screw. It provides controlled interaction through the guide wire and engagement structures that allow the lag screw to slide appropriately during fracture healing while preventing uncontrolled medial deviation through the preassembled set screw constraint.
3Ease of operation
If the intramedullary nail is provided with a coupling unit that is preassembled within the nail, then the ease of operation is improved by simplifying the surgical procedure, but the device complexity increases
Solution Approach 1:
The coupling unit is preassembled within the intramedullary nail during manufacturing, so that during surgery only the insertion of the preassembled unit into the bone is required. This shifts the complexity from the surgical environment to the manufacturing process, simplifying the operation while consolidating the structural complexity into a pre-engineered component.
Data Source
AI summary
An implant system for use in orthopedic surgery for fixation of bone includes an intramedullary nail and a coupling unit. The intramedullary nail has a medial side, a lateral side and a proximal portion defining a longitudinal axis. The proximal portion includes a bore defining a first axis substantially parallel to the longitudinal axis of the proximal portion and a transverse bore configured to receive a bone fastener. The coupling unit is movably arranged within the bore of the proximal portion and includes one or more bone fastener engagement members at one or both of the lateral side and the medial side of the intramedullary nail.