Intramedullary Nail Locking via Expandable Insert Radial Constriction
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Solution Overview
Problem
Existing bone fixation methods using intramedullary nails and bone screws often result in loosening and debris creation due to forced tapping into plastic or metal bushings, which compromises the stability of the screw lock.
Innovation Solution
An intramedullary nail with a hollow cavity and expandable inserts that allow bone screws to be loosely inserted and then locked in place through radial constrictive pressure, minimizing the need for bushings and reducing loosening and debris issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If forced tapping into plastic or metal bushings is used to lock bone screws, then the screws can be secured to the intramedullary nail, but loosening of the grip occurs and debris is created
Solution Approach 1:
The patent removes the bushing component entirely from the system. Instead of using separate plastic or metal bushings that require forced tapping, the intramedullary nail incorporates integrated threaded bores directly into its structure. Bone screws are inserted directly through these threaded bores, eliminating the intermediate bushing layer that generates debris and loses grip.
Solution Approach 2:
The patent combines the functions of the intramedullary nail and the locking mechanism into a single integrated structure. The threaded bores are formed directly as part of the nail body, merging the structural support function with the screw retention function. This integration eliminates the need for separate bushings and reduces the number of interfaces where debris can be generated.
2Reliability
If forced tapping into bushings is used to secure screws, then bone fixation can be achieved, but the complexity of the procedure increases due to debris management and potential loosening
Solution Approach 1:
By removing the bushing component and the forced tapping process, the patent simplifies the overall procedure. The elimination of debris generation removes the need for additional cleaning steps and reduces the risk of debris-related complications, thereby reducing procedural complexity while maintaining fixation reliability.
Solution Approach 2:
The threaded bores are pre-formed as integral parts of the intramedullary nail structure before insertion. This preliminary preparation eliminates the need for intraoperative tapping or threading operations, simplifying the surgical procedure and reducing the steps required to achieve secure screw fixation.
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 provides stable and secure locking of bone screws relative to the intramedullary nail, enhancing bone fixation stability while preventing loosening and debris creation, allowing for efficient and reliable bone fracture stabilization.
Implementation Method 1
each insert being movable between a resting configuration in which a width of its insert opening is smaller than a width of a bone fixation element to be inserted through the corresponding cross bore and a stressed configuration in which the width of the insert opening is expanded
Implementation Method 2
a width of the insert opening is expanded to a width greater than that of the bone fixation element to be inserted through the corresponding cross bore
Implementation Method 3
a compression member movable into the cavity to apply a force to the inserts moving the inserts from the resting configuration to the stressed configuration
Data Source
AI summary
An apparatus for treating a bone comprises an implant to be received within the bone, including a plurality of bores extending therethrough and a cavity formed therewithin, each of the bores being dimensioned to receive a bone fixation element and a plurality of inserts receivable in the cavity. Each insert includes an opening extending therethrough and configured to align with a corresponding bore. Each insert is movable between a resting configuration in which an opening width is smaller than a width of a bone fixation element inserted therethrough and a stressed configuration in which the opening width is expanded to a width greater than that of the bone fixation element in combination with a compression member movable into the cavity to apply a force moving the inserts from the resting configuration to the stressed configuration, withdrawal thereof reducing the force and permitting a return to the resting configuration.