Orthopedic Screw Driver Stop Mechanism
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current orthopaedic compression screw and lag screw systems are prone to operator error, leading to excessive compression force that can misalign bones or cause screws to splay apart, inhibiting proper fracture stabilization.
Innovation Solution
A system comprising a lag screw driver with a stop mechanism and a compression screw driver that engages the stop to prevent over-rotation, utilizing a lag screw with a middle rack and a compression screw having a first threaded and second unthreaded portion to create a positive stop, ensuring controlled compression force application.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a compression screw and lag screw system is used to stabilize bone fractures, then fracture stabilization is achieved, but excessive compression force can cause bone misalignment or screw splay
Solution Approach 1:
The patent applies preliminary action by pre-configuring a stop mechanism on the lag screw driver that physically limits the rotation of the compression screw driver. This stop mechanism is established before the compression procedure begins, preventing excessive compression force from being applied in the first place, rather than correcting the problem after it occurs.
Solution Approach 2:
The stop mechanism acts as an intermediary element between the compression screw driver and the lag screw driver. It mediates the interaction by providing a physical barrier that prevents the compression screw driver from rotating beyond the safe limit, thereby controlling the compression force applied to the bone fracture.
2Ease of operation
If visual aids like line indications are provided on compression screw drivers, then surgeons can limit compression force, but operator error still occurs leading to excessive compression
Solution Approach 1:
The system applies self-service by making the compression screw driver self-limiting through the integrated stop mechanism. The driver automatically prevents itself from rotating beyond the safe compression limit, eliminating the need for the surgeon to continuously monitor and judge the appropriate compression force, thereby preventing operator error.
Solution Approach 2:
The stop mechanism provides immediate physical feedback to the surgeon when the safe compression limit is reached. The mechanical engagement of the stop creates a tangible sensation that clearly indicates the maximum safe rotation point, eliminating ambiguity and preventing excessive compression that can occur with visual aids alone.
3Force
If the compression screw is allowed to rotate freely, then compression force can be applied, but the screws may splay apart inhibiting proper fracture stabilization
Solution Approach 1:
The stop mechanism is pre-configured on the lag screw driver to limit the rotation of the compression screw driver before the compression procedure begins. This preliminary constraint ensures that the compression screw cannot rotate enough to cause screw splay, maintaining proper screw alignment throughout the procedure.
Solution Approach 2:
The stop mechanism serves as an intermediary that mediates between the need to apply compression force and the need to maintain screw alignment. It allows sufficient rotation to achieve the required compression force while simultaneously preventing excessive rotation that would cause the screws to splay apart.
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 effectively limits excessive compression force, preventing bone misalignment and screw splay, thereby ensuring reliable fracture stabilization and preventing over-compression of fractured bones.
Implementation Method 1
A threaded section 36 of the compression screw 33 passes through the nail 31 and engages a rack 35 disposed on a side of the lag screw 32. Rotating the compression screw 33 applies an axial force to the lag screw 32
Implementation Method 2
the lag screw 32, and the bone fragment affixed to the end 37 of the lag screw 32, in a direction along the length of the compression screw 33
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
Systems, devices and methods are disclosed for limiting compression of a fracture imposed by a lag screw of a fixation system that includes a fixation device, a lag screw and a compression screw. The disclosed devices, systems and methods prevent over-compression of a fracture by a lag screw caused by over rotation of the compression screw. Specifically, implementations of a lag screw driver and a compression screw driver are provided whereby an engagement between the lag screw driver and compression screw driver prevents any further lateral movement of the lag screw, thereby providing a complete stop to further advancement of the lag screw and any additional compression.