Distal Targeting Device for Intramedullary Nail Alignment
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Solution Overview
Problem
The challenge in accurately locking long intramedullary nails with distal attachment screws is complicated by nail deflection during insertion, which changes the location of cross bores, making precise alignment difficult due to anatomical constraints and the need for minimally invasive surgery, often requiring freehand techniques under x-ray guidance.
Innovation Solution
A targeting apparatus with an adjustable aiming device and radiolucent target indicator, featuring a clamping mechanism and Z-direction adjustment, allows for precise alignment of distal bores using oblique x-ray imaging, minimizing fluoroscopy time and avoiding misdrilling, while facilitating minimally invasive surgery with reduced operating room time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If freehand drilling technique is used under x-ray guidance, then surgical flexibility is maintained, but alignment precision deteriorates due to nail deflection and instrument interference
Solution Approach 1:
The targeting apparatus is attached to the nail before insertion, allowing the cross bore locations to be pre-marked on the bone surface while the nail is still in its undeflected state. This preliminary action captures the correct alignment references before deflection occurs during insertion.
Solution Approach 2:
The patent introduces radiopaque markers that transfer the cross bore locations from the nail to the bone surface, serving as an intermediary that preserves alignment information despite nail deflection. These markers act as a mediator between the nail's bore positions and the actual drilling locations.
2Difficulty of detecting and measuring
If instruments are placed on the image plane for freehand drilling, then direct visualization is achieved, but instrument interference increases blocking the x-ray view
Solution Approach 1:
The cross bore locations are marked on the bone surface before drilling begins, eliminating the need to have drilling instruments in the x-ray path during alignment. The targeting apparatus remains on the image plane for visualization, but the actual drilling instruments can be positioned elsewhere.
3Ease of manufacture
If distal locking is performed through soft tissue with curved femur anatomy, then minimally invasive approach is achieved, but bore location precision deteriorates due to nail curvature
Solution Approach 1:
The cross bore locations are transferred to the bone surface while the nail is in its undeflected, straight state before insertion. This preliminary marking ensures that even when the nail curves to conform to the femoral anatomy during insertion, the marked locations on the bone remain accurate for drill alignment.
Solution Approach 2:
The patent replaces direct mechanical alignment through the curved soft tissue path with an optical/radiographic system using radiopaque markers visible on x-ray imaging. This substitution allows precise location transfer without being constrained by the mechanical curvature of the nail in the femoral canal.
4Stability of the object's composition
If multiple screws are placed for static locking, then nail stability improves, but surgical time and complexity increase
Solution Approach 1:
The targeting apparatus with marked cross bore locations remains in place throughout the procedure, allowing for rapid sequential placement of multiple screws without requiring repositioning or realignment. The pre-marked locations enable efficient screw placement for static locking while maintaining surgical productivity.
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 the accuracy and efficiency of distal locking in intramedullary nail procedures by providing a reproducible method for locating cross bores, reducing fluoroscopy time, and minimizing the risk of misalignment, thus improving surgical outcomes and reducing surgical complexity.
Implementation Method 1
A radiolucent target indicator (150) mounted on the adjustable aiming device has a radiolucent body (151) including first and second spaced parallel planar portions (152, 154) each having a spaced radiopaque element (160, 162) therein
Data Source
AI summary
A targeting device for targeting a cross bore in a bone nail has an arm member coupled to an end portion of the bone nail and an aiming portion forming part of the arm member extending parallel to a longitudinal axis of the bone nail. An adjustable aiming device is mounted on the aiming portion, the adjustable device having a guide bore alignable with the cross bore in the nail. The adjustable device is moveable with respect to the aiming portion in a direction perpendicular to a plane containing both the nail longitudinal axis and central axis of the cross bore. A target indicator is mounted on the adjustable aiming device. The target indicator has a radiolucent body including a planar portion having spaced parallel radiopaque elements therein.