Bone Drilling Cannula with Movable Pins for Curved Surfaces
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Solution Overview
Problem
Existing surgical drilling guides often slip on curved or angled bone surfaces due to insufficient tooth or serration contact, leading to inaccurate hole positioning during orthopedic procedures.
Innovation Solution
A surgical drilling guide cannula with axially moveable secondary pins around the bore, each with a sharpened distal end, that conform to the bone surface and are locked in place to ensure firm contact, regardless of bone curvature or drilling angle, using mechanisms like tapping, spring pressure, or hydraulic pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fixed teeth or serrations are used on the drill guide to prevent slippage, then grip on flat bone surfaces is improved, but the guide slips on curved or angled bone surfaces due to insufficient tooth contact
Solution Approach 1:
The patent transforms the static fixed teeth into dynamic movable pins that can independently adjust their positions. The pins are arranged circumferentially and can move radially to conform to the bone surface contour, maintaining contact across curved and angled surfaces while preserving grip stability through their sharp distal ends that bite into the bone.
Solution Approach 2:
The continuous serrated edge is segmented into discrete movable pins distributed circumferentially around the guide. This segmentation allows each pin to independently respond to local bone surface variations, enabling the guide to adapt to complex curved geometries while maintaining multiple contact points for reliable grip.
2Adaptability or versatility
If multiple movable pins are added to improve bone surface contact, then adaptability to curved surfaces is improved, but device complexity increases
Solution Approach 1:
The movable pins are nested within radial bores formed in the guide wall, with each pin able to slide axially within its bore. This nesting arrangement allows the pins to be compactly integrated into the guide structure while maintaining the ability to extend radially for bone contact, minimizing overall device complexity.
Solution Approach 2:
The pins are designed to be manually advanced by the surgeon during positioning, using simple tapping or pushing motions. This self-service approach eliminates the need for complex automated actuation mechanisms, springs, or hydraulics, reducing device complexity while still achieving bone surface conformity.
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 guide cannula maintains firm contact with the bone surface, providing stable positioning for accurate drilling across various bone profiles and angles, reducing the risk of slippage and ensuring precise hole placement.
Implementation Method 1
This forcing action is preferably performed by the action of tapping the pins at their proximal ends, such that each moves distally until contact is made with the bone surface
Implementation Method 2
The pins can also be forced into contact with the bone profile by other methods, such as by the application of spring pressure
Implementation Method 3
or by use of hydraulic pressure to force them towards the bone surface
Data Source
AI summary
A drilling guide cannula, having a serrated distal end in the form of axially moveable teeth which enables all or most of the teeth to maintain biting contact with the bone surface, essentially independently of the curvature of the bone surface and the drilling angle. The cannula outer wall incorporates a number of pins arranged circumferentially around the drilling bore. These pins slide axially relative to the cannula, preferably in bored holes or in channels formed within the wall of the cannula. Each of the secondary pins has a sharpened distal end, each constituting a moveable tooth. The cannula is applied to the bone to be drilled at the desired drilling position and angle, and the pins are forced axially towards the bone surface. The pins take up the contour of the bone surface and each pin bites into the bone surface to rigidly position the drilling guide cannula.