Spinal Drill Bit with Funnel-Shaped Pilot Hole for Pedicle Screw Alignment
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Solution Overview
Problem
The placement of pedicle screws in spinal surgery is challenging due to the small size of bone structures, lack of visibility, and criticality of surrounding anatomical structures, leading to potential misalignment and damage, which is dependent on the surgeon's skill and expertise.
Innovation Solution
A spinal surgical treatment system comprising a drill bit with a cylindrical distal end and a milling cutter that creates a funnel-shaped hole, guiding the pedicle screw for precise alignment, and a motorized device with a force sensor to control the movement of the drill and screw for precise placement, potentially assisted by a surgical robot.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional freehand drilling and screwing tools are used, then the surgeon can perform the procedure with available tools, but the placement precision of pedicle screws is insufficient and depends on surgeon skill
Solution Approach 1:
The patent applies preliminary action by creating a funnel-shaped pilot hole before inserting the pedicle screw. The drill bit with conical geometry pre-shapes the bone trajectory, guiding the screw into precise alignment. This preliminary hole formation ensures accurate screw placement without requiring complex real-time control systems during screw insertion.
Solution Approach 2:
The patent uses an intermediary guide structure - the funnel-shaped pilot hole created by the specialized drill bit. This intermediary feature mediates between the drilling operation and screw insertion, providing a physical guide that ensures precise screw alignment while simplifying the overall system compared to complex robotic or navigation systems.
2Manufacturing precision
If a cylindrical hole is drilled in the pedicle, then the drilling process is simple, but the pedicle screw cannot be properly centered and aligned
Solution Approach 1:
The patent applies asymmetry by using a drill bit with conical/funnel-shaped geometry instead of a simple cylindrical drill. The asymmetric conical shape creates a pilot hole that naturally guides and centers the pedicle screw during insertion, improving alignment precision while adding only moderate complexity to the drilling process.
Solution Approach 2:
The patent changes the geometric parameter of the pilot hole from cylindrical to funnel-shaped. This parameter change in hole geometry provides self-centering capability for the screw, improving alignment precision without requiring complex active control systems during screw insertion.
3Manufacturing precision
If the drill bit diameter is made equal to the screw diameter, then the screw fits tightly, but the screw cannot be properly guided into the hole
Solution Approach 1:
The patent segments the hole formation process into two distinct stages: first creating a funnel-shaped pilot hole with a conical drill bit, then inserting the pedicle screw. This segmentation allows the pilot hole to provide guidance while the screw threads engage the bone walls, maintaining both guidance capability and anchoring strength.
Solution Approach 2:
The patent performs preliminary action by creating the funnel-shaped pilot hole before screw insertion. This pre-formed guide structure enables proper screw centering and alignment, while the subsequent screw insertion maintains tight engagement with the bone walls for strong anchoring.
Data Source
AI summary
A surgical treatment system comprises a drill bit extending along a proximo-distal drill bit axis suitable for drilling a hole in the pedicle of a vertebra when the bit is rotated. The bit includes, successively along the drill bit axis, a distal end, a cylindrical drill centred on the drill bit axis for drilling the hole by cutting into and removing bone material from the pedicle to give a distal end portion of the hole a cylindrical shape, and a milling cutter for cutting bone material from the pedicle of the vertebra to give a proximal end portion of the hole a funnel shape gradually widening from the distal end portion of the hole. A pedicle screw extends along a proximo-distal screw axis and is designed to be screwed into the hole by being rotated after the drill bit has drilled the hole and has been removed from this hole.