Drill Guide with Angle Verification for Orthopedic Screw Placement
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Solution Overview
Problem
Surgeons face difficulties in accurately inserting bone screws at the correct angle during orthopedic surgery, leading to issues such as the screw head impinging on polyethylene bearing surfaces, causing osteolysis, and reducing compressive forces due to excessive torque or incorrect pilot hole drilling, which can result in bone degradation and fracture propagation.
Innovation Solution
A drill guide instrument with a handle and a part-spherical convex surface that interfaces with bone plates, featuring visual and tactile references to indicate the maximum allowable pilot hole angle, ensuring proper screw positioning and preventing excessive angulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the surgeon continues to torque the bone screw to allow it to seat properly, then the bone screw seating is improved, but the compressive forces holding the plate to the bone are reduced due to bone degradation from cutting flutes
Solution Approach 1:
The drill guide is used beforehand to establish the correct drilling angle and depth for the pilot hole, preventing the need for excessive torque or multiple attempts. By preparing the correct path in advance, the bone structure is preserved and compressive forces are maintained while ensuring proper screw seating.
Solution Approach 2:
The drill guide acts as an intermediary tool between the surgeon and the bone, providing a physical reference system that ensures the pilot hole is drilled at the precise angle and depth required. This intermediary device eliminates the need for forceful torqueing by establishing the correct geometry from the start.
2Manufacturing precision
If the surgeon drills a new pilot hole at a different angle to correct improper screw seating, then the screw positioning is improved, but bone damage increases which may cause fracture propagation
Solution Approach 1:
The drill guide provides pre-established angular and depth references that guide the first drilling attempt to be correct, eliminating the need for corrective drilling. The visual and tactile references on the guide ensure the pilot hole is created with proper geometry before any bone damage can occur.
Solution Approach 2:
The drill guide incorporates visual references (markings, windows) and tactile references (protrusions, surfaces) that provide real-time feedback to the surgeon during the drilling process. This feedback mechanism ensures the correct angle and depth are achieved on the first attempt, preventing the need for additional drilling that would cause bone damage.
3Ease of operation
If the surgeon relies on visual estimation to insert the bone screw at the correct angle, then the surgical process is simplified, but the positioning accuracy deteriorates leading to screw head impingement on polyethylene bearing surfaces
Solution Approach 1:
The drill guide serves as a mechanical intermediary that translates the required precise angle into a simple alignment task for the surgeon. Instead of relying on difficult visual estimation, the surgeon simply aligns the guide's references with anatomical landmarks or implant features, and the guide's geometry ensures the correct screw angle is achieved.
Solution Approach 2:
The drill guide transforms the abstract parameter of screw angle (which is difficult to estimate visually) into concrete physical parameters such as the position of visual references relative to each other, the depth of tactile protrusions, or the orientation of guide surfaces. These physical parameters are much easier to control and verify than angular estimation alone.
Data Source
AI summary
A method and instrument is used for inserting a bone screw through a hole in a bone plate into bone at a maximum angulation of a bone screw central longitudinal axis with respect to a central axis of the hole. The maximum angulation places the head of the bone screw at or below an outwardly facing surface of the bone plate. The instrument has a distal end including a gauge element spaced proximally from an end surface of the distal end when in contact with a counterbore surrounding the plate hole a distance less than a depth of the counterbore. The instrument is tilted with respect to a central axis of the bone plate hole to an angle wherein the gauge element remains at or below the outwardly facing surface of the bone plate adjacent the counterbore. A hole is drilled through a guide bore in the instrument.