Engineered Components

Steering system Plate End cap Positioning rings Stabilizers String Placement

Suction and lubrication systems Drill Stand

Problem Definition

Drill a curved hole through the spine Used for medical procedures

i.e. spinal surgery, hip replacement, bone screws

Improved patient recovery time Less invasive anterior and posterior

approaches Increased mobility

Objectives Angle of approach equal to 45° Hole diameter of 5.5 – 7 millimeters

Definition of Scoliosis

Condition that involves complex lateral and rotational curvature of the spine Congenital – anomalies

present at birth Idiopathic – occurs during

lifetime Developed from other

symptoms

Current Scoliosis Treatments

Bracing is recommended when initial curve magnitude is between 20% and 40% Reduction of curvature between 25 and

35 degrees Negative side effects of discomfort and

psychological anguish Surgical procedure involving screws and

inserting metal rods to straighten the spine Time consuming with a six month recovery

time

Budget

Item Proposed ($) Spent ($) Difference ($)Rotary Drill Bit 20 20.02 -0.02

Flexible Shaft 30 58.97 -28.97Casing 100 22.24 77.76

Power System 50 98.97 -48.97Experiment Budget 1000 295.04 704.96

Total 1200 495.24 704.76

Technical Approach

Procedures Three phases performed concurrently Design phase – design components Build phase – assemble drill and

model spine Test phase – drill curved hole in spine

Milestones Progress Report, Student Expo

Presentation, Poster Presentation, Final Report, Delivery of Prototype

Gantt Chart

Prototype Components

Suction and Lubrication System

Current Drill Prototype

Plate steering system Three strings Angle of strings to shaft: 15° , 30° , 45° ,

60° Cutting Head

Carbide burr

Drill Stand

Concept drawing Designed to hold drill

during surgical procedure

To minimize number of hands needed to complete procedure

Placed on operating room tray

3-Phase Drilling

Phase 1 Insertion into vertebrae

Phase 2 Navigating the bend

Phase 3 Directed drilling

Material Testing

Drilled curved hole Point- and Push-the-Bit Compound curve

Model Spine 2:1 scale Represents layersof bone

Deflection Testing

Deflection Angle (°) Ave

Mass (kg) Weight (N) Trial 1 Trial 2 Trial 3 Angle (°)1 9.81 10 6 5 72 19.62 24 14 16 183 29.43 33.5 24 25 27.54 39.24 34 32 41 35.675 49.05 42.5 37 45 41.5

Horizontal Position (mm) Vertical Position (mm)

Mass (kg)x-

coordinatey-

coordinate Mass (kg)x-

coordinatey-

coordinate

0 0 0 0 0 0

1 7 -0.5 1 4 0

1.5 9 -1 1.5 11 -2

2.4 15 -4 2.4 20 -6.5

4.6 32 -10 3.5 33.5 -12

Deflection Results

0 5 10 15 20 25 30 35

-12

-10

-8

-6

-4

-2

0f(x) = − 0.336978810663021 x + 1.14593301435407R² = 0.960292217669766

Position of Cutting Head

Y-coordinate (mm)

X-c

oord

inate

(m

m)

0 5 10 15 20 25 30 35 40

-14

-12

-10

-8

-6

-4

-2

0f(x) = − 0.378953940066593 x + 1.09166897891232R² = 0.97468237974755

Position of Cutting Head (ver-tical set-up)

Y-coordinate (mm)

X-c

oord

inate

(m

m)

Progress Challenges

Unexpected Technical Challenges Drilling through plaster Completing surgical procedure in one

phase Keeping drill level Keeping tension in the strings Modeling drill tip using mathematical

equations

Deliverables

Written technical progress report Delivered [12/12/06]

Final drill prototype [5/7/07]

Test model with drilled holes [5/7/07]

List of further recommendations [5/7/07]

Drawings and prints for future assembly (CD format)

[5/7/07]

Written final report [5/7/07]