Download Overview of Injury Research

FRACTURE PROPERTIES OF CHICKEN
BONES WITH AND WITHOUT MARROW
101A1
Edwin Akrong – Background & Hypothesis
Ping-Chien (Sam) Wu – Methods & Protocol
Sagar Singh – Deliverables & Pitfalls
Reesa Child – Equipment & Budget
Deeksha Gulati – Budget Justifications
Department of Bioengineering
Background:
Bone structural properties are important in treating fractures. A
bone’s susceptibility to fracture is correlated to its modulus of
elasticity and its capacity to absorb energy. Similar to rods and
beams, bones deform when a load is applied. Bones absorb
energy that is released when fractured, which occurs when
sufficient loads are applied. Maximum force and stiffness for
chicken bone with marrow were experimentally determined to be
335.24±26.79N and 1203.0±94.1N/m, respectively.
Hypothesis(es) & Aim(s) or Objective(s):
Aims
• To use a 3-Point Bending Test to determine the failure
properties of chicken bones with marrow and without marrow.
Hypothesis
• Chicken bones without marrow will have weaker structural
properties than those with marrow and will demonstrate a 10%
reduction in maximum force, and 5% reduction in stiffness.
Department of Bioengineering
Edwin Akrong
Methods & Protocol:
• Set up Instron machine and calibrate. Use previously determined loading
and sampling rate.
• Remove meat from each chicken leg bone. Store each bone in a dampened
paper towel until time of use. 5 samples of chicken bone will be used.
• Cut off the ends of the bone with tendons attached with the bone saw to
expose the inner part of the bone. Remove bone marrow with the seeker.
• Using a dial caliper, make necessary geometric measurements of the bone
specimen.
• Mount the specimen in the bending jig. Note the orientation and
point of contact of the bone. Determine the position and length between
clamps, which will be the same for all bone specimens.
• Conduct the bending test and record resulting fracture pattern.
• Repeat the above steps with the four other bone specimens,
acquiring data for each test.
•Stiffness will be determined by fitting a linear regression to the data points in
between 5% and 75% of the maximum force.
•A two-tailed unpaired t-test with α=0.05 will be used to compare the stiffness
and maximum force of bone with marrow and bone without marrow.
Department of Bioengineering
Ping-Chien (Sam) Wu
Proposed Deliverables/Findings:
BONE
PROPERTIES
DIAMETER
(mm)
THICKNESS
(mm)
AREA (10^3m^2)
STIFFNESS
(N/cm)
MAX
FORCE (N)
Example Plot of Force vs. Displacement
Chicken 1
8.010
0.500
0.2016
1289.3
329.77
Chicken 2
5.900
0.440
0.1094
1166.6
343.65
300
Chicken 3
6.850
0.480
0.1474
1111.3
343.65
250
Chicken 4
7.920
0.500
0.1971
1317.2
365.85
Chicken 5
6.820
0.500
0.1461
1130.7
293.26
Mean
7.100
0.484
0.1603
1203.0
335.24
Standard
Deviation
0.878
0.026
0.0388
94.1
26.79
Fracture
Point
Maximum Force
400
Force (N)
350
200
150
100
50
0
0
0.2
0.4
0.6
0.8
Displacement (cm)
Variance
0.770
0.001
0.0015
8862.6
717.72
Figure 1: Table of Preliminary results of breaking marrow-filled bones along with a sample specimen graph of Force against Displacement.
•Table above demonstrates the preliminary results of specimen breaking with
bone marrow present.
•Relative numerical results indicate it is feasible to remove the bone marrow
and obtain measurable results.
•It is expected that maximum force and stiffness in specimens without marrow
would be about 10% smaller and 5% smaller, respectively, than the results
shown above. Specimen Force-Displacement graphs would be similar in
shape, but would show less variance in results.
Department of Bioengineering
Sagar Singh
Potential Pitfalls:
Possible Problems:
•Determining and applying a consistent means of removing the bone
marrow from each specimen.
•Hollow bones do not provide a completely homogeneous specimen for
breakage, since the internal geometry of the bones may differ. Hence,
there might be inconsistency within groups of results.
Proposed Solutions:
•Using a photoresistor and sending a beam of light through the hollow
portion of the bone and assigning an arbitrary threshold amplitude of
light (threshold voltage), which each bone specimen must adhere to,
ensuring consistency. The light will allow the determination of how much
of the bone marrow has been removed.
Department of Bioengineering
Sagar Singh
Equipment/Materials and Budget & Justification:
Equipment: The 3-point bending test will be conducted using
the Instron Model 4444 materials testing machine and bending
jig .
Supplies: 5 chicken legs to provide sufficient data; knives and
cutting board to remove the meat from the chicken bones;
calipers and rulers to make measurements of the specimen.
New Purchased Equipment: 1)Mopec Inc. Bone Cutting
Autopsy Saw, Supplier: Fisher Scientific (Fisher Catalogue),
Catalogue Number: NC9570925, Price: $75.90; 215.9mm blade,
open frame 304.8mm. This is needed to cut both ends off of the
bones so that the bone resembles a uniform rod. 2)Fisherbrand
Seeker with Bent End, Supplier: Fisher Scientific (Fisher
Catalogue), Catalogue Number: 08-995, Price: $12.32 (Ea);
nickel-plated steel probe with round handle, curved point tapered
and blunt at end, overall length: 152mm. This will be used to
remove the marrow inside the bone, so that the bone mimics a
hollow uniform rod.
Department of Bioengineering
Reesa Child & Deeksha Gulati