The Effect of Tensile Strength Loss on
Collagen Organization in
Anterior Cruciate Ligament Grafts
Post-Reconstruction Surgery
Team LEGS
ACL Injuries
http://www.youcanbefit.com/images/ACL%20tear.bmp
ACL Reconstruction
o In 2000, over 2 billion dollars were spent on
about 175, 000 ACL reconstructions
(Spindler and Wright, 2008)
o No consensus among surgeons on the ideal
surgical/graft choices, fixation methods, etc.
o 3 Common Graft Types
ACL Allograft
http://www.aclsolutions.com/images/Seif_what%20is%20ACL.jpg
Patellar Tendon Graft
http://www.aclsolutions.com/images/Seif_patellar%20tendon%20graft.jpg
Hamstring Graft
http://www.aclsolutions.com/images/Seif_hamstring%20graft.jpg
Previous Studies
o Graft degradation – tension loss in the
long-run after surgery (Arnold et al., 2005)
o Graft tension directly related to laxity of
the knee (Friedrich et al., 1998)
o Crimping patterns of other tendon and
ligaments as related to short term
mechanical stress (Franchi et al., 2009)
Uniqueness of Project
o This study will analyze:
 Three graft types
 Performance of grafts under long term
mechanical loading
 Relation of performance to collagen fiber
morphology using Optical Coherence
Tomography (OCT)
Passive Knee Motion
http://img.alibaba.com/photo/106928473/CONTINUOUS_PASSIVE_MOTION_equipment.jpg
Continuous passive
knee motion emulator
Research Questions
o How does the rate of tension loss differ
among commonly used grafts during and
after CPM?
o How do the differing morphologies of these
graft tissues relate to their variable
biomechanical performance?
Hypotheses
o Different grafts will have different rates of
tension loss during CPM
o The microstructural organization of
collagen is related to the rates of tension
loss among the grafts
Collagen Crimping
Methodology Overview
o Experimental Set-up
 Specimen Preparation
 Experimental Groups
o Pre-Test Imaging
 OCT
 PLM
o ACL Reconstruction
 Tension transducer
o CPM
o Post-Test Imaging
Experimental Set-Up
o 5 pairs of knees
o Experimental Groups
 Control
 Experimental
o Specimen Preparation
 Harvest grafts
 Storage
Pre-Test Imaging
o Optical Coherence
Tomography (OCT)
 “optical ultrasound”
 Instant, direct; no
sample preparation
o Polarized Light
Microscopy (PLM)
 Transmit visible light
through sample
 Tissue fixation
Pre-Test Imaging
o PLM
 Crimp angle
 Crimp arc-length
 Crimp base length
o OCT
 Crimp period
CPM
o 200N
o 1500 cycles
mts.com
Post-Test Imaging
o OCT
 Crimp period
o PLM
 Crimp angle
 Crimp arc-length
 Crimp base length
Acknowledgments
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Dr. Adam Hsieh
Hyunchul Kim
Dr. Yu Chen
Thomas Harrod
Rebecca Thomas
Courtenay Barrett
Timeline: Successes
 Received $1500 from HHMI Undergraduate Research
Fellowship
 Contacted Maryland State Anatomy Board for specimen
 Obtained lab & storage space
 Obtained Imaging Equipment
 Obtained testing equipment
 Contacted orthopedic surgeon
 Wrote thesis proposal
Timeline: Sophomore Year
 Contact more experts, particularly surgeons
 Continue to collect/review relevant literature/articles for
final thesis
 Apply to more grants (NSF, ACCIAC)
 Design team website
 Start training for lab techniques: histology, cutting tissue,
MTS testing
Timeline: Junior Year
 Data collection
 Present research/progress at the fall Colloquium
 Present poster at the spring Undergraduate Research Day
 Develop an outline for the final thesis and complete the first
3 chapters (Introduction, Literature Review, Methodology)
 Continue to review literature
 Apply to more grants
 Submit paper for journal publication if possible
 Update website as needed
Timeline: Senior Year
 Finish data collection and analysis
 Complete senior thesis
 Confirm at least 5 experts to sit on the panel of
reviewers/discussants
 Present and defend team thesis at the Team Thesis
Conference
 Final updates for website
Timeline: Senior Year
Finish data collection and analysis
Complete senior thesis
Confirm at least 5 experts to sit on the
panel of reviewers/discussants
Present and defend team thesis at the
Team Thesis Conference
Questions?
References
o Arnold, M. R., Lie, D. T. T., Verdonschot, N., de Graaf, R., Amis, A. A., &
van Kampen, A. (2005). The remains of anterior cruciate ligament graft
tension after cyclic knee motion. American Journal of Sports Medicine, 33(4),
536-542.
o Franchi, M., Quaranta, M., Macciocca, M., De Pasquale, V., Ottani, V., &
Ruggeri, A. (2009). Structure relates to elastic recoil and functional role in
quadriceps tendon and patellar ligament. Micron, 40(3), 370-377.
o Friederich, N. F., & O'Brien, W. R. (1998). Anterior cruciate ligament graft
tensioning versus knee stability. Knee Surgery, Sports Traumatology, Arthroscopy,
6(1), S38-S42.