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 Studieso 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

Continuous passive knee motion emulator

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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 CPMo Post-Test Imaging

Experimental Set-Up

o 5 pairs of kneeso 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

mts.com

o 200No 1500 cycles

Post-Test Imaging

o OCT Crimp period

o PLM Crimp angle Crimp arc-length Crimp base

length

Acknowledgments

o Dr. Adam Hsieho Hyunchul Kimo Dr. Yu Cheno Thomas Harrodo Rebecca Thomaso 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 analysisComplete senior thesisConfirm at least 5 experts to sit on

the panel of reviewers/discussantsPresent 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.