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The effect of graft position for a single bundle ACL reconstruction – FEA Study Ravi Sundaramurthy (B.Eng Biomedical) Dr. David Parker (FRACS) Dr. Qing Li (PhD, University of Sydney). Background- Graft Placement. Isometric Minimum strain of graft Preserves the life of the graft longest
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The effect of graft position for a single bundle ACL reconstruction – FEA Study Ravi Sundaramurthy (B.Eng Biomedical) Dr. David Parker (FRACS) Dr. Qing Li (PhD, University of Sydney)
Background- Graft Placement • Isometric • Minimum strain of graft • Preserves the life of the graft longest • Knee biomechanics not represented • Anatomical • Placed at footprint of original ACL • Approximates knee biomechanics better • Higher failure rates, stretching etc
Literature Review Several FEA models on knee • Donohue et al, 2002 etc • Very few studies on ACL reconstruction using FEA models • Pena E et al, 2005* *Pena E et al, Influence of the tunnel angle in ACL reconstructions on the biomechanics of the knee joint, Clinical Biomechanics, 2006, p508-516
Aims • Build an accurate FE model of the knee • Analyse effect of changing ACL graft position on • Biomechanics of the knee • Stress and strain on the graft and major ligaments
Methods • Describe what was actually done • Created a FE Model of knee using what program? • How many knees did you use?
Assumptions in the Model Meniscus and articular cartilage not modelled Muscles (Passive and active) not modelled Knee is modelled in Full Extension Ligament is modelled as linear non-viscoelastic Pre-tensioning of ligaments and grafts not considered
Result Anterior Tibial Loading • 190.7 N Posterior Femoral Load
Results External Tibial Rotation • 5 N.m External Torque
Internal Tibial Rotation • 5 N.m Internal Tibial Rotation
Internal Tibial Rotation No ACL Loading
Conclusion • Several trends were observed in ligament stress, strain and knee kinematics with varying graft position • An alternative method to clinical studies was used to study effect of graft position
Future Directions Effect of Different Flexion Angles Model ligaments as non-linear viscoelastic Study effect of muscles, meniscus etc Study Double Bundle technique Study effect of more graft materials