Purpose
This study investigates the influence of various femoral anterior cruciate ligament
graft fixation methods on the amount of tension degradation and the initial fixation
strength after cyclic flexion-extension loading in a porcine knee model.
Methods
One hundred twenty porcine digital extensor tendons, used as 4-stranded free tendon
grafts, were fixated within porcine femoral bone tunnels by use of extracortical button,
cross-pin, or interference screw fixation. One hundred twenty porcine patellar tendon–bone
grafts were fixated by use of cross-pin, interference screw, or press-fit fixation.
Each femur-graft complex was submitted to cyclic flexion-extension loading for 1,000
cycles throughout different loading ranges, and the total loss of tension was determined.
After cyclic testing, the grafts were loaded to failure, and the data were compared
with a pullout series without cyclic loading.
Results
Tension degradation after 1,000 cycles of flexion-extension loading averaged 62.6%
± 10.0% in free tendon grafts and 48.9% ± 13.35% in patellar tendon–bone grafts. There
was no influence of the loading range on the total amount of tension degradation.
The total amount of tension degradation was the highest with interference screw fixation
of free tendon and patellar tendon–bone grafts. Despite excessive loss of tension,
the initial fixation strength of the femur-graft complex was not reduced.
Conclusions
The method of femoral graft fixation significantly influenced tension degradation
during dynamic flexion-extension loading. Femoral graft fixation methods that secure
the graft close to the tunnel entrance and that displace the graft substance from
the center of the bone tunnel show the largest amount of tension degradation during
cyclic flexion-extension loading. The graft substance, not the fixation site, was
the weakest link of the graft complex within this investigation.
Clinical Relevance
We believe that the graft fixation method should be considered when aiming to improve
the precision of femoral graft placement in anterior cruciate ligament reconstruction.
Key Words
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Article info
Publication history
Published online: August 24, 2009
Accepted:
March 4,
2009
Received:
December 16,
2008
Footnotes
The authors report no conflict of interest.
Identification
Copyright
© 2009 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.
