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Content uploaded by Hamid Naghibi
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A validated detailed subject-specific FE model of
a cadaveric human right knee was developed,
based on experimental laxity tests in a six
DOF testing apparatus (Figure 1). The ACL was
removed from the model to be representative
for total ACL rupture. Two different
reconstruction surgery procedures were
simulated: single quadrupled hamstring
bundle (averaged stiffness: 776N/mm), and
double bundle with gracilis (k=370N/mm) as
posterolateral (PL), and semitendinosus
tendon (k=534N/mm) as anteromedial (AM)
bundle.
Lachman and Drawer tests were experimentally
performed on the intact knee joint. For both
single bundle and double bundle
reconstructions, femoral and tibial graft
insertion locations (within the ACL footprints)
and graft fixation force (within the surgical
range) were optimized in FE models, based on
the experimentally measured laxities during
the Lachman and Drawer tests.
A full gait cycle was simulated with three
different FE models including: intact,
optimized single bundle and optimized double
bundle reconstructed knees. The kinematics
and contact pressure at tibial cartilage were
compared in intact knee, ACL-deficient,
optimal single bundle and optimal double
bundle reconstructed knees.
Both single and double bundle hamstring
reconstructions with optimized graft
positioning (Figure 2), recovered the intact
knee anterior-posterior stability during the
gait (Figure 3). Comparing with ACL-
ruptured knee, although single bundle
reconstruction could improve the rotational
stabilities, the double bundle grafted knee
revealed even closer rotational laxities to
intact knee (Figure 3). At contralateral toe-
off region in the gait cycle, single bundle
and double bundle reconstructed knees
showed a contact pressure increase at
medial tibial cartilage by, respectively, 18%
and 11%, with respect to the intact knee
model. On the lateral plateau, these
increases were observed to be 10% (single
bundle) and 3% (double bundle).
Objective
Anterior cruciate ligament (ACL) injuries are
among the most common knee injuries,
which makes the following ACL reconstruction
surgery one of the most performed
orthopedic surgeries. Arthroscopic single
bundle hamstring reconstruction is of interest
for many orthopaedic surgeons for many
years, where some others believe
implementing double bundle reconstruction
might better recover the missed ACL function.
The aim of this study, therefore, was to assess
the influence of these two different ACL
reconstruction techniques on the knee joint
biomechanical outcomes, based on a
validated detailed FE model of human knee
joint and cadaveric experiments.
THE INFLUENCE OF ACL RECONSTRUCTION SURGICAL TECHNIQUE ON THE
KNEE BIOMECHANICS: SINGLE VERSUS DOUBLE BUNDLE
RECONSTRUCTIONs
Hamid Naghibi Beidokhti1, Dennis Janssen1, Ton van den Boogaard2, Nico Verdonschot1,3
1Orthopaedic Research Lab, Radboud University Nijmegen Medical Centre, The Netherlands;
2Department of Applied Mechanics, University of Twente, The Netherlands,
3Department of Biomechanics, University of Twente, The Netherlands.
Hamid Naghibi, MSc
Hamid.NaghibiBeidokhti@radboudumc.nl
Orthopaedic Research Laboratory
Radboud university medical center
P.O. Box 9101, 6500 HB Nijmegen, The Netherlands
www.biomechanics.nl
This study is a part of BIOMECHTOOLS funded by
European Research Council under the Seventh
Framework Program (FP/2007-2013) / ERC Grant Agreement n.
323091
Conclusions
oIn comparison with the ACL ruptured knee
joint, the two implemented optimized ACL
reconstruction techniques (single bundle
and double bundle) could acceptably
recover the intact knee kinematics and
contact pressure at tibial cartilage.
oOptimized double bundle reconstruction,
however, revealed a better rotational
laxity recovery.
Figure 3: Anterior/posterior translational (top) and
Internal/external rotational (middle) kinematics
during a full gait cycle, and tibial cartilage
contact pressure at gait contralateral toe-off
region (bottom), for different cases.
Results
Methods
Figure 2: Optimized insertion sites for single and
double bundle reconstructions
Figure 1: The six-dof knee testing apparatus (top), and
the validated subject-specific FE model of the knee.