TOWARD A SUBJECT-SPECIFIC SINGLE BUNDLE ACL RECONSTRUCTION BASED ON SURGEON’S GRAFT TYPE SELECTION

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23rd Congress of the European Society of Biomechanics, July 2 - 5, 2017, Seville, Spain
TOWARD A SUBJECT-SPECIFIC SINGLE BUNDLE ACL
RECONSTRUCTION BASED ON SURGEON’S GRAFT TYPE SELECTION
Hamid Naghibi Beidokhti (1), Dennis Janssen (1), Tony G. van Tienen (1), Sebastiaan van de
Groes(2), Ton van den Boogaard (3), Nico Verdonschot (1)
1.Orthopaedic Research Lab, Radboud University Nijmegen Medical Centre, The Netherlands;
2.Orthopaedic Department, Radboud University Medical Center, The Netherlands; 3.Department of Applied
Mechanics, University of Twente, The Netherlands.
Introduction
There are different options in ACL-reconstruction
surgery in terms of graft type, insertion sites and graft
insertion tension [1]. Although these choices are an
ongoing debated topic among orthopedic surgeons, FE
models, as a pre-planning tool, can provide more
insight to better understanding on implications of
different choices on successfulness of the surgery. The
aim of this study is to introduce a novel method to
provide the surgeon with the optimal patient-specific
ACL reconstruction surgical variables based on the
surgeon’s graft type preference and patient-specific
graft stiffness, as the graft stiffness can be estimated
before the graft insertion.
Materials and Method
Based on a series of experimental laxity tests on a
cadaveric knee joint a subject-specific FE model of the
knee was developed (Figure 1-a). The knee,
subsequently, was subjected to three different loading
regimes for FE model validation purposes (Figure 1-b).
Beside the intact knee model, the ACL ruptured knee
was modeled in which ACL was removed from the
model. Three different graft types were implemented
including hamstring (HMST), patellar tendon (PT) and
quadriceps tendon (QUAD). Based on the range
reported in the literature, for each graft type, three
different stiffness, low, middle and high stiffness were
assigned to each graft [2]. The ACL reconstruction
surgery was simulated for each graft. Subsequently, an
anterior load of 100N was applied to tibia below the
joint space, and the joint was flexed from full extension
to 90°. Based on the experimentally measured
kinematics of the intact knee joint, in each grafted case,
surgical variables were optimized as: femoral and tibial
graft insertion sites and graft insertion force.
Results:
As Figure 1-c and Figure 1-d illustrate, all hamstring
grafts were located more to posterolateral (PL), as well
as the stiffest quadriceps tendon and low and averaged
stiffness patellar tendon. The low and averaged
quadriceps tendon and the stiffest patellar tendon grafts
inclined to be positioned to anteromedial (AM)
regions. As revealed from Table 1, quadriceps tendon
grafts need to be tensioned more than two others. As
predicted, within each graft type, in general, the stiffer
grafts require less tension before graft fixation. The
optimized grafted joints could considerably improve
the anterior-posterior, valgus-varus and internal-
external laxities.
a)
b)
c)
d)
Figure 1: the developed FE model of the cadaveric knee
(a),inserted contact pressure sensor in the knee joint as a
part of FE model validation experiments (b), optimized graft
tibial (c) and femoral (d) insertion sites for different graft
types with different stiffness
Patellar
Tendon
Hamstring
(quadrupled)
Quadriceps
tendon
Stiffness
(N/mm)
620
670
730
570
776
980
330
465
600
Optimized
Graft Pre-
Tension(N)
29
39
31
63
41
45
86
85
65
Table 1: the optimized graft insertion tensions for three
types of graft with low, middle and high stiffness.
Conclusion
The method presented in this study can be a beneficial
pre-planning tool for ACL reconstruction surgery, to
calculate the most optimal patient-specific operative
parameters (insertion sites and graft tension), based on
the surgeon’s graft type preferences.
References
1. Cerulli et al, J Joint, 1: 18-24, 2013.
2. Frank et al, J Bone Jt Surg, 1984: 344-352, 1984.
Acknowledgements
This study was a part of BioMechTools, received funding
from the European Research Council under the European
Union's Seventh Framework Program (FP/2007-2013) / ERC
Grant Agreement n. 323091.