Transcript Folie 1 - uibk.ac.at

Measurement of invivo anterior cruciate ligament strain during
dynamic jump landing
2011
.A. Taylor a, M.E.Terry c, G.M.Utturkar a, C.E.Spritzer b, R.M.Queen c, L.A.Irribarra
Abstract
Despite recent attention in the literature, anterior cruciate ligament (ACL)
injury mechanisms are controversial and incidence rates remain high. One
explanation is limited data on in vivo ACL strain during high-risk, dynamic
movements. The objective of this study was to quantify ACL strain during
jump landing. Marker-based motion analysis techniques were integrated
with fluoroscopic and magnetic resonance (MR) imaging techniques to
measure dynamic ACL strain non-invasively.
Abstract
First, eight subjects’ knees were imaged using MR. From these images,
the cortical bone and ACL attachment sites of the tibia and femur were outlined to
create 3D models. Subjects underwent motion analysis while jump landing using
reflective markers placed directly on the skin around the knee. Next, biplanar
fluoroscopic images were taken with the markers in place so that the relative
positions of each marker to the underlying bone could be quantified. Numerical
optimization allowed jumping kinematics to be superimposed on the knee model,
thus reproducing the dynamic in vivo joint motion. ACL length, knee flexion, and
ground reaction force were measured. During jump landing, average ACL strain
peaked 55 +/- 14 ms (mean and 95% confidence interval) prior to ground impact,
when knee flexion angles were lowest.
1. Introduction
Over 200,000 anterior cruciate ligament (ACL) injuries occur in the United States
every year, half of which are experienced by young athletes between 15 and 25
years of age (Miyasaka et al., 1991; AAOS, 2008).
The consequences of ACL deficiency incurred from ACL injury include pain,
instability, damage to the menisci, and early-onset osteoarthritis (OA) (Fairclough et
al., 1990; Roos et al., 1995; Fithian et al., 2002; Hill et al., 2005).
For these reasons, between 100,000 and 175,000 patients elect to undergo ACL
reconstruction annually (Koh, 2005; Griffin et al., 2006). Although surgical
intervention provides good short-term outcomes, long-term results are less
consistent (Asano et al., 2002; Wolf and Lemak, 2002; Lohmander et al., 2004; von
Porat et al., 2004; Grossman et al., 2005).
1. Introduction
Some studies have suggested that current reconstructive techniques do not decrease
the probability of developing OA when compared to non-operative treatment (Fink et
al., 2001; Lohmander et al., 2004; von Porat et al., 2004; Lohmander et al., 2007;
Butler et al., 2009).
Kreuzbandimplantate helfen nicht bei der Verringerung der Wahrscheinlichkeit von
Osteoarthritis im Vergleich zu nicht operierten Kreuzbandbehandlungen
Because ACL injury affects such a young population (Roos et al., 1995; Beynnon et
al., 2005) and surgery has mixed results in preventing early-onset OA (Fithian et al.,
2002; Lohmander et al., 2007), there has been great interest in developing ACL injury
prevention programs (Hewett et al., 1999; Heidt et al., 2000; Myklebust et al., 2003;
Gilchrist et al., 2008).
Introduction
However, the levels of success achieved by current prevention programs have
shown varied efficacy (Hewett et al., 1999; Soderman et al., 2000; Myklebust
et al., 2003; Mandelbaum et al., 2005; Pfeiffer et al., 2006; Barber- Westin et
al., 2009) and despite their implementation, high rates of non-contact ACL
injuries persist (Agel et al., 2005).
Trainingsprogramme sind nicht unbedingt wirksam
-die hohe Anzahl an „Nicht-Kontakt“ ACL Verletzungen bleibt
These findings suggest that there is an incomplete understanding of the
underlying injury mechanisms. Specifically, there are limited in vivo data on
ACL strain, a critical parameter for predicting ACL failure.
Numerous studies have investigated ACL injury mechanisms using
videographic and motion analyses (Chappell et al., 2002; Chappell et al.,
2007; Krosshaug et al., 2007a, 2007b; Boden et al., 2009; Hewett et al.,
2009; Nagano et al., 2009). These studies provide important kinematic data,
but do not directly measure ACL strain.
Many previous studies have examined ACL loading in cadavers (Draganich
and Vahey, 1990; Markolf et al., 1990; Woo et al., 1991; Li et al., 1999;
Kanamori et al., 2000; DeMorat et al., 2004).
Although these data give valuable information on ACL function, their
application to in vivo environments are restricted by an inability to recreate
complex multi-planar loading conditions experienced during dynamic jumping
and cutting activities.
Using implantable strain gauges, some in vivo measurements of ACL strain have
also been reported (Beynnon and Fleming, 1998; Fleming et al., 1999; Cerulli et al.,
2003; Fleming and Beynnon, 2004). Beynnon and Fleming et al. (Beynnon et al.,
1997; Fleming et al., 1998; Fleming et al., 1999) ran a series of in vivo strain studies
to understand how an ACL graft would be loaded during common post-surgical
rehabilitation exercises and daily tasks.
These data were the basis for many pertinent clinical rehabilitation guidelines.
However, there are limited data on ACL strains during sport-specific dynamic
movements. Dynamic ACL strain data are needed to accurately predict what motions
predispose the ACL to injury.
The objective of this study was to measure in vivo ACL strain non-invasively during a
dynamic jumping activity using a novel method developed by our laboratory.
All subjects were imaged with a 3Tmagnet (Trio Tim, Siemens Medical
Solutions USA, Malvern, PA). Coronal, sagittal, and axial images were taken
with the patient supine and the knee in a relaxed position.
Coronal…Frontalebene (blau)
Axilaebene…Transversalebene (gelb)
Sagittalebene (rosa)
From these images, the outer margins of the cortical bone and ACL
attachment site were outlined using solid- modeling software.
These tracings were compiled to create subject-specific 3D models of each
tested knee. The location of the ACL was confirmed using orthogonal image
sets. This methodology accurately measures the location of the ACL footprint
center to within 0.3 mm, as described previously (Abebe et al., 2009).
Subjects next underwent a 3D motion analysis using an eight camera motion
capture system with a sampling rate of 240 Hz (Motion Analysis Corporation,
Santa Rosa, CA).
Also, centered within the capture volume were four embedded force plates
(AMTI, Boston, MA, USA) with a sampling rate of 2400 Hz
Additionally, non- symmetric clusters of markers were also placed
on the thigh and shank until a total of 28 markers were positioned
on the leg (Fig. 1). The primary goal of this complex marker set
was to over-constrain each anatomical segment (thigh, shank) so
that the effects of skin motion could be minimized via numerical
optimization, as demon- strated by previous investigators
(Andriacchi et al., 1998; Alexander and Andriacchi, 2001; Ngai et
al., 2009; Ngai and Wimmer, 2009).
Marker data were captured initially during a static standing trial
with the subject’s feet shoulder width apart for one second. Next,
subjects performed five successful trials of a jump landing task.
Starting from a platform 0.47 m off of the ground and half their
standing height away from the force plate’s edge, subjects were
asked to jump from the platform onto two force plates, then
immediately jump straight up with maximal effort and land back
on the same force plates again.
….subjects were imaged with the markers still in the same positions using biplanar
fluoroscopy (DeFrate et al., 2004; Caputo et al., 2009)
…the 3D joint model was imported into the environment and viewed from two
orthogonal directions corresponding to the location of the image sources of each
fluoroscope.
Next, the position and orientation of the model were manipulated manually in six
degrees-of-freedom (6DoF) until their projections, as viewed from the two orthogonal
directions, matched the outlines on the fluoroscopic images (Fig. 2).
3. Results
3.1. Validation study
Linear regression demonstrated that the two techniques had excellent
correlation,with a coefficient of determination of 0.92. Root mean square error
between the measurements was 0.5 mm. These results indicate that the
combined methodology accurately measures ACL deformation up to 45° of
flexion during a quasi-static lunge.
The study showed that the peak ACL strain occurred 55+/-14 ms prior to impact
when ACL length was 12 +/- 7% longer than an MRI based reference length. In the
future, this system will be used to examine kinematic parameters that elevate ACL
strain. After ground contact, the ACL length initially spiked to a local maximum, but
quickly decreased as the knee bent. The post impact local maximum in the ACL
length demonstrated local maximum in the ACL length demonstrated 5% less
relative strain than the absolute maximum prior to impact.
In the current study, we detected peak ACL strains 55 ms prior strains 55 ms prior
to impact, when flexion angles were their lowest. This is consistent with the finding
that non-contact ACL injuries most commonly occur with the knee in less than 30°
of flexion.
Moreover, videographic analyses of real time sports injuries have determined that a
significant number of non-contact injuries are associated with a perturbation prior to
contact with the ground (Olsen et al., 2004; Krosshaug et al., 2007a, 2007b; Boden
et al., 2009), a time when we observed higher ACL lengths.
…15–19% ultimate strain threshold range reported by Butler et al.
One limitation of the combined method is that it was unable to be validated
dynamically.
A second limitation is that the presented technique was only validated to measure
ACL deformations accurately up to 45° of flexion. However, because most injuries
occur at flexion angles less than30° (Chaudhari ….
Finally, strain was approximated by normalizing ACL length to the reference
length measured in a relaxed position during MR imaging, where the fibers of the
ACL appeared taut. It is difficult to know precisely the reference length of the ACL
in vivo since it cannot support axial compression.
These data will provide valuable information for developing prevention programs
aimed at reducing the incidence of ACL injury.
Valgus plus internal rotation moments increase anterior
cruciate ligament strain more than either alone.
http://europepmc.org/abstract/med/21266934
Shin CS, Chaudhari AM, Andriacchi TP
Department of Mechanical Engineering, Sogang University, Seoul, Republic of Korea.
[email protected]
Medicine and Science in Sports and Exercises 2011, 43(8):1484-1491
PURPOSE: To test the influence of combined knee valgus and internal tibial
rotation moment on anterior cruciate ligament (ACL) strain during single-leg
landing. We tested the following hypotheses: the combination of the valgus
and internal rotation moments observed during single-leg landing produces a
higher ACL strain than either moment applied individually, the combined
rotational moments at the physiological levels observed could theoretically
increase strain in the ACL high enough to rupture the ACL, and the location of
the peak contact force was at the posterior-lateral side for combined loading.
METHODS: The study was conducted by applying in vivo human loading data
to a validated simulation model of the three-dimensional dynamic knee joint to
predict ACL strains.
Valgus plus internal rotation moments increase anterior cruciate
ligament strain more than either alone.
METHODS:
The knee model was created using sagittal MR images of a cadaveric knee
MR images were segmented and imported into dynamic motion simulation
software (MSC.ADAMS) This knee model includes nonlinear elastic ligament
bundles (the ACL, the posterior cruciate ligament (PCL), the medial collateral
ligament (MCL), the lateral collateral ligament (LCL), posterior capsules, and
the patellar ligament with properties from published data.
The contact forces at the cartilage-to-cartilage articulation were defined.
Three musculotendinous groups (the quadriceps, the medial/lateral
hamstrings, and the medial/lateral gastrocnemius) were modeled as linear
tension springs with the same pretension and stiffness used in the experiment
to provide the appropriate tension to hold the initial knee flexion angle at 25before impact load and to simulate eccentric contraction in the quadriceps as
done in the physical experiment (42)
Valgus plus internal rotation moments increase anterior cruciate
ligament strain more than either alone.
RESULTS: The peak ACL strain increased nonlinearly when either applied
valgus moment or internal rotation moment was increased in the model. When
the two rotational moments were applied individually, neither caused ACL
strain >0.077. However, when applied in combination, the two rotational
moments had a much larger effect, and the predicted peak ACL strain
increased up to 0.105. During landing, the peak contact force occurred at the
posterior-lateral side of the tibial cartilage in the model when the combined
maximum valgus moment and tibial internal rotation moments were applied.
CONCLUSIONS: Combined knee valgus and internal rotation moments
increases ACL strain more than either alone. The combination of a valgus and
internal rotational moment at magnitudes that occurs in vivo during landing can
cause ACL strains that may be high enough to cause ACL rupture. This
predicted high ACL strain and the contact force location suggest that combined
valgus and internal tibial rotational moments during single-leg landing are
relevant to ACL injuries.
Valgus plus internal rotation moments increase anterior cruciate
ligament strain more than either alone.
Valgus plus internal rotation moments increase anterior cruciate
ligament strain more than either alone.
FIGURE 2—An illustration of the knee model with the simulated dynamic landing
apparatus showing five musculotendinous bundles (the quadriceps, the hamstrings,
and the gastrocnemius). The knee joint has unconstrained tibiofemoral movement.
Functional hip and ankle joints were modeled with spherical joints. Vertical dynamic
impact loading, valgus moment, and tibial internal rotation moment were applied for
simulation input. Peak ACL strain is the main simulation output. ACL strain was
calculated as engineering strain (ε = (L - L0) / L0). L0 is the slack length of the ligament.
L is the current length of the ligament, which is estimated as the distance between the
two insertion points (36). Before external loading is applied, the muscles of the knee
joint are pretensioned to hold 25- of flexion. The impact force was applied at the
top of the femoral axis of the thigh. In addition, different combinations of valgus moment
and tibial internal rotational moment were applied at the knee joint.
Valgus plus internal rotation moments increase anterior cruciate
ligament strain more than either alone.
Effect of increased quadriceps tensile stiffness on peak anterior
cruciate ligament strain during a simulated pivot landing
David B. Lipps1,†,*, Youkeun K. Oh2, James A. Ashton-Miller1,2,3 and Edward M. Wojtys3,4
http://onlinelibrary.wiley.com/doi/10.1002/jor.22531/full
ACL injury prevention programs often involve strengthening the knee muscles. We
posit that an unrecognized benefit of such training is the associated increase in the
tensile stiffness of the hypertrophied muscle. We tested the hypothesis that an
increased quadriceps tensile stiffness would reduce peak anteromedial bundle
(AM-)ACL relative strain in female knees. Twelve female cadaver knees were
subjected to compound impulsive two-times body weight loads in compression,
flexion, and internal tibial torque beginning at 15° flexion. Knees were equipped
with modifiable custom springs to represent the nonlinear rapid stretch behavior of
a normal and increased stiffness female quadriceps (i.e., 33% greater stiffness).
Peak AM-ACL relative strain was measured using an in situ transducer while
muscle forces and tibiofemoral kinematics and kinetics were recorded.
Effect of increased quadriceps tensile stiffness on peak anterior cruciate ligament
strain during a simulated pivot landing
David B. Lipps1,†,*, Youkeun K. Oh2, James A. Ashton-Miller1,2,3 and Edward M. Wojtys3,4
http://onlinelibrary.wiley.com/doi/10.1002/jor.22531/full
A 3D ADAMS™ dynamic biomechanical knee model was used in silico to interpret
the experimental results which were analyzed using a repeated-measures
Wilcoxon test. Female knees exhibited a 16% reduction in peak AM-ACL relative
strain and 21% reduction in change in flexion when quadriceps tensile stiffness
was increased by 33% (mean (SD) difference: 0.97% (0.65%), p = 0.003). We
conclude that increased quadriceps tensile stiffness reduces peak ACL strain
during a controlled study simulating a pivot landing.
Published by Wiley Periodicals, Inc. J Orthop Res 32:423–430, 2014.
© 2013 Orthopaedic Research Society.
Figure 1. Diagram of the modified
Withrow-Oh testing apparatus.
Inset: Force-displacement relationship
for a nonlinear quadriceps spring
representing the normal and increased
stiffness female quadriceps values.
Abbreviations:
W=drop weight;
T=torsional device;
L=6-axis load cell;
Q=quadriceps tendon;
H=hamstrings tendon;
G=gastrocnemius tendon.
Figure modified from Lipps et al.14
and Oh et al.26,28
Anterior cruciate ligament injuries in soccer: Loading
mechanisms, risk factors, and prevention programs 2014
•Boyi Daia, Dewei Maob, William E. Garrettc, Bing Yud, ,
Abstract
Anterior cruciate ligament (ACL) injuries are common in soccer. Understanding ACL
loading mechanisms and risk factors for ACL injury is critical for designing effective
prevention programs. The purpose of this review is to summarize the relevant
literature on ACL loading mechanisms, ACL injury risk factors, and current ACL injury
prevention programs for soccer players. Literature has shown that tibial anterior
translation due to shear force at the proximal end of tibia is the primary ACL loading
mechanism. No evidence has been found showing that knee valgus moment is the
primary ACL loading mechanism. ACL loading mechanisms are largely ignored in
previous studies on risk factors for ACL injury.
Anterior cruciate ligament injuries in soccer: Loading mechanisms, risk factors, and
prevention programs 2014
•Boyi Daia, Dewei Maob, William E. Garrettc, Bing Yud, ,
Abstract
Identified risk factors have little connections to ACL loading mechanisms. The results
of studies on ACL injury prevention programs for soccer players are inconsistent.
Current ACL injury prevention programs for soccer players are clinically ineffective
due to low compliance. Future studies are urgently needed to identify risk factors for
ACL injury in soccer that is connected to ACL loading mechanisms, and have causeand-effect relationships with injury rate, and develop new prevention programs to
improve compliance.
Anterior cruciate ligament injuries in soccer: Loading mechanisms, risk factors, and
prevention programs 2014
•Boyi Daia, Dewei Maob, William E. Garrettc, Bing Yud, ,
The problem of ACL injury has been well described, however, the injury mechanisms
and risk factors for ACL injury are still not well understood and identified.
Consequently current ACL injury prevention programs have limitations that prevent
them from being effective. Therefore, the purpose of this review is to summarize the
relevant literature on ACL loading mechanisms, ACL injury risk factors, and current
ACL injury prevention programs for soccer players.
Future studies are urgently needed to identify risk factors for ACL injury in soccer
that is connected to ACL loading mechanisms and have cause-and-effect
relationships with injury rate, and develop new prevention programs to improve
compliance.
Perspective article
Hip extension, knee flexion paradox: A new mechanism for noncontact ACL injury
Javad Hashemi a,b,n, Ryan Breighner a, Naveen Chandrashekar c, Daniel M. Hardy b,g, AjitM. Chaudhari d,
Sandra J. Shultz e, James R. Slauterbeck f, Bruce D. Beynnon
2010
Abstract
…To date, numerous non-contact ACL injury mechanisms have been proposed, but none provides a detailed picture of
sequence of events leading to injury and the exact cause of this injury remains elusive. In this perspective article, we propose a
new conception of non-contact ACL injury mechanism that comprehensively integrates risk factors inside and outside the knee
joint. The proposed mechanism is robust in the sense that it is biomechanically justifiable and addresses a number of
confounding issues related to ACL injury
In diesem Perspektive Artikel wird ein neues Konzept des Nichtkontakts ACL
Verletzungsmechanismus vorgestellt, der umfassend Risikofaktoren innerhalb und
außerhalb des Kniegelenks integriert. Der vorgeschlagene Mechanismus ist in jenem
Sinne robust, dass er biomechanisch zu rechtfertigen ist. Zusätzlich behandelt er
einige verwirrende Fragen bezogen auf ACL Verletzungen.
In der Literatur bisher angeführte Verletzungsvorgänge ACL
i)
anterior shear force mechanisms - major contributor to the anterior shear force is the
contraction of quadriceps muscles resulting in significant anterior tibial translation at low
knee flexion angles
ii)
axial compressive load mechanism
iii)
hyperextension mechanism
iv)
valgus collapse mechanism — owing either to pure abduction of the distal tibia relative to the
femur or to tibiofemoral internal/external rotations
v)
internal rotation of the tibia
vi)
combined valgus and anterior shear
vii) combined valgus and internal tibial torque
viii) valgus and external tibial torque
ix)
valgus, anterior tibial shear, and axial torque about the long axis of the tibia
The mechanical and/or structural properties of the ACL are not considered important
in these mechanisms partly because it is presumed, perhaps precipitately, that little
can be done to alter ACL size and strength.
In almost all of the ACL injury mechanism literature (with the exception of Ireland,
1999), sagittal plane hip kinematics are ignored as a direct contributor to ACL
loading.
It is also frequently assumed that excessive muscle-generated forces or torques cause ACL injury, but never
the opposite. A lack of adequately protective co-contraction of both knee and hip muscles is seldom
considered as a cause of ACL injury, despite being more plausible.
Es wird auch häufig angenommen, dass hohe, durch Muskeln erzeugte, Kräfte oder
Drehmomente ACL Verletzungen verursachen, jedoch nie das Gegenteil. Ein Mangel
an ausreichendem Schutz durch Co-Kontraktion sowohl der Knie- als auch
Hüftmuskulatur wird selten als Ursache der ACL-Verletzung angesehen, obwohl dies
mehr plausibel wäre.
In this perspective article, we propose a new non-contact mechanism of injury that is
inherently different from extant mechanisms and provides a more complete picture of
the events leading to injury.
We propose that ACL injury occurs because of the concurrence of specific
neuromuscular events, external loads due to ground contact/impact, and certain
subject-specific anatomical disadvantages.
The theorized mechanism is that non-contact ACL injury occurs when the following
factors converge:
(1) delayed or slow co-activation of quadriceps and hamstrings muscles,
(2) a dynamic ground reaction force applied while the knee is near full extension
(3) a shallow medial tibial plateau and a steep posterior tibial slope
(4) a stiff landing due to incompatible hip and knee flexion velocities.
2.1. Delayed or slow co-activation of quadriceps and hamstring muscles
It is well known that co-contraction of the quadriceps and hamstring muscles
provides active protection for the knee and its passive restraints….
We suggest that a loss of active tibiofemoral stability, resulting in increased reliance
on passive structures, is a necessary (but not sufficient) condition for ACL injury.
We suggest that all participants, male or female, are susceptible to this delay.
Wir weisen darauf hin, dass alle Teilnehmer, männlich oder weiblich, anfällig für
diese Verzögerung sind.
2.2. Application of an impulsive ground reaction force while the knee is near full extension
Sagitale Ebene
JCF…joint compressive force
QPF…quadriceps patellar tendon force
HF…hamstring force
GRF…ground reaction force (could exceed
4000N)
𝐽𝐶𝐹 = 𝐺𝑅𝐹 + 𝑄𝑃𝐹 + 𝐻𝐹
Roter Pfeil ist leicht verwirrend. Exaktere Erklärung ist
auf der nächsten Seite dargestellt.
Annahmen:
Keine Beugung im Kniegelenk
Ohne Reibung muss die JCF normal zur Kontaktfläche wirken
GRF wirkt senkrecht, d.h. es wirkt keine Reibungskraft am Boden
Keine Muskelkraft wirkt, da die Muskeln mit Verzögerung aktiviert werden.
Ebenfalls verwirrend, dass die Muskelkräfte eingezeichnet sind.
2.2. Application of an impulsive ground reaction force while the knee is near full extension
Posterior femur translation force PFTF
(Zerlegung der GRF in PFTF und JCF)
PFTF
Die Reibungskraft im Kniegelenk zwischen tibia
und femur wird in dieser Arbeit nicht
berücksichtigt.
Anterior tibial translation force bewirkt eine
Bewegung der Tibia Richtung anterio,
bzw. die Posterior femur translation force eine
Bewegung des Femur in Richtung posterior
ATTF
Je größer die „posterior tibial slope“ desto
größer die anterior tibial translation force
Vergleiche dazu Hangabwärtstreibende Kraft
beim Skifahren
GRF
Anterior tibial translation force (Zerlegung der GRF)
2.2. Application of an impulsive ground reaction force while the knee is near full extension
In the literature, there are numerous assertions that the ACL is the primary
restraint against anterior tibial translation at low flexion angles. If this is true,
during landing near full extension, with a delay in co-contraction of
quadriceps and hamstring muscles, there is see- mingly no protective
mechanism to stop anterior tibial translation other than the ACL. However,
this begs the question, ‘‘If delayed co- activation of quadriceps and hamstring
muscles (for instance, due to fatigue) and a dynamic ground reaction force
are all that is required for injury, why are higher ACL injury rates not
observed?’’ The answer to the above question is that, according to literature,
there are many other mechanisms by which the ACL is protected from injury,
even if a deficiency in muscular protection occurs. Several of these protective
mechanisms will be discussed in later sections.
2.3.1. Posterior slope of the tibial plateau and its orientation relative to the femur
Bei gebeugtem Kniegelenk und gleicher
Überlegung ergibt sich:
The JCF, which is again perpendicular the
plateau, will be directed posteriorly. This
creates a posteriorly directed shear force
shown by the red arrow which will resist
anterior tibial translation.
D.h bei gebeugtem Knie erzeugt die
Bodenreaktionskraft GRF eine Kraft, welche
die Tibia nach hinten drückt.
2.3.1. Posterior slope of the tibial plateau and its orientation relative to the femur
2.3 Posterior slope of the tibial plateau and its orientation relative to the femur
Wilk et al. (1996) reported the generation of posteriorly directed shear
forces in flexion angles ranging from 12° to 104° in squatting and 18° to
104° in leg press. The large joint compressive forces reported (6139 N in
squats and 5762 N in leg press) must be directed posteriorly, as shown in
Fig. 2b, to create an overall posteriorly directed shear force in the
presence of anteriorly directed patellar tendon (quadriceps) forces. Lutz et
al. (1993) report similar findings, showing posteriorly directed shear forces
acting on the tibia in closed kinetic chain exercises at flexion angles of 30–
90° .
Scherkraft wirkt nach hinten bei diesen Beugewinkelbereichen.
Biomechanically, it could be argued that this posteriorly directed
component of the JCF plays an equal, if not greater ACL protective role
than the posteriorly directed component of the hamstrings force. Subjects
with mild tibial slope will benefit from this protection after very small
amounts of knee flexion. On the contrary, subjects with steep tibial slopes
will experience this added benefit only after moderate knee flexion.
2.3.2 Shallow medial tibial plateau depth
It has also recently been shown that the depth of the medial tibial concavity may
be a more critical risk factor in anterior.
Those subjects with shallow or flat medial tibial plateaus, such as the one shown
in Fig. 3a are at 3 times greater risk of injuring their ACLs for a 1 mm decrease in
the depth of concavity. Deeper plateaus, such as the one in Fig. 3b, provide more
stable seating of the medial femoral condyle on the tibial plateau.
2.4. A stiff landing due to incompatible hip and knee flexion velocities in the sagittal
plane
Fall1:
Wenn Unter- wie Oberschenkel
wie abgebildet (graue Pfeile) gedreht
werden, bewegt sich das Knie einfach
nach vorne und es kommt zu keiner
Translation zwischen Tibia und Femur
Fall 2:
Wenn Unter- und Oberschenkel wie
abgebildet (grau, rote Pfeile) gedreht
werden, kann dadurch eine rückwärts
gerichtete Translation des Femurs
gegenüber der Tibia erfolgen. Eine
Drehung des OS gegen den
Uhrzeigersinn kann durch eine zu
starke Muskelaktivierung der
Hüftstrecker erfolgen.
An in-vitro study of joint geometry and loading effects on
anterior cruciate ligament strain and knee kinematics
Breighner, Ryan 2012
http://repositories.tdl.org/tdl-ir/handle/2346/45231
To better understand the influence of tibial geometry on ACL strain and
injury, several studies of various knee-loading conditions were conducted
on cadaver knees. The knees were first imaged using MRI, and
measurements of their respective tibial geometries were taken.
Subsequently, the knees were installed in the simulator and muscle
forces were applied. In one of these studies, hip extensor-generated joint
compressive forces were also applied, followed by an impulsive ground
reaction force.
The results of these studies indicate that tibial slope and medial tibial
depth are significant predictors of ACL strain and that prelanding joint
compression is protective of the ACL under dynamic loading.
Additionally, it was shown that MCL strain increases more appreciably as
a result of valgus loading as compared to the ACL. This information,
coupled with the material properties of the two ligaments suggest that
isolated ACL injury cannot result from purely valgus loadings.
In vitro: unter künstlichen Bedingungen im Labor beobachtet oder durchgeführt
In vivo: im lebenden Objekt, am lebenden Organismus beobachtet oder durchgeführt
Clinically Relevant Injury Patterns After an Anterior Cruciate
Ligament Injury Provide Insight Into Injury Mechanisms
Jason W. Levine,* MD, Ata M. Kiapour,* MS, Carmen E. Quatman,
Nov. 2012
Background: The functional disability and high costs of treating anterior cruciate ligament
(ACL) injuries have generated a great deal of interest in understanding the mechanism of
noncontact ACL injuries. Secondary bone bruises have been reported in over 80% of
partial and complete ACL ruptures.
Purpose: The objectives of this study were (1) to quantify ACL strain under a range of
physiologically relevant loading conditions and (2) to evaluate soft tissue and bony injury
patterns associated with applied loading conditions thought to be responsible for many
noncontact ACL injuries.
Study Design: Controlled laboratory study.
Methods: Seventeen cadaveric legs (age, 45 6 7 years; 9 female and 8 male) were tested
utilizing a custom-designed drop stand to simulate landing. Specimens were randomly
assigned between 2 loading groups that evaluated ACL strain under either knee abduction
or internal tibial rotation moments. In each group, combinations of anterior tibial shear
force, and knee abduction and internal tibial rotation moments under axial impact loading
were applied sequentially until failure. Specimens were tested at 25° of flexion under
simulated 1200 N quadriceps and 800 N hamstring loads. A differential variable reluctance
transducer was used to calculate ACL strain across the anteromedial bundle. A general
linear model was used to compare peak ACL strain at failure. Correlations between
simulated knee injury patterns and loading conditions were evaluated by the chi² test for
independence.
Clinically Relevant Injury Patterns After an Anterior Cruciate Ligament Injury
Provide Insight Into Injury Mechanisms
Jason W. Levine,* MD, Ata M. Kiapour,* MS, Carmen E. Quatman,
Nov. 2012
Results: Anterior cruciate ligament failure was generated in 15 of 17 specimens
(88%). A clinically relevant distribution of failure patterns was observed including
medial collateral ligament tears and damage to the menisci, cartilage (Knorpel), and
subchondral bone (unterhalb des Knorpels). Only abduction significantly contributed to
calculated peak ACL strain at failure (P = .002).
While ACL disruption patterns were independent of the loading mechanism, tibial
plateau injury patterns (locations) were significantly (P = .002) dependent on the
applied loading conditions.
Conclusion: The current findings demonstrate the relationship between the
location of the tibial plateau injury and ACL injury mechanisms. The resultant
injury locations were similar to the clinically observed bone bruises across the
tibial plateau during a noncontact ACL injury. These findings indicate that
abduction combined with other modes of loading (multiplanar loading) may act to
produce ACL injuries.
Clinically Relevant Injury Patterns After an Anterior Cruciate Ligament Injury
Provide Insight Into Injury Mechanisms
Clinically Relevant Injury Patterns After an Anterior Cruciate Ligament Injury
Provide Insight Into Injury Mechanisms 2012
Testing Apparatus
A custom-designed testing apparatus was used to simulate landing from a jump
under a wide range of loading conditions (Figure 1).
Each specimen was rigidly fixed at the proximal femur to a 6-axis load cell, while
the tibia was orientated vertically with the foot positioned superiorly. All specimens
were tested at 25° of flexion.
The load cell was suspended such that the orientation of the femur could be rotated
about all 3 axes to align the tibia with the vertical loading axis. A mass pulley
system was used to apply 1200 N to the quadriceps tendons and 800 N to the
hamstring tendons, while maintaining the physiological line of action of each
tendon.
Analog data were collected at 4 kHz. Two arrays of 3 infrared light-emitting diode
markers were rigidly attached to the femur and tibia to capture knee kinematics
using an Optotrak 3020 (Northern Digital, Waterloo, Ontario, Canada)
3-dimensional motion capture system at 400 Hz.
The ACL strain was calculated based on measurements from a differential variable
reluctance transducer (DVRT) with a linear range of 3 mm that was arthroscopically
placed on the anteromedial (AM) bundle of the ACL.
Diagnostic Value of Knee Arthrometry in the Prediction of
Anterior Cruciate Ligament Strain During Landing
Ata M. Kiapour,*y PhD, Samuel C. Wordeman,z§ BS, Mark V. Paterno,k{ PT, PhD, SCS, ATC,
Carmen E. Quatman,z# MD, PhD, Jason W. Levine,y MD, Vijay K. Goel,y PhD,
Constantine K. Demetropoulos,** PhD, and Timothy E. Hewett,z§{#yyzz PhD
Investigation performed at the Engineering Center for Orthopaedic Research Excellence
(ECORE), The University of Toledo, Toledo, Ohio
Background: Previous studies have indicated that higher knee joint laxity may be indicative of
an increased risk of anterior cruciate ligament (ACL) injuries. Despite the frequent clinical use
of knee arthrometry in the evaluation of knee laxity, little data exist to correlate instrumented
laxity measures and ACL strain during dynamic high-risk activities.
Purpose/Hypotheses: The purpose of this study was to evaluate the relationships between ACL
strain and anterior knee laxity measurements using arthrometry during both a drawer test and
simulated bipedal landing (as an identified high-risk injurious task).
Study Design: Controlled laboratory study.
Methods: Twenty cadaveric lower limbs were tested using a CompuKT knee arthrometer to
measure knee joint laxity. Each specimen was tested under 4 continuous cycles of anteriorposterior shear force (6134 N) applied to the tibial tubercle. To quantify ACL strain, a differential
variable reluctance transducer (DVRT) was arthroscopically placed on the ACL (anteromedial
bundle), and specimens were retested. Subsequently, bipedal landing from 30 cm
was simulated in a subset of 14 specimens (mean age, 45 6 6 years; 6 female and 8 male)
using a novel custom-designed
Diagnostic Value of Knee Arthrometry in the Prediction of
Anterior Cruciate Ligament Strain During Landing
Results:
During simulated drawer tests, 134 N of applied anterior shear load produced a
mean peak anterior tibial translation of 3.1 mm and a mean peak ACL strain of 4.9%
Anterior shear load was a significant determinant of anterior tibial translation
(P=.0005) and peak ACL strain (P = .04).
A significant correlation (r = 0.52, P=.0005) was observed between anterior tibial
translation and ACL strain.
Cadaveric simulations of landing produced a mean axial impact load of 4070 N.
Simulated landing significantly increased the mean peak anterior tibial translation to
10.4 mm and the mean peak ACL strain to 6.8% compared with the prelanding
condition.
Significant correlations were observed between peak ACL strain during simulated
landing and anterior tibial translation quantified by knee arthrometry.
Combined in Vivo/in Vitro Method to Study Anteriomedial
Bundle Strain in the Anterior Cruciate Ligament Using a
Dynamic Knee Simulator 2013
1 Introduction
About 80,000 to 250,000 ACL injuries occur in North America each year [1].
These injuries result in about 2109 dollars in treatment costs [2]. About 50% of
the injured are aged 15–25….. Einleitung lesen, da sie einen sehr guten
Gesamtüberblick bietet.
2 Methode
Motion capture of a subject landing from a jump was performed. The resulting
kinematics and GRF data were input into a biomechanical
model to calculate time history of muscle forces. These muscle
forces and hip/ankle joint motion profiles were then applied on an
instrumented cadaver knee using the dynamic knee simulator. The
resulting ACL strain was then measured in real time
The dynamic knee simulator system. The
cadaver knee (K) is connected to the
turnbuckles that are connected to
surrogate hip (HI) and ankle (A) joints. The
hip joint moves in the vertical direction
(dark double head arrow) and the ankle
moves in the horizontal direction (white
double head arrow). The ankle joint also is
unconstrained in the mediolateral direction
(whitedouble headed dotted arrow).
Three muscle force actuators (Q,H, and G)
are connected to the knee, and they apply
dynamic quadriceps, hamstring, and
gastrocnemius muscle forces (dark
single head arrows). The hip moment
actuator (HM) connected to the turnbuckle
below the hip applies flexor-extensor
moment.
The load cells connected to the actuator
rod ends are not seen in this view
Sehr professionelle Lösung zur Erfassung der ACL-Kräfte bei einem Kniekadaver
http://www.youtube.com/watch?v=athYrUMk2Ik&list=PLu0YtbFBcm4bmpV0gKp4
E-IQyKI-Mhjsx&index=1
The knee joint is a complex structure. There are six degrees of freedom (DoF) between the tibia and the femur controlled by many muscles, tendons, and ligaments. Normal knee
flexion involves translation of the tibia along the femur as well as rotation, making knee simulations computationally difficult. Analyzing the biomechanical effects of individual
components in the knee can provide relevant information for developing new surgical treatments or prosthetic devices. The CORE lab uses a six DoF robot to move cadaveric knees
through ranges of motion with forces up to 2,250 N and 1,000 N-m from 0 to 120 degrees of flexion. Measurement of the joint coordinate system (JCS) during passive knee flexion (i.e.
with zero forces) allows us to measure the motion of the tibia relative to the femur pre- and post-surgical treatments. Muscle actuators can simulate up to 1,000 N of static loading to
determine the biomechanical contribution of each muscle individually. Instrumentation of the knee with a Tekscan pressure sensor allows us to measure patellofemoral or tibiofemoral
contact forces in vivo. A microstrain differential variable reluctance transducer (DVRT) can measure ligament or tendon strain with +/- 1 µm accuracy. The Orthopaedics & Sports
Medicine arthroscopy room is available for performing surgical treatments on cadaveric specimens which allows us to measure the effectiveness of various types of procedures or
prosthetic devices. The ability to measure the biomechanical properties of the various components within the knee in vivo while undergoing clinically relevant forces and ranges of
motion can lead to new developments in several aspects of medicine. We are currently focusing on the role of the ACL in stabilization of the knee and exploring conditions under
which the ACL is at risk for rupture
Weitere ACL Kadaver Untersuchung beim Laufen
http://p3.smpp.northwestern.edu/Project/ACL.htm
Anatomievideo Knie
http://www.youtube.com/watch?v=_q-Jxj5sT0g