1 Biomechanical Properties of the Anterolateral Ligament (ALL) of the Knee compared with those of the Iliotibial tract (ITT) Project Master 2 Research Biomechanics K.Elmajri † P.Neyret ‡ and S. Lustig ‡ Center Albert Trillat, Croix Rousse Hopspital and Laboratoire de Biomécanique et Mécanique des Chocs IFSTTAR- UCBL, Lyon, France. D. Mitton ‡ and S. Nicolle † (LBMC) Laboratoire de Biomécanique et Mécanique des Chocs IFSTTAR-UCBL, Lyon, France
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Biomechanical Properties of the Anterolateral Ligament (ALL) of the Knee compared with those of the Iliotibial tract (ITT)
Project Master 2 Research Biomechanics K.Elmajri †
P.Neyret ‡ and S. Lustig ‡ Center Albert Trillat, Croix Rousse Hopspital and Laboratoire de Biomécanique et Mécanique des Chocs IFSTTAR-UCBL, Lyon, France.D. Mitton ‡ and S. Nicolle † (LBMC) Laboratoire de Biomécanique et Mécanique des Chocs IFSTTAR-UCBL, Lyon, France
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Anterolateral Ligament (ALL) why ?
Recently discovered ligament extends from the lateral femoral condyle to the midpoint between fibular head and lateral margin of tibial plateau (Watt et al 2015) . No complete consensus about ALL anatomy.Material and structural properties lake (Zens et al 2014)Prime controller in anterolateral rotational stability of the knee (ALRI) suggested with no consensus (Parsons et al 02015) (Guenther et al 2015). Clinical use ALRI knee started (Steven Claes et al 2015)
Introduction
Current study
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Iliotibial tract (ITT) why ?
Known also as Maissiat's Band or IT Band ,it is a longitudinal fibrous reinforcement of the fascia lata. It originates at the anterolateral iliac crest and inserts at the lateral condyle of the tibia at Gerdy's tubercle. It assists in extension, abduction, and lateral rotation of the hip. It has wide range of clinical use as a graft in knee surgery.Its mechanical properties have been studied extensively (Dawidowicz et al 2015) The effect of emballeming methods on its Mechanical properties studied (Sichting et al 2015) .
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Formaldehyde free preservation solution used in the technique of embalmment at the Rockefeller anatomy laboratory, faculty of medicine Grange Blanche, Lyon, France.
(Arterial Safebalm®) Commercialised by OGF society. Contain 7,2 % m/m of bronopol diluted with water . Concentration for use between 0, 4 and 0, 8 % m/m of bronopol.Arrêté du 6 septembre 2013 NOR: AFSP1322819A , by the ministr of sociales and heath affaires ,Version consolidée au 11 avril 2014
(Arterial Safebalm®) why?
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Aim of studyTo inspect the mechanical properties of ALL and ITT .
Bone-ligament-bone ALL Specimens Free ITT Specimens
Harvested from cadavers embalmed with (Safebalm®)
By comparing the results with previous studies
Testing
By Stress analysis experimentally
3 Fields → Plateforme for 1 Methodolgy
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Materials4 ALL 7 ITT
2 Cadavers
Preservation of cadavers (Safe balm®)
Weight (kg)
Height (cm)
Sexe Age (yrs)
75.5 190 F 80
65.5 168 M 62
Dissection instruments
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Experiment designe Stress analysis The upper bit fixed on the INSTRON Force sensor CDP-03 Expected efforts were around 200 N
Specimens Mounting
Laser line to assure Specimen Orientation
Two cameras Photron FASTCAM SA3Angle between cameras of 30° Frequency set to 50 Hz.For ITT sample speckle pattern
Cameras data processed under VIC3D 2010, Correlated Solutions ®
Specimen harvesting stored at +4°C
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The same dissections technique documented by photos .To identify different anatomical structures at anterolateral knee region, many preparatory dissection sessions have been carried out and analyzed in the light of literatures results concerning the anatomy of (ALL) and a basic reference (LaPrade, Robert F, Posterolateral knee injuries: anatomy, evaluation, and treatment )
The iliotibial incised 10 cm proximal to LFC
Skin and subcutaneous tissue dissected, flap is created and reflected anteriorly
MethodologyDissection
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Superficial layer of ITT opened then freed from underlying adhesion from proximal to distal up to Anterior Tibial Tuberosity without disturbing deep layer connection with Biceps components.
Kaplan fibres which blend the ITT to lateral femoral condyle cut-off.
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Identify the Stretched Structures )Mitchell I. Kennedy et al 2015.(
3cm wide ITT specimen dissected up to the Gerdy tubercle with care not to injure the adjacent fibres of ALL
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Tenotomy of the biceps femoris 10 cm proximal to the fibular head followed. Lateral access to the anterolateral region of the knee continue without violation of the adjacent extra-articular soft tissues
To inspect the layers of the stretched structures at the distal end of FCL, a Window is made by longitudinal incision over the distal end of the (gain) of FCL
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Components of biceps tendon and bursa identified without separation
Knee opened posterior to the patella
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Synovial membrane, capsule and capsule-osseous layer identified and isolated in-out.
The dissection of ALL performed first from antero-proximal to postero-distal in a plan between capsule and capsulo-osseous layer at the antero-proximal area
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Soft dissection superficial to the FCL (gain), conserve the adhesion of the stretched structures to lateral meniscus. Using the first plan outlet and always superficial to (gain) of FCL, the soft dissection directed toward the patella then proximally then posteriorly then distally toward the middistance between lateral tibial plateau and fibular head
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Leaving the area of adhesion between the thin membranous structure (ALL) and capsule-osseous layer at lateral meniscus
Soft Dissection isolate a thin Membranous Structure (ALL) superficial to Fibular Collateral Ligament .
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Two types of tests 1-Relaxation Test to probe Viscoelastic Structures Properties (Liu, K., G et al 2013)2-Elongation Test at Constant Speed Until Rupture to identifies A-Non-Linear Behaviour And B-Failure
Uniaxial loadStrain100% of Initial LengthVelocity of ~35 mm/s-1
Global Strain (Grip-to Grip Displacement) by INSTRON Transducer Local Strain by Image Correlation Tensile Load by Specific Transducer (TME)
Relaxation Modulus → relation between Stress and applied Constant Strain at (5%)Relaxation Modulus E (t) = A t-n (Fractional Model or Power Law)
n near 0 in both cases so ALL and ITT are Primarily Elastic ITT~10 times more resistant and slightly more viscous than ALL (5% strain)
Material Parameters Test in relaxation
A (Pa.sn )Average
nAverage
ITT 7.03E7 ± 6.19E7 0.06846 ± 0.01648
ALL 6.66E6 ± 7.77E6 0.04606 ± 0.02212
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Elongation tests at constant speed ALL & ITT highly non-linear behaviour (significant stiffening with the strain)
≈1% strain part
Example stress-strain curve at constant strain rate, ITT sample N° 157_2015_ITT_R1
at 5% strain, during traction test at constant speed → behaviour already frankly non-linear
preliminary relaxation test at 5% strain → relaxation modulus affected by deformation→ does not correspond to the linear viscoelastic module.
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In nonlinear deformation regime during relaxation tests, a better estimation of the parameter A can be obtained directly from the curve 'stress-strain' by analyzing the beginning of this curve.
apparent elastic modulus (~ 212 MPa ) does not match the apparent linear elastic modulus at small deformations (~ 0.5 MPa) (slope of the curve at 1% strain)
Compare Viscoelastic M measured at 5% (A ~ 81.7) and Apparent Elastic M at 5% (~ 212 MPa)
Order of magnitude between Elastic M and Viscoelastic M is respected Elastic M > Viscoelastic M probably due to preconditioning during the relaxation test (Sverdlik, 2002).
Elongation tests at constant speed stress-strain curve at constant strain rate ITT sample N° 157_2015_ITT_R1
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The first part of the stress-strain curve including Stiffness is taken into account in the modeling
ITT is 6 times more resistant to large deformations than ALL
Endpoint corresponding to the top of the stress-strain curve
Damage (concave inflection) and break (drop in stress) are not counted in
ITT damage and rupture occur at deformation 3-2 times smaller
Apparent Elastic modulus corresponding to the highest point of the slope in the nonlinear regime curve
Damage parameters corresponding to the start of softening
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No complete consensus.
VI - Discussion
VI-I- ALL anatomy
Distal FCL → many parts (Todd et al 2014)
FCL in → circle of tendinous fibers ligament (Tubbs et al 2006)
FCL in → tunnel (Vieira et al 2007)
Capsule + FCL + surrounding muscles parts →blend (Song et al 2014).
knee varus+ flexion + internal rotation → stretched structure (Kennedy et al 2015)
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1-Reflected Arm LHBF passed up to insert on the posterior edge of the Iliotibial Tract (ITT).2-Anterior Arm LHBF and 3-Anterior Arm SHBF connected and merged with the capsule anterior to FCL it then continued anteriorly on the fibulato partially blend with the anterior tibiofibular ligament, and inserted on the lateral tibialtuberosity approximately 1 cm posterior to Gerdy’s tubercle.
4-Bursa separated distal FCL from (Ant Ar LHBF)5-Lateral Aponeurotic Expantion SHBF covered FCL, had many fibrous attachments to the lateral and posterior aspects of FCL.
6-Facial Arm SHBF which form with the capsulo-osseous layer of ITT; the fascial confluence
LHBF: direct arm (3) Anterior arm(4)SHBF: Capsular arm (8) direct arm (10) anterior arm (11) lateral aponcurosas (12). BB Bicepital bursa LG Lat gastrocnemius
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YM At 20% Strain MPa
Mean Ultimate Stress MPa
Mean Ultimate Strain%
~38 (Safebalm®) embalmed 9.2 43.7
(Zens et al. 2015) fresh-frozen specimens) 1.2 32.78 36
VI-II- ALL mechanical properties
YM current study higher why ?Age related changes (hammer et al 2012)Preservation methods (hanno et al, 2012)
Compared with results (Zens et al., 2015 fresh-frozen specimens) Safe balm® embalmed ALL Mean YM at 20% strain is higher
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Current study ITT results compare results with (Hammer et al 2012) 8 ITT specimens from 12 ITT of 10 young fresh donors
stress ranges YM
0-4 N/mm² 84.7±30.2 (0-4N/mm²),
4-11 N/mm² 335.4±101.9 (4-11N/mm²)
4N/mm² toUS 369.1±191.5
Current study ( Arterial Safebalm®) 225.7 ± 99.4
Current study ITT results compared with (FR Noyes et al 1984). 90 specimens
Maximum Load Maximum stress MPa
Distal iliotibial tract ,18-mm width
769 ± 99 19. 1 ± 2.9
Fascia lata ,16-mm width 628 ± 35 78.7 ± 4.6
Current study (Arteria Safebalm®) embalmed
32.78
Current study ITT results compared with (Steinke etal 2012) 13 fresh specimens ,partial plastination
YMof the fresh
YM Ethanol-fixed
specimens
YM After rinsing with
tap water
YM Formaldehyde
fixation
YM Formaldehyde-fixed
specimens rinsed
Apparent Elastic MCurrent study
(Arterial Safebalm®)
averaged 397.3 N/mm2
Averaged 673.2 N/mm2
averaged 377.4 N/mm2
Averaged 490.3 N/mm2
averaged 452.6 N/mm2
averaged 225.7 ± 99.4
VI-III- ITT mechanical properties
YM old Higher than the young age Stress range ITT = (the tracts were removed in the region of most parallel fibers )
Widths Strain Differences Effort ? ITT = (The Narrowing Of The Fascia to form the condensed fibers of the distal iliotibial tract immediately above its tibial insertion sometimes called the iliotibial band)
Partial plastination Ages of the donors ? Rinsing tap water 50% reduced YM
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Study year specimens Exponent (n)
In (E(t) = At n )
Hybrid Modulus A
Lakes et al 1999 0.0716
Hingorani et al 2004 Rabbit Medial Collateral Ligament
0.0582
Provenzano et al 2011 Freshly Harvested, Rat Medial Collateral Ligaments
0.051 4.5 MPa.s0.051
Current study 2015 ALL )Safe balm (®embalmed
0.0661 ~1 MPa.s0.046 From The Beginning Of Stress-Strain Curve
~7 MPa.s0.046 at 5% Of Strain
Current study 2015 ITT )Safe balm (®embalmed
0.0461 1.66 MPa.s0.046 From The Beginning Of Stress-Strain Curve
6.66 MPa.s 0.046 at 5% of Strain
Comparing The Viscoelastic Behaviours In Biological Tissues
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Multiple controversies -Anatomy -Biomechanical parameters -Fixation methodsn In Small deformations : ALL and ITT are Primarily Elastic ITT~10 times more resistant and slightly more viscous than ALL (at 5% strain) In large deformations : ITT is 6 times more resistant to large deformations than ALL ITT damage and rupture occur at deformation 3-2 times smaller for levels Stress1.3 to 2 times higherALL -anatomical structures definition -major limitation Inherited Lateral knee -complexity -non-homogeneity literatures -controversy ITT -practically not same structure in all literatures.
Comparability or discrepancies ?Multidisciplinary Methodology -objectively comparable platforms.Factors effect comparing mechanical properties (müller et al 2004) Anatomical definitionFresh or preserved statePreservation methods Strain rate,Temperature Hydration Age-related changes
VI-Conclusion
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The lateral knee region is known by its complex functional anatomyThere is a risk of introducing imbalance to a sensitive ligamentous balance or alter the proprioceptive function or affect the stability of the lateral meniscus.
Injury to the integrity of biceps tendons components in this region or direct injury to the FCL could happen during surgery in this region .
As the injuries of FCL augment ALRI of the knee it is worth to study the effect of passing the graft deep to the LCL in lateral extra articular reconstructions , an injury could arise from fixing distal FCL to its tunnel which prevent FCL normal gliding within this tunnel.
VII-Clinical Relevance
Clinical investment of (ALL) in controlling Anterolateral rotatory instability (ALRI) needsmore consensuses and its actual clinical use need an evaluation for sufficient follow-up .Enhance our knowledge about the anterolateral knee would be invested in :1-Management of acute knee injury 2-The study of graft placement isometry in ACL reconstruction.3- Isometry of lateral extra-articular reconstructions to control (ALRI) with ITT whenindicated.
