Final report - Polytechnique Montréal

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Final report - Polytechnique Montréal
Rapport de stage
Programme Meditis
Artificial Ligaments Revisited
Michèle Voyer
Travail présenté à :
L’Hocine Yahia
3 septembre 2013
Table des matières
Stage Méditis ............................................................................................................................. 1
Introduction ............................................................................................................................ 3
Environnement de travail ....................................................................................................... 4
Aspects techniques du stage ................................................................................................. 5
Expérience acquise ............................................................................................................... 7
Expérience de stage .............................................................................................................. 7
Habiletés techniques ............................................................................................................. 7
Habiletés relationnelles.......................................................................................................... 8
Encadrement ......................................................................................................................... 8
Contribution........................................................................................................................... 8
Formation .............................................................................................................................. 9
Article de revue : Arificial Ligaments : a Critical Review ...................Erreur ! Signet non défini.
Article corrigé : Treatment of Sub-Acute Anterior Cruciate Ligament Rupture......................... 24
Recommandations ......................................................................................................................
Conclusion ............................................................................................................................... 17
Références .............................................................................................................................. 18
Stage Meditis
Introduction
Lors de mon stage obligatoire à l’École Polytechnique, j’ai eu la chance de travailler avec Pr.
Yahia dans le cadre d’une initiation à la recherche. Durant ma session d’hiver 2012, j’ai été
récipiendaire de la bourse MEDITIS offerte aux étudiants de premier cycle grâce à ma participation à
un échange étudiant durant la session d’automne 2012 à Stockholm en Suède. Elle m’a permis, entre
autres, d’obtenir ce stage au sein du Laboratoire d’Innovation et d’Analyse de la Bio-performance
(LIAB) cet été. Du 13 mai au 16 août 2013, j’ai effectué diverses tâches, et ce principalement dans le
domaine des ligaments artificiels et de la reconstruction du ligament croisé antérieur. Le document ciprésent témoigne en somme de mon expérience acquise cet été. Il présente d’abord
mon
environnement de travail dans son ensemble. Puis, il explique de façon plus exhaustive mes
fonctions et mes projets. Finalement, il aborde les habiletés que j’ai développées, mon impact au sein
du laboratoire ainsi que fait des liens avec les notions préalablement apprises à Polytechnique.
Environnement de travail
Le LIAB se situe dans le pavillon principal de l’École Polytechnique dans une grande salle où
plusieurs stagiaires, étudiants de maîtrise et doctorants provenant de diverses sphères de l’ingénierie
et des sciences biomédicale se côtoient. On y retrouve une vingtaine de bureaux, dont celui auquel
j’ai été assigné.
Le développement durable, défini comme «un développement qui répond aux besoins du
présent sans compromettre la capacité des générations futures à répondre aux leurs […], [qui]
s’appuie sur une vision à long terme qui prend en compte le caractère indissociable des dimensions
environnementale, sociale et économique des activités de développement. » (Gouvernement du
Québec, 2006), est depuis longtemps très présent à Polytechnique. Il se traduit par les nombreuses
initiatives que l’institution a prises au cours des dernières années.
Lors de la construction du nouveau pavillon, l’utilisation de matériaux recyclés a eu une grande
importance et 82% des déchets de construction ont été conservés à des fins de récupération. De
plus, il existe maintenant un système de récupération de pluie permettant d’utiliser 92% moins d’eau
qu’un bâtiment typique. Aussi, 66% de l’énergie servant au chauffage du pavillon Lassonde provient
des cheminées du pavillon principal où la chaleur est évacuée. L’installation d’une grande quantité
de fenêtres, de toits verts, de système de détection de mouvement pour l’éclairage et la climatisation
sont des gestes qui contribuent à sensibiliser autant les étudiants que le corps professoral, ainsi qu’à
promouvoir le développement durable (École Polytechnique de Montréal, 2012). À plus petite échelle,
il est possible de constater un certain effort environnemental également. Effectivement, on retrouve
au LIAB un contenant pour le papier ainsi que le carton, et le tri des déchets est bien respecté.
Je n’avais pas de responsabilités à proprement parler. J’ai eu des consignes de la part de mon
superviseur à propos du projet et de d’autres tâches plus courtes.
Aspects techniques du stage
Le stage complété cet été avait pour but l’initiation à la recherche. Par conséquent, je n’ai pas
eu à calculer, à développer des formules, à utiliser des outils ou à dessiner, ce qui rend la tâche de
vous expliquer les défis techniques rencontrés un peu difficile. En fait, mon stage a davantage été
orienté vers l’écriture d’articles et vers l’apprentissage du fonctionnement de la profession de
chercheur.
D’abord, mon projet principal, celui sur lequel j’ai travaillé quasiment jusqu’à la fin du mois
d’août, consistait à rédiger un article de revue sur l’ensemble du domaine actuel de la reconstruction
chirurgicale suivant une rupture du ligament croisé antérieur dans l’industrie. Il s’agit d’un vaste sujet
où plusieurs variables entrent en jeu, telles que le matériel à utiliser pour le ligament synthétique, les
fixations chirurgicales tibiales et fémorales ainsi que le protocole de réhabilitation à favoriser suite à
l’opération. L’article sera destiné à la publication dans Biomaterials Science, un nouveau magazine
scientifique.
Une longue et exhaustive lecture de la littérature scientifique a été nécessaire pour
comprendre ce qu’est cette condition médicale et ce qu’elle implique pour le patient qui en est atteint.
Puis, j’ai entamé ma cueillette de données, lors de laquelle j’ai consulté des articles spécifiques aux
aspects que je voulais aborder, soient le matériel, les fixations et la réhabilitation. L’utilisation du site
de la bibliothèque de Polytechnique était un excellent moyen pour y parvenir. Finalement, je suis
passée à la rédaction. Il s’agissait bien entendu de mon premier article scientifique, ainsi je n’avais
pas réalisé à quel point tout devait être référencé rigoureusement. J’ai donc mis beaucoup trop de
temps à relire des articles afin d’y chercher des informations bien précises; articles que j’avais, de
surcroît, mal triés dans mes dossiers. Ce délai n’était pas prévu, ce qui m’a fait prendre un peu de
retard.
De temps en temps, mon superviseur me donnait des tâches supplémentaires à effectuer. En
premier lieu, j’ai eu à parfaire un ancien article clinique à des fins de publication. Il s’agissait d’un
article scientifique sur une expérience menée par Nicolas Duval, un collaborateur de longue de date
du Pr. Yahia. Il avait conduit une étude sur l’implantation des ligaments LARS chez des patients
nécessitant une reconstruction de ligament croisé antérieur, et cet article avait été précédemment
refusé par certains magazines scientifiques. J’ai donc dû lui ajouter davantage de substance en
référençant les parties non-appuyées par la littérature et en clarifiant les explications. Des
modifications au niveau du format ont aussi dû être appliquées afin d’assurer la conformité au
magazine Clinical biomechanics. Ce n’est pas toujours évident de réviser un texte que nous-même
n’avons pas écrit, et qui se base sur une expérience à laquelle nous n’avons pas participé, ni assisté.
Il a été également difficile de contacter Duval, l’auteur en question. D’ailleurs, ce dernier n’a toujours
pas été rejoint. Par conséquent, son article n’a pas encore été envoyé au magazine.
En second lieu, toujours dans l’optique de l’initiation au domaine de la recherche et dans
l’apprentissage de ses protocoles, j’ai eu comme tâche de rédiger une soumission de projet Engage
au CRSNG. Ces lettres de soumission présente une idée de projet dans son ensemble, la
problématique actuelle qui motive ledit projet, les compétences du laboratoire ainsi que les
retombées économiques et sociales sur le Canada. En plus d’apprendre la structure formelle de ces
soumissions ainsi que leur contenu, je me suis familiarisée au concept de demande de financement
et aux autres options qu’ont les laboratoires de recherche pour financer leurs activités telles que
l’Institut canadien de rechercher en santé (CIHR).
En dernier lieu, j’ai écrit une première ébauche de lettre de support. Lorsqu’un laboratoire ou
un groupe de recherche souhaite recevoir une contribution financière du gouvernement, comme nous
l’avons fait avec le CRSNG, il est possible de soumettre également une lettre d’appui d’un partenaire
industriel. Il s’agit d’un cours texte dans lequel la compagnie explique le projet ainsi que les
avantages générés par celui-ci. De plus, la lettre montre de façon exhaustive comment le partenaire
industriel viendra en aide au laboratoire. Bref, elle indique le montant d’argent investi dans la
recherche. Ce genre de lettre provient de la compagnie, mais il n’est pas rare qu’un premier jet soit
écrit par le groupe de recherche et envoyé au partenaire industriel par la suite.
Expérience acquise
Expérience de stage
Habiletés techniques
Comme mentionné ci-dessus, il est difficile pour moi de vous répertorier le savoir-faire
technique acquis durant mon été au Laboratoire d’Innovation et d’Analyse de la Bio-performance, vue
la nature de mon stage. Cependant, je peux vous présenter, comme montre le tableau ci-dessous,
ce que j’ai appris, mes forces et mes faiblesses.
Habiletés acquises
Points forts
Points faibles
Recherche dans la littérature
Écriture d’un article
scientifique
Maîtrise de la langue anglaise
et de la rédaction
Écriture d’une soumission
Organisation des références
Engage
Écriture d’une lettre de
Esprit de synthèse
support
Tableau 1 : Habiletés acquises, points forts et points faibles
Durant mon stage, je me suis donc familiarisée aux moteurs de recherche pour les articles
scientifiques, tels que PubMed et Elsevier. J’ai d’ailleurs appris à en rédiger un, ainsi que d’autres
textes courants dans le domaine de la recherche en ingénierie, soient une lettre de demande de
financement Engage ainsi qu’une lettre de support. J’ai toujours considéré la composition de textes
comme une de mes forces. Or, vue la nature de mes tâches cet été, je peux affirmer que cet aisance à
l’écriture m’a définitivement donné un coup de pouce. Par ailleurs, puisqu’actuellement la science se
communique en anglais, mon article devait être écrit dans cette langue. Je juge mon niveau d’anglais
satisfaisant, ce qui, encore une fois, a joué de mon côté. Autrement, la rédaction de plus d’une dizaine
de pages aurait été assez fastidieuse. Mon manque d’organisation dans le tri des références m’a
retardé un peu. Je n’ai pas été constante dans la façon dont j’enregistrais mes articles causant ainsi
quelques erreurs quand le temps est venu d’appuyer mes informations.
Habiletés relationnelles
Quant au côté interpersonnel du stage, il m’est arrivé à de nombreuses reprises d’avoir à
contacter d’autres professionnels. Effectivement, la recherche est un domaine propice aux
correspondances, puisque des contributions interdisciplinaires et/ou d’ailleurs sont souvent requises.
J’ai donc échangé principalement avec mon superviseur Pr. L’Hocine Yahia ainsi qu’avec un
important collaborateur, l’orthopédiste Dr. Michel Leroux en personne et via courriels électroniques.
Nous avons eu deux ou trois rencontres durant l’été les trois ensemble. Les discussions visaient à
s’entendre sur nos buts et nos attentes, à tous se mettre à jour ainsi qu’à se fixer de nouvelles dates
limites. Puisqu’il faut que j’évalue mes performances en la matière, je les qualifierais de
satisfaisantes. Je crois avoir bien su agir en réunion, exprimer mes idées et écouter les propos
d’autrui.
Encadrement
Au début du stage de recherche, je ne connaissais rien de la reconstruction ligamentaire et
encore moins des ligaments synthétiques. Pr. Yahia m’a donc rencontrée afin de faire un survol du
domaine. Je me suis vite fait une idée, et après la lecture de quelques articles d’introduction qu’il
m’avait conseillés, j’ai pu entamer des recherches plus étoffées sur le sujet. Après environ un mois
de complété, j’ai eu l’incroyable chance d’assister en salle d’opération à deux chirurgies de
reconstruction après rupture du ligament croisé antérieur effectuées par Dr. Michel Leroux. Cette
visite à l’Hôpital du Haut-Richelieu m’a permis de mettre en images tout le contenu que j’avais lu à ce
propos. De la greffe du tendon du quadriceps à l’installation des vis d’interférence chirurgicales, j’ai
pu observer l’ensemble des étapes. J’ai également eu la chance de discuter avec le chirurgien et lui
poser mes questions. En ce qui a trait à l’encadrement de l’écriture de mon article de revue, le temps
a manqué, et je n’ai pas eu encore de rétroaction. Cependant, j’ai pu avoir quelques critiques de la
part de mon superviseur concernant l’article dont j’ai dû faire les corrections. Je devais ajouter plus
des références parce que ce dans un article scientifique, rien ne doit être écrit sans appui de la
littérature. Je n’avais pas compris à quel point avant ce stage.
Contribution
Comme mentionné à plusieurs reprises, j’ai beaucoup écrit cet été, mais rien n’est encore
publié. Toutefois, mon travail, particulièrement l’écriture d’un article de revue sur les matériaux
synthétiques, les fixations chirurgicales et les protocoles de réadaptation, n’a pas été vain. Je suis
fière de ce que j’ai produit comme effort et suis persuadée, publication ou non, d’avoir contribué à
clarifier le domaine de la chirurgie après rupture du ligament croisé antérieur. Que ce soit pour la
communauté scientifique ou simplement pour Pr. Yahia; le temps nous le dira. Effectivement, mon
texte peut servir de base pour de futures expériences dans ce domaine telles que des essais
mécaniques sur différents types de ligaments artificiels. Il s’agit d’ailleurs déjà d’un projet dans la mire
du LIAB. De plus, c’est ce projet qui était l’objet des lettres de soumission Engage et de support que
j’ai composées. Bien entendu, il s’agit d’un projet tout nouveau au LIAB. Il requiert donc que
davantage de temps soit investi.
J’ai également effectué quelques corrections sur un ancien article clinique concernant les
ligaments LARS qui n’avait pas été publié à l’époque. Si ce dernier parvient à être publié,
potentiellement dans le magazine Clinical Biomechanics, il pourrait avoir sur la compagnie française
LARS d’excellentes retombées et ultimement une approbation par la FDA.
Formation
Dans le cursus normal du baccalauréat en génie biomédical, les étudiants ont un aperçu de la
structure des articles scientifiques dans le cours de Biologie moléculaire et cellulaire pour ingénieurs
donné à la deuxième année de la première année. J’ai également entendu dire que dans le cadre du
cours de Biomatériaux donné à la cinquième session, les étudiants doivent en écrire un. À mon avis,
ce sont des connaissances qui sont faciles à acquérir en stage. Par conséquent, je crois qu’il ne
serait pas si pertinent d’assigner ce genre de travaux plus tôt dans le cheminement scolaire.
Artificial Ligaments: A Critical Review
Introduction
Reconstruction of the anterior cruciate ligament is a surgery that is performed thousands and
thousands of time each year. Its physiological position, its movements of flexion, torsion and traction
and finally its lack of vascularization make the ACL the perfect target for early rupture. From the
lateral femoral condyle, the ligament deploys itself with an hourglass shape until it reaches the
specific area anterior to the middle of the tibial condyles, the tibial plateau 17. The internal rotation and
the anterior gliding are mainly stabilized by the ACL, which makes it undeniably essential for
professional athletes or even active people in general 18. Indeed, several movements like jumping,
squatting and changing directions involve this specific ligament. Furthermore, it has the
proprioceptive ability to adapt to unexpected load, sharp changes of speed or direction with the help
of a nerve influx coming from the mechanoreceptors located mainly in the stumps and going towards
the muscles in order to contract fibers and avoid ACL rupture 15,26,27. In the latter case, deficiency in
proprioception will appear60,61.
Even though the reconstructive surgery has been performed a multitude of times around the
world, no standard protocol exists. Therefore, it comes to the orthopedist to choose which material,
fixation device and rehabilitation program he feels like using. This becomes an actual weakness for
the surgical procedure because there is an increasing amount of changing parameters and no solid
protocol onto base improvements. Many past articles and reviews were written with that purpose
however, to our knowledge; none has included the appropriate material, fixation device and
rehabilitation protocol, all at the same time19,20,21,22,23.
First, this article wishes to enlighten the choice between autograft and synthetic materials. In
the latter case, comparisons will be made between different graft providers such as Leeds-Keio,
Trevira and finally LARS which are the main players in the ACL industry. The goal is also to remove
the controversy that exists around synthetic ligament since the 80’s25, when they were known to
cause severe synovitis. Second, the review will assess methods of fixation; interference screws,
cross-pins, Evolgate and Endobutton. Fixations are known to be the weakest point of the implant,
since ruptures occur more often at the insertion site27. Basically, the surgeon drills two tunnels; one in
the femur and one in the tibia, oriented in a way that the new anterior cruciate ligament can be placed
at the original position. Afterwards, each device is installed in one of the tunnel in order to maintain
the implant in place28. Finally, because of the lack of standardization in the rehabilitation field, it is
relevant to compare different protocols as well. The post-operation process has to lower the swelling,
retrieve range of motion in the injured knee, assures symmetry with the uninvolved one and proper
gait30.
Material
In the past 40 years, the ACL reconstruction industry has changed a lot. Before, only allograft
and autograft were acceptable, mainly because synthetic materials that were used at that time had a
bad press. For instance, Dacron from Stryker, carbon fibres and Gore-Tex were accused of not being
fatigue-resistant enough, having a high laxity and having abrasion between fibres1,2. This is not so
relevant nowadays, because of a new generation of artificial ligaments.
Autograft
This procedure is the gold standard in the industry and consists of harvesting a part of the
patellar tendon or the hamstring tendon in order to use it as a new anterior cruciate ligament. It is a
typical surgery because it has been done for a while now and the long term effects are currently well
known. Therefore it is considered as a safe choice. However, nowadays, this operation is often
performed on high-level athletes, which means the need for a high and early resistant graft is urgent,
whence the purpose of this review.
Weaknesses of autogenous grafts are unavoidable. Indeed, they are particularly fragile during
the first two years, because transformation from the tendon to an ACL is being initiated. This amount
of time is evidently not suitable for athletes; they don’t have time for a slower and softer rehabilitation
protocol44. In fact, according to Liu et al., the process for autografts involves a brace during two
months and a 9-month wait for a full freedom23.
Leeds Keio
The LK implant was first designed as a tutor1 with a regenerative purpose. Its flat mesh of
longitudinal and transverse fibres made of polyester was engineered to stimulate collagen ingrowths.
Some studies found that it was indeed the case33.
After 18 months Maracci et al. found type I collagen around and within the broken graft. In
another study, Zaffagnini et al.34 sampled after 20 years of usage a part of the graft and its
neoligament. The biopsy reveled around 95% of small and poorly organized collagen fibres and 5% of
synthetic material, which indicated a fair ligamentization process. On the other hand, this finding is
quite questionable due to the fact that the experience was only done once. Therefore, other
researches were considered in order to assess the mechanical properties of the LK graft and finally
conclude on its relevance in the industry. LK grafts were found to cause laxity (56%), rupture (28%)
and to perform poorly in a long-term period32,35. In general, the results were not so positive, mainly
due to strong laxity and complications42. It is also important to note that LK graft would especially not
be suited for athletes for reasons mentioned above. There is no reliable data concerning
proprioception.
Trevira
This German graft is a popular synthetic ligament made out of 200 microfilaments of
polyethylene terephthalate (PET)36. In a study on the polymer’s biocompatibility, no synovitis
reactions occurred, even though some wear particles could be found. In fact, they were probably the
result of abrasion caused by the surgery itself36. Surgeons started using Trevira in the reconstruction
of the anterior cruciate ligament in 19803 and resulted of a fairly good outcome. Its maximal tensile
strength of 1866 N is similar to the natural ligament (~1700N), which is wanted, because an
excessive or a lack of stress on other anatomical components can be harmful3.
On a thorough study by Krudwig W 10., it was interesting to note that after a follow-up of almost
5 years, 27 % of his patients experienced swelling in moderate activity or at a sedentary condition,
26% felt pain because of it and 11% had from moderate to great extension/flexion deficit.
Nevertheless, when it comes to patient’ satisfaction, a non-negligible criteria, 83% rated their surgery
more than 5/10. This graft has also shown to stimulate connective tissue ingrowth 10,36,37, which links
the artificial ligament to the bone surface. Therefore, all the 13 cases of rupture, including seven
spontaneous ones, happened in the cross section direction in the extra-articular part of the graft11.
This may indicate a lack of strength and solidity, or show the influence of proprioception on
resistance. In another study from the nineties on Trevira’s longer outcomes, 22/88 (25%) was a
rupture case43.
Lars
Ligament Augmentation and Reconstruction System (LARS) is another PET ligament
developed in France in the eighties, but only became really popular in the beginning of this century3.
The cylindrical implant has two distinctive parts that make it very unique. The first one is surgically
placed in the bone tunnels and its tightly woven fibers offer solidity and modulate viscoelasticity. The
second part consists of free fibers running parallel to each other; it’s the intra-articular portion of the
graft. It enhances the fatigue resistance and constitutes an enabling environment for collagen and
fibroblasts ingrowth38. Basically, it aims to mimic the natural ACL’s architecture without losing
proprioceptive capacities7.
During surgery, the LARS ligaments will be sutured to the remaining stumps, as long as the
remnant does not disturb visibility (Cyclops lesion), in order to potentially reintegrate a nervous path
in the newly installed ACL26. During knee extension, the ACL, of course, stretches, but twists as well,
causing abrasion between fibers15. Therefore, surgeons usually pre-twist the graft during operation so
it unwinds during contraction39. Those grafts were often criticized and accused of causing synovitis.
This is no longer relevant, because only two cases were reported, and they were caused by deficient
surgical technique and not by the LARS itself. Like mentioned before, PET fibers are indeed
biocompatible. In fact, a previous study conducted by Tabrizian et al. proved that, at a long-term level,
the newly formed ACL will cover the synthetic fibers until the latter disintegrate. This phenomenon
happens gradually in order to give the ACL time before bearing all the tension itself41. Nau et al. also
showed better results for LARS than the autograft in the first year. Thus, a more rapid rehabilitation
protocol is conceivable. According to Liu et al., the process involves three weeks of crutch and full
freedom after three to four months23.
The literature is quite unanimous about the LARS ACL graft. It is without a doubt a decent
alternative for allograft and autograft. According to the company’s mechanical tests, the graft has a
resistance to traction ranging from 1500 N to 4700 N depending on the number of fibres. Moreover, it
has been proven to have a lower laxity, a better knee joint stability23 and a shorter period of
rehabilitation than the autograft method, without compromising range of motion 23,44.
Fixation
Fixation devices are undeniably important, but known to be the weakest link of the
reconstruction surgery, more particularly tibial fixation45,46. Their role is to somehow fix the graft to the
bone tunnels, while avoiding infections and tunnel enlargement.
Endobutton
Endobutton has a rectangular metal part through which a loop string passes. The latter also
passes through the graft; therefore the metal end sits across the extra-articular bone tunnel ending.
In a comparative study done by Monaco et al., the Endobutton does not particularly stand out
amongst other fixation methods in terms of failure load and stiffness. It was used as a femoral fixation
and helped with a bioabsorbable screw as a tibial fixation. One thing was interesting to notice. In this
comparative study, all pairs’ failure was due to tibial fixations, except the one with Endobutton on the
femoral side. The ultimate failure load was near average (775N)46 which shows that Endobutton is not
that reliable compared to other femoral devices. In some comparative studies between Endobutton
and cross-pins, no significant differences were found in terms of biomechanical properties, stability
and patient satisfaction. However, it seemed that cross-pins were more suitable for accelerated
rehabilitation (short-term), but required more care and more procedures at a long term level58,59.
Transcondylar fixation
Those devices, also known as cross-pins, consist of a screw inserted perpendicularly to the
ligament and the bone tunnel and into the bone condyles. The graft is folded in a way that the screw
is surrounded by the graft46.
Fabbriciani et al.45 came up with rather good results concerning this type of fixation. According
to his study, it was the only femoral device amongst others, especially screws, able to bear higher
maximal and yield loads (890 N) than the natural anterior cruciate ligament (725 N). Moreover, it was
less prone to slipping and had low levels of elongation and deformation. Of course, those tests were
performed on animal knees, but the assessment can still be relevant. On the other hand, some rare
cases of cross-pin breakage occurred53,56. Three patients had a prominent bump caused by the
device, and another one had its skin penetrated by the screw. The origin of these failures is not well
defined. It could have been an inadequate penetration of the screw, a defective batch or overly
intense rehabilitation therapy.
Interference Screw
Once the ligament is inserted in the bone tunnels, the interference screw is placed between the
cortical bone surface and the ligament. Therefore, when tension is applied on the ligament, slipping is
avoided. Those devices are trickier than others because results vary considerably from a study to
another. It is mainly due to the diversity of parameters, such as the material the screw is made of, the
diameter and length of the screw etc. Furthermore, some surgeons use it only as a tibial fixation,
some use it for both femoral and tibial fixation and some use it with staples.
As a tibial fixation device and along with staples, interference screw scored better outcomes in
Fabbriciani’s study45. Although none of the other methods of fixation scored higher results in terms of
stiffness, yield load and maximum load than the natural ACL, interference screws were the closest
from it. The Evolgate was not in that particular study.
They are already commonly used as a femoral fixation, whether it’s stainless steel or bioactive
polymer. Metal ones are prone to ligament tear and interference with future surgeries or MRI scans.
However, bioactive ones are less used, hence may have biocompatibility or resistance problems 48.
Despite all that, many studies show that no significant differences exist between those two types, in
terms of mechanical properties, failure rate and patient satisfaction48,55. In a recent 2012 study
comparing cross-pins and interference screws for femoral fixation, it was proven that stability was
significantly inferior with screws. On the other hand, according to them, this had no effect on clinical
outcome. It is important to note that this was an only one-year follow-up study; therefore there is still a
possibility of negative effects occurrence later in the patient’s life.
Evolgate
The Evolgate is made of three important titanium components: a coil that lines the tunnel’s
inner surface and strengthens the walls, a screw that fixes the graft in the coil and finally a washer to
secure position46,52.
It has been compared with interference screws for the tibial fixation, and results were very
promising. Evolgate could bear a mean load of 1237 N before rupture of the graft, not even slippage
of the graft. Interference screws could not even carry half of Evolgate’s load and failed because of
slippage most of the time52. It is without a doubt a solid fixation, considering the fact that assessment
was performed with porcine bones and old cadavers’ anterior cruciate ligaments. Needless to say
those are not the typical patients with a ruptured ACL. Hence, they would have probably yielded
higher loads.
Rehabilitation
Post-operative care is the most important factor for a fast and safe return to sport and daily
activities. There is currently no real defined protocol that surgeons can follow. A good rehabilitation
process allows the recovery of range of motion, knee symmetry, stability and ideally proprioception.
The latter is very important; a study showed that it influences patient satisfaction and abilities more
than the ligament stability itself71. Recovery also aims to lower complications such as osteoarthritis.
Standard VS Accelerated Program
The standard method involves wearing a brace for at least two weeks in full extension, with
restricted weight bearing. Return to sport can be possible after six months. An accelerated protocol
allows patient to have a full knee extension, and full weight-bearing as early as the first day after
operation. In the second week, a strengthening program is established, and by the first month, a full
return to daily activities is possible64. Return to sport depends on the subject. A gain of strength,
range of motion and stability resulted of that study.
It would have been very interesting to know about tunnel widening of those patients, because a
2006 study65 showed that those types of protocols enlarge, after ten months, bone tunnels on the
femoral and tibial sides. The causes are vague; micromotions against bone walls or wear made by
fluids could be involved. Nevertheless, the percentages of enlargement were quite small (< 15%) and
no difference in functional stability was found. Moreover, the consequences of tunnel widening over
time are not even yet known. Hence, the relevance of those results is rather questionable.
Proprioception VS Strength Program
The proprioception program focuses on enhancing balance and sense of position of an
individual after an ACL reconstruction. Patients visit a physiotherapy clinic twice a week during an
hour or so. Equipment like inflatable disks, trampoline and exercise balls is used. They are also
mandated home exercises every day when no appointment with the physiotherapist is scheduled 62.
The strength program aims to increase muscle strength and endurance and does not involve
proprioceptive drills. Patients visit a physiotherapy clinic twice a week during an hour or so. They are
also mandated home exercises every day when no appointment with the physiotherapist is
scheduled62.
In a thorough study conducted by Cooper et al., they assessed those two protocols by
comparing different elements after surgery (from four to fourteen weeks post-op.) and after six week
rehabilitation process. They evaluated swelling, walking, squatting/kneeling, climbing stairs, pain and
overall condition. The first three elements showed significant differences between the two programs.
In fact, all results favored the strength group. The rest of the criteria showed no real difference 62.
Therefore, it is possible to conclude that at less than four months after operation, it is more suitable to
focus rehabilitation on muscle increase and endurance than proprioception. A review article showed
as well that proprioception drills should be performed further on 66. For a rehabilitation made more
than 6 months after surgery, results were similar. Needless to say, both strength and proprioception
treatments were beneficial. However, it was proven that only quadriceps strength was significantly
improving functional abilities, which is the main goal in a rehabilitation protocol63.
Discussion
Above, the graft’s material, the surgical fixations and the recovery therapies were three
aspects considered separately. First, potential materials were assessed, and it can be confirmed that
all of those are suitable for surgery. However, because of a lack of early mechanical strength, stability
and fast recovery from certain synthetic ligaments and autograft, LARS ligament yielded better
results. It is biocompatible, strong, stable, and allows a fast rehabilitation. In this article, allografts
were omitted, for failure concerns69,71 and recurring cross-infections2,70. Also, there is no distinction
between implant from patellar tendon and hamstring tendon, because the emphasis was meant to be
put on synthetic materials.
Second, fixations were separated into femoral and tibial sides. It was found that the Evolgate
system as a tibial fixation combined with a cross-pin on the femoral side could be a great
arrangement. Then again, none of these devices are dangerous if used, but this combination could be
optimal.
Third, what can be pulled out of the rehabilitation assessment is that proprioception and
strength recovery are essential. However, in order to stimulate cell growth and gain knee stability,
early strength drills should be done, especially ones for quadriceps. Depending on each patient, after
a couple of months, proprioceptive exercises should be performed along with balance drills. Of
course, from two to three physiotherapy sessions are highly recommended each week in order to
retrieve complete range of motion.
That being said, considering those three features all together is even more representative and
therefore relevant. Indeed, it is difficult to predict the results that would be yielded from every
combination. For example, it is known that LARS allows a rapid rehabilitation, but along with a certain
tibial fixation, it might not work. Therefore, a lot of combination testing is going to have to be
performed in order to find the best outcome. That brings us to ask ourselves if it’s that much more
beneficial to have components very resistant to loads. Or would it be more preferable to have a highresistant graft with a weaker fixation? Dr. Michel Leroux, a collaborator orthopaedist from the HautRichelieu Hospital, Quebec, Canada, confirmed that being able to reutilize the same graft when
fixation fails is very rare. In the other way around, when graft fails, removal of the broken ligament
and the fixation device as well is necessary. Thus, perhaps fixations should always be weaker in
resistance than the graft itself.
Moreover, this article review covers a lot of articles from different time periods and different
countries in the world. Consequently, diverse generations of graft or device and many surgical
techniques specific to an orthopaedist were involved and might have distorted some results.
Medicine, especially surgery, is a continuously evolving field. Hence, some bad outcomes may not be
actually accurate. We are very aware that not every hospital has the same available equipment for
ACL reconstruction, but the purpose was to underline the best one to use. Like it was mentioned
before, none is dangerous in any case. Furthermore, the time gap between anterior cruciate ligament
rupture and the actual operation can influence results as well. A too short delay might cause
arthrofibrosis or rush a patient that is not mentally ready67. A too long delay before operation can alter
surrounding components and cause meniscal tears68.
Conclusion
Obviously, having those results means more specific biomechanical testing has to be done to
confirm those theoretical conclusions. For instance, LARS ligament should be tested in traction,
torsion and flexion along with its fixation. Loads should correspond to what real athletes are submitted
to, not only to daily activities, such as squatting down and jogging. Some companies are currently
working on their next generation of ACL. LARS works on coating the graft with a chemical agent that
would enhance even more cell growth and proprioception. This should be taken in consideration as
well.
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Article corrigé
TREATMENT OF SUB -ACUTE ANTERIOR CRUCIATE LIGAMENT RUPTURE
AUTHORS INFORMATION
Nicolas Duval, MD FRCS(C),
And
Pauline Lavoie, MD, LMCC, MSc
Laboratoire de Recherche en Imagerie et Orthopédie,
Centre de Recherche du CHUM,
Hôpital Notre-Dame,
1560 rue Sherbrooke Est,
Montréal (Québec),
Canada H2L 4M1
And
Duval Orthopédique Clinic,
1487 Boulevard des Laurentides,
Laval (Québec),
Canada H7M 2Y3
Tel : +1 450 6633901
Fax : +1 450 6630776
Author for correspondence: Dr. Nicolas Duval; e-mail: [email protected]
FORMAT
ABSTRACT : 148 WORDS
FULL TEXT : 3 801 WORDS
FIVE TABLES
TREATMENT OF SUB -ACUTE ANTERIOR CRUCIATE LIGAMENT RUPTURE
Nicolas Duval, MD FRCS(C), Orthopaedic surgeon and Pauline Lavoie, MD, LMCC, MSc (Epidemiology and Biostatistics)
1
Author for correspondence: Dr. Nicolas Duval; e-mail: [email protected]
Article Info
Abstract
Article History
Background: The present study aims to compare the outcome of conservative
Received:
management, non-operative treatment (NOT) of sub-acute ACL rupture with that
of surgical patellar autograft (Bone-patellar tendon-bone, BPTB) or of
Published:
implantation of a LARS artificial ligament.
Methods: Between 1996 and 2001, 29 patients were prospectively randomized
Keywords
between NOT, BPTB and LARS. Patients were followed until the end of 2007.
Findings: There were 7 failures in the NOT group, 1 in the BPTB group and 2 in
Knee
Anterior cruciate ligament
Artificial ligament
the LARS group.
Interpretation: Results showed that non-operative treatment of sub-acute ACL
tear resulted in a significantly poorer outcome, leading to surgery for
symptomatic instability, compared to surgical treatment with either BPTB or
Long-term results
LARS. The LARS artificial ligament may be an option for the surgical
management of sub-acute tears of the ACL as there was no long-term significant
difference between BPTB and LARS in terms of survival, clinical outcome and
patient satisfaction.
1
Laboratoire de Recherche en Imagerie et Orthopédie, Centre de Recherche du CHUM, Hôpital Notre-Dame, 1560 rue Sherbrooke
Est, Montréal (Québec), Canada H2L 4M1, and Duval Orthopédique Clinic, 1487 Boulevard des Laurentides, Laval (Québec), Canada
H7M 2Y3
Tel : +1 450 6633901, Fax : +1 450 6630776
1.
Introduction
Once a sub-acute rupture of the anterior cruciate ligament (ACL) is diagnosed in an active person, the orthopaedic surgeon
must decide which option is in the patient's best interest: conservative or surgical treatment. However voluminous the literature
concerning ruptures of the ACL is, data remain scarce on their long-term outcome so that even today, deciding remains
problematic.
Because of the biomechanical importance of the ACL, the surgeon is inclined to favour surgery as the best option, but the
technical difficulty of the intervention and the post-surgical complications like persisting pain, reduced range of motion and
persistent instability (Johnson et al., 1992; Vergis et al., 1995; Hughston, 1985 ) entice the surgeon to opt in some cases for a
conservative approach. It has been shown that the ACL contains mechanoreceptors which provide information concerning
joint position and interaction between the joint and muscles (Yahia et al., 1991, 1992). The presence of mechanoreceptors
which contribute to the dynamic stability of the knee, combined with the accessory stabilizers -menisci and collateral
ligaments- support the idea that the knee can remain functional without its ACL when patients stay within their activity limits
(Dye et al., 1996; Duval et al., 1997). In the end, our knowledge of the long-term outcome of such conservative management
rests on very few publications (Anderson et al., 1989; Casteleyn et al., 1996; Ciccoti et al., 1984; Daniel et al., 1994; Patte et
al., 1989; Shirakura et al., 1995).
For several years, the ACL reconstruction with autograft from the middle-third of the patellar tendon (BPTB) has been
performed by numerous surgeons. A high rate of success has been reported with this approach (Deehan et al., 2000;
Arnoczky et al., 1982; Bessette et al., 1990; Lavoie et al., 2001). The major disadvantages are donor site morbidity, patellar
fractures, patella tendonitis, scar formation, alteration of quadriceps function, and numbness caused by the division of the
infrapatellar branch of the saphenous nerve. These potential disadvantages are related to the tendon harvest site, as the
patient’s own tendon is used. The morbidity associated with harvesting the patellar tendon and the consequent prolonged
rehabilitation it imposes have stimulated the search for alternatives. The use of the LARS (Ligament Advanced Reinforcement
System, Arc-sur-Tille, France) artificial ligament represents one such alternative (Lavoie et al., 2000; Nau et al., 2002).
The present study compares the long-term results obtained after a non-operative management and after surgical treatment for
sub-acute ACL ruptures. A second aim of the study is to compare among the surgical candidates, the outcomes after either
BPTB or reconstruction with a LARS ligament.
Resorting to artificial ligaments intimately refers to the notion of failure (DiGiovine et al., 1991). Examining a number of novel
aspects of artificial ligaments (Drouin et al., 1991; Duval et al., 1997; Yahia et al., 1994) has led to the hypothesis that the
insertion of a forefront of new developmental synthetic grafts LARS Terresuisse-polyethylene terephtalate (PET) ligament can
buttress the biological healing of the newly ruptured ACL and result in good long-term outcomes.
1
The LARS intra-osseous segment is composed of longitudinal fibres bound together by a transverse knitted structure while an
intra-articular segment is composed of parallel longitudinal fibres twisted at 90° clockwise or counter-clockwise for use in right
and left knees, respectively. The main innovation of this artificial ligament lies in its ability to mimic the natural ligamentous
architecture and to reduce shearing forces by orientating the free fibres of the intra-articular portion of the graft (Yahia et al.,
1994; Sati et al., 1996). Therefore, every time a knee flexion occur, the LARS ligament unwinds instead of twisting, reducing
considerably the combined loading of traction, flexion and torsion, while reducing abrasion (Gely et al., 1984). Furthermore,
the PET fibres of the intra-articular segment are designed to encourage tissue formation due to the porosity of the material,
allowing ingrowths from the surrounding osseous tunnels , thereby helping the healing process and creating a stronger and
more reliable synthetic graft (Trieb et al., 2004). Furthermore, such tissue ingrowths between the ligament fibres may
contribute to the viscoelasticity of the graft and protect against friction at the opening of the bony canal and between the fibres
themselves. In a previous study, we conducted a two-year follow-up randomized controlled trial that compared the BPTB
autograft with the LARS artificial ligament method of ACL reconstruction in 53 patients with chronic instability (Nau et al.,
2002). While similar overall results were obtained for both groups, these results may suggest that a full return to activity may
be hastened by using the LARS artificial ligament rather than the conventional BPTB technique.
Comparing the latter study to some alarming ones clamming artificial ligaments dangerous makes obvious the need to study
further this novel synthetic ligament. It will impact on the prosthetics industry and on surgeons’ choices when it comes to
choosing the appropriate care.
2.
Materials and Methods
2.1 Patient selection
2.2
Between September 1996 and December 2001, 30 patients with a unilateral sub-acute rupture of the ACL were randomized
prospectively to either a non-operative treatment (NOT) or to a surgical treatment (ST). For the present study, a rupture was
considered sub-acute if the time lapse between the trauma and the consultation with the orthopaedic surgeon was less than
six months. Patients were excluded if their past history included surgery to the ACL, knee infection or lesion to another
ligament of that knee. A concomitant meniscal tear did not lead to exclusion.
At the first consultation, the following data were gathered: past history, physical examination, Tegner score, a self-assessment
of the knee reported as the Knee and Osteoarthritis Score (KOOS), a MRI and an antero-posterior stress radiograph at 20° of
flexion, sustained by a Telos instrument (Marburg, Germany) with a maximal force mode of 250 N. At the next visit, the
research project was presented to the patient. When an informed consent was granted, the Consent Form (approved by the
2
Ethics Committee of the hospital) was signed and the randomization initiated. Patient descriptive and demographic
characteristics are summarized in Table 1.
Table 1
Demographic and descriptive data of patients with a sub-acute ACL rupture
Treatment group
NOT
BPBPTB
LARS
Number of patients
11
9
9
Female
3
3
3
Male
8
6
6
Right knee
7
6
6
Left knee
4
3
4
Meniscal tear
2
2
4
Mean (SD)
Mean (SD)
Mean (SD)
31.1 (8.7)
29.6 (8.5)
30.1 (11.4)
11.1 (6.5)
14.9 (6.7)
15.1 (7.5)
6.5 (1.1)
6.0 (1.8)
7.2 (0.9)
Age (years)
Time lapse in weeks (Injury to
treatment)
Follow-up (years)
2.2 Randomization
For the first randomization, 30 sealed envelopes served to assign patients to either NOT (n=12) or ST (n=18). One patient
withdrew from the study after being randomized to the conservative arm and was thus removed from the study. The patients in
the ST group were further randomized to either BPTB (n=9) or LARS (n=9). The treatment NOT consisted of an aggressive
rehabilitation program and the use of a functional knee brace, to start the day after randomization and pursued for at least 6
months. Surgical techniques for BPTB and LARS have been previously reported (Clancy, 1988; Laboureau et al., 1997). Postoperative rehabilitation was identical for those two cohorts: weight bearing as tolerated, without a brace, and an intensive
physiotherapy regimen initiated, 3 times a week for a minimum of three months, and prolonged until the patient felt ready to
resume sport activities.
2.3 Data collection
3
A standardized evaluation was performed, from the day of the first post-randomization physiotherapy session, for both the
NOT and the ST groups. Each patient was followed by a research-assistant at 2, 6, 12 months and annually thereafter. The
last evaluations were in September 2007. Each visit included physical examination, Tegner score, KOOS, and a Telos stress
radiograph.
The Tegner score activity scale is designed as a score of activity level to complement other functional scores for patients with
ligamentous injuries. The instrument scores a person's activity level between 0 and 10 where 0 is 'on sick leave/disability' and
10 is 'participation in competitive sports such as soccer at a national or international elite level'.
The KOOS is developed as an instrument to assess the patient’s opinion about their knee and associated problems. KOOS is
meant to be used over short and long time intervals; to assess changes from week to week induced by treatment (medication,
operation, physical therapy) or over years due to the primary injury or post traumatic OA. KOOS consists of 5 subscales; Pain,
other Symptoms, Function in daily living (ADL), Function in sport and recreation (Sport/Rec) and knee related Quality of life
QOL. The last week is taken into consideration when answering the questions. Standardized answer options are given (5
Likert boxes) and each question gets a score from 0 to 4. A normalized score (100 indicating no symptoms and 0 indicating
extreme symptoms) is calculated for each subscale. The result can be plotted as an outcome profile.
The Telos stress radiograph system is equipped with a screw threaded shaft that permits stress to be applied gradually to the
knee. With the patients lying on the side to be tested and the knee flexed to 20°, an anterior displacing force of 15kg (147 N) is
gradually applied to the tibia, and standard radiographs are taken after that force had been applied for one minute. The
patients are instructed to relax the leg muscles. Fluoroscopy is used to check the exact lateral position of the knee. For
comparison with digital read-out, the same measurements are taken on the unaffected knee of each patient. Anterior tibial
translation is calculated by measuring the displacement of the midpoint between the tangents to the posterior contours of the
tibial condyles, drawn perpendicular to the tibial plateau and relative to the position of the corresponding midpoint between the
posterior aspects of the femoral condyles.
None of the patients was lost to follow-up albeit the occasional omission by a few patients, for personal reasons, of the annual
visit. Failure was defined as the visit to the surgeon when, because of symptomatic knee instability, the decision was reached
that surgery was necessary for the NOT patients, or a surgical revision for previous BPTB or LARS.
2.4 Statistical analysis
Statistical analysis was made using SPSS Version 15.0. For statistical comparison of survival, Kaplan Meier Survival analysis
was used. For the outcomes related to the patient satisfaction with one's knee (KOOS), level of activity (Tegner) and
4
instrumented anterior laxity value (Telos stress X-Ray), paired t-test were used comparing the difference in scoring prior to,
and after treatment. A threshold of 0.05 was used as a value of significant difference.
3.
Results
3.1 Treatment Survival
Tables 2, 3 and 5 depict the survival of the different treatments. Patients managed by LARS or BPTB showed better survival
than those treated conservatively. These differences are statistically significant. Indeed, 7 implants out of 12 failed for the NOT
group, as oppose to 2 for the LARS and 1 for the BPTB. There is no significant survival difference between the LARS and
BPTB groups. Our cohort suffered no complication.
Table 2
Distribution of treatment failures
Treatment outcome
Treatment
Number of patients randomized
Failure
Success
NOT
11
7
4
LARS
9
2
7
BPTB
9
1
8
Table 3
Comparison between treatment groups
Survival difference between treatments
Treatment
z
p
NOT vs LARS
2.0258
0.032
NOT vs BPTB
2.6808
0.008
LARS vs BPTB
0.5295
0.516
3.2 KOOS, Tegner score and instrumented laxity testing
5
Table 4 presents the data pertaining to these questionnaires and examinations. Patients managed by LARS or BPTB showed
improvement in 4 of the 5 KOOS subscales, as well as in the Tegner score and the Telos anterior laxity value. These surgeryassociated improvements are statistically significant. The stiffness sub-scale indicated no difference between the pre-and postoperative results, and no statistical value could be calculated since the standard deviation was zero.
The NOT patients demonstrated neither improvement nor deterioration of statistical significance for 4 of the 5 KOOS
subscales, as well as for the Telos value. As was the case for the BPTB and LARS, the stiffness subscale showed no
difference pre- and post-conservative management and for the same reason obtains no statistical value. The Tegner score
improved after the conservative treatment. That difference has statistical relevance.
4.
Discussion
These data lean in the same direction as the survival, shown to be better in the LARS and BPTB patients, when compared to
those of the NOT group.
The analysis of the outcomes in patients afflicted by an ACL sub-acute rupture proved fascinating. A constellation of elements
concur in certain patients treated conservatively to produce satisfactory results whereas in others, the evolution leads to
chronic instability and thence to surgery. Once an ACL has ruptured, the purpose of surgery in the sub-acute stage is the
stabilization of a not yet unstable knee and to prevent instability, should the conservative treatment fail. Yet, however abundant
the published material devoted to the ACL is , the lack of knowledge concerning the proprioceptive factors conducing to a
functional stability in spite of a ruptured ACL is undeniable. It is impossible to conceive a selective, objective prevention of
instability, and to precisely confirm that the mechanical receptors are truly the cause of those divergent
Table 4
Paired t-test comparing pre and post-treatment questionnaires and examinations by treatment group
Difference of the mean between pre and post-treatment examination
KOOS
NOT
SD
p
ADL
-13.24
18.71
0.50
Pain
-11.11
19.6419
0.570
QOL
-6.25
35.3553
0.844
Sport
2.50
53.0330
0.958
Stiffness
0
0
x
6
Tegner
-1.91
2.071
0.012
Telos(mm)
0.857
2.8681
0.459
LARS
SD
p
ADL
-12.21
26.2936
0.05
Pain
-11.53
21.0824
0.02
QOL
-23.21
23.5609
0.000
Sport
-25.26
32.3382
0.003
Stiffness
0
0
x
Tegner
-1.67
1.572
0.000
Telos(mm)
2.036
3.6609
0.05
BPTB
SD
p
ADL
-13.24
12.0073
0.001
Pain
-11.31
20.4549
0.05
QOL
-33.31
24.3015
0.000
Sport
-38.08
26.7347
0.000
Stiffness
0
0
x
Tegner
-1.33
1.500
0.029
Telos(mm)
2.929
2.9500
0.039
KOOS
KOOS
results. The orthopaedic surgeon is limited to a subjective experience-based prevention.
A meta-analysis of the literature demonstrates the extent towards which the emphasis is directed such as technical surgical
details as well as short-term outcomes (Casteleyn, 1999). Few prospective randomized studies have looked at the long-term
functional impact beyond a four-year follow-up. Moreover, data analysis is complicated by a lack of uniformity in reporting of
the results, by a large number of patients being lost to follow-up and by the fact that treatment success or failure -as assessed
by the surgeon - does not necessarily match that of the patients (Lavoie et al., 2000, 2001). It is for those reasons that, for this
study, our strategy leaned towards recruiting a small cohort of patients who could be closely followed by the research
assistants, going as far as home or workplace visits to minimize the losses to follow-up. We sought a maximum of information,
both from the surgeon and the patients. An objective measure of the laxity of every knee was obtained by a standardized
stress-film. Other aspects were worthy of interest (e.g. the IKDC score) but considering the small size of the cohort, the
statistical data would have been weakened.
Table 5
7
Treatments survival curves (0=NOT, 1=LARS, 3=BPTB)
Recruiting the patients proved long and arduous as shown by the five-year recruitment period although a large number of
patients were solicited. The inclusion / exclusion criteria as well as patients' hesitation to enter a prospective, randomized
protocol were contributing factors. The main difficulty seems related to the ease for patients to obtain information about a
ruptured ACL, from other surgeons or even on the Internet. Consequently, it is frequent to meet a patient who, at the first
encounter with the surgeon, already has a biased opinion about which treatment is best for him, rather than submit to the
hazard of randomization. Such was the case for the one patient who abandoned our study, after being randomized to NOT,
convinced by external sources that surgery was the most appropriate treatment in his case.
Considering the abundance of papers describing the surgical techniques, their high rate of success and the ease of ACL
reconstruction in the day-surgery set-up, the superiority of ST over NOT may appear evident. One should not forget that the
role of early surgery is to stabilize a knee before instability sets in and to avoid morbidity. As Dye proposed (Dye , 1996), the
goal of treatment is to maximize a knee's envelope of function as safely and predictably as possible and encourage patient to
stay within the range of loading the knee can accept. The natural history of a ruptured ACL is still not clear. Surgical
stabilization of a knee which would remain stable after a conservative treatment represents an unnecessary surgery which
submits the patient to the complications that may ensue. Thus, it is important to quantify the differences between a surgical
and a conservative management offered to a patient suffering from a sub-acute ACL tear, since the knowledge of the factors
which lead to instability is so thin.
The results of our study bring us to the conclusion that an isolated sub-acute rupture of the ACL in an active person about 30
years of age, which is around our patients’ mean age, carries significantly less risk of becoming a symptomatically unstable
knee if operated sooner rather than being attended conservatively. The critical period covers the first two years, during which
the vast majority of failures occur.
8
This study brings out another interesting fact. Whereas a significant survival difference exists between BPTB and NOT, as well
as between LARS and NOT, no significant difference was found between BPTB and LARS. Not one knee operated with LARS
failed beyond 4 years. This fact argues against the large number of past reports disapproving of the utilization of artificial
ligaments (de Smedt, MAscharenas et Legnani). A few factors offer support to this observation. Firstly, the structure of the
ligament, its «de-enzymized» polyester, and its set of multiple intra-articular fibres may be better tolerated than other materials
such as carbon fibres and other textile structures like braids. Clinical synovitis was not observed throughout this study,
although one cannot exclude microscopic alterations of the synovial membrane. Secondly, the preservation of the soft tissues
of the ACL and the fact that LARS now acts as a stent during the biological repair, rather than as its prosthetic replacement
(Lukianov et al., 1989; Sledge et al., 1992), the presumed role granted artificial ligaments in the past, also support the ne w
point of view the industry will have to have on synthetic ligaments. Lastly, early stabilization of the knee may favour protection
from the mechanoreceptors and the secondary stabilizers of the knee, during the critical period identified as the first two years
when most of the failures take place. It also may explain the prolonged LARS survival, matching the good results obtained with
BPTB treatment.
The patients recruited for this study presented with a sub-acute rupture of the ACL. None had a symptomatic chronic rupture.
Another study, conducted simultaneously to this one, looked exclusively at patients presenting a rupture sustained more than
6 months previously. It will be reported separately. At 10 to 20 years after the diagnosis, on average, 50% of those with a
diagnosed ACL or meniscus tear have osteoarthritis with associated pain and functional impairment: the young patient with an
old knee. Osteoarthritis development in the injured joints is caused by intra-articular pathogenic processes initiated at the time
of injury, combined with long-term changes in dynamic joint loading (Lohmander et al., 2007).
Another recent study by Talbot et al. (Talbot et al., 2004) examined the use of the LARS artificial ligament for ligament
reconstruction in knee dislocations. Twenty patients were included with a mean follow-up of 27.4 months. Each patient was
evaluated using the Lysholm score, underwent clinical examination to identify ligamentous laxity and range of motion, and
completed the ACL quality of life (ACL-QOL) questionnaire. The mean Lysholm score was 71.7, which is lower than scores
reported by several other studies (range of 74.7 to 91.3) investigating the outcomes of knee dislocations treated with surgery
as reported by Fanelli (Faneli, 2003). Following the same trend, Telos radiometry revealed a mean residual laxity of 5 mm in
patients post-surgery, which is also greater than these previously reported results. The average range of motion post-surgery
was 118° with a mean fixed flexion contracture of 2°.
Since its initial description, the central third of the patella tendon with bone on either end of the graft (BPTB) has become the
“gold standard” for primary ACL reconstruction (Miller et al., 2002). However, it became evident that patients often suffered
from pain from the donor area, and surgeons started to use hamstrings tendons instead.
9
The advantages for synthetic ligaments are pretty simple. Using a synthetic ligament will allow the surgeon to use smaller
incisions, reduce surgical time and have access to a variety of grafts. It will allow the patient to avoid donor site morbidity and
weakening of the extensor or flexor apparatuses. Synthetic reconstruction also provides a safer alternative to those patients
who are at higher risk of complications under anesthesia. Considering that the surgeon would not have to take time to harvest
and prepare the BPTB autograft, he would be able to complete the reconstruction faster thus avoid having the patient under
anesthesia for longer periods of time (Krudwig, 2002).
5.
Conclusion
Based on the results of our study with a five years follow-up and on the data of the International Literature, we can say that the
new generation of Lars® artificial ligament used as graft in the ACL reconstruction, even if not yet FDA approved, provides an
excellent alternative to the BPTB autograft. Indeed, despite other studies showing bad integration of synthetic materials
causing synovitis or infections, the study shows the graft’s biocompatibility, since no rejection occurred. Also, in the next future
it will be bioactive similar to the approach developed by Chen et al (Chen et al., 2007) to enhance even more the cell growth.
Various research projects to make a new bioactive ligament (biomimetic ligament), where nanofibers of polyethylene
terephthalate (PET) and bioactive groups attached on the synthetic ligament can link the growth factors, the adhesive proteins
and the type I collagen as well as the fibroblasts are in progress.
Conflict of interest statement
This work was supported by a grant from LARS, 5 rue de la Fontaine 21560 Arc sur Tille, France. LARS was not involved in
the study design, in the collection, analysis and interpretation of data, in the writing of the manuscript and in the decision to
submit the manuscript for publication.
Acknowledgements
We thank Mr. S. Bélanger and Ms. P. Larouche for help in reviewing patients and Dr M. Boisvert, Prof L'Hocine Yahia and
student Michèle Voyer for help with preparing the manuscript.
This work was approved by the Ethic committee of CHUM - Hôpital Notre-Dame.
References
10
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12
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13
Recommandations
PROBLÉMATIQUE
LARS conçoit des ligaments artificiels de nouvelle génération. Contrairement aux autres
compagnies de l’industrie, ce ligament LARS n’est pas constitué que de fibres longitudinales
de polyester. Ses deux extrémités prennent la forme d’un réseau solide de polytéréphtalate
d'éthylène offrant ainsi une plus grande résistance et une viscoélasticité davantage contrôlée.
Les prothèses ligamentaires actuelles ne sont pas tout à fait adéquates, car les cas
d’infections, de ruptures et de trop longue période de réhabilitation sont cause d’échecs. Les
ligaments LARS, distribués exclusivement au Canada par la compagnie québécoise J.K.
Orthomedic, offrent d’excellents résultats cliniques, mais requièrent davantage de données
biomécaniques pour une accréditation par la FDA. De plus, Dr. Michel Leroux, orthopédiste
ayant une dizaine d’années d’expérience dans la chirurgie de la reconstruction du ligament
croisé antérieur avec LARS, a développé une technique chirurgicale qui consiste à tresser le
ligament synthétique au tendon du quadriceps sain prélevé du patient ayant subi une rupture
ligamentaire. Il insère ensuite cet hybride dans l’articulation du genou en guise de ligament
croisé antérieur. Des tests biomécaniques pourraient donc contribuer à un brevet éventuel
garantissant l’exclusivité de cette technique.
PROJET DE RECHERCHE
Le projet, étendu sur une période de six mois, visera à caractériser in vitro les propriétés
mécaniques du ligament LARS lorsque combiné à un tendon (patellaire ou du quadriceps).
Une vingtaine de prothèses hybrides (dont la partie biologique serait issue de chiens par
exemple) seront fabriquées par le Dr. Leroux avant d’être testées au Laboratoire d’Innovation
et d’Analyse de la Bio-performance (LIAB) à l’École Polytechnique de Montréal. Des mesures
de forces de rupture, des tests de traction, des tests de fluage et de relaxation seront effectués
par le MTS Bionix ou Boss du centre hospitalier universitaire Ste-Justine. Un étudiant à la
maîtrise exécutera ces évaluations.
COMPÉTENCES DE RECHERCHE
Pr. L’Hocine Yahia, chercheur expérimenté dans les domaines de la biomécanique et des
biomatériaux, sera à la barre de ce projet. Il a d’ailleurs déjà plusieurs publications à son actif
traitant des prothèses ligamentaires LARS et autres. L’orthopédiste Michel Leroux, tel que
mentionné ci-haut, perfectionne sa technique depuis dix ans au sein de l’Hôpital du HautRichelieu.
CONTRIBUTION AU TRANSERT DES TECHNOLOGIES
14
Le LIAB et la compagnie LARS souhaitent caractériser le ligament artificiel hybride du Dr.
Leroux. Les résultats cliniques sont excellents, mais ne sont pas suffisants à l’approbation
américaine faite par la FDA. Des mesures quantitatives précises sont nécessaires.
Ultimement, une demande de brevet sera envisageable, si la technique génère des résultats
concluants.
RETOMBÉES SUR LE CANADA
Le Canada est à ce jour l’unique pays en Amérique du Nord où on y opère la reconstruction de
ligament croisé antérieur à l’aide de la prothèse LARS. Une accréditation future de la FDA
comporte plusieurs avantages au Canada :
1) Elle soulignerait l’initiative de Santé Canada lorsque qu’il a approuvé ce ligament
synthétique en 1993.
2) J.K. Orthomedic se verrait ouvrir un énorme marché, celui des États-Unis, en plus de
divers autres pays faisant confiance à la FDA. Il va sans dire, qu’une bonne image de
LARS sera également réfléchie au Canada lui-même, et incitera d’autres chirurgiens à
opter pour cette méthode novatrice, stimulant ainsi l’économie canadienne.
3) Elle inciterait encore plus de chercheurs à poursuivre leur recherche dans ce domaine,
générant par conséquent de nouvelles idées de perfectionnement de la méthode.
Bien entendu, une plus grande visibilité ainsi que de nouvelles techniques d’avancement
contribueront à améliorer la condition de vie de plusieurs athlètes canadiens, notamment nos
joueurs de hockey, cibles courantes de la rupture ligamentaire, ainsi que des Canadiens et
Canadiennes en général.
RÉFÉRENCES
1- Gao, K., S. Chen, L. Wang, W. Zhang, Y. Kang, Q. Dong, H. Zhou and L. Li, Anterior
Cruciate Ligament Reconstruction With LARS Artificial Ligament: A Multicenter Study With 3 to
5 Year Follow-up. Arthroscopy: The Journal of Arthroscopic and Related Surgery, 2010. 26(4) :
515-23.
2- Hauser, R.A. , E.E. Dolan, H.J. Phillips, A.C. Newlin, R.E. Moore and B.A. Woldin, Ligament
Injury and Healing: A Review of Current Clinical Diagnostics and Therapeutics. The Open
Rehabilitation Journal, 2013. 6 : 1-20.
3- Huang, J., Q. Wang, F. Shen, Z. Wang and Y. Kang, Cruciate ligament reconstruction using
LARS artificial ligament under arthroscopy: 81 cases report. Chin Med J, 2010. 123(2) : 160164.
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4- Legnani, C, A.Ventura, C. Terzaghi, E. Borgo and W. Albisetti, Anterior cruciate ligament
reconstruction with synthetic grafts. A review of literature. International Orthopaedics (SICOT),
2010. 34 : 465-71.
5- Liu, Z., X. Zhang, Y. Jiang and B.F. Zeng, Four-strand hamstring tendon autograft versus
LARS artificial ligament for anterior cruciate ligament reconstruction. International
Orthopaedics (SICOT), 2010. 34 : 45-49.
6- Machotka, Z., I. Scarborough, W. Duncan, S. Kumar and L. Perraton, Anterior cruciate
ligament repair with LARS (ligament advanced reinforcement system): a systematic review.
Sports Medicine, Arthroscopy, Rehabilitation, Therapy & Technology, 2010. 2:29.
7- Mascarenhas, R and P.B MacDonald, Anterior cruciate ligament reconstruction: a look at
prosthetics- past, present and possible future. MJM, 2008. 11(1) : 29-37.
8- Nau T., P. Lavoie, N. Duval, A new generation of artificial ligaments in reconstruction of the
anterior cruciate ligament. The Journal Of Bone And Joint Surgery, 2002. 84: 356-60.
9- Parchi, P., A. Baluganti, L. Dolfi, G. Ciapini, F. Chiellini and M. Lisanti, ACL reconstruction
with LARS artificial ligament: review and results at medium term follow-up. 1st Orthopaedic
Division University of Pisa.
10- Tabrizian M., Leroy-Gallisot A., Yahia L’H., Technical report: Evaluation of synthetic LARS
knee ligaments, Biomechanics and Biomaterials Research Group, École Polytechnique de
Montréal, 1996, pp.1-34.
11- Yahia, L’H., N. Hagemeister, G. Drouin, C.H. Rivard, S. Rhalmi and N. Newman,
Evaluation of Cruciate Ligament Prostheses : Criticism of the Current Concepts and
Procedures. Biomechanics and Biomaterials Research Group, 1997.
12- Murray, A.W. and M.F. Macnicol, 10-16 year results of Leeds-Keio anterior cruciate
ligament reconstruction. The Knee, 2004. 11 : 9-14.
13- Rading J. and Peterson L., Clinical experience with the Leeds-Keio artificial ligament in
anterior cruciate ligament reconstruction. A prospective two-year follow-up study. Am J Sports
Med, 1995. 3: 316-9.
14- Boszotta H, W. Helperstorfer, Long-term results of arthroscopic implantation of a Trevira
prosthesis for replacement of the anterior cruciate ligament. Aktuelle Traumatol, 1994.
24(3):91-4.
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Conclusion
Pour conclure, je considère que mon stage au sein du laboratoire d’innovation et
d’analyse de la bio-performance avec le Pr. L’Hocine Yahia s’est bien déroulé. J’ai eu la
chance d’effectuer quelques corrections sur un article inédit écrit par Nicolas Duval. J’ai
également écrit un article de revue sur le domaine de la reconstruction chirurgicale en
abordant les thèmes des matériaux synthétiques, des fixations tibiales et fémorales ainsi que
des protocoles de réhabilitation. J’ai eu la chance d’échanger fréquemment avec un chirurgien
expert dans son domaine, et même, de le voir à l’œuvre dans deux de ses opérations. Ce
stage d’initiation à la recherche ne requérait aucune préparation avant son commencement, et
je n’ai pas eu besoin de quelconque aide de la part du Service de stage et placement pendant
celui-ci. Bref, je peux affirmer avec certitude m’être familiarisée avec le domaine de la
recherche en ingénierie cet été, ce qui était le but.
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Références
École Polytechnique de Montréal. Pavillons Claudette-Mackay-Lassonde et Pierre-Lassonde,
Des bâtiments verts. Tiré de http://www.polymtl.ca/lassonde/doc/Lassonde_Ecolo_3.pdf.
Gouvernement du Québec. Développement durable, Environnement, Faune et Parcs. Tiré de
http://www.mddefp.gouv.qc.ca/developpement/definition.htm.
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