Functional evaluation of anterior cruciate ligagment autografts in pre-clinical animal models

Introduction Rupture of the Anterior Cruciate Ligament (ACL) affects about 1 person over 3000 every year. The current standard care is based on ligament reconstruction by autograft from tendon tissues and is considered as the gold standard. Yet, autograft reconstruction presents serious limitations. Recent developments in artificial ligaments are promising and could potentially address the currently growing demand from surgeons and patients for an off-the-shelf alternate solution. However, before these can be commonly used in clinical routine, their biocompatibility and biomechanical performance for the short and long terms must be studied in pre-clinical animal models. Building upon the work of [1], we propose in this contribution a methodology for assessing the biomechanical performance of artificial ligaments, and to provide reference data (autografts) using an animal model (sheep) at 3 months after implantation. Materials and Methods Surgery and specimen preparation 14 fresh frozen lower limbs were used in this study, seven left (autograft implantation) and seven right (contralateral) knees. These were harvested from seven sheep sacrificed 3 months after implantation. The biomechanical analysis of the knees consisted of four successive in vitro experiments: three kinematics tests (flexion-extension, varus-valgus laxity and anterior drawer tests) and a pull-out destructive test. Kinematics analysis: flexion-extension and laxity tests The kinematic analysis was performed using specific motorized devices adapted from previously described and validated ones [1]. The protocol combined motion analysis of tripods screwed in the bony structures and 3D personalized reconstruction (figure 1) from low-dose X-ray system (EOS, EOS Imaging, Paris, France) [1,2,3,4]. Pull-out destructive tests The pull-out tests were performed using an INSTRON 5566 testing machine (Instron Ltd., Buckingham-shire, England) instrumented with a 5 kN load cell. After conditioning, a tension load was applied to the specimen (5 mm/min) until total failure. Data analysis: mobility assessment and statistical tests The following parameters were extracted to allow the comparison with the literature [1] (i) Internal rotation Ry (°) value for a 40° flexion angle (Ry_40), (ii) Anterior Tibial Translation (mm) for 100 N loading (ATT_100), (iii) Varus Valgus amplitude (°) at 4 Nm loading (VV_4) and (iv) the Failure load (N) (FL). Results and discussion The results shows a good consistency for kinematic parameters of the contralateral knees. The failure load was clearly different due to the interindividual variability. As concerns the autograft, a reduction of internal rotation during the flexion motion and an increase of the laxity in ATT could be observed. The failure load was also decreased for the grafted knee.This work was supported by the French National Research Agency (ANR project n°ANR-08-ETEC-003

Pas-à-pas : trachéostomie temporaire par sonde chez le chien et le chat

La trachéostomie temporaire assure le rétablissement de la perméabilité des voies respiratoires en cas d’obstruction aiguë ou anticipée des voies respiratoires hautes. Les indications les plus fréquentes regroupent donc le syndrome obstructif des races brachycéphales, la paralysie laryngée, les traumatismes cervicaux, les corps étrangers laryngés, l’œdème laryngé et les néoplasies pharyngées, laryngées ou trachéales supérieures. L’abord chirurgical et la technique de mise en place sont relativement aisés mais plusieurs astuces doivent être adoptées pour faciliter la gestion postopératoire des animaux en soins intensifs. En effet, des complications à court terme très fréquentes, comme les obstructions et délogements de sonde, peuvent survenir brutalement et s’avérer mortelles. Dans ce sens, l’utilisation de sondes à double lumière et le fait de réserver le gonflement des ballonnets aux cas nécessitant une ventilation mécanique facilitent grandement la gestion postopératoire et diminuent la survenue de complications. En général, la surveillance rapprochée et le retrait de la sonde dès que possible confèrent aux animaux opérés d’une trachéostomie temporaire un bon pronostic, bien que celui-ci reste dépendant de la condition initiale et de la survenue de complications à long terme comme les sténoses trachéales

La sténose pulmonaire congénitale du chien (du déterminisme aux perspectives chirurgicales)

La sténose pulmonaire est une des malformations congénitales cardiaques les plus fréquentes chez le chien. Après quelques rappels sur l'anatomie, la physiologie et la sémiologie cardiaque l'auteur aborde le déterminisme, l'épidémiologie et la pathogénie de cette affection et présente les différents moyens diagnostiques. Dans une dernière partie, l'auteur développe les différentes thérapeutiques médicamenteuses, puis laisse une grande part au traitement chirurgical, notamment par cathétérisme interventionnel. L'auteur conclut en proposant un algorithme décisionnel lors de sténose pulmonaire.NANTES-Ecole Nat.Vétérinaire (441092302) / SudocSudocFranceF

La paralysie laryngée, du diagnostic au traitement

La paralysie laryngée est une cause fréquente d’obstruction des voies aériennes supérieures chez le chien et dans une moindre mesure chez le chat. Les animaux atteints sont préférentiellement des chiens de grande race d’âge avancé. La paralysie laryngée résulte d’une atteinte neuromusculaire du larynx. Rarement congénitale, elle est plus fréquemment acquise et peut être le reflet d’une cause sous-jacente systémique telle qu’une polyneuropathie. Les animaux sont présentés pour des anomalies respiratoires non spécifiques (stridor, intolérance à l’effort, dyspnée, toux, changement de voix et pouvant aller jusqu’à une cyanose et des pertes de connaissance) qui sont en général peu visibles jusqu’à ce que l’atteinte soit bilatérale. Le diagnostic de certitude se fait par observation directe du larynx par laryngoscopie sous sédation : un défaut d’abduction d’un ou des deux cartilages aryténoïdes est alors visible pendant l’inspiration, faisant obstacle au passage de l’air. Un traitement médical doit être instauré rapidement suivi d’une prise en charge chirurgicale, la procédure recommandée étant une latéralisation cricoaryténoïdienne unilatérale. Le pronostic après intervention est généralement bon à excellent malgré un risque de bronchopneumonie par fausse déglutition à vie

Biomechanical evaluation of a bioactive artificial anterior cruciate ligament

This study aimed to assess the biomechanical performance of a new generation of artificial ligament, which can be considered “bioactive” and “biointegrated,” implanted in sheep. Thirty sheep were implanted: 15 sheep received the artificial ligament grafted with a bioactive polymer (grafted) and 15 received the artificial ligament without a bioactive polymer (non-grafted). The animals were sacrificed 3 or 12 months after implantation. The knee kinematics, namely flexion-extension, anterior drawer, and varusvalgus tests, were evaluated using a fully characterized custom-made device. Afterward, the specimens were tested under uniaxial tension until failure.The flexion-extension showed significant differences between (grafted or non-grafted) artificial and native ligaments 3 months after implantation. This difference became non-significant 12 months postoperatively.The anterior tibial drawer was significantly increased 3 months after implantation and remained significantly different only for non-grafted ligament 12 months after implantation.Twelve months after implantation, the differences between grafted and non-grafted ligament biomechanical properties were significant in terms of stiffness. In terms of load to failure, grafted ligaments seem to have had slightly better performance than non-grafted ligaments 12 months postoperatively. Overall these results suggest that grafted artificial ligaments have slightly better biomechanical characteristics than non-grafted artificial ligaments 12 months after implantation in sheep

Biological and Biomechanical Evaluation of the Ligament Advanced Reinforcement System (LARS AC) in a Sheep Model of Anterior Cruciate Ligament Replacement: A 3-Month and 12-Month Study

PurposeThe purposes of this study were to assess tissue ingrowth within the Ligament Advanced Reinforcement System (LARS) artificial ligament (LARS AC; LARS, Arc sur Tille, France) and to study the biomechanical characteristics of the reconstructed knees in a sheep model of anterior cruciate ligament (ACL) replacement.MethodsTwenty-five female sheep underwent excision of the proximal third of the left ACL and intra-articular joint stabilization with a 44-strand polyethylene terephthalate ligament (mean ultimate tensile failure load, 2,500 N). Animals were killed either 3 or 12 months after surgery. Explanted knees were processed for histology (n = 10) or mechanical tests including tests of laxity and loading to failure in tension (n = 15).ResultsWell-vascularized tissue ingrowth within the artificial ligament was only observed in the portions of the ligament in contact with the host's tissues (native ligament and bone tunnels). Ligament wear was observed in 40% of explanted knees. The ultimate tensile failure loads of the operated knees at both time points were inferior to those of the contralateral, intact knees (144 ± 69 N at 3 months and 260 ± 126 N at 12 months versus 1,241 ± 270 N and 1,218 ± 189 N, respectively) (P < .01). In specimens with intact artificial ligaments, failure occurred by slippage from the bone tunnels in all specimens explanted 3 months postoperatively and in half of the specimens explanted 12 months postoperatively.ConclusionsThis study provides evidence that the LARS AC has a satisfactory biointegration but that it is not suitable for ACL replacement if uniform tissue ingrowth is contemplated. Despite good clinical performance up to 1 year after implantation, none of the reconstructions approached the mechanical performance of the normal ACL in the ovine model. Partial tearing of the artificial ligament, which led to a significant decrease in ultimate tensile strength, was observed in 40% of cases in the ovine model.Clinical RelevanceThe LARS is not a suitable scaffold for ACL replacement. Further animal studies are needed to evaluate its potential for augmentation of ligament repair.Agence Nationale pour la Recherche (ANR), France [Grant LIGART 06-TECSAN-006-01

Bone Regeneration in Sheep Using Acropora Coral, a Natural Resorbable Scaffold, and Autologous Mesenchymal Stem Cells

International audienc

Preventive Moderate Continuous Running-Exercise Conditioning Improves the Healing of Non-Critical Size Bone Defects in Male Wistar Rats: A Pilot Study Using µCT.

Although physical exercise has unquestionable benefits on bone health, its effects on bone healing have been poorly investigated. This study evaluated the effects of preemptive moderate continuous running on the healing of non-critical sized bone defects in rats by µCT. We hypothesized that a preemptive running exercise would quicken bone healing. Twenty 5-week-old, male, Wistar rats were randomly allocated to one of the following groups ( = 10): sedentary control (SED) or continuous running (EX, 45 min/d, 5 d/week at moderate speed, for 8 consecutive weeks). A 2 mm diameter bone defect was then performed in the right tibia and femur. No exercise was performed during a 4 week-convalescence. Healing-tissue trabecular microarchitectural parameters were assessed once a week for 4 weeks using µCT and plasma bone turnover markers measured at the end of the study protocol (time point T12). At T12, bone volume fraction (BV/TV; BV: bone volume, TV: tissue volume) of the healing tissue in tibiae and femurs from EX rats was higher compared to that in SED rats ( = 0.001). BV/TV in EX rats was also higher in tibiae than in femurs ( < 0.01). The bone mineral density of the healing tissue in femurs from EX rats was higher compared to that in femurs from SED rats ( < 0.03). N-terminal telopeptide of collagen type I in EX rats was decreased compared to SED rats ( < 0.05), while no differences were observed for alkaline phosphatase and parathyroid hormone. The study provides evidence that preemptive moderate continuous running improves the healing of non-critical sized bone defects in male Wistar rats

Primary hyperparathyroidism due to a cystic parathyroid adenoma in a cat

A 15-year-old neutered female domestic shorthair cat was presented for weight loss, polydipsia/polyuria and lethargy. A large fluctuant mass was palpated in the ventral right cervical region. Biochemistry results were consistent with primary hyperparathyroidism. Parathyroid hormone level in the fluid was higher to that observed in the plasma, consistent with a cystic parathyroid lesion. Right parathyroidectomy and thyroidectomy were performed without complications. Ionized calcium normalized within a few hours. Histopathology yielded a diagnosis of cystic parathyroid adenoma. Follow-up showed complete recovery of clinical signs and normalization of ionized calcium. This case shows an uncommon presentation of feline primary hyperparathyroidism secondary to a cystic parathyroid adenoma and is, to our knowledge, the first case presented with a large palpable mass in which parathyroid hormone concentration was measured. This report highlights the value of selective hormonal analyses of the cystic fluid to confirm the origin of the cystic lesion pre-operatively