Papers by Keyword: Ligament

Abstract: Tendons and ligaments injuries have become more and more common due to the increase of the general populations interest in sports and physical activities. Beginning with the 1970s many researchers have tried to reconstruct the torn ligaments and tendons, at first using products such as Polyflex and Proplast ligaments, with poor results. In recent years the use LARS ligament has been researched. The Ligament Augmentation and Reconstruction System, now at its 3^rd generation, is an artificial ligament made out of polyethylene terephthalate (PET) that over time allows tissue ingrowth, recreating the natural orientation of anatomical ligament and tendon fibers.

Abstract: There are a few years, it has become the use of artificial discs and effectively to compensate for damaged discs in humans due to the eccentric load applied on the spine. As we know very well that the success of a disc implantation depends strongly on the initial stability of the implant and the integration of the bone tissue of the vertebrae with these discs in the long term. Due to the optimal distribution of mechanical stresses in the surrounding bone. It is for this reason that the search for reasonable solutions to compensate the damaged disk and reduce the stresses in the cortical bone and spongy has become a very important research axis. Several alternatives have been studied, including implant design, prosthesis geometry, prosthetic components and biomaterials used. In this regard, we have proposed two new models for some innovative artificial disks by some of the biomechanics researchers and we have installed these discs between the two vertebrae L5 and S1 of the spine, to ensure spinal stability and avoid slipping, we installed a posterior attachment system (6 screws plus 2 rods) at the pedicular levels of the lumbar vertebra (S1-L5, L5-L4).It is for this technique that we have used finite elements in three dimensions and using the software ANSYS to know the extent of the realization of these discs under the influence of the load applied to them. The numerical results show that these disks played a very important role in the absorption of the stresses and to minimize, On the other hand, the lumbar inter-somatic cage (Model II) filled with cancellous bone is too great a role in reducing the stress compared to another synthetic (Model I) disc. In general, the new model of the inter-somatic cage filled with cancellous bone and reinforced by a posterior fixation system has given a lower level of stress in the cortical bone and the spongy bone of the lumbar vertebra (L5) compared to the healthy disk (D1).

Abstract: Anterior cruciate ligament (ACL) reconstruction technique was under tremendous improvement during last 10 years; anatomical versus transtibial technique gradually increased, with soft tissue graft overcoming bone-tendon-bone, and biodegradable exceeding metallic implants. Still, complications related to ACL reconstruction are reported; one of it is pretibial cyst formation. Pretibial cyst formation is reported to develop between 2 and 5 years post-operation. We report a case in which the cyst was developed at 2 years after surgery; a biocomposite screw was used for fixation on tibial site, in an ACL reconstruction done with soft tissue autograft. The MRI examination suggested the diagnostic, which was confirmed by histological examination of the cyst. The screw suffered multiple fragmentation; the remnants were retrieved and analyzed. The knee stability was not affected by the cyst development. After retrieval of the screw and appropriate rehabilitation, the patient recovery was complete. The presented case confirms that even biocomposite screw may be related to these sorts of complications, mainly related to plain biodegradable screws. The case offers a point of start for analysis of the literature. A precise ethology of this kind of complications is still unknown; a lot of theories have been developed, two of them seem to be related to our case. Technical improvement together with long time surveillance of cases in which biocomposite implants were used may improve our knowledge concerning the fate of these implants.

Abstract: The aim of this study was to estimate the mechanical properties and evaluate the biocompatibility of silk and PGA scaffolds as an artificial ligament to an ACL reconstruction. The scaffold for the artificial ligament was braided / knitted silk or PGA thread. The mechanical properties, cell growth, and subcutaneous tissue reactions were determined for both types of scaffolds. The breaking load of the PGA scaffold was double that of the sericin removed silk scaffold (SRSS). However, the initial attachment and growth of human ACL cells on the SRSS was superior to the PGA scaffold. In addition, the immune response was significantly higher on the PGA scaffold after 72 h (p<0.05) compared with the sericin removed silk scaffold by T lymphocyte and mononuclear cells (MNCs) in vitro cultures. In vivo, the ACL scaffold made from silk or PGA were implanted in the subcutaneous layer in rats and harvested 1 week later. A histological evaluation of the scaffolds explants revealed the presence of monocytes in the SRSS, and an absence of giant cells in all cases. An inflammatory tissue reaction was more conspicuous around the silk scaffold containing sericin and even more around the PGA scaffold compared with SRSS. These results support the conclusion that a properly prepared SRSS, aside from providing benefits in terms of biocompatibility both in vitro and in vivo, can provide suitable scaffolds for the support of ACL cell growth. These results suggest that a SRSS for ACL repair can overcome the current limitations with the PGA scaffold. And SRSS is biocompatible, and the in vitro T cell and MNCs culture model showed inflammatory responses that were comparable to those observed in vivo.

Abstract: This paper explores the ligament-dependent behaviour of specific work of fracture of polymeric materials using a recently-developed modified EWF model. It is demonstrated that the non-linear relationship between specific work of fracture (wf) and ligament length (l) is a result of specimen boundary influence on the evolution of plastic zone. A transition ligament (l*) is defined, below which, the height of under-developed plastic zone is equal to the ligament length, and as a result, a linear wf-l relation will be observed. The plastic zone will saturate at the transition ligament, and its height will no longer increase when l > l*. This will result in a non-linear wf-l relation. Experimental wf-l data available in the literature are analysed using the modified EWF model and very good agreements are achieved.