Finite Element Analysis of Transhumeral and Transtibial Percutaneous Osseointegrated Endoprosthesis Implantation

Cadaveric mechanical testing of a percutaneous osseointegration docking system (PODS) for osseointegration (OI) prosthetic limb attachment revealed that translation of the exact system from the humerus to the tibia may not be suitable. The PODS, designed specifically for the humerus achieved 1.4–4.8 times greater mechanical stability in the humerus than in the tibia despite morphology that indicated translational feasibility. To better understand this discrepancy, finite element analyses (FEAs) modeled the implantation of the PODS into the bones. Models from cadaveric humeri (n = 3) and tibia (n = 3) were constructed from CT scans, and virtual implantation preparation of an array of endoprosthesis sizes that made contact with the endosteal surface but did not penetrate the outer cortex was performed. Final impaction of the endoprosthesis was simulated using a displacement ramp function to press the endoprosthesis model into the bone. Impaction force and maximum first principal (circumferential) stress were recorded to estimate stability and assess fracture risk of the system. We hypothesized that the humerus and tibia would have different optimal PODS sizing criteria that maximized impaction force and minimized first principal stress. The optimal sizing for the humerus corresponded to implantation instructions, whereas for the tibia optimal sizing was three times larger than the guidelines indicated. This FEA examination of impaction force and stress distribution lead us to believe that the same endoprosthesis strategy for the humerus is not suitable for the tibia because of thin medial and lateral cortices that compromise implantation.

Studying the influence of Solcoseryl drug and vitamin C on the inflammatory reaction and proliferation of fibroblastic cells in the filed of polypropylene endoprosthesis implantation

Introduction: Applying a coating on hernia endoprosthesis prevents recurrent anterior abdominal wall hernias, reduces inflammatory response and stimulates reparative processes in the area of its implantation. The aim of investigation was to study the effect of Solcoseryl and Vitamin C in a collagen-stimulating coating of hernioendoprosthesis on a morphological picture in anterior abdominal wall plastic surgery. Materials and methods: The study was performed on 180 laboratory mice divided into three groups of 60 animals each: the first group animals were implanted with polypropylene endoprostheses without a collagen-stimulating coating, the second group animals – polypropylene endoprostheses with a collagen-stimulating coating with Vitamin C, and the third group animals – polypropylene endoprostheses with a collagen-stimulating coating with Solcoseryl. The laboratory animals were withdrawn from the experiment on the 10th, 30th, 60th, and 90th days. The excised sections of the abdominal wall were stained with G+E to determine the nature of inflammation and the number of cell elements. Results and discussion: When using endoprostheses with a collagen-stimulating coating, the stages of inflammatory process proceeded more quickly, which was confirmed by a reliable (р ≤ 0.05) decrease in the number of neutrophils, macrophages and lymphocytes at all stages of the study. By the 90th day of the experiment, the number of fibroblasts in the control group was by 22.64% less than in the study groups with a coating. Conclusion: A cytological and histological analysis in the control group determined a consistent decrease in an exudative phase of inflammatory reaction. When using endoprosthesis with coatings, its acceleration and lower intensity was noted throughout the study. In the group with Solcoseryl, the formation of a dense connective capsule around the endoprosthesis indicates its quality and better adaptation of the endoprosthesis in body tissues.

Impact of Digital Supported Process Workflow Optimization for Hip Joint Endoprosthesis Implantation on Hospital - Specific Process and Quality Ratios

Considering the continuous change within the German health care system, German hospitals are forced to realize efficiency gains and, at the same time, try to enhance their quality standards. Digital support systems in surgery rooms intend to improve operational efficiency and reduce failure quotas. A dataset with 383 hip joint endoprosthesis surgeries from a German hospital was analysed using statistical methods, among others logit model, odds ratio and ANCOVA. Results show that digitally supported surgery results in a shorter hospital stay time and reduces acute hemorrhagic anemia as a postoperative complication. Finally, it is possible to conclude that the Surgical Procedure Manager reduces surgical risks.

Preemptive angioplasty for contralateral leg stenosis following EXCLUDER Iliac Branch Endoprosthesis implantation

The GORE EXCLUDER Iliac Branch Endoprosthesis (IBE) device is designed to seal off a common iliac artery (CIA) aneurysm, preserving the internal iliac artery during endovascular aortic repair. We report the case of an 84-year-old man with isolated saccular right CIA aneurysm (35 mm) and a relatively small terminal aorta (24 mm). The IBE device was successfully placed, and intraoperative angiography revealed no leakage or delay. However, postoperative computed tomography revealed marked compression of the contralateral leg by a bridging component. Although his ankle–brachial index was preserved, its acute occlusion was judged highly possible; we decided to perform preemptive angioplasty. The angiography revealed the stenosis only in the left anterior oblique view, and angioplasty was uneventfully performed. The leg was successfully patent at 1-year follow-up. When compression by IBE and bridging component in the terminal aorta is expected, caution should be preserved at intraoperative angiography following the device deployment.

THE CONDITION OF CELLULAR IMMUNITY IN PATIENTS WITH OSTEOARTHROSIS BEFORE AND AFTER ENDOPROSTHESIS IMPLANTATION

Impairments of immune system are an important mechanism of the degenerative dystrophic processes in the arthral tissues onset and development.The objective of this research was to study the cellular immunity condition in patients with osteoarthrosis before and after endoprosthesis implantation. The research methods included immunophenotyping of lymphocytes in the peripheral blood. The immunologic impairments before the surgery referred to change in T-cell immunity reflecting in the imbalance of immunoregulatory subpopulations (decrease of T-suppressor level and increase of T-helper content). At that the number of NK-cells rose which didn’t exclude a possible connection with the cartilage tissue degradation impurities on the background of B-cell number decrease. During the post-surgery period the decrease in T-helper and T-suppressor numbers was detected which may be related to their migration to implantation area due to the decrease of their number in the systemic circulation, at that no significant changes in T-lymphocytes were observed. By contrast, there was a decrease of NK-cell number at higher level of B-cell number showing an adequate response of the bodies for surgery aggression. The results of immunological research are worth being taken into account when preparing patients for endoprosthesis implantation surgery for the purpose of prescribing the immune-correcting drugs for pre-existing impairments of cellular immunity as well as in the post-surgery period to relieve the effects of surgical interference aggravating the impairments in this population of patients.

Proximal endovascular blood flow shunt for thoracoabdominal aortic aneurism without total aortic clamping

<p>The authors present a surgical approach to type III and IV Crawford aneurysms that does not need total aortic clamping, which allows the more objective prevention of direct ischemic damage, as well as its exclusion by the endoprosthesis implantation, shunting the flow to the synthetic graft.</p>

Patient-specific models of human trachea to predict mechanical consequences of endoprosthesis implantation

Nowadays, interventions associated with the implantation of tracheal prostheses in patients with airway pathologies are very common. This surgery may promote problems such as migration of the prosthesis, development of granulation tissue at the edges of the stent with overgrowth of the tracheal lumen or accumulation of secretions inside the prosthesis. Among the movements that the trachea carries out, swallowing seems to have harmful consequences for the tracheal tissues surrounding the prosthesis. In this work, a finite-element-based tool is presented to construct patient-specific tracheal models, introducing the endotracheal prosthesis and analysing the mechanical consequences of this surgery during swallowing. A complete description of a patient-specific tracheal model is given, and a fully experimental characterization of the tracheal tissues is presented. To construct patient-specific grids, a mesh adaptation algorithm has been developed and the implantation of a tracheal prosthesis is simulated. The ascending deglutition movement of the trachea is recorded using real data from each specific patient from fluoroscopic images before and after implantation. The overall behaviour of the trachea is modified when a prosthesis is introduced. The presented tool has been particularized for two different patients (patient A and patient B), allowing prediction of the consequences of this kind of surgery. In particular, patient A had a decrease of almost 30 per cent in his ability to swallow, and an increase in stresses that were three times higher after prosthesis implantation. In contrast, patient B, who had a shorter trachea and who seemed to undergo more damaging effects, did not have a significant reduction in his ability to swallow and did not present an increase in stress in the tissues. In both cases, there are clinical studies that validate our results: namely, patient A underwent a further intervention whereas the outcome of patient B’s surgery was completely successful. Notwithstanding the fact that there are a lot of uncertainties relating to the implantation of endotracheal prostheses, the present work gives a new insight into these procedures, predicting their mechanical consequences. This tool could be used in the future as pre-operative planning software to help thoracic surgeons in deciding the optimal prosthesis as well as its size and positioning.