Investigations into Ti-15Mo-W Alloys Developed for Medical Applications

Surgical Strategy for Sternal Closure in Patients with Surgical Myocardial Revascularization Using Mammary Arteries

BACKGROUND

Coronary artery bypass grafting has evolved from all venous grafts to bilateral mammary artery (BIMA) grafting. This was possible due to the long-term patency of the left and right internal mammary demonstrated in angiography studies compared to venous grafts. However, despite higher survival rates when using bilateral mammary arteries, multiple studies report a higher rate of surgical site infections, most notably deep sternal wound infections, a so-called "never event".

METHODS

We designed a prospective study between 1 January 2022 and 31 December 2022 and included all patients proposed for total arterial myocardial revascularization in order to investigate the rate of surgical site infections (SSI). Chest closure in all patients was performed using a three-step protocol. The first step refers to sternal closure. If the patient's BMI is below 35 kg/m2, sternal closure is achieved using the "butterfly" technique with standard steel wires. If the patient's BMI exceeds 35 kg/m2, we use nitinol clips or hybrid wire cable ties according to the surgeon's preference for sternal closure. The main advantages of these systems are a larger implant-to-bone contact with a reduced risk of bone fracture. The second step refers to presternal fat closure with two resorbable monofilament sutures in a way that the edges of the skin perfectly align at the end. The third step is skin closure combined with negative pressure wound therapy.

RESULTS

This system was applied to 217 patients. A total of 197 patients had bilateral mammary artery grafts. We report only 13 (5.9%) superficial SSI and only one (0.46%) deep SSI. The preoperative risk of major wound infection was 3.9 +/- 2.7. Bilateral mammary artery grafting was not associated with surgical site infection in a univariate analysis.

CONCLUSIONS

We believe this strategy of sternal wound closure can reduce the incidence of deep surgical site infection when two mammary arteries are used in coronary artery bypass surgery.

Importance of Tissue Doppler Evaluation in Dilated Cardiomyopathy: The Value of Diastolic Filling Pattern as a Prognostic Predictor

(1) Background: The presence of restrictive left ventricular diastolic filling pattern (LVDFP) is associated with an unfavorable prognosis in many cardiac diseases, but few data are available on the prognostic implications of this pattern in patients with dilated cardiomyopathy (DCM). We aimed to establish the main prognostic predictors at the 1- and 5-year follow-ups in DCM patients and the value of restrictive LVDFP in increasing morbidity and mortality. (2) Methods: A prospective study of 143 patients with DCM divided in non-restrictive LVDFP group (95 patients) and restrictive group (47 patients). The patients were evaluated at a 5-year follow-up through an in-patient visit during the pre-pandemic period and hybrid methods (face-to-face, teleconsultation and home monitoring with a telemedicine application) during the pandemic period. Statistical analysis compared the two groups in terms of NYHA class, quality of life, hospitalizations/emergency department (ED) visits due to HF exacerbation and total mortality. (3) Results: The mortality rate in the restrictive group was markedly higher than that in the non-restrictive group at 1 year (17.02% vs. 10.59%, respectively, p < 0.05) and at 5 years (68.08% vs. 50.53%, p < 0.05). In the restrictive group, hospitalizations/ED visits due to HF decompensations at 1 year were significantly higher (85.11% vs. 57.89%, p < 0.05), with hospitalizations for ventricular arrhythmia being almost three times higher (21.28% vs. 7.37%, respectively, p < 0.05). The percentage of patients with a favorable evolution (in terms of NYHA class and quality of life) at the 1- and 5-year follow-ups were higher in the non-restrictive LVDFP group. The main prognostic predictors in patients with DCM at the 1-year follow-up were: restrictive LVDFP, age > 75 years, markedly dilated LV, comorbidities (DM, COPD), 2nd-degree mitral regurgitation and severe pulmonary hypertension (p < 0.05). (4) Conclusions: At the 1- and 5-year follow-ups, the presence of the restrictive LVDFP in DCM patients was independently associated with a poor prognosis, being the best clinical predictor for unfavorable evolution, after adjustment for other well-established predictive parameters in DCM patients.

Design of Ti-Mo-W Alloys and Its Correlation with Corrosion Resistance in Simulated Body Fluid (SBF)

Titanium and its based alloys are frequently selected for designing biomedical implants and it is thus necessary to study as detailed as possible their corrosion behavior in biological solutions, such as those in the human body environment. In this paper, with the use of molecular orbital calculation, we designed and developed alloys in the Ti-19Mo-xW system (x = 7, 8, 9, and 10 wt%) and investigated the influence of different contents of tungsten on the behavior of Ti-19Mo-xW alloy samples following corrosion in simulated body fluid (SBF). The values of Bo¯ (bond order) and Md¯ (the metal-orbital energy level) were calculated for each alloy and correlations were established between Bo¯ and the content of tungsten. It was found that with the increase in tungsten content, the value of Bo¯ increases. Regarding the values of the corrosion resistance in SBF that resulted from the investigated alloys, the Ti19Mo7W alloy is distinguished by the lowest value of the corrosion current density and the lowest corrosion rate.

Same Clinical Reality of Spontaneous Rupture of the Common Iliac Artery with Pseudoaneurysm Formation-Comparison of Two Therapeutical Solutions, Endovascular Stent-Graft and Open Surgical Correction, for Two Cases and Review of the Literature

The incidence of isolated iliac artery aneurysms is approximately 2% and common iliac artery pseudoaneurysms are even rarer. A pseudoaneurysm is a localized hemorrhage as opposed to an actual aneurysm, which affects the entire vascular wall. They are typically asymptomatic and only detectable accidentally while looking for other causes. If large and symptomatic, they typically exhibit pressure symptoms as a result of the compression of the structures around them. Common symptoms include generalized stomach pain, urological problems, gastrointestinal bleeding, and neurological symptoms such as leg paralysis or sciatica-like back pain. Rarely, they may exhibit hemodynamic instability together with an aneurysm rupture, which has a high fatality rate. Due to the unique presentation, the diagnosis is typically rarely made and there is little experience with treating it. We report two cases of common iliac artery pseudoaneurysm found in two patients who had no notable medical history and who we chose to repair through the endovascular technique in the first case, an approach that has gained more ground for vascular repair worldwide, making it the current go-to method, and for the second case we chose a more traditional approach, through open surgery.

Minimally Invasive Surgical Repair of a Partial Atrioventricular Canal Defect in a 20-Year-Old Patient-A Case Report and Review of Literature

The association of an ostium primum-type defect with a cleft anterior mitral valve is known in the medical literature as the partial form of an atrioventricular canal. We present a case report about a 20-year-old woman with minimal symptomatology that discovered her pathology on routine echocardiography. Today, surgical operation remains the gold standard in such pathologies, especially mandatory when there is important valvular regurgitation and left-to-right shunt. Currently living in the era of fast and good cosmetic outcomes, minimally invasive and endovascular approaches should be developed and more often practiced. This scientific presentation is the first step in showing our department steps in performing minimally invasive surgeries as a routine.

Giant Sternal Chondrosarcoma in a 50-Year-Old Patient

Chondrosarcomas represent approximately 20% of primary malignant bone cancers, being known as the most frequent neoplasia of the anterior thoracic wall. In our case, we present a case of a primary sternal chondrosarcoma in a 50-year-old female patient that has been polychemiotherapy and radiotherapy treated for breast cancer. Despite the initial treated malignancy of breast cancer in the personal pathologic history of the patient, it was discovered that the sternal tumor was not a metastatic disease from the breast neoplasm. After multiple investigations, the patient was successfully treated for the sternal chondrosarcoma after a radical sternal resection with a chest wall reconstruction completed with two titanium plates that were anchored on the ribs and with the placement of methyl methacrylate mesh.

Tibolone, alendronate, and simvastatin enhance implant osseointegration in a preclinical in vivo model

OBJECTIVES

The objective of the study was to evaluate and compare the effect of different drugs such as simvastatin, alendronate, and tibolone for titanium implant osseointegration enhancement.

MATERIALS AND METHODS

Eighty female albino Wistar rats were equally divided into five groups: Group I (ovariectomy), Group II (sham ovariectomy), Group III (alendronate + ovariectomy), Group IV (simvastatin + ovariectomy), and Group V (tibolone + ovariectomy). Three months after ovariectomy, we performed bilateral titanium intramedullary nailing in all groups, followed by oral administration of alendronate, simvastatin, or tibolone for 12 weeks. Examinations included micro-CT, mechanical pull-out test, histology, and bone serum markers.

RESULTS

Peri-implant micro-CT analysis showed a significantly higher overall bone tissue in tibolone compared to the ovariectomy group, while no significant difference was found between the treatment groups. Sham ovariectomy, alendronate, and tibolone groups had a higher body mass density compared to ovariectomy and simvastatin groups. All treatment groups had a greater thickness of the peri-implant compact bone layer compared to ovariectomy group, but the results were not statistically significant. Tibolone presented the highest values in pull-out test, but alendronate showed more consistently positive results compared to other groups. Osteocalcin had in the tibolone group almost three times the value in the ovariectomy group, but the results were not statistically significant.

CONCLUSION

The hypothesis that alendronate, simvastatin, and tibolone enhance the osseointegration process of intramedullary titanium implants in ovariectomized rats has been accepted, while tibolone could offer the best results.

Failure Analysis of Retrieved Osteosynthesis Implants

Failure of osteosynthesis implants is an intricate matter with challenging management that calls for efficient investigation and prevention. Using implant retrieval analysis combined with standard radiological examination, we evaluated the main causes for osteosynthesis implant breakdown and the relations among them for a series of cases. Twenty-one patients diagnosed with implant failure were assessed for this work. For metallurgical analysis, microscopy techniques such as scanning electron microscopy (SEM), stereomicroscopy, and optical microscopy were employed. The results showed that material structural deficiencies (nine patients) and faulty surgical techniques (eight patients) were the main causes for failure. An important number of patients presented with material structural deficiencies superimposed on an imperfect osteosynthesis technique (six patients). Consequently, the importance of failure retrieval analysis should not be overlooked, and in combination with other investigational techniques, must provide information for both implant manufacturing and design improvement, as well as osteosynthesis technique optimization.

New Dental Implant with 3D Shock Absorbers and Tooth-Like Mobility-Prototype Development, Finite Element Analysis (FEA), and Mechanical Testing

Background: Once inserted and osseointegrated, dental implants become ankylosed, which makes them immobile with respect to the alveolar bone. The present paper describes the development of a new and original implant design which replicates the 3D physiological mobility of natural teeth. The first phase of the test followed the resistance of the implant to mechanical stress as well as the behavior of the surrounding bone. Modifications to the design were made after the first set of results. In the second stage, mechanical tests in conjunction with finite element analysis were performed to test the improved implant design. Methods: In order to test the new concept, 6 titanium alloy (Ti6Al4V) implants were produced (milling). The implants were fitted into the dynamic testing device. The initial mobility was measured for each implant as well as their mobility after several test cycles. In the second stage, 10 implants with the modified design were produced. The testing protocol included mechanical testing and finite element analysis. Results: The initial testing protocol was applied almost entirely successfully. Premature fracturing of some implants and fitting blocks occurred and the testing protocol was readjusted. The issues in the initial test helped design the final testing protocol and the new implants with improved mechanical performance. Conclusion: The new prototype proved the efficiency of the concept. The initial tests pointed out the need for design improvement and the following tests validated the concept.