Computational Fluid Dynamic Analysis of customised 3D-printed bone scaffolds with different architectures.

Through the recent years, tissue engineering has been proven as a solid substitute of autografts in the stimulation of bone tissue regeneration, through the development of three dimensional (3D) porous matrices, commonly known as scaffolds. In this work, we analysed two scaffold structures with 500µm pore size, by performing computational fluid dynamics simulations, to compare permeability, Wall Shear Stress (WSS), velocity and pressure distributions. Taking into account those parameters the geometry named as "PCL-50" was the best to anticipate showing a superior performance in supporting cell growth due to the improved flow characteristics in the scaffold.Clinical Relevance- Bone defects that require invasive surgical treatment with high risks in terms of success and effectiveness. Bone tissue engineering (BTE) in combination with the use of computational fluid dynamics (CFD) analysis tools aim to assist in designing optimal scaffolds that better promote bone growth and repair. The fluid dynamic characteristics of a porous scaffold plays a vital role in cell viability and cell growth, affecting the osteogenic performance of the scaffold.

Comparison of the Weil and Triple Weil Osteotomies: A Clinical Retrospective Study.

INTRODUCTION: The Weil and triple Weil osteotomies are two widely used procedures in the surgical treatment of metatarsalgia. The aim of this comparative retrospective study was to evaluate the functional results and determine the complications of the two types of osteotomies in a series of patients who underwent surgery due to third rocker metatarsalgia. MATERIAL AND METHODS: In this paper, 71 patients were included between September 2015 and October 2020. The average age was 58 years old (age range: 28-72). Of all the patients, 27 suffered from metatarsalgia due to systemic (extra-regional) or regional diseases were excluded. The remaining 44 patients, after six months of unsuccessful conservative treatment, underwent surgery. Based on the preoperative planning to restore the peripheral parabolic curve of the metatarsals, when a shortening of less than or equal to 3 mm was required, a Weil osteotomy was performed. However, when a shortening of more than 3 mm was required, a triple Weil osteotomy was performed. Therefore, two groups of patients were formed, and a total of 90 osteotomies were performed. During the postoperative period, all the patients were clinically and radiographically assessed. The American Orthopedic Foot and Ankle Society (AOFAS) score was used for the assessment of the functional result, while the pain was assessed using the Visual Analogue Scale (VAS). RESULTS:  The mean follow-up was 24 months. The average operative time for the Weil and the triple Weil osteotomies was 22.8 minutes and 31.5 minutes, respectively. In group A, preoperatively, the average AOFAS score was 31/100, and postoperatively, it was 89/100. In group B, the corresponding values were 30/100 and 93/100, respectively. In group A, the preoperative VAS score was 7.8/10, while the postoperative VAS score was 1.3/10. In group B, the corresponding values were 8.2/10 and 1.7/10, respectively. In group A, stiffness had a percentage equal to 60.9%, and a floating toe was noticed in 16 osteotomies. In group B, superficial infection represented the commonest complication, with an incidence of 25.6%. CONCLUSION: Both Weil and triple Weil osteotomies are effective procedures in the surgical treatment of patients who suffer from third-rocker metatarsalgia. In both cases, correct preoperative planning is of paramount importance for the outcome. However, in terms of the appearance of the floating toe, it seems that in cases where a ray's shortening of more than 3 mm is required, the triple osteotomy is superior to the Weil osteotomy.

Biomechanical Analysis of the Change of the Metatarsophalangeal Joint's Center of Rotation After Weil and Triple Weil Osteotomies: A Comparative Cadaveric Study.

Background The aim of the present biomechanical study on cadavers was to determine both the center of rotation of the metatarsophalangeal joints and the position of the tendons of the interosseous muscles after the Weil and triple Weil osteotomies, and to compare these parameters in order to clarify the pathogenesis of dorsal stiffness and floating toe. Materials and methods Seven fresh-frozen cadaveric feet were utilized. After completing the preparation of both the plantar and the dorsal surface, we performed the dissection of the entire second, third and fourth rays, and each ray was fixed to a wooden wall mounted on a movable frame. The biomechanical analysis was based on an equilibrium system made of pulleys, threads, and variable weights. Geometrical analysis of both osteotomies and fluoroscopy was used to determine the initial and final metatarsophalangeal joint's center of rotation, as well as the change of interosseous muscles position. Results On comparing the results of the findings, we noticed that after Weil osteotomy, the metatarsophalangeal joint's center of rotation was proximally and plantarly displaced by 3.5 mm compared to the control group, and by 3.7 mm in comparison to the triple Weil osteotomy group. In the latter, the center of rotation was displaced by 0.817 mm compared to the control group. Furthermore, after the Weil osteotomy, the position of the interossei tendon was above the metatarsal longitudinal axis. Conclusion In cases where a metatarsal shortening of 5 mm or greater is desired, the Weil osteotomy causes a statistically significant plantar displacement of the metatarsophalangeal joint's center of rotation, compared to cases where triple Weil osteotomy is performed.

Recellularization potential of small diameter vascular grafts derived from human umbilical artery.

BACKGROUND: The primary therapeutic strategy in cardiovascular disease is the coronary artery bypass surgery, which in- volves the use of small diameter vascular grafts (<6 mm). Human umbilical arteries could be used as a source for the development of these grafts. OBJECTIVE: The aim of this study was the decellularization of human umbilical arteries and the evaluation of their re- cellularization potential. METHODS: Decellularization of human umbilical arteries was performed with a detergent based protocol. Histological analysis was performed in order to determine the effect of decellularization. Then, recellularization was performed by using two different approaches. The first approach was the dynamic seeding of human umbilical arteries with Mesenchymal Stromal Cells and the second approach involved the recellularization by using a bioreactor system. RESULTS: Histological analysis showed the successful removal of cellular and nuclear materials from the umbilical arteries. In addition, successful recellularization of the vessels was observed with both approaches. CONCLUSION: The results of this study indicated that human umbilical arteries could serve as an alternative material for the proper development of small diameter vascular grafts.

Biomechanical evaluation of plating techniques for fixing mandibular angle fractures: the introduction of a new 3D plate approach.

PURPOSE: The aim of this study was to comparatively evaluate the use of a three-dimensional (3D) square-shaped plate for the treatment of mandibular angle fractures. MATERIALS AND METHODS: Synthetic mandible replicas were used to evaluate the effectiveness of the 3D square plate along with three other mandibular angle plating techniques. The plating techniques consisted of: (1) a 3D miniplate (2 x 2 holes, square, 2 mm); (2) a 3D miniplate (6 x 2 holes, curved, 2 mm); (3) two miniplates (four holes, straight, 2 mm and 1.6 mm); and (4) one single miniplate (four holes, straight, 2 mm). Each group was subjected to incisal and homolateral molar region loading by a tensile materials testing machine (Monsanto Tensometer 20). Load stiffness values and peak measurements of the fracture gap distraction at the superior aspect of the mandible were measured. The mean values (+/-standard deviation) were derived and compared using one-way analysis of variance, with statistical significance set at p < 0.05. RESULTS: For homolateral molar loading, statistically significant differences existed within groups (p < 0.05). For incisal edge loading, no statistically significant differences were found for stiffness among the fixation methods tested. Gap distraction at the superior aspect of the mandible was limited for three of the groups tested. CONCLUSION: Under the conditions tested, the 3D square plate system provided the most favorable mechanical behavior.