Comparison of four different screw configurations for the fixation of Fulkerson osteotomy: a finite element analysis.

BACKGROUND: Conventionally, two 4.5 mm cortical screws inserted toward the posterior tibial cortex are usually advocated for the fixation of Fulkerson osteotomy. This finite element analysis aimed to compare the biomechanical behavior of four different screw configurations to fix the Fulkerson osteotomy. MATERIALS AND METHODS: Fulkerson osteotomy was modeled using computerized tomography (CT) data of a patient with patellofemoral instability and fixed with four different screw configurations using two 4.5 mm cortical screws in the axial plane. The configurations were as follows: (1) two screws perpendicular to the osteotomy plane, (2) two screws perpendicular to the posterior cortex of the tibia, (3) the upper screw perpendicular to the osteotomy plane, but the lower screw is perpendicular to the posterior cortex of the tibia, and (4) the reverse position of the screw configuration in the third scenario. Gap formation, sliding, displacement, frictional stress, and deformation of the components were calculated and reported. RESULTS: The osteotomy fragment moved superiorly after loading the models with 1654 N patellar tendon traction force. Since the proximal cut is sloped (bevel-cut osteotomy), the osteotomy fragment slid and rested on the upper tibial surface. Afterward, the upper surface of the osteotomy fragment acted as a fulcrum, and the distal part of the fragment began to separate from the tibia while the screws resisted the displacement. The resultant total displacement was 0.319 mm, 0.307 mm, 0.333 mm, and 0.245 mm from the first scenario to the fourth scenario, respectively. The minimum displacement was detected in the fourth scenario (upper screw perpendicular to the osteotomy plane and lower screw perpendicular to the posterior tibial cortex). Maximum frictional stress and maximum pressure between components on both surfaces were highest in the first scenario (both screws perpendicular to the osteotomy plane). CONCLUSIONS: A divergent screw configuration in which the upper screw is inserted perpendicular to the osteotomy plane and the lower screw is inserted perpendicular to the posterior tibial cortex might be a better option for the fixation of Fulkerson osteotomy. Level of evidence Level V, mechanism-based reasoning.

Bespoke Implants for Cranial Reconstructions: Preoperative to Postoperative Surgery Management System.

Traumatic brain injury is a leading cause of death and disability worldwide, with nearly 90% of the deaths coming from low- and middle-income countries. Severe cases of brain injury often require a craniectomy, succeeded by cranioplasty surgery to restore the integrity of the skull for both cerebral protection and cosmetic purposes. The current paper proposes a study on developing and implementing an integrative surgery management system for cranial reconstructions using bespoke implants as an accessible and cost-effective solution. Bespoke cranial implants were designed for three patients and subsequent cranioplasties were performed. Overall dimensional accuracy was evaluated on all three axes and surface roughness was measured with a minimum value of 2.209 µm for Ra on the convex and concave surfaces of the 3D-printed prototype implants. Improvements in patient compliance and quality of life were reported in postoperative evaluations of all patients involved in the study. No complications were registered from both short-term and long-term monitoring. Material and processing costs were lower compared to a metal 3D-printed implants through the usage of readily available tools and materials, such as standardized and regulated bone cement materials, for the manufacturing of the final bespoke cranial implants. Intraoperative times were reduced through the pre-planning management stages, leading to a better implant fit and overall patient satisfaction.

Design and Additive Manufacturing of Medical Face Shield for Healthcare Workers Battling Coronavirus (COVID-19).

During the coronavirus disease-19 pandemic, the demand for specific medical equipment such as personal protective equipment has rapidly exceeded the available supply around the world. Specifically, simple medical equipment such as medical gloves, aprons, goggles, surgery masks, and medical face shields have become highly in demand in the health-care sector in the face of this rapidly developing pandemic. This difficult period strengthens the social solidarity to an extent parallel to the escalation of this pandemic. Education and government institutions, commercial and noncommercial organizations and individual homemakers have produced specific medical equipment by means of additive manufacturing (AM) technology, which is the fastest way to create a product, providing their support for urgent demands within the health-care services. Medical face shields have become a popular item to produce, and many design variations and prototypes have been forthcoming. Although AM technology can be used to produce several types of noncommercial equipment, this rapid manufacturing approach is limited by its longer production time as compared to conventional serial/mass production and the high demand. However, most of the individual designer/maker-based face shields are designed with little appreciation of clinical needs and nonergonomic. They also lack of professional product design and are not designed according to AM (Design for AM [DfAM]) principles. Consequently, the production time of up to 4 - 5 h for some products of these designs is needed. Therefore, a lighter, more ergonomic, single frame medical face shield without extra components to assemble would be useful, especially for individual designers/makers and noncommercial producers to increase productivity in a shorter timeframe. In this study, a medical face shield that is competitively lighter, relatively more ergonomic, easy to use, and can be assembled without extra components (such as elastic bands, softening materials, and clips) was designed. The face shield was produced by AM with a relatively shorter production time. Subsequently, finite element analysis-based structural design verification was performed, and a three-dimensional (3D) prototype was produced by an original equipment manufacturer 3D printer (Fused Deposition Modeling). This study demonstrated that an original face shield design with <10 g material usage per single frame was produced in under 45 min of fabrication time. This research also provides a useful product DfAM of simple medical equipment such as face shields through advanced engineering design, simulation, and AM applications as an essential approach to battling coronavirus-like viral pandemics.