Large bone defect treatments have always been one of the important challenges in clinical practice and created a huge demand for more efficacious regenerative approaches. The bone tissue engineering (BTE) approach offered a new alternative to conventional bone grafts, addressing all clinical needs. Over the past years, BTE research is focused on the study and realisation of new biomaterials, including 3D-printed supports to improve mechanical, structural and biological properties. Among these, polylactic acid (PLA) scaffolds have been considered the most promising biomaterials due to their good biocompatibility, non-toxic biodegradability and bioresorbability. In this work, we evaluated the physiological response of human foetal osteoblast cells (hFOB), in terms of cell proliferation and osteogenic differentiation, within oxygen plasma treated 3D-printed PLA scaffolds, obtained by fused deposition modelling (FDM). A mechanical simulation to predict their behaviour to traction, flexural or torque solicitations was performed. We found that: 1. hFOB cells adhere and grow on scaffold surfaces; 2. hFOB grown on oxygen plasma treated PLA scaffolds (PLA_PT) show an improvement of cell adhesion and proliferation, compared to not-plasma treated scaffolds (PLA_NT); 3. Over time, hFOB penetrate along strands, differentiate, and form a fibrous matrix, tissue-like; 4. 3D-printed PLA scaffolds have good mechanical behaviour in each analysed configuration. These findings suggest that 3D-printed PLA scaffolds could represent promising biomaterials for medical implantable devices in the orthopaedic field.

Background: Patellar instability can cause pain and disability. A finite element model of a healthy human knee was performed to analyze the role of quadriceps and medial retinaculum imbalance in patellar instability. Methods: The model was created by matching magnetic resonance and computed tomography images of a normal adult patient’s knee. Muscle force intensities were calculated by static optimization, considering the lower limb muscles, knee movement and the ground reaction during walking. Patellar instability was experimentally generated by progressively uncoupling muscular forces, (90 N versus 110 N), while at the same time, the load derived from the quadriceps was gradually reduced by 20%. Results: This loss in force symmetry of 10 N on the retinaculum may produce a displacement of approximately 7 mm, with an increase in patellar contact forces of approximately 44%. When the quadriceps force is reduced by 10% and the unbalanced medial retinaculum acts together, the displacements are in the order of 14 mm, and the patellar contact forces increase by 84%. Conclusion: A reduced quadriceps force alone is not able to cause significant patellar instability, while an imbalance of forces at the level of the retinaculum could lead to patellar instability, especially when the two effects are combined. A better understanding of joint relationships and muscle synergies can help to improve clinical approaches to patella instability

Clavicle midshaft fractures are mostly treated surgically by open internal reduction with a superior or anteroinferior plate and screws or by intramedullary nailing. Screw positioning plays a critical role in determining the stress distribution. There is a lack of data on the screw position and the appropriate number of cortices required for plate fixation. The aim of this study is to evaluate the mechanical behavior of an anterior plate implanted in a fractured bone subjected to 120° of lateral elevation compared to a healthy clavicle using numerical simulations. Contact forces and moments used were obtained from literature data and applied to the healthy and fractured finite element models. Stresses of about 9 MPa were found on the healthy clavicle, while values of about 15 MPa were calculated on the plate of the fractured one; these stress peaks were reached at about 30° and 70° of elevation when the stress shielding on the clavicle sums all the three components of the solicitation: compression, flexion, and torsion. The stress distribution in a clavicle fracture stabilized with plates and screws is influenced by several factors, including the plate’s position and design, the type of screw, and the biomechanical forces applied during movements.

The purpose of this article is to investigate the effects of the fibula on the torsional stiffness of the lower limb. A comprehensive model of the lower limb was constructed, including the resected femur, patella, tibia, fibula, and foot, with tendons and ligaments. Two configurations were developed, with and without the presence of the fibula, to evaluate the resulting stress state and consequently determine the contribution of the fibula to the torsional stiffness of the lower limb. The finite element method was used to analyse how the fibula affects the stress distribution in the lower extremity under body weight loading and torsional forces. A detailed three-dimensional solid model of the lower extremity with and without the fibula was constructed. Loading conditions were imposed simulating an axial compressive load of 700 N applied to the upper extremity of the resected femur and a torsional load of 6000 Nmm applied to the proximal femur, and a fixed constraint was imposed on the foot. Removing the fibula results in an increase in stress on all the tendons and ligaments tested. The increases ranged from 4 % (patellar tendon) to 21 % (lateral retinaculum). This suggests that the fibula plays a significant role in the distribution of mechanical stress in the lower extremity. The most affected structures are the lateral retinaculum and the posterior cruciate ligament, both with a 21 % increase in stress, suggesting that these structures may compensate more for the absence of the fibula. The fibula plays a critical role in maintaining the structural integrity and biomechanical function of the lower extremity. It acts as a lateral strut, contributing to the stability of the ankle and knee by providing an attachment point for several muscles and ligaments that are essential for coordinating complex movements and providing stability during dynamic activities.

The impact of COVID-19 on sport and physical activity has been a subject of considerable interest and concern. Padel satisfies the desire for social interaction and a return to sport after a period of inactivity. The aim of this study is to show a correlation between return to sport and related injuries in a population of Padel players. The study was carried out in a survey mode, consisting of a questionnaire with four sections and fifty questions on the biographical data of the individual, lifestyle before and after the pandemic, knowledge and playing level of Padel and injuries. The self-administered online questionnaire was developed and validated by a panel of physiotherapists, orthopaedic surgeons, and physiatrists with experience in clinical practice and/or musculoskeletal research. The study was conducted in a survey mode from a smartphone or computer via a link to a multiple-choice document. The link to the questionnaire was distributed via mailing lists, social media, and chat applications.