1,078 research outputs found
BIOINGEGNERIA DEL SISTEMA MOTORIO
No full textL’opera tratta con ottica ingegneristica i seguenti argomenti: la conoscenza del
sistema motorio, la bioingegneria del movimento, l’analisi e la sintesi del movimento
umano. L’obiettivo non è solo quello di fornire allo studente di bioingegneria
un’impostazione metodologica atta ad affrontare i numerosi e diversificati
problemi che si possono incontrare nello studio del movimento umano, ma anche
di fornirgli le conoscenze di base per comprendere le problematiche del settore e
dialogare con competenza con colleghi di formazione medica. Da questo punto di
vista la trattazione può risultare interessante e formativa anche per medici, fisioterapisti,
tecnici ortopedici e preparatori atletici e favorire l’integrazione di competenze
multidisciplinari su argomenti che, di fatto, multidisciplinari lo sono
The effects of external loads and muscle forces on the knee joint ligaments during walking: A musculoskeletal model study
No full textA musculoskeletal model was developed to analyze the tensions of the knee joint ligaments during walking and to understand how they change with changes in the muscle forces. The model included the femur, tibia, patella and all components of cruciate and collateral ligaments, quadriceps, hamstrings and gastrocnemius muscles. Inputs to the model were the muscle forces, estimated by a static optimization approach, the external loads (ground reaction forces and moments) and the knee flexion/extension movement corresponding to natural walking. The remaining rotational and translational movements were obtained as a result of the dynamic equilibrium of forces. The validation of the model was done by comparing our results with literature data. Several simulations were carried out by sequentially removing the forces of the different muscle groups. Deactivation of the quadriceps produced a decrease of tension in the anterior cruciate ligament (ACL) and an increase in the posterior cruciate ligament (PCL). By removing the hamstrings, the tension of ACL increased at the late swing phase, while the PCL force dropped to zero. Specific effects were observed also at the medial and lateral collateral ligaments. The removal of gastrocnemius muscles produced an increase of tension only on PCL and lateral collateral ligaments. These results demonstrate how musculoskeletal models can contribute to knowledge about complex biomechanical systems as the knee joint
The effects of a posterior-stabilized prosthesis on knee ligament loads during walking: a musculoskeletal modelling study
No full textBackground
The correct balancing of the knee joint ligaments in case of total knee arthroplasty is fundamental for the functional outcome. Hence, it could be of interest for surgeons to understand how the ligaments' tension and intraarticular forces change after the implantation of a knee prosthesis, not only in clinical tests but particularly during functional activities. Many studies have compared the effects of different implant designs but without any reference to changes compared to the natural knee.
Methods
In this study, a posterior-stabilized prosthesis was virtually implanted in a three-dimensional musculoskeletal model of the knee joint. Through a dynamic simulation of the gait cycle, the knee kinematics, ligaments' tension and tibial-femoral contact force were quantified and compared with those obtained by the intact knee model.
Findings
In the presence of the prosthesis, the tibia preserved the two peaks of anterior displacement in correspondence with the peaks of knee flexion, even if reduced in relation to the intact knee. The superficial and deep Medial Collateral Ligaments supported the highest load, compensating for the absence of the cruciate ligaments. After the introduction of the prosthesis, the tibial-femoral contact force showed the same trend obtained in the natural knee model, however it appeared reduced compared to the intact knee condition and approached the experimental data recorded by an instrumented prosthesis.
Interpretation
This study quantified the changes induced by the posterior-stabilized implant in terms of kinematics, ligament tensions and intraarticular forces during walking, demonstrating how musculoskeletal models can support gaining insight into complex biomechanical systems
L’ordre de la charité et la charité en son ordre: Jean-Luc Marion, interprète de Pascal
No full text
The effects of a posterior cruciate ligament injury on the knee joint biomechanics during walking
No full textThe effects of anterior cruciate ligament sacrifice on the behavior of the knee joint, tested through the use of a musculoskeletal model Abstracts
No full textFausto Sozzini, la mortalità d’Adamo e la teologia moderna
No full textFausto Sozzini, Adam's Mortality and Early Modern Theology. In his dispute with Francesco Pucci, Fausto Sozzini argues that man was not created immortal but, being by nature subject to death, he could be made perpetually immune only through divine grace, which was a gift not included in his creation. It has thus been suggested that the Pucci-Sozzini querelle should be read as an expression of the broader debate that opposed the two 'souls' of modern theology, that is the Thomistic and the Augustinian. By reconstructing the late medieval theological debate on the mortality of Adam in the condition of innocence, the Author tries to show that Sozzini's theses are greatly indebted to Duns Scotus' criticisms of Thomas Aquinas
The effects of the rectus femoris muscle on knee and foot kinematics during the swing phase of normalwalking
No full textThe role of rectus femoris (RF) muscle during walking was analyzed through musculoskeletal models to understand the effects of muscle weakness and hyperactivity. Such understanding is fundamental when dealing with pathological gait, but the contribution of RF as a bi-articular muscle is particularly difficult to estimate. Anybody software was used for inverse dynamics computation, and SimWise-4D for forward dynamics simulations. RF force was changed in the range of 0 to 150%, and the resulting kinematics were analyzed. Inverse dynamics showed a short positive RF power in correspondence with the onset of knee extension in the swing phase. Forward dynamics simulations showed an increasing knee flexion and initial toe contact when the RF force was decreased, and increasing knee extension and difficult foot clearance when the RF force was increased. The step became shorter with both increased and reduced RF force. In conclusion, the RF actively contributes to the knee extension in the swing phase. RF also contributes to obtaining a proper step length and to preparing the foot for initial heel contact. So the effect of RF muscle as a bi-articular muscle seems fundamental in controlling the motion of distal segments. RF overactivity should be considered as a possible cause for poor foot clearance in some clinical cases, while RF weakness should be considered in cases with apparent equinus
- …
