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Electromechanical delay of the knee flexors muscles after anterior cruciate ligaments reconstruction using semitendinosus tendon. Preliminary study
No full textIncreasing in electromechanical delay has been found in patients after ACL reconstruction using both semitendinosus and gracilis tendons. Using only one tendon may improve electromechanical delay results in patients after ACL reconstruction surgery. The purpose of the study is to evaluate electromechanical delay in ACL reconstruction patients after one tendon surgery technique. In particular, in this study, patients undergone the reconstruction surgery using the semitendinosus tendon will be evaluated. An isokinetic dynamometer will be used for the test. After warming up, patients will be ask to perform a maximally explosive isometric
A Novel Approach for Patellofemoral Tracking Using a Knee Model Reconstructed with a Three-Dimensional Printer
No full textThis study proposes a new approach to evaluate the patellofemoral tracking using a knee model composed of femur, tibia, and patella reconstructed with a three-dimensional (3D) printer. Magnetic resonance images were used to create a CAD (Computer-Aided Design) file that is subsequently used as input for a 3D printer machine. Artificial ligaments were used to mimic the stability of the knee. The quadriceps tendon was simulated using a polyvinylchloride cord attached to the tibial insertion and the patella. The model was fixed to a tensile test machine and four static tests were performed by applying 200 N load in the proximal–distal direction through the cord at 30°, 60°, and 90° of knee flexion. The position of the patella was measured using a motion-tracking system with a custom-made navigation system. The mediolateral displacement of the patella was 1.01 ± 0.13 mm at 30° of knee flexion and 7.99 ± 0.07 mm at 90° of flexion. The patella lateral tilt was 2.79° ± 0.67° at 30° of flexion and 6.42° ± 0.11° at 90° of flexion. In conclusion, our low-cost knee model closely simulates the patellar behavior of cadaveric specimens as the results are in agreement with literature data on similar static in vitro experiments
Quadriceps muscles activity during gait: comparison between PFPS subjects and healthy control
No full textPurpose
The purpose of the study was to evaluate if during a common activity as walking,
altered quadriceps muscular activity may be present in patellofemoral pain
syndrome (PFPS) patients.
Methods
Forty subjects with clinically diagnosed PFPS and forty healthy males matching
in age, weight, height and level of sport activity were enrolled in the study.
Subjects were asked to walk on an instrumented walking path at their selfselected
speed. Force platform and motion tracking system were used for the analysis of
the gait. Wireless surface EMG probes were used to evaluate quadriceps muscles
activity. Rectus femoris, vastus medialis and lateralis activity percentage, onset
and offset time, walking speed, cadence, step length, stride length, knee ROM
during gait were measured and reported. Tegner activity questionnaire was
reported.
Results
Patient group showed a significant increasing in all quadriceps muscles activity
when compared to the control (p < 0.05). In particular, for VM and VL muscle
onset time was anticipated and offset time was postponed in PFPS group when
compared with healthy group (p < 0.05). Knee range of motion during walking
was significantly decreased in the patient group.
Conclusions
Young athletes with PFPS showed increased length of quadriceps muscles activity
and reduced functional knee Rom while walking, comparing with healthy
subjects, in particular muscular onset was anticipated in respect of the loading
response event of the gait. Nonetheless, walking parameters were not affected by
these alterations
Electromechanical delay of the knee flexor muscles after anterior cruciate ligament reconstruction using semitendinosus tendon.
No full textThe purpose of the study was to evaluate whether using only the semitendinosus as a tripled short graft would affect the electromechanical delay (EMD) of the knee flexors. EMD was evaluated in volunteers (N = 15) after they had undergone surgery for anterior cruciate ligament (ACL) reconstruction where the semitendinosus tendon alone was used as a graft. The results were compared with the intact leg and healthy controls (N = 15). After warming up, each subject performed four maximally explosive isometric contractions on an isokinetic dynamometer. Torques were measured by the dynamometer, while the electrical activity of the semitendinosus and biceps femoris muscles was detected using surface electromyography. EMD was found to be significantly increased (p = 0.001) in patients who had undergone ACL reconstruction compared to the controls. On the contrary, no significant differences (p = 0.235) were found for the biceps femoris muscle between the two groups. Similar results were found when the study group was compared with the intact leg group (p = 0.027 for semitendinosus and p = 0.859 for biceps femoris). Harvesting the semitendinosus tendon increases the EMD for the semitendinosus muscle but does not influence the EMD outcomes for the biceps femoris muscle
Biomechanical behaviour of native and sutured bronchi. An in-vitro study
No full textBACKGROUND: Biomechanical behaviour evaluation of a suture is an important information for the surgeon to choose the best technique to perform. OBJECTIVE: To assess the biomechanical behavior of the native and mechanically sutured bronchi. METHODS: Ten bronchi were harvested from slaughtered pigs and then randomly separated in two groups, a control intact group and a sutured group where specimens were cut in half and sutured, to evaluate mechanical properties during a tensile test using a loading frame machine. In addition optoelectric motion tracking system was used to evaluate suture profile motion during the test. RESULTS: Significant differences (p < 0.05) were found between the two groups for the parameters investigated. The control group showed a higher maximal stress resistance and stiffness than the suture group, while elongation at rupture was increased in the sutured group. All the sutures broke in symmetric manner, as the mean of the side difference of the sutured specimens was 0.93 ± 0.80 mm at rupture. CONCLUSIONS: Biomechanical behaviour of native and sutured bronchi was evaluated, giving highly reproducible parameters regarding mechanical properties that may help clinicians and bioengineers to rationalize the choice for a particular suture material or suture technique, increasing surgical outcomes
Electromechanical delay of the knee flexor muscles after anterior cruciate ligament reconstruction using semitendinosus tendon
No full text
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Pericardium matrix buttressing hinders the stapled bronchial stump healing
No full textBackground Biomechanical and histological properties of stapled bronchi with and without bovine pericardial matrix plus collagen reinforcement are analyzed. Materials and methods Pneumonectomy with mechanical bronchial suture was performed in the swine model. Pigs were randomly assigned to three groups: three-row staplers without reinforcement (Traditional), with reinforcement (Buttressed) and control "wild type", non-resected normal bronchus (Normal). Intraoperative test was carried for air leaks at 20/30/40 mm Hg endobronchial pressure. After 60 d, tracheobronchial specimen was harvested, stocked, and analyzed. Tensile test was performed using INSTRON 5965 loading frame machine. Maximal strain resistance value, length of elongation at rupture parameter, and stiffness coefficient (K) were evaluated. Histological analysis was performed. Sample size calculation was assessed (four per group), and the Student t-test was used to statistically evaluate differences in biomechanical variables. Results No fistula occurred. Biomechanical analysis showed that maximal strain resistance is 41.22 ± 2.11 N (Traditional), 24.53 ± 3.47 N (Buttressed), and 30.91 ± 0.29 N (Normal); elongation at rupture is 16.01 ± 1.82 mm (Traditional), 12.89 ± 0.48 mm (Buttressed), and 9.32 ± 0.11 mm (Normal). Finally, K is 2.59 ± 0.16 N/mm (Traditional), 1.91 ± 0.33 N/mm (Buttressed), and 3.32 ± 0.01 N/mm (Normal). Stumps without reinforcement proved higher resistance and length of elongation than reinforced ones. Normal bronchial tissue shows the highest stiffness coefficient. Statistical analysis produced significant values for each biomechanical feature. Group Buttressed stumps show greater thickness and a substantial inflammatory reaction with granulation tissue along the whole scar and around areas of discontinuity within the scar, not yet healed. Conclusions Reinforcing the mechanical suture line of bronchial stump with bovine pericardial matrix plus collagen shows suboptimal biomechanical and histological characteristics compared to using the stapler alone
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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