Anterior cruciate ligament (ACL) is one of the most commonly injured structures in distortion injuries of the knee joint. Currently, there is no consensus among the professional community regarding the basic principles and timing of ACL injury management. An analysis of several retrospective studies from the 2008-2023 period provides information on ACL preservation procedures and a comparison of these results with those of ACL reconstruction surgery using a graft. The most comprehensive information was provided by a large meta-analysis conducted by Van der List et al. in 2019, which compared 1101 patients from 13 studies who had undergone an ACL preservation surgery. Wilson et al. carried out a retrospective study of patients who underwent ACL repair with InternalBrace (Arthrex© implant system) ligament augmentation. In their meta-analysis, Van der List et al. reported the failure rate of 7-11% and the functional outcome score > 85% of maximum scores in the scoring systems used (Lysholm, KOOS, IKDC score) for the preservation procedures. Wilson et al. in their retrospective study reported the failure rate of 10.4% and the functional outcome > 87% of maximum scores in the scoring systems used. These values are consistent with similar outcomes reported in patients undergoing ACL reconstruction surgery using a graft. According to the available literature, the primary ACL refixation with InternalBrace augmentation for proximal ruptures appears to be a safe technique with satisfactory outcomes when properly timed and indicated. In acute proximal ruptures, this technique should be considered as an alternative to ACL reconstruction using a graft, with potential benefits of preserving the original tissue and proprioception of the ligament. A prospective randomized study which would compare these two surgical techniques is still lacking in the literature.
- Klíčová slova
- ACL, InternalBrace., primary repair, proximal rupture,
- MeSH
- lidé MeSH
- ligamentum cruciatum anterius chirurgie MeSH
- poranění předního zkříženého vazu * chirurgie MeSH
- rekonstrukce předního zkříženého vazu * metody MeSH
- retrospektivní studie MeSH
- výsledek terapie MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- anglický abstrakt MeSH
- časopisecké články MeSH
- přehledy MeSH
This study investigates the risk of head injuries, specifically concussions, from falling objects in workplace accidents. A case study focuses on a construction worker who sustained a head injury despite wearing a protective helmet. Utilizing finite element (FE) analysis, the helmet-head system was modeled to assess impact forces and head accelerations. The helmet, made of High-Density Polyethylene with a 6-point suspension system, was tested against falling objects of 332 g and 665 g. Simulations, conducted from heights of 5 to 25 m, revealed that objects weighing as little as 332 g could cause severe concussions from a 10-meter fall. These findings demonstrate that helmets, while mitigating some impact, absorb significantly less energy than the kinetic energy of falling objects. The analyses carried out confirmed the worker's statement that his injury was caused by a foreign object falling on his head, which was protected by a helmet.
- Klíčová slova
- Concussion, FE analysis, Fall from height, Forensic biomechanics, Head impact, Legal medicine,
- MeSH
- analýza metodou konečných prvků MeSH
- biomechanika MeSH
- komoce mozku * prevence a kontrola MeSH
- lidé MeSH
- pracovní nehody * prevence a kontrola MeSH
- prostředky k ochraně hlavy * MeSH
- úrazy pádem * prevence a kontrola MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- kazuistiky MeSH
BACKGROUND: This study is focused on the opening technique of the cervical vertebrae during laminoplasty which serves to substantially reduce the most severe adverse effects of the simple resection of posterior vertebral elements. This computational study aims to clarify by an optimisation approach what shape and position upon the lamina the groove should have. METHODS: The computational model was developed in the computational software COMSOL Multiphysics 5.6a based on a computer tomography data obtained from the C4 vertebra. For finding the optimal minimum or maximum of a function (surface), optimisation algorithms are developed following the Nelder-Mead algorithm. RESULTS: The reaction-opening force increases with a decreasing groove radius and an increasing position from the vertebra body. The created area increases with a decreasing groove radius and a decreasing position. As the opening happens mostly only above the groove, the opening area increases only in this location. Moreover, the von Mises stress peak value is almost twice as large as in the case of maximization of the opening area, which might result in breaking of the lamina as the thickness of the lamina would be reduced to its minimum. CONCLUSION: The groove radius and position can affect the opening force and the opening area in case of double door laminoplasty. The opening force is highly influenced by the groove position and radius. The best position for placing the groove is in the middle of the lamina and the radius of the groove should be as large as possible.
- Klíčová slova
- Laminoplasty, finite element method, groove position, optimisation, spine,
- MeSH
- algoritmy MeSH
- biomechanika MeSH
- krční obratle diagnostické zobrazování chirurgie MeSH
- laminoplastika * škodlivé účinky MeSH
- lidé MeSH
- počítačová rentgenová tomografie MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
The presented text deals with research into the influence of the printing layers' orientation on crack propagation in an AlSi10Mg material specimen, produced by additive technology, using the Direct Metal Laser Sintering (DMLS) method. It is a method based on sintering and melting layers of powder material using a laser beam. The material specimen is presented as a Compact Tension test specimen and is printed in four different defined orientations (topology) of the printing layers-0°, 45°, 90°, and twice 90°. The normalized specimen is loaded cyclically, where the crack length is measured and recorded, and at the same time, the crack growth rate is determined. The evaluation of the experiment shows an apparent influence of the topology, which is essential especially for possible use in the design and technical preparation of the production of real machine parts in industrial practice. Simultaneously with the measurement results, other influencing factors are listed, especially product postprocessing and the measurement method used. The hypothesis of crack propagation using Computer Aided Engineering/Finite Element Method (CAE/FEM) simulation is also stated here based on the achieved results.
- Klíčová slova
- AlSi10Mg, DMLS, compact tension specimen, crack, cyclic loading, fatigue, printing topology,
- Publikační typ
- časopisecké články MeSH
BACKGROUND: The expansion of the cervical vertebrae lamina appears to be crucial to related surgical procedures. The dimensions of the groove influence the strain concentration within the lamina of the vertebra and, thus, the potential success or failure of respective surgical procedure. The aim of this computational study is to clarify both the role of the size of the groove with concern to both the open door and the double door laminoplasty techniques. METHODS: Finite element models were created via computer tomography with varying lamina groove dimensions. Displacements were applied to the models at the open side of the vertebral arch and the vertebral body was constrained prior to movement along all the axes. The maximal opening size measured on the inner side of the lamina and the percentage increase in the initial spinal areas were subsequently analyzed. FINDINGS: The elastic strain concentration value was observed for the groove in all cases, while the maximal principal elastic strain concentration value was observed at the opposite side to the groove cut into the lamina, also in all cases. The maximal area increase related to the 4 mm groove accompanied by the preservation of the ventral cortex of the bone. INTERPRETATION: The study suggested three conclusions a) the wider the groove, the greater is the opening potential, b) the maximal opening size following laminoplasty is not dependent on the depth of the bone cut for this type of groove, c) no benefit accrues in terms of the opening size following the cutting of a supplementary groove at the beginning of the lamina.
- Klíčová slova
- Biomechanics, Double door, Finite element, Laminoplasty, Open door,
- MeSH
- krční obratle diagnostické zobrazování chirurgie MeSH
- laminoplastika * MeSH
- lidé MeSH
- počítačová rentgenová tomografie MeSH
- retrospektivní studie MeSH
- výsledek terapie MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
The purpose of the study was to compare the stability of the plate osteosyntheses of intra-articular calcaneal fractures using various types of a sustentacular screw insertions. A geometrical model of a calcaneal fracture was created. The fracture was fixed with a plate and screws with a uniform distribution. The individual models differed regarding the position of the sustentacular screw. The screw was inserted using three different variants: Model A: into the tip of sustentaculum tali, Model B: under the sustentaculum tali, and Model C: into the inferior peripherial rim of the sustentacular fragment. In all three variants, the screw was either locked into the plate via threads or unlocked. The model was loaded with force in the vertical direction. The stiffness of individual models was evaluated using the finite element method, which was expressed as the maximum force (Fmax) that the system was able to transmit and by determining the magnitude and distribution of reduced stress (σred) on the individual parts of the model of a fixed calcaneal fracture. The greatest stiffness of the system was observed in the Model B (Fmax = 335.8 N). The least stiffness was observed in Model C (Fmax = 296.3 N). This model also produced the greatest load on bone tissue was observed (σmaxred = 67.5 MPa). The least load on bone tissue was measured in Model B (σmaxred = 53.7 MPa). The load on the plate was similar in all three models (814.0-820.0 MPa). The analyses suggest that in a plate osteosynthesis of a calcaneal fracture, the insertion of a sustentacular screw under the tip of the sustentaculum tali is acceptable in terms of osteosynthesis stability. This sustentacular screw position reduces the risk of the screw penetrating into the talocalcaneal joint.
- Klíčová slova
- Sustentacular screw, calcaneus, finite element method, fracture, stability,
- MeSH
- biomechanika MeSH
- fraktury kostí * chirurgie MeSH
- kostní destičky MeSH
- kostní šrouby MeSH
- lidé MeSH
- patní kost * chirurgie MeSH
- vnitřní fixace fraktury MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
Rigid polyurethane (PUR) foam, which has an extensive range of construction, engineering, and healthcare applications, is commonly used in technical practice. PUR foam is a brittle material, and its mechanical material properties are strongly dependent on temperature and strain rate. Our work aimed to create a robust FE model enabling the simulation of PUR foam machining and verify the results of FE simulations using the experiments' results. We created a complex FE model using the Arbitrary Lagrangian-Eulerian (ALE) method. In the developed FE model, a constitutive material model was used in which the dependence of the strain rate, damage initiation, damage propagation, and plastic deformation on temperature was implemented. To verify the FE analyses' results with experimentally measured data, we measured the maximum temperature during PUR foam drilling with different densities (10, 25, and 40 PCF) and at various cutting speeds. The FE models with a constant cutting speed of 500 mm/s and various PUR foam densities led to slightly higher Tmax values, where the differences were 13.1% (10 PCF), 7.0% (25 PCF), and 10.0% (40 PCF). The same situation was observed for the simulation results related to various cutting speeds at a constant PUR foam density of 40 PCF, where the differences were 25.3% (133 mm/s), 10.1% (500 mm/s), and 15.5% (833 mm/s). The presented results show that the ALE method provides a good match with the experimental data and can be used for accurate simulation of rigid PUR foam machining.
- Klíčová slova
- Arbitrary Lagrangian Eulerian, PUR foam, finite element (FE) analyses, machining,
- Publikační typ
- časopisecké články MeSH
Rigid polyurethane (PUR) foam is products used as a biomedical material for medical device testing. Thermal stability is a very important parameter for evaluating the feasibility of use for testing surgical instrument load during drilling. This work aimed to perform experimental measurements to determine the dependence of the mechanical properties of a certified PUR on temperature, strain rate and density. Experimental measurements were realised for three types of the PUR samples with different density 10, 25 and 40 pounds per cubic foot. The samples were characterised in terms of their mechanical properties evaluated from tensile and compression tests at temperatures of 25 °C, 90 °C and 155 °C. Furthermore, the structures of the samples were characterised using optical microscope, their thermal properties were characterised by thermogravimetric analysis, and their density and stiffness with the effect of temperature was monitored. The results show that it is optimal not only for mechanical testing but also for testing surgical instruments that generate heat during machining. On the basis of experimental measurements and evaluations of the obtained values, the tested materials are suitable for mechanical testing of medical devices. At the same time, this material is also suitable for testing surgical instruments that generate heat during machining.
- Klíčová slova
- mechanical properties, polyurethane foam, rigid polyurethane foam, temperature, thermal loading,
- Publikační typ
- časopisecké články MeSH
The aim of our study was to identify potential critical levels of implantation of an osseointegrated prosthesis for above-knee amputees. The implant used was the OPRA system. It was inserted in the femur at four different amputation heights, characterized by their residual limb ratios (0.299, 0.44, 0.58 and 0.73). The stress and strain distribution was evaluated in the bone-implant system during walking, considering a body mass of 100 kg. Considerably high stimulus (11,489 με) in the tissue near the tip was found at the highest implantation level. All models presented small non-physiologic stress values in the tissue around the implant. The results revealed that the implantation level has a decisive effect on bone-implant performance. Mainly, the analysis indicates adverse biomechanical conditions for implantations in very short residual limbs.
- Klíčová slova
- Critical implantation level, OPRA system, above-knee amputees, finite element analysis, osseointegrated prosthesis, residual limb length,
- MeSH
- amputace MeSH
- amputovaní * MeSH
- femur fyziologie chirurgie MeSH
- implantace protézy * MeSH
- koleno chirurgie MeSH
- lidé středního věku MeSH
- lidé MeSH
- osteointegrace * MeSH
- testování materiálů MeSH
- zatížení muskuloskeletálního systému MeSH
- Check Tag
- lidé středního věku MeSH
- lidé MeSH
- mužské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
Ankle fractures are complex injuries with variable prognoses that depend upon many factors. The aim of the treatment is to restore the ankle joint biomechanical stability with maximum range of motion. Most ankle fractures are fibular fractures, which have a typical oblique fracture line in the distal fibula located in the area of the tibiofibular syndesmosis. The aim of this study was to simulate numerically several fixation techniques of the distal fibular fractures, evaluate their stability, determine their impact on surrounding tissue load, and correlate the results to clinical treatment experience. The following three models of fibular fracture fixation were used: (a) plate fixation with three screws attached above/below and lag screws, (b) plate fixation with two screws attached above/below and lag screws, and (c) three lag screws only. All three fracture fixation models were analyzed according to their use in both healthy physiological bone and osteoporotic bone tissue. Based on the results of Finite Element Analysis for these simulations, we found that the most appropriate fixation method for Weber-B1 fibular fractures was an unlocked plate fixation using six screws and lag screws, both in patients with physiological and osteoporotic bone tissue. Conversely, the least appropriate fixation method was an unlocked plate fixation with four screws and lag screws. Although this fixation method reduces the stress on patients during surgery, it greatly increased loading on the bone and, thus, the risk of fixation failure. The final fixation model with three lag screws only was found to be appropriate only for very limited indications.
- MeSH
- analýza selhání vybavení MeSH
- biologické modely * MeSH
- fibula zranění patofyziologie chirurgie MeSH
- fraktury kotníku patofyziologie chirurgie MeSH
- kostní destičky * MeSH
- lidé MeSH
- mechanický stres MeSH
- pevnost v tahu MeSH
- pevnost v tlaku MeSH
- počítačová simulace MeSH
- protézy - design MeSH
- tření MeSH
- vnitřní fixace fraktury přístrojové vybavení metody MeSH
- výsledek terapie MeSH
- zatížení muskuloskeletálního systému MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
