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.

• 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

• MeSH
• anatomie MeSH
• Publikační typ
• biografie MeSH
• nekrology MeSH

• O autorovi
• Čihák, Radomír, 1928-2016 Autorita

It is a well-known fact that the length of an artery in situ and the length of an excised artery differs. Retraction of blood vessels is usually observed. This pre-tension plays crucial role in arterial biomechanics. It augments an artery wall load-bearing capacity. This paper presents the longitudinal pre-strain of the human aorta as an index of human age. The length of abdominal aortas was measured during autopsies before and after segment resection. The longitudinal pre-strain was calculated in 130 donors; 100 male and 30 female bodies. The pre-strain was defined as the ratio between in situ length and the length after the excision. The mean pre-strain was found to be 1.18±0.10 for male and 1.14±0.10 for female sample (mean±standard deviation). The age in the male group was 41.6±15.9 years; and 47.7±17.7 years in the female group. Statistical analysis revealed the correlation coefficient between age and pre-strain r=-0.821 and r=-0.839 in male and female group, respectively. The analysis also confirmed close correlation between aortic circumference and age; and between circumference and pre-strain. Linear and power law regression equations were employed and prediction intervals were computed. The power law estimates the age more accurately than linear one model. Nevertheless, especially for small values of the pre-strain (aged individuals) the linear model can be advantageous.

• MeSH
• aorta abdominalis patologie   MeSH
• aterosklerotický plát patologie   MeSH
• ateroskleróza patologie   MeSH
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• mechanický stres MeSH
• regresní analýza MeSH
• soudní patologie MeSH
• stárnutí fyziologie   MeSH
• Check Tag
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

• MeSH
• analýza metodou konečných prvků * MeSH
• kolenní kloub anatomie a histologie   fyziologie   MeSH
• lidé MeSH
• modely anatomické MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

The longitudinal prestrain of arteries facilitates their physiological function. Remodeling, adaptation and aging result in an age-dependent magnitude of the pretension. Although the phenomenon is known, detailed statistics, especially for human arteries, are lacking. This study was designed to propose the regression model capable of estimating the prestrain of the human abdominal aorta. The length of the abdominal aorta before, l, and after excision from the body, L, the diameter, heart weight, thickness of left ventricle and degree of atherosclerosis were collected in autopsies of 156 male cadavers of known age. Longitudinal prestrain was quantified by means of the stretch ratio λ=l/L. Statistical analysis revealed significant dependence between age, prestrain, diameter and atherosclerosis, which were best fitted to the power law equation. Longitudinal prestretch reduced with age significantly; λmean=1.30±0.07 for age<30 (n=29), whereas λmean=1.06±0.03 for age>59 (n=31) with p-value<0.0001. Raw data gave linear correlation coefficients as follows: λ-age (R=-0.842); l-age (R=0.023); L-age (R=0.476); (l-L)-age (R=-0.811). It was concluded that longitudinal prestrain decreases nonlinearly with age and both age and diameter are suitable predictors of the prestrain. Data suggests that unloaded length elongates with age in contrast to the elastic retraction.

• MeSH
• aorta abdominalis patologie   patofyziologie   MeSH
• ateroskleróza patofyziologie   MeSH
• lidé středního věku MeSH
• lidé MeSH
• mechanický stres MeSH
• regresní analýza MeSH
• stárnutí fyziologie   MeSH
• Check Tag
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

• MeSH
• biomechanika MeSH
• kardiovaskulární systém MeSH
• laboratoře organizace a řízení   trendy   využití   MeSH
• lidé MeSH
• lokomoce MeSH
• matematické výpočty počítačové MeSH
• muskuloskeletální systém MeSH
• počítačová simulace MeSH
• protézy a implantáty trendy   využití   MeSH
• stomatologie metody   trendy   MeSH
• tkáňové inženýrství využití   MeSH
• univerzity organizace a řízení   trendy   MeSH
• Check Tag
• lidé MeSH

• MeSH
• discus articularis čelistního kloubu fyziologie   patologie   MeSH
• financování organizované využití   MeSH
• interpretace statistických dat MeSH
• magnetická rezonanční tomografie metody   využití   MeSH
• nemoci čelistí patofyziologie   MeSH
• protézy kloubů využití   MeSH
• záznam mezičelistních vztahů metody   přístrojové vybavení   MeSH

• Klíčová slova
• FE Analýza,
• MeSH
• biometrie metody   přístrojové vybavení   MeSH
• lidé MeSH
• modely anatomické MeSH
• nestabilita kloubu MeSH
• pohyb MeSH
• prospektivní studie MeSH
• protézy kloubů MeSH
• rozsah kloubních pohybů MeSH
• temporomandibulární kloub * anatomie a histologie   fyziologie   růst a vývoj   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• práce podpořená grantem MeSH

This paper deals with a knee joint endoprosthesis finite element analysis. Based on a three dimensional geometric model of a lower extremity, a mechanical axis of the limb was designed. This axis is important for several reasons. Firstly, the endoprosthesis was positioned due to its direction, secondly, boundary conditions was defined on its proximal and distal end and finally, the axis enabled reasonable simplification of the model which led to the time saving analysis while preserving principal features of the model like the natural boundary conditions or knee joint's degrees of freedom . Having this, one leg stance was simulated. Results of the analysis were encouraging for future models. Especially the choice of the mechanical axis was suitable and enabled a better distribution of contact pressures and stress on both femoral and tibial component compared to our former models. Also their magnitudes correspond better the manufacturer's experience and our findings. The stresses did not exceeded 30MPa for the UHMWPE tibial plateau and 100MPa for the femoral component. The contact pressures were lower than 40MPa.

• MeSH
• biologické modely MeSH
• femur anatomie a histologie   patofyziologie   MeSH
• financování organizované MeSH
• kolenní kloub anatomie a histologie   patofyziologie   MeSH
• lidé MeSH
• mechanický stres MeSH
• protézy kolene MeSH
• rozsah kloubních pohybů MeSH
• tibie anatomie a histologie   patofyziologie   MeSH
• tlak MeSH
• zatížení muskuloskeletálního systému MeSH
• Check Tag
• lidé MeSH

OBJECTIVE: Clinical observations and mathematical models show that dental implants are influenced by the magnitude of loading. Therefore, the knowledge of mandible movement during mastication is important to assess occlusal and masticatory force vectors. The purpose of this study was to detect the path of movement of the lower jaw and to distinguish stages of mastication, duration of bolus processing and peak amplitude of mastication. METHOD: Motion analysis was used to record three-dimensional mandible movements. Individualized sensors were rigidly attached to the mandible of 51 study participants. At the beginning of the measurement, all subjects were asked to move the mandible in extreme positions (maximal opening and maximal lateral movements). Then, each subject masticated a bite of hard and soft food. Duration of bolus mastication and peak amplitude of mastication movement in mesio-distal, cranio-caudal and vestibulo-oral axes related to peak amplitude of marginal movements were evaluated for each subject. The chewing record of each subject was divided into three phases (chopping, grinding and swallowing), and the duration of mastication and number of closing movements were evaluated. RESULTS: The findings of this pilot study suggest that masticatory movements vary in individuals. Bolus character influences the process duration, but not the frequency of closing movements. Neither gender nor age had any influence on either the time or frequency of bolus processing. CONCLUSION: Relationships to directions and magnitudes of acting chewing force should be more precisely examined since transversally acted forces during grinding are important factors in tooth/implant overloading.

• MeSH
• audiovizuální záznam MeSH
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• mandibula fyziologie   MeSH
• polykání MeSH
• potraviny MeSH
• senioři MeSH
• síla skusu MeSH
• žvýkání fyziologie   MeSH
• Check Tag
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH
• senioři MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH