Understanding the intricacies of human movement coordination and variability during running is crucial to unraveling the dynamics of locomotion, identifying potential injury mechanisms and understanding skill development. Identification of minimum number of cycles for calculation of reliable coordination and its variability could help with better test organization and efficient assessment time. By adopting a cross-sectional study design, this study investigated the minimum required cycles for calculating hip-knee, hip-ankle and knee-ankle coordination and their variability using a continuous relative phase (CRP) method. Twenty-nine healthy adults ran on a treadmill at speeds of 9, 12.5, and 16 km.h-1 while 3D kinematic data of their lower limbs were recorded using 6 optoelectronic cameras. Using Intraclass Correlation Coefficient (ICC) analysis, reliability between CRP and its variability (CRPv) in different gait cycles (3, 5, 10, 20, 30) was assessed for each speed. A minimum of 10 cycles was required for CRP calculation across all speeds, whereas CRPv necessitated a minimum of 30 cycles for moderate to good reliability. While increasing the number of cycles improved ICC values for inter-joint CRP, the same trend was not consistently observed for CRPv, emphasizing the importance of separately assessing CRP and its variability metrics.

• Klíčová slova
• Continuous relative phase, Reliability, Running biomechanics, Variability,
• MeSH
• běh * fyziologie   MeSH
• biomechanika MeSH
• chůze (způsob) * fyziologie   MeSH
• dospělí MeSH
• hlezenní kloub * fyziologie   MeSH
• kolenní kloub * fyziologie   MeSH
• kyčelní kloub fyziologie   MeSH
• lidé MeSH
• mladý dospělý MeSH
• průřezové studie MeSH
• Check Tag
• dospělí MeSH
• lidé MeSH
• mladý dospělý MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH

BACKGROUND: Variations observed in biomechanical studies might be attributed to errors made by operators during the construction of musculoskeletal models, rather than being solely attributed to patient-specific geometry. RESEARCH QUESTION: What is the impact of operator errors on the construction of musculoskeletal models, and how does it affect the estimation of muscle moment arms and hip joint reaction forces? METHODS: Thirteen independent operators participated in defining the muscle model, while a single operator performed 13 repetitions to define the muscle model based on 3D bone geometry. For each model, the muscle moment arms relative to the hip joint center of rotation was evaluated. Additionally, the hip joint reaction force during one-legged stance was assessed using static inverse optimization. RESULTS: The results indicated high levels of consistency, as evidenced by the intra- rater and inter-rater agreement measured by the Intraclass Correlation Coefficient (ICC), which yielded values of 0.95 and 0.99, respectively. However, the estimated muscle moment arms exhibited an error of up to 16 mm compared to the reference musculoskeletal model. It was found that muscles attached to prominent anatomical landmarks were specified with greater accuracy than those attached over larger areas. Furthermore, the variability in estimated moment arms contributed to variations of up to 12% in the hip joint reaction forces. SIGNIFICANCE: Both moment arm and muscle force demonstrated significantly lower variability when assessed by a single operator, suggesting the preference for employing a single operator in the creation of musculoskeletal models for clinical biomechanical studies.

• Klíčová slova
• Hip joint, Moment arm, Musculoskeletal model, Variability,
• MeSH
• biologické modely MeSH
• biomechanika MeSH
• kosterní svaly * fyziologie   MeSH
• kyčelní kloub * fyziologie   MeSH
• lidé MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

The geometrical representation of muscles in computational models of the musculoskeletal system typically consists of a series of line segments. These muscle anatomies are based on measurements from a limited number of cadaveric studies that recently have been used as atlases for creating subject-specific models from medical images, so potentially restricting the options for personalisation and assessment of muscle geometrical models. To overcome this methodological limitation, we propose a novel, completely automated technique that, from a surface geometry of a skeletal muscle and its attachment areas, can generate an arbitrary number of lines of action (fibres) composed by a user-defined number of straight-line segments. These fibres can be included in standard musculoskeletal models and used in biomechanical simulations. This methodology was applied to the surfaces of four muscles surrounding the hip joint (iliacus, psoas, gluteus maximus and gluteus medius), segmented on magnetic resonance imaging scans from a cadaveric dataset, for which highly discretised muscle representations were created and used to simulate functional tasks. The fibres' moment arms were validated against measurements and models of the same muscles from the literature with promising outcomes. The proposed approach is expected to improve the anatomical representation of skeletal muscles in personalised biomechanical models and finite element applications.

• Klíčová slova
• Line of action, Lower limb, Moment arms, Musculoskeletal geometry, Skeletal muscle,
• MeSH
• biologické modely * MeSH
• biomechanika MeSH
• kosterní svaly * diagnostické zobrazování   fyziologie   MeSH
• kyčelní kloub * diagnostické zobrazování   fyziologie   MeSH
• lidé MeSH
• magnetická rezonanční tomografie MeSH
• mrtvola MeSH
• počítačová rentgenová tomografie MeSH
• počítačové modelování podle konkrétního pacienta * MeSH
• senioři nad 80 let MeSH
• Check Tag
• lidé MeSH
• senioři nad 80 let MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH

OBJECTIVES: The aims of the study were to assess the kinematics of the lower limbs and pelvis during normal walking in professional ballet dancers and to investigate relationships between movements of segments of the lower limbs and pelvis. METHODS: Thirty one professional ballet dancers and twenty eight controls completed five walking trials at their preferred speed. Kinematic data in the basic anatomical planes for ankle, knee, and hip joints as well as for the pelvis were collected with an optoelectronic motion system. RESULTS: The female ballet dancers had in comparison with the controls significantly larger (p < 0.01) knee flexion in the swing phase and hip abduction in the preswing phase. Compared to the control group, the male ballet dancers had significantly larger dorsiflexion in the final stance and the total pelvic tilt range of motion. The number of significant correlations between kinematic parameters was higher in the female ballet dancers. CONCLUSIONS: It can be concluded that specific movement techniques and compensatory strategies used in ballet dance can alter relationships between movements of segments of the lower limbs during normal walking. The relationships between movements in the joints of the lower limbs and pelvis are stronger in women.

• MeSH
• biomechanika fyziologie   MeSH
• chůze (způsob) fyziologie   MeSH
• dospělí MeSH
• hlezenní kloub fyziologie   MeSH
• koleno fyziologie   MeSH
• kyčelní kloub fyziologie   MeSH
• lidé MeSH
• mladiství MeSH
• mladý dospělý MeSH
• postura těla fyziologie   MeSH
• rozsah kloubních pohybů fyziologie   MeSH
• sexuální faktory MeSH
• tanec * MeSH
• Check Tag
• dospělí MeSH
• lidé MeSH
• mladiství MeSH
• mladý dospělý MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• srovnávací studie MeSH

BACKGROUND: Over the past thirty years, there has been dramatic increase in incidence of Achilles tendon rupture in the athletic population. The purpose of this study was to compare the lower extremity mechanics of Achilles tendon ruptured runners with healthy controls. METHODS: The participants with a past history of an Achilles tendon repair (n = 11) and healthy control (n = 11) subgroups were matched on sex, age, type of regular physical activity, mass, height, footfall pattern and lateral dominancy. Running kinetics and kinematics of the ankle, knee and hip were recorded using a high-speed motion capture system interfaced with a force platform. Achilles tendon length was measured using ultrasonography. Main outcome measures were lower extremity joint angles and moments during stance phase of running and Achilles tendon lengths. RESULTS: Athletes from Achilles tendon group had an affected gastro-soleus complex. Athletes with history of Achilles tendon rupture had reduced ankle range of motion during second half of the stance phase of running (Δ7.6°), an overextended knee during initial contact (Δ5.2°) and increased affected knee range of motion (Δ4.4°) during the first half of stance phase on their affected limb compared to the healthy control group. There was a 22% increase in the maximal hip joint moment on contralateral side of the Achilles tendon group compared to the healthy controls. CONCLUSION: These results suggest a compensation mechanism, relatively extended knee at initial ground contact against the deficit in the muscle-tendon complex of the triceps surae. Overextension during sporting activities may place the knee at risk for further injury. Avoidance of AT lengthening and plantarflexion strength deficit after surgery and during rehabilitation might help to manage AT rupture since these factors may be responsible for altered running kinematics.

• Klíčová slova
• Achilles tendon, Injury, Knee, Ultrasonography,
• MeSH
• Achillova šlacha diagnostické zobrazování   zranění   patofyziologie   MeSH
• běh fyziologie   MeSH
• biomechanika fyziologie   MeSH
• dospělí MeSH
• hlezenní kloub fyziologie   MeSH
• hodnocení výsledků zdravotní péče MeSH
• incidence MeSH
• kolenní kloub fyziologie   MeSH
• kosterní svaly patofyziologie   MeSH
• kyčelní kloub fyziologie   MeSH
• lidé středního věku MeSH
• lidé MeSH
• poranění šlachy komplikace   epidemiologie   rehabilitace   MeSH
• rozsah kloubních pohybů fyziologie   MeSH
• ruptura patofyziologie   chirurgie   MeSH
• sportovci statistika a číselné údaje   MeSH
• ultrasonografie MeSH
• Check Tag
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• srovnávací studie MeSH

PURPOSE: Estimation of hip joint loading is fundamental for understanding joint function, injury and disease. To predict patientspecific hip loading, a musculoskeletal model must be adapted to the patient's unique geometry. By far the most common and cost effective clinical images are whole pelvis plain radiographs. This study compared the accuracy of anisotropic and isotropic scaling of musculoskeletal model to hip joint force prediction by taking patient-specific bone geometry from standard anteroposterior radiograms. METHODS: 356 hips from 250 radiograms of adult human pelvis were analyzed. A musculoskeletal model was constructed from sequential images of the Visible Human Male. The common body position of one-legged stance was substituted for the midstance phase of walking. Three scaling methods were applied: a) anisotropic scaling by interhip separation, ilium height, ilium width, and lateral and inferior position of the greater trochanter, b) isotropic scaling by pelvic width and c) isotropic scaling by interhip separation. Hip joint force in one-legged stance was estimated by inverse static model. RESULTS: Isotropic scaling affects all proportions equally, what results in small difference in hip joint reaction force among patients. Anisotropic hip scaling increases variation in hip joint force among patients considerably. The difference in hip joint force estimated by isotropic and anisotropic scaling may surpass patient's body weight. CONCLUSIONS: Hip joint force estimated by isotropic scaling depends mostly on reference musculoskeletal geometry. Individual's hip joint reaction force estimation could be improved by including additional bone geometrical parameters in the scaling method.

• MeSH
• anizotropie MeSH
• biologické modely * MeSH
• biomechanika MeSH
• dospělí MeSH
• kyčelní kloub fyziologie   MeSH
• lidé MeSH
• postura těla fyziologie   MeSH
• referenční hodnoty MeSH
• Check Tag
• dospělí MeSH
• lidé MeSH
• mužské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH

We test whether locomotor posture is associated with body mass and lower limb length in humans and explore how body size and posture affect net joint moments during walking. We acquired gait data for 24 females and 25 males using a three-dimensional motion capture system and pressure-measuring insoles. We employed the general linear model and commonality analysis to assess the independent effect of body mass and lower limb length on flexion angles at the hip, knee, and ankle while controlling for sex and velocity. In addition, we used inverse dynamics to model the effect of size and posture on net joint moments. At early stance, body mass has a negative effect on knee flexion (p < 0.01), whereas lower limb length has a negative effect on hip flexion (p < 0.05). Body mass uniquely explains 15.8% of the variance in knee flexion, whereas lower limb length uniquely explains 5.4% of the variance in hip flexion. Both of the detected relationships between body size and posture are consistent with the moment moderating postural adjustments predicted by our model. At late stance, no significant relationship between body size and posture was detected. Humans of greater body size reduce the flexion of the hip and knee at early stance, which results in the moderation of net moments at these joints.

• MeSH
• algoritmy MeSH
• biologické modely MeSH
• biomechanika MeSH
• chůze (způsob) fyziologie   MeSH
• chůze fyziologie   MeSH
• dolní končetina fyziologie   MeSH
• dospělí MeSH
• hlezenní kloub fyziologie   MeSH
• index tělesné hmotnosti MeSH
• kolenní kloub fyziologie   MeSH
• koleno fyziologie   MeSH
• kotník fyziologie   MeSH
• kyčelní kloub fyziologie   MeSH
• lidé MeSH
• lineární modely MeSH
• mladý dospělý MeSH
• postura těla fyziologie   MeSH
• rozsah kloubních pohybů fyziologie   MeSH
• velikost těla fyziologie   MeSH
• Check Tag
• dospělí MeSH
• lidé MeSH
• mladý dospělý MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH

Periprosthetic bone loss in response to total hip arthroplasty is a serious complication compromising patient's life quality as it may cause the premature failure of the implant. Stress shielding as a result of an uneven load sharing between the hip implant and the bone is a key factor leading to bone density decrease. A number of composite hip implants have been designed so far to improve load sharing characteristics. However, they have rarely been investigated from the bone remodeling point of view to predict a long-term response. This is the first study that employed a mechano-biochemical model, which considers the coupling effect between mechanical loading and bone biochemistry, to investigate bone remodeling after composite hip implantation. In this study, periprosthetic bone remodeling in the presence of Carbon fiber polyamide 12 (CF/PA12), CoCrMo and Ti alloy implants was predicted and compared. Our findings revealed that the most significant periprosthetic bone loss in response to metallic implants occurs in Gruen zone 7 (-43% with CoCrMo; -35% with Ti) and 6 (-40% with CoCrMo; -29% with Ti), while zone 4 has the lowest bone density decrease with all three implants (-9%). Also, the results showed that in terms of bone remodeling, the composite hip implant is more advantageous over the metallic ones as it provides a more uniform density change across the bone and induces less stress shielding which consequently results in a lower post-operative bone loss (-9% with CF/PA12 implant compared to -27% and -21% with CoCrMo and Ti alloy implants, respectively).

• Klíčová slova
• Bone remodeling, Composite hip implant, Finite element method, Irreversible thermodynamics, Mechano-biochemical model, Total hip arthroplasty,
• MeSH
• analýza metodou konečných prvků MeSH
• biologické modely * MeSH
• biomechanika MeSH
• biomimetické materiály škodlivé účinky   MeSH
• karbonové vlákno MeSH
• kostní denzita účinky léků   MeSH
• kyčelní kloub účinky léků   fyziologie   chirurgie   MeSH
• kyčelní protézy škodlivé účinky   MeSH
• mechanický stres * MeSH
• modul pružnosti účinky léků   MeSH
• nylony škodlivé účinky   chemie   MeSH
• pooperační období MeSH
• remodelace kosti účinky léků   MeSH
• slitiny škodlivé účinky   MeSH
• uhlík chemie   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• srovnávací studie MeSH
• Názvy látek
• karbonové vlákno MeSH
• nylon 12 MeSH Prohlížeč
• nylony MeSH
• slitiny MeSH
• uhlík MeSH

Hip contact stress is considered to be an important biomechanical factor related to development of coxarthrosis. The effect of the lateral coverage of the acetabulum on the hip contact stress has been demonstrated in several studies of hip dysplasia, whereas the effect of the anterior anteversion remains unclear. Therefore, the joint hip contact stress during normal level walking and staircase walking, in normal and dysplastic hips, for small and large acetabular anteversion angle was computed. For small acetabular anteversion angle, the hip contact stress is slightly increased (less than 15%) in staircase walking when compared with normal walking. In hips with large angle of acetabular anteversion, walking downstairs significantly increases the maximal peak contact stress (70% in normal hips and 115% in dysplastic hips) whereas walking upstairs decreases the peak contact stress (4% in normal hips and 34% in dysplastic hips) in comparison to normal walking. Based on the presented results, we suggest that the acetabular anteversion should be considered in biomechanical evaluation of the hips, especially when the lateral coverage of the acetabulum is small.

• MeSH
• acetabulum fyziologie   MeSH
• artróza kyčelních kloubů patofyziologie   MeSH
• biologické modely MeSH
• chůze fyziologie   MeSH
• kyčelní kloub fyziologie   MeSH
• lidé MeSH
• mechanický stres * MeSH
• zatížení muskuloskeletálního systému fyziologie   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Many disorders of the hip can be treated with a suitable osteotomy based on the improvement of mechanical conditions in the hip joint. These operations, such as osteotomies are very complex. The surface replacement has also been developed as an alternative to a total hip replacement for young and more active people. It is up-to-date to concern with biomechanics of pathological hips and it is necessary to supplement the existing clinical findings with the results of mechanical analyses. Several finite element (FE) models are presented in this paper. The first one offers solutions to the strain-stress analysis of the physiological hip. The second one represents dysplastic hip joint. Another two computational models of both hips of a young patient were created (FE model of physiological hip and pathological hip affected by Perthes disease with a deformed shape of the femoral head). Also a computational model is presented, which enables us to investigate strain and stress parameters in the hip joint with applied surface replacement. The strain and stress analysis was performed by means of finite element method (FEM) in ANSYS system.

• MeSH
• analýza metodou konečných prvků * MeSH
• biologické modely MeSH
• biomechanika MeSH
• kyčel fyziologie   patofyziologie   chirurgie   MeSH
• kyčelní kloub fyziologie   patofyziologie   chirurgie   MeSH
• lidé MeSH
• mechanický stres MeSH
• náhrada kyčelního kloubu MeSH
• osteotomie MeSH
• počítačová simulace MeSH
• poranění kyčle patofyziologie   chirurgie   MeSH
• vývojové onemocnění kostí patofyziologie   chirurgie   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• srovnávací studie MeSH