Comparison between two low profile attachments for implant mandibular overdentures

ObjectiveIn this research it was aimed to evaluate stress distribution on the implants supporting a complete overdenture in addition to compare between two different types of low-profile attachments for implant-retained mandibular overdenture with two techniques (with/without using connecting bar).Materials and methodsTwo 3D finite element models were constructed simulating supported lower complete overdenture with two implants and with two implants and bar. Where, models components were modeled in 3D on commercial general purpose CAD/CAM software. Four runs were carried out, two runs on each model, as linear static analysis.ResultsUsing bar is generally preferred for mucosa and cortical bone, while its effect can be considered as negligible on overdenture. On the other hand, it slightly increases the stresses on spongy bone. Using bar ensures the same level of energy transfer to the spongy bone and increases its maximum Von Mises stresses by about 50%. In addition, increase in maximum Von Mises stress was noticed by about 1% on cortical bone.ConclusionUsing bar is not recommended for patients with flat ridge.     

Finite element modeling of the breakage behavior of agricultural biomass pellets under different heights during handling and storage

It is very important to determine the amount of mechanical damage to biomass pellets during handling, transportation, and storage. However, it is difficult to determine the amount of damage to biomass pellets caused by existing external forces. However, a useful method is the finite element methods, which can be used in different engineering fields to simulate the posture of the material under defined boundary conditions. In this research, a drop test simulation of biomass pellet samples was performed by using the finite element method. An experimental study (compressive test) was carried out to measure some mechanical properties of the sample and use the obtained data in the finite element method simulation. The stress–strain curve of different biomass pellets was determined. Yield strength, Poisson’s ratio, ultimate strength and modulus of elasticity, and stress were identified. In the end, the maximum equivalent stress, highest contact force (generated normal force from target surface at impact), and shape of deformation of samples at impact were obtained from simulation results. The drop scenario was created with 25 steps after the impact site, and the FEM simulation was solved. The maximum stress value was 9.486 MPa, and the maximum generated force was 485.31 N. at step 8 of the FEM simulation. When the stress magnitudes were assessed, simulation outputs indicated that simulation stress values are inconsistent with experimental data.     

Fatigue Loading Effect in Custom-Made All-on-4 Implants System: A 3D Finite Elements Analysis

ObjectivesThis study aims to evaluate the fatigue stress around custom-made all-on-4 implants system to find out which type of implants have a better performance under different graded multidirectional occlusal forces.Material and methods3D normal and implanted models simulating the “All-on-4” concept were created and analyzed under three different conditions of occlusal loadings. Two types of static and fatigue were applied. Stress distribution was analyzed based on von Mises and Goodman theories in ANSYS environment in addition to the safety factor. Statistical tests were performed to assess the significance of the results as well as the reproducibility of the results.ResultsThe results showed stress increasing reaching a value of 48%, 29% in tilted implants compared to vertical implants and normal cases respectively. In contrast, tilted implants appeared to be less stable (safety factor may reach 0.7) and they may fail during the application of occlusal forces. The safety factor of cortical bone decreased by about 91% in the implanted model compared to the normal model, indicating a higher possibility of bone remodeling around the bone.ConclusionThe orientation and position of occlusal forces had an important influence on stress distribution between the implant and the surrounding bone, and fatigue loading caused greater stresses in comparison with static loading. Lower amounts of stress were found in the vertical implants, ensuring a higher safety factor and a longer clinical service. In contrast, the critical safety factor values are observed in tilted implants, which may fail under the influence of applied occlusal forces.     

Biomechanical comparison of sinus floor elevation and alternative treatment methods for dental implant placement

Objective: In this study, we compared the success of sinus lifting and alternative treatment methods in applying dental implants in cases lacking adequate bone due to pneumatization of the maxillary sinus. Methods: In a computer environment, 3D models were created using computerized tomography data from a patient. Additionally, implants and abutments were scanned at the macroscopic level, and the resulting images were transferred to the 3D models. Five different models were examined: a control model, lateral sinus lifting (LSL), short dental implant placement (SIP), tilted implant placement (TIP) and distal prosthetic cantilever (DC) use. Vertical and oblique forces were applied in each model. The compression, tension and von Mises stresses in each model were analyzed by implementing a finite element analysis method. Results: In our study, the LSL method was observed to be the closest to the control model. The TIP model showed high stress values under conditions of oblique forces but showed successful results under conditions of vertical forces, and the opposite results were observed in the SIP model. The DC model provided the least successful results among all models. Conclusions: Based on the results of this study, the LSL method should be the first choice among treatment options. Considering its successful results under conditions of oblique forces, the SIP method may be preferable to the TIP method. In contrast, every effort should be made to avoid the use of DCs.     

Finite element analysis of different loading conditions for implant-supported overdentures supported by conventional or mini implants

The effect of implants’ number on overdenture stability and stress distribution in edentulous mandible, implants and overdenture was numerically investigated for implant-supported overdentures. Three models were constructed. Overdentures were connected to implants by means of ball head abutments and rubber ring. In model 1, the overdenture was retained by two conventional implants; in model 2, by four conventional implants; and in model 3, by five mini implants. The overdenture was subjected to a symmetrical load at an angle of 20 degrees to the overdenture at the canine regions and vertically at the first molars. Four different loading conditions with two total forces (120, 300 N) were considered for the numerical analysis. The overdenture displacement was about 2.2 times higher when five mini implants were used rather than four conventional implants. The lowest stress in bone bed was observed with four conventional implants. Stresses in bone were reduced by 61% in model 2 and by 6% in model 3 in comparison to model 1. The highest stress was observed with five mini implants. Stresses in implants were reduced by 76% in model 2 and 89% increased in model 3 compared to model 1. The highest implant displacement was observed with five mini implants. Implant displacements were reduced by 29% in model 2, and increased by 273% in model 3 compared to model 1. Conventional implants proved better stability for overdenture than mini implants. Regardless the type and number of implants, the stress within the bone and implants are below the critical limits.     

A three-dimensional finite element model of the human anterior cruciate ligament: a computational analysis with experimental validation

In this study, the force and stress distribution within the anteromedial (AM) and posterolateral (PL) bundles of the anterior cruciate ligament (ACL) in response to an anterior tibial load with the knee at full extension was calculated using a validated three-dimensional finite element model (FEM) of a human ACL. The interaction between the AM and PL bundles, as well as the contact and friction caused by the ACL wrapping around the bone during knee motion, were included in the model. The AM and PL bundles of the ACL were simulated as incompressible homogeneous and isotropic hyperelastic materials. The multiple-degrees-of-freedom (DOF) knee kinematics of a cadaveric knee were first obtained using a robotic/universal force-moment sensor testing system. These data were used as the boundary conditions for the FEM of the ACL to calculate the forces in the ACL. The calculated forces were compared to the in situ force in the ACL, determined experimentally, to validate the model. The validated FEM was then used to calculate the force and stress distribution within the ACL under an anterior tibial load at full extension. The AM and PL bundles shared the force, and the stress distribution was non-uniform within both bundles with the highest stress localized near the femoral insertion site. The contact and friction caused by the ACL wrapping around the bone during knee motion played the role of transferring the force from the ACL to the bone, and had a direct effect on the force and stress distribution of the ACL. This validated model will enable the analysis of force and stress distribution in the ACL in response to more complex loading conditions and has the potential to help design improved surgical procedures following ACL injuries.     

Finite element analysis of implant-supported prosthesis with pontic and cantilever in the posterior maxilla

The aim of this study was to evaluate the influence of pontic and cantilever designs (mesial and distal) on 3-unit implant-retained prosthesis at maxillary posterior region verifying stress and strain distributions on bone tissue (cortical and trabecular bones) and stress distribution in abutments, implants and fixation screws, under axial and oblique loadings, by 3D finite element analysis. Each model was composed of a bone block presenting right first premolar to the first molar, with three or two external hexagon implants (4.0 × 10 mm), supporting a 3-unit splinted dental fixed dental prosthesis with the variations: M1 – three implants supporting splinted crowns; M2 – two implants supporting prosthesis with central pontic; M3 – two implants supporting prosthesis with mesial cantilever; M4 – two implants supporting prosthesis with distal cantilever. The applied forces were 400 N axial and 200 N oblique. The von Mises criteria was used to evaluate abutments, implants and fixation screws and maximum principal stress and microstrain criteria were used to evaluate the bone tissue. The decrease of the number of implants caused an unfavorable biomechanical behavior for all structures (M2, M3, M4). For two implant-supported prostheses, the use of the central pontic (M2) showed stress and strain distributions more favorable in the analyzed structures. The use of cantilever showed unfavorable biomechanical behavior (M3 and M4), mainly for distal cantilever (M4). The use of three implants presented lower values of stress and strain on the analyzed structures. Among two implant-supported prostheses, prostheses with cantilever showed unfavorable biomechanical behavior in the analyzed structures, especially for distal cantilever.     

Biomechanical analysis and comparison of 12 dental implant systems using 3D finite element study

Finite element analysis plays an important role in dental implant design. The objective of this study was to show the effect of the overall geometry of dental implants on their biomechanics after implantation. In this study, 12 dental implants, with the same length, diameter and screw design, were simulated from different implant systems. Numerical model of right mandibular incisor bone segment was generated from CT data. The von-Mises stress distributions and the total deformation distributions under vertical/lateral load were compared for each implant by scores ranking method. The implants with cylindrical shapes had highest scores. Results indicated that cylindrical shape represented better geometry over taper implant. This study is helpful in choosing the optimal dental implant for clinical application and also contributes to individual implant design. Our study could also provide reference for choice and modification of dental implant in any other insertion sites and bone qualities.     

Finite element analysis of peri-implant bone volume affected by stresses around Morse taper implants: effects of implant positioning to the bone crest

Abstract

Objectives: The purpose of the present study was to evaluate the distribution and magnitude of stresses through the bone tissue surrounding Morse taper dental implants at different positioning relative to the bone crest. Materials and Methods: A mandibular bone model was obtained from a computed tomography scan. A three-dimensional (3D) model of Morse taper implant-abutment systems placed at the bone crest (equicrestal) and 2?mm bellow the bone crest (subcrestal) were assessed by finite element analysis (FEA). FEA was carried out on axial and oblique (45°) loading at 150 N relatively to the central axis of the implant. The von Mises stresses were analysed considering magnitude and volume of affected peri-implant bone. Results: On vertical loading, maximum von Mises stresses were recorded at 6-7?MPa for trabecular bone while values ranging from 73 up to 118?MPa were recorded for cortical bone. On oblique loading at the equiquestral or subcrestal positioning, the maximum von Mises stresses ranged from 15 to 21?MPa for trabecular bone while values at 150?MPa were recorded for the cortical bone. On vertical loading, >99.9vol.% cortical bone volume was subjected to a maximum of 2?MPa while von Mises stress values at 15?MPa were recorded for trabecular bone. On oblique loading, >99.9vol.% trabecular bone volume was subjected to maximum stress values at 5?MPa, while von Mises stress values at 35?MPa were recorded for >99.4vol.% cortical bone. Conclusions: Bone volume-based stress analysis revealed that most of the bone volume (>99% by vol) was subjected to significantly lower stress values around Morse taper implants placed at equicrestal or subcrestal positioning. Such analysis is commentary to the ordinary biomechanical assessment of dental implants concerning the stress distribution through peri-implant sites.     

A method of quantification of stress shielding in the proximal femur using hierarchical computational modeling

Stress shielding is a biomechanical phenomenon causing adaptive changes in bone strength and stiffness around metallic implants, which potentially lead to implant loosening. Accordingly, there is a need for standard, objective engineering measures of the “stress shielding” performances of an implant that can be employed in the process of computer-aided implant design. To provide and test such measures, we developed hierarchical computational models of adaptation of the trabecular microarchitecture at different sites in the proximal femur, in response to insertion of orthopaedic screws and in response to hypothetical reductions in hip joint and gluteal muscle forces. By identifying similar bone adaptation outcomes from the two scenarios, we were able to quantify the stress shielding caused by screws in terms of analogous hypothetical reductions in hip joint and gluteal muscle forces. Specifically, we developed planar lattice models of trabecular microstructures at five regions of interest (ROI) in the proximal femur. The homeostatic and abnormal loading conditions for the lattices were determined from a finite element model of the femur at the continuum scale and fed to an iterative algorithm simulating the adaptation of each lattice to these loads. When screws were inserted to the femur model, maximal simulated bone loss (17% decrease in apparent density, 10% decrease in thickness of trabeculae) was at the greater trochanter and this effect was equivalent to the effect of 50% reduction in gluteal force and normal hip joint force. We conclude that stress shielding performances can be quantified for different screw designs using model-predicted hypothetical musculoskeletal load fractions that would cause a similar pattern and extent of bone loss to that caused by the implants.     

A method of quantification of stress shielding in the proximal femur using hierarchical computational modeling

Stress shielding is a biomechanical phenomenon causing adaptive changes in bone strength and stiffness around metallic implants, which potentially lead to implant loosening. Accordingly, there is a need for standard, objective engineering measures of the "stress shielding" performances of an implant that can be employed in the process of computer-aided implant design. To provide and test such measures, we developed hierarchical computational models of adaptation of the trabecular microarchitecture at different sites in the proximal femur, in response to insertion of orthopaedic screws and in response to hypothetical reductions in hip joint and gluteal muscle forces. By identifying similar bone adaptation outcomes from the two scenarios, we were able to quantify the stress shielding caused by screws in terms of analogous hypothetical reductions in hip joint and gluteal muscle forces. Specifically, we developed planar lattice models of trabecular microstructures at five regions of interest (ROI) in the proximal femur. The homeostatic and abnormal loading conditions for the lattices were determined from a finite element model of the femur at the continuum scale and fed to an iterative algorithm simulating the adaptation of each lattice to these loads. When screws were inserted to the femur model, maximal simulated bone loss (17% decrease in apparent density, 10% decrease in thickness of trabeculae) was at the greater trochanter and this effect was equivalent to the effect of 50% reduction in gluteal force and normal hip joint force. We conclude that stress shielding performances can be quantified for different screw designs using model-predicted hypothetical musculoskeletal load fractions that would cause a similar pattern and extent of bone loss to that caused by the implants.     

Effect of an interspinous implant on loads in the lumbar spine.

Interspinous process implants are increasingly used to treat canal stenoses. Little information exists about the effects of implant height and stiffness on the biomechanical behavior of the lumbar spine. Therefore, a three-dimensional nonlinear finite element model of the osseoligamentous lumbar spine (L1 to L5) was created with a slightly degenerated disc at L3/L4. An interspinous implant was inserted at that segment. Implants with different heights and stiffnesses were studied. The model was loaded with the upper body weight and muscle forces to simulate walking and 25 degrees extension. Implant forces are influenced strongly by the height and negligibly by the elastic modulus of the implant. Intersegmental rotation at implant level is markedly reduced, while intradiscal pressure is slightly increased. Implant size and stiffness have only a minor effect on intradiscal pressure. The maximum von Mises stress in the vertebral arch is strongly increased by the implant.     

Quantifying near metal visibility using dual energy computed tomography and iterative metal artifact reduction in a fracture phantom

PurposeTo quantitatively assess CT image quality and fracture visibility using virtual monochromatic imaging and iterative metal artifact reduction (iMAR) in a femoral bone fracture phantom with different fixation implants.MethodsA custom made phantom was scanned at 120-kVp and 140-kVp single-energy and 100/150-kVp dual-energy. Three stainless steel and two titanium implants with different thicknesses were placed on the phantom containing simulated one and two mm fractures. Single-energy CT images were reconstructed with and without iMAR, while DECT images were reconstructed at monochromatic energies between 70 and 190 keV. Non-metal scans were used as a reference. A Fourier power spectrum method and fracture model were used to analyze several anatomical areas.ResultsCT-value deviations of titanium implants were much lower compared to stainless steel implants. These deviations decreased for both DECT and iMAR. Fracture visibility, measured with the fracture model, improved the most when DECT was used while artifact reduction benefitted more from iMAR. The optimal monochromatic energy for metal artifact reduction, based on CT-value deviation, varied for each metal between 130 and 150 keV. The fracture model provided a signal-to-noise ratio for the near metal fracture visibility, providing the optimal keV.ConclusioniMAR and high keV monochromatic images extracted from DECT both reduce metal artifacts caused by different metal fixation implants. Quantitative femoral phantom results show that DECT is superior to iMAR regarding fracture visualization adjacent to metal fixation implants. The introduction of new artifacts when using iMAR impedes its value in near metal fixation implant imaging.     

Determination of orthotropic bone elastic constants using FEA and modal analysis

Finite element models have been widely employed in an effort to quantify the stress and strain distribution around implanted prostheses and to explore the influence of these distributions on their long-term stability. In order to provide meaningful predictions, such models must contain an appropriate reflection of mechanical properties. Detailed geometrical and density information is now readily available from CT scanning. However, despite the use of phantoms, a method of determining mechanical properties (or elastic constants) from bone density has yet to be made available in a usable form.In this study, a cadaveric bone was CT scanned and its natural frequencies were measured using modal analysis. Using the geometry obtained from the CT scan data, a finite element mesh was created with the distribution of density established by matching the mass of the FE bone model with the mass of the cadaveric bone. The maximum values of the orthotropic elastic constants were then established by matching the predictions from FE modal analyses to the experimental natural frequencies, giving a maximum error of 7.8% over 4 modes of vibration. Finally, the elastic constants of the bone derived from the analyses were compared with those measured using ultrasound techniques. This produced a difference of <1% for both the maximum density and axial Young's Modulus. This study has thereby produced an orthotropic finite element model of a human femur. More importantly, however, is the implication that it is possible to create a valid FE model by simply comparing the FE results with the measured resonant frequency of the CT scanned bone.     

A nonlinear viscoelastic finite element model of polyethylene

A nonlinear viscoelastic finite element model of ultra-high molecular weight polyethylene (UHMWPE) was developed in this study. Eight cylindrical specimens were machined from ram extruded UHMWPE bar stock (GUR 1020) and tested under constant compression at 7% strain for 100 sec. The stress strain data during the initial ramp up to 7% strain was utilized to model the "instantaneous" stress-strain response using a Mooney-Rivlin material model. The viscoelastic behavior was modeled using the time-dependent relaxation in stress seen after the initial maximum stress was achieved using a stored energy formulation. A cylindrical model of similar dimensions was created using a finite element analysis software program. The cylinder was made up of hexahedral elements, which were given the material properties utilizing the "instantaneous" stress-strain curve and the energy-relaxation curve obtained from the experimental data. The cylinder was compressed between two flat rigid bodies that simulated the fixtures of the testing machine. Experimental stress-relaxation, creep and dynamic testing data were then used to validate the model. The mean error for predicted versus experimental data for stress relaxation at different strain levels was 4.2%. The mean error for the creep test was 7% and for dynamic test was 5.4%. Finally, dynamic loading in a hip arthroplasty was modeled and validated experimentally with an error of 8%. This study establishes a working finite element material model of UHMWPE that can be utilized to simulate a variety of postoperative arthroplasty conditions.     

Hip joint contact force in the emu (Dromaius novaehollandiae) during normal level walking

The emu is a large, (bipedal) flightless bird that potentially can be used to study various orthopaedic disorders in which load protection of the experimental limb is a limitation of quadrupedal models. An anatomy-based analysis of normal emu walking gait was undertaken to determine hip contact forces for comparison with human data. Kinematic and kinetic data captured for two laboratory-habituated emus were used to drive the model. Muscle attachment data were obtained by dissection, and bony geometries were obtained by CT scan. Inverse dynamics calculations at all major lower-limb joints were used in conjunction with optimization of muscle forces to determine hip contact forces. Like human walking gait, emu ground reaction forces showed a bimodal distribution over the course of the stance phase. Two-bird averaged maximum hip contact force was approximately 5.5 times body weight, directed nominally axially along the femur. This value is only modestly larger than optimization-based hip contact forces reported in literature for humans. The interspecies similarity in hip contact forces makes the emu a biomechanically attractive animal in which to model loading-dependent human orthopaedic hip disorders.     

Vertical and lateral forces applied to the bar during the bench press in novice lifters

The purpose of this study was to determine the vertical and lateral forces applied to the bar during a maximal and a submaximal effort bench press lifts. For this study, 10 male and 8 female recreational lifters were recruited (mean height: 1.71 ± 0.08 m; mass: 73.7 ± 13.6 kg) and were asked to perform a maximal and submaximal (80% of maximal lift) bench press. These lifts were performed with a bar instrumented to record forces applied to it, via the hands, in the vertical direction and along the long axis of the bar. To determine the position of the bar and timing of events, 3D kinematic data were recorded and analyzed for both lifts. The subjects in this study averaged a maximal lift of 63 ± 29 kg (90 ± 31% bodyweight). The peak vertical force was 115 ± 22% (percentage of load), whereas for the submaximal condition it was 113 ± 20%; these forces were statistically different between conditions; they were not when expressed as a percentage of the load (p > 0.05). During all the lifts, the lateral forces were always outward along the bar. The lateral force profile was similar to that of the vertical force, albeit at a lesser magnitude. During the lift phase, the peak lateral force was on average 26.3 ± 3.9% of the vertical force for the maximal lift and 23.7 ± 3.9% of the vertical force for the submaximal lift. Given that the amount of force applied laterally to the bar was a similar percentage of vertical force irrespective of load, it appears that the generation of lateral forces during the bench press is a result of having the muscles engaged in generating vertical force.     

Thigh–calf contact: Does it affect the loading of the knee in the high-flexion range?

Recently, high-flexion knee implants have been developed to provide for a large range of motion (ROM>120°) after total knee arthroplasty (TKA). Since knee forces typically increase with larger flexion angles, it is commonly assumed that high-flexion knee implants are subjected to larger loads than conventional knee implants. However, most high-flexion studies do not consider thigh–calf contact which occurs during high-flexion activities such as squatting and kneeling. In this study, we hypothesized that thigh–calf contact reduces the knee forces during deep knee flexion as the tibio-femoral load shifts from occurring inside the knee towards the thigh–calf contact interface. Hence, the effect of thigh–calf contact on the knee loading was evaluated using a free body diagram and a finite element model and both the knee forces and polyethylene stresses were analyzed. Thigh–calf contact force characteristics from an earlier study were included and a squatting movement was simulated. In general, we found thigh–calf contact considerably reduced both the knee forces and polyethylene stresses during deep knee flexion. At maximal flexion (155°), the compressive knee force decreased from 4.89 to 2.90 times the bodyweight (BW) in case thigh–calf contact was included and the polyethylene contact stress at the tibial post decreased from 49.3 to 28.1 MPa. Additionally, there was a clear correlation between a subject's thigh and calf circumference and the force reduction at maximal flexion due to thigh–calf contact (R=0.89). The findings presented in this study can be used to optimize the mechanical behavior of high-flexion total knee arthroplasty designs.     

Incorporating uncertainty in mechanical properties for finite element-based evaluation of bone mechanics

Finite element (FE) models of bone, developed from computed tomography (CT) scan data, are used to evaluate stresses and strains, load transfer and fixation of implants, and potential for fracture. The experimentally derived relationships used to transform CT scan data in Hounsfield unit to modulus and strength contain substantial scatter. The scatter in these relationships has potential to impact the results and conclusions of bone studies. The objectives of this study were to develop a computationally efficient probabilistic FE-based platform capable of incorporating uncertainty in bone property relationships, and to apply the model to a representative analysis; variability in stresses and fracture risk was predicted in five proximal femurs under stance loading conditions. Based on published variability in strength and modulus relationships derived in the proximal femur, the probabilistic analysis predicted the distributions of stress and risk. For the five femurs analyzed, the 1 and 99 percentile bounds varied by an average of 17.3 MPa for stress and by 0.28 for risk. In each femur, the predicted variability in risk was greater than 50% of the mean risk calculated, with obvious implications for clinical assessment. Results using the advanced mean value (AMV) method required only seven analysis trials (1h) and differed by less than 2% when compared to a 1000-trial Monte-Carlo simulation (400 h). The probabilistic modeling platform developed has broad applicability to bone studies and can be similarly implemented to investigate other loading conditions, structures, sources of uncertainty, or output measures of interest.     

A mathematical high bar–human body model for analysing and interpreting mechanical-energetic processes on the high bar

The aims of this study were:

1. To study the transfer of energy between the high bar and the gymnast.

2. To develop criteria from the utilisation of high bar elasticity and the utilisation of muscle capacity to assess the effectiveness of a movement solution.

3. To study the influence of varying segment movement upon release parameters.

For these purposes a model of the human body attached to the high bar (high bar–human body model) was developed. The human body was modelled using a 15-segment body system. The joint-beam element method (superelement) was employed for modelling the high bar. A superelement consists of four rigid segments connected by joints (two Cardan joints and one rotational–translational joint) and springs (seven rotation springs and one tension–compression spring). The high bar was modelled using three superelements. The input data required for the high bar–human body model were collected with video-kinematographic (50 Hz) and dynamometric (500 Hz) techniques. Masses and moments of inertia of the 15 segments were calculated using the data from the Zatsiorsky et al. (1984) model. There are two major phases characteristic of the giant swing prior to dismounts from the high bar. In the first phase the gymnast attempts to supply energy to the high bar–human body system through muscle activity and to store this energy in the high bar. The difference between the energy transferred to the high bar and the reduction in the total energy of the body could be adopted as a criterion for the utilisation of high bar elasticity. The energy previously transferred into the high bar is returned to the body during the second phase. An advantageous increase in total body energy at the end of the exercise could only be obtained through muscle energy supply. An index characterising the utilisation of muscle capacity was developed out of the difference between the increase in total body energy and the energy returned from the high bar. A delayed and initially slow but even reduction of hip and shoulder angles provided more advantageous release conditions. The total body energy could be improved by up to 15%, the vertical CM release velocity by up to 10% and the angular momentum by up to 35%.