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In order to verify whether orthostatic posturography (OP) can support clinical assessment of total hip (THA) and knee arthroplasty (TKA), 81 subjects with THA and 100 with TKA were recruited and compared with 59 healthy volunteers. All patients were tested one or two days prior to surgery; 42 subjects (20 THA and 22 TKA) were tested again after six months, and 34 (14 THA and 20 TKA) yet again after 12 months. OP was performed using a Kistler 9286A piezoelectric force plate and the following postural parameters (PPs) were adopted on account of their functional meaning: mean velocity and the root mean square of the distance of the centre of pressure (CoP), sway area, and 95% of the CoP power frequency. Eye condition and fatigue related to the test duration were also examined. The three most meaningful PPs were identified and a logarithmic transformation was then applied to these, as well as standardization. Almost all the PP values were higher preoperatively in the patients as compared with the healthy subjects and it was possible to detect many statistically significant differences between patients and healthy subjects. However, when examining the 181 subjects at the preoperative stage, the PPs did not show congruence with the clinical scores as well as they did during follow-up. Therefore, the use of the OP is not recommended to monitor patients undergoing THA or TKA.

Hip prostheses should meet the anatomical and physiological characteristics of patients; this is the rationale for designing modular implants of different sizes. To optimize implant geometry, it is necessary to consider, not only the prosthesis component design, but also the final configuration of the implanted leg. This means the necessity to consider the specific morphological and functional condition of ""that"" patient and not only of ""that"" hip to restore, at best, limb functions. Variations in the length of the implanted limb are frequent; therefore, the variations in the three geometrical features of the hip prosthesis neck, which can affect the restoration of the anatomical symmetry of the limbs, were investigated: (i) neck lengths (Ln ), between 50.5 and 64.5 mm; (ii) cervico-diaphyseal (CD) angle ( ã ), between 135 and 125 degrees and; (iii) anteversion (AV) angle ( â ), between 0 and 15 degrees . Adopting a three-dimensional (3D) simplified biomechanical model, the resultant load acting on the hip was estimated for each different design solution; corresponding stress distributions and contact pressures at the interface between the prosthesis head and the ultra high molecular weight polyethylene (UHMWPE) layer were evaluated by 3D finite element (FE) analyses and using the Strozzi approach. The following values have been assumed as physiological values: ã = ã p = 125 degrees , â = â p = 15 degrees and Ln = 57 mm; it was found that to contrast limb lengthening, if the CD angle varies from 135-125 degrees (with neck length Ln = 64.5 mm and AV = 0 degrees ), the joint resultant load decreases by 8.8% (7.2% if AV = 15 degrees ); the contact pressure de-creases by 5.8%, (5% if AV = 15 degrees ); the bending moment in the stem neck increases by 10.9% (13.8% if AV = 15 degrees ) and the torque increases by 1% (12.8% if AV = 15 degrees ).

Falls and loss of consciousness (FLoC) is the leading cause of serious health problems, above all in the elderly population, since the subjects involved are not able to ask for help and may lie in critical conditions for a long time, thus deteriorating into severe conditions which can even lead to death. Therefore, developing a device capable of automatically detecting a FLoC and activating an alarm call seems to be of utmost importance. This study intended to develop such a device using an accelerometer sensor. Four hundred and sixty simulated falls were performed by 20 subjects: 10 young subjects and 10 elderly subjects. The young subjects were asked to perform 200 FLoCs as well as 60 non common activities (NCAs), whereas the elderly subjects were asked to carry out only 200 activities of daily living (ADL). The signal used to detect the fall event was acquired by a single accelerometer placed on the subjects' belts. The test set was divided into two groups of the same size: Training Set (TS) and Verification Set (VS). The first set was meant to determine the related algorithm, whereas the second set was intended to check its reliability. The proposed algorithm was devised to detect the effects of the three phases of a FLoC (impact of the body on the ground, lying position and immobility) into the acceleration and jerk signals along the cranio-caudal axis (CCA). The correct detection of all FLoC cases and the absence of false positives among ADL corroborate the usefulness of the device proposed.

The challenging problem of wing design for small business aircraft configurations is here explored using evolutionary computing. The activity focuses on the aerodynamic analysis and optimization of a laminar wing in cruise and high lift conditions. The main feature of the work is the application of natural laminar flow technology which in turn implies pressure gradient optimization. The optimization study is performed by using chained CFD based aerodynamic numerical methods in an evolutionary optimization framework. A major issue is the simulation of the rear-mounted engine mass flow inlet in cruise conditions, which introduces a remarkable geometry complication and computational time increase into the optimization process. The first section gives some details about the design and analysis system. The reference configuration is analyzed to show the starting point of the aerodynamic design. Then the optimization problem definition and the adopted strategy is discussed. The final section is devoted to the aerodynamic analysis of the obtained optimal configuration.

The use of accelerometers is discussed to evaluate standing vertical jump. Two accelerometers, mounted on each ankle and connected to a wearable system, were used for signal acquisition, and a piezoelectric platform was used to verify the results. Fifty-one subjects were enrolled, subdivided into a group of healthy subjects and 2 groups who had different surgery for Achilles tendon rupture. Each subject performed 5 countermovement and 5 squat jumps; 11 subjects also performed 5 countermovement jumps with voluntary leg rotations during the flight phase. A training set was used to assess signal processing, and a validation set was used to verify its accuracy. A peak detection algorithm was developed to quantify flight time from the acceleration modulus, and its results were compared with platform data. The Pearson correlation coefficient of ankle accelerations and the integral of each signal were adopted to describe, respectively, the movement coordination and the limbs rotation during the flight time. The flight times obtained from the accelerometers and force plate were highly correlated (Spearman's coefficient >0.95); they were compared, for each jump, and the maximum mean error, for subject, was 4.8%. The movement coordination was in good agreement with subjects' clinical features and with the different jump phases. The signal integral presented significant differences, among jumps, related to leg rotations (p < 0.0005). The method proposed allows the monitoring of standing vertical jump using the fight time and gives information on the legs coordination and on the motor strategies of the lower limbs. Therefore, it can be used to obtain performance reference also outside labs, both in clinical and sport settings.

CAD reconstruction of anatomical regions from computerized tomography (CT) scans is a very common approach in orthopaedic biomechanics. The CAD model is discretized into finite volume sub-domains and finite element (FE) analyses are performed in order to predict the distribution of stresses generated by applied loads. However, quality and reliability of numerical results depend on the level of accuracy reached in the meshing process. This paper analyzes some critical parameters that may affect the overall efficiency of the CT–FEM transformation process: scan threshold range, object size, and complexity. An optimization procedure for minimizing geometric errors on size and shape of reconstructed objects is presented. Finally, accuracy of stress predictions is evaluated for FE models that include known amounts of geometric errors. Compression and bending loads are considered. Results show that geometric and stress errors rapidly decrease as the objects to be reconstructed become larger in size. Optimal threshold ranges can be identified clearly for both an epoxy-resin benchmark model and a real bone specimen cut from a human lumbar vertebra. This allows geometric errors to be reduced significantly.

Fall and Loss of Consciousness (FLoC) is the leading cause of serious health problems, above all in the elderly population, since the subjects involved are not able to ask for help and may lie in critical conditions for a long time thus deteriorating into severe conditions which can even lead to death. Therefore developing a device capable of automatically detecting a FLoC and activate an alarm call seems to be of utmost importance. The present study is intended to develop such a device using an accelerometer sensor. 460 simulated falls were performed by 20 subjects: 10 young subjects and 10 elderly subjects. The young subjects were asked to perform 200 FLoCs as well as 60 non common activities (NCAs), whereas the elderly subjects were asked to carry out only 200 activities of daily living (ADL). The signal used to detect the fall event was acquired by a single accelerometer placed on the subjects’ belts. The test set was divided into two groups of the same size: Training Set (TS) and Verification Set (VS). The first set was meant to determine the related algorithm, whereas the second set was intended to check its reliability. The proposed algorithm was devised to detect the effects of the three phases of a FLoC (impact of the body on the ground, lying position and immobility) into the acceleration and jerk signals along the Cranio-Caudal Axis (CCA). The correct detection of all FLoC cases and the absence of false positives among ADL do corroborate the usefulness of the device proposed..

Static posturography may provide for an objective support to the clinical observation during the evaluation of rehabilitation and functional recovery after total hip arthroplasty (THA) or total knee arthroplasty (TKA). Unfortunately though, many of the studies focused on this topic, have so far given unclear and partially contradictory results. The aim of the present study was to identify those clinically significant Postural Parameters (PPs) likely to enable to discriminate between normal subjects and THA and TKA patients, evaluated immediately before surgery and in the first year of follow-up (f-up). Two hundred forty-nine subjects (men and women) were enrolled in the study. They were split into a Reference Group (RG) and an Experimental Group (EG), made of THA and TKA patients evaluated before surgery as well as at a sixmonth and one-year follow-ups. The test was performed with Open Eyes and Closed eyes. Four Postural Parameters (PPs) were adopted to identify statistically significant differences (SSDs): mean velocity (MV), Sway Area (SA), the root mean square of the resultant distance (RMSD), and the 95% power frequency (PF_95); the last two PPs were considered in the fore-aft (suffixed with fa) and mediallateral (suffixed with ml) directions. Correlation with Anthropometric Parameters was explored and, when found, PP values were normalized. Gender differences were also considered. The data obtained are consistent with the clinical situation of the subjects and in good agreement with literature data. All the PPs of the RG did not exhibit SSDs between male and female subjects, but some SSDs with gender were found in the EG. The PPs adopted did not appear to be influenced by false within-subject (i.e. fatigue) and between-subject variability (i.e. anthropometry or positioning) and they allow to identify differences among groups. The results obtained highlight the presence of SSDs between the RG and the EG in terms of both RMSD, indicating an increased sway, and MV, indicating an increased cost for standing, especially in the medial-lateral direction. SA was found to be most robust parameter. The PPs values registered at follow-up in the EG get closer to those registered in the RG. A worsening in terms of performance seems to occur at the six-month follow-up compared to the pre-operative session and recovery seems to be slower in TKA subjects compared to THA subjects. Manuscript received February 1, 2008 L. Quagliarella is with the Sezione di Ingegneria Biomedica, University of Bari, Bari, BA 70124 Italy (phone: +39-080-5478617; fax: +39-080-5565425; e-mail: l.quagliarella@bioingegneria.uniba.it). N. Sasanelli is with the Sezione di Ingegneria Biomedica, University of Bari, Bari, BA 70124 Italy (e-mail: n.sasanelli@bioingegneria.uniba.it). V. Monaco is with IMT Lucca Institute for Advanced Studies, Lucca, LU 55100 Italy (e-mail: v.monaco@imtlucca.it). G. Belgiovine is with the Sezione di Ingegneria Biomedica, University of Bari, Bari, BA 70124 Italy (e-mail: g.belgiovine @bioingegneria.uniba.it). B. Moretti is with the Sezione di Ortopedia, University of Bari, Bari, BA 70124 Italy (e-mail: b.moretti@ortop2.uniba.it). In the EG, there is an extremely pronounced increase in RMSDml, both in EO and in CE, compared with the RG. This important feature is considered as the single best predictor of future falling risk in the literature. Finally, PF_95fa values are higher than PF_95ml values in the THA group and even higher in the TKA group, mostly in the Closed Eyes condition. The SSDs observed between the RG and the EG do highlight an increase in both RMSD and MV, i.e. a greater energy cost to maintain posture, especially in the ML direction. The decreased PP values in T2 call for a more in-depth analysis since they seem to contradict the widespread conviction that ascribes performance worsening to fatigue, especially in THA and TKA subjects. Unfortunately it is not possible to make a direct comparison with other studies because the designs of the studies in question differ a lot. The need for a methodological harmonization is therefore once again making itself felt.

Piezoelectric force platforms are electronic instruments widely used for posturography in movement analysis laboratories. As is well known, drift affects piezoelectric transducers; therefore, the accuracy of piezoelectric measurement systems should be periodically checked. The objectives of this paper were as follows: (1) to detect the occurrence of drift in the posturographic signals derived from a piezoelectric force plate (FP) using an easy-to-use standard procedure; (2) to determine the impact on drift itself of two clinically relevant factors: applied load [for values related to children/adolescent weights (range 49-588 N)] and test duration; and (3) to suggest numerical solutions, if any, to compensate for drift effects. Drift in piezoelectric FPs is essentially caused by leakage currents and/or poor insulation resistances. Moreover, it may be considered as a low-frequency event affecting the accuracy of standing posture descriptive parameters. The measurement system outputs available to the end user, namely ground reaction force (GRF) components and center of pressure (CoP) sway, were analyzed both in the time and frequency domains. According to the obtained results, it was possible to demonstrate that drift significantly affects the signals of the posturography system under study and that it can be assessed by the analysis of the GRF and CoP component values. As it exhibits a constant rate versus time, drift can be well approximated by a linear regression line. The main results are represented by the independence of drift rate from applied load and test duration and by finding that drift can relevantly affect CoP evaluation for test duration that is equal or longer than 1 min when the applied load is less than 245 N (which could be the case for children and young slim adolescents). High-pass numeric filtering with a cutoff frequency of 0.15 Hz and linear detrending can compensate drift in the presented case.

The design activity within the European 6th framework project EUROLIFT II is targeted towards an improvement of the take-off performance of a generic transport aircraft configuration by a redesign of the trailing edge flap. The involved partners applied different optimization strategies as well as different types of flow solvers in order to cover a wide range of possible approaches for aerodynamic design optimization. The optimization results obtained by the different partners have been cross-calculated in order to eliminate solver dependencies and to identify the best obtained design. The final selected design has been applied to the wind tunnel model and the test in the European Transonic Wind Tunnel (ETW) at high Reynolds number confirms the predicted improvements.

Movement functional analysis of vertical jump allows to quantify the motor capabilities of lower limbs and so to determine the performance level and the effectiveness of the trial programs. Force platforms and stereophotogrammetric systems are the reference instruments, but they cannot be used in "non-structured" environments. In this study a novel measurement system, able to give objective performance indication about motor capabilities of subject involved in vertical jumping, has been developed and validated. It is based on a low-cost, small and low-weight triaxial accelerometer, a portable datalogger and a suitable analyzing software. The realized system presents plusmn 10g FSR and 78 mg resolution and has been employed in the acquisition of vertical jump performed by 124 subjects. The acceleration signal has been processed by a dedicated algorithm for the estimation of flight time. The results have been compared to the same parameter, calculated using the Ground Reaction Force (GRF) given by a force platform. The flight time, measured by acceleration and GRF, presents a good correlation (0,96) and a percent error of 4,2% and allows to discriminate the high jump performance between athletes and normal subjects (p

The present work concerns the problem of evaluating and quantifying the severity of Parkinson disease, by means of the identification and the analysis of objective biomedical parameters direct linked to the primary Parkinsonian symptoms. Previously, a simple, inexpensive and non-invasive measurement system with a suitable software able to record, to manage and to enterprise the acquired data, has been developed (Sasanelli et al., 2002) to measure the palmar grip strength in isometric conditions. Afterwards, a study that evaluates the filtering and phase noise effects and the performances of different methods used to estimate the characteristic parameters of the palmar grip, has been proposed. In this paper the authors propose a more detailed statistical analysis to investigate the statistical difference among the several defined biomedical parameters, with the aim to distinguish pathologic subjects from healthy ones. Moreover a compared study between the results obtained in our proposed analysis technique and the achieved from standard clinical test ones, has been carried out by highlighting the more meaningful correlations

In this work the analysis of biomedical data characterizing motor activities of the limbs is carried out with the aim to extract useful information for evaluate the state of subjects affected by Parkinson's disease. Previously, a simple and inexpensive system that measures the force of palmar grip has been presented, then a suitable software protocol able to record, to manage and to enterprise the acquired data, has been realized. Afterwards, a first analysis in time domain has led to identify some biomedical parameters characterizing motor activities of limbs; the study of these parameters and the analysis of the correlations between the acquired data, has permitted to develop suitable models describing the time behavior of the palmar grip. In this paper the authors propose a more detailed study that evaluates the filtering, phase noise effects and the performances of different methods used to estimate the characteristic parameters of the palmar grip

The present work is concerned with the problem of recording and analyzing biomedical data characterizing motor activities of the limbs in patients suffering from Parkinson's disease. The aim of the paper is the individuation of suitable parameters useful for detecting subjects affected by Parkinson's disease, revealing the state of the patient. So, a simple and inexpensive system that measures the force of palmar grip is presented and discussed and a suitable software protocol able to record and manage the acquired data is developed. Finally, some biomedical parameters have been identified, characterizing motor activities of limbs. The study of these parameters and the analysis of the correlations between the acquired data, permits us to extract useful information and details for objective evaluation of Parkinson pathology, taking into account the metrological characteristics of the used measurement system.

An investigation was started aimed at a better understanding of the complex phenomena leading to chemical degradation and morphological deterioration of UHMW polyethylene cups in total hip prostheses. Analysis was performed on retrieved implants which needed revision due to inflammation and pain problems. Preliminary results obtained by parallel XPS and SEM/EDX experiments gave evidence, for the first time, that silicon traces are involved in the process of particle formation and segregation onto the surface of the cups. The extent of modification of the surface chemical composition of cups and the process of particle segregation seem to be correlated to both the implant time and to some particular features of patient (age, activity, style of life, etc.). Investigation on a large number of samples is in progress in order to test this hypothesis. The results obtained so far confirmed the potential of surface spectroscopies (XPS) in biomaterial investigations.

An approach to the self-adaptation of the parameters of a genetic algorithm to the optimization problem is described. The characterizing feature of the system presented is the structure of the evolving individuals, that are more similar to cells rather than to isolated genes with the introduction of a program chromosome besides the chromosome of the optimization problem variables. The basic scheme of the evolutionary optimizer is a multiple objective genetic algorithm based on the introduction of the dominance criteria in the selection mechanism. Some preliminary results are presented on a multimodal single-objective test function and the directions of future work are outlined.