E. Pavan

Politecnico di Milano, Milano, Lombardy, Italy

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Publications (23)10.04 Total impact

  • [show abstract] [hide abstract]
    ABSTRACT: Most analytical studies found in literature only focus on specific aspects of Duchenne muscular dystrophy (DMD) gait and posture (joint range of motion, standing balance, variations of gait spatial-temporal parameters). Some of them analyze single cases and do not provide a comprehensive evaluation of locomotion. There are few studies about DMD gait patterns, most of them concerning small groups of patients, sometimes not homogeneous, in which the clinical manifestations of the next stages of DMD were present. The goal of our study was to analyze the characteristics of gait patterns in early stage patients, when clinical and functional evaluation do not allow to quantify initial walking worsening or to identify the changes adopted to compensate for muscle weakness. Gait Analysis Laboratory by using a six-camera motion capture system (Vicon, Oxford Metrics, UK), set at a sampling rate of 60 Hz. Subjects were asked to walk barefoot at their usual cadence, along a 10-m walkway, where one force platform (Kistler, Switzerland), embedded in the middle portion of the pathway, measured the foot-ground reaction forces. Retroreflective markers were placed on the subjects according to the protocol described in Davis et al. A group of 15 patients aging from 5 to 6.8 years was compared with a similar age control group composed of 9 healthy children. Spatial and temporal parameters showed significant differences between the two groups: cadence was increased and step length was decreased significantly in the DMD group. We found a significant increase in the range of anterior-posterior pelvic tilt and in pelvic rotation. In the frontal plane there was a tendency for an increased pelvic obliquity. Dynamic range of motion in sagittal plane showed a significant difference at the ankle, with an increased plantarflexion in swing in the dystrophic patients. Maximum dorsiflexion was reduced in the DMD group. Kinetic analysis showed significant differences in power generation and absorption at the hip joint and at the ankle joint. At knee there was a reduced flexor moment in mid-stance. Ankle showed a reduced dorsiflexor moment in terminal stance and pre-swing with a consequent reduction in the peak-to-peak excursion. CONCLUSION AND CLINICAL REHABILITATION IMPACT: It was shown that instrumented gait analysis, being more sensitive than other clinical and functional assessment methods, allowed to quantify the very early modifications characterizing locomotion worsening in the first stage of the DMD.
    European journal of physical and rehabilitation medicine 09/2011; 47(4):587-94. · 2.06 Impact Factor
  • C Frigo, E E Pavan, R Brunner
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    ABSTRACT: The mechanical effect of hamstrings and quadriceps contractions on hip and knee joint motion was investigated using a dynamic model of the musculoskeletal system. The model consisted of 13 anatomically linked segments. The geometry of bones, joints, and muscle attachments was derived from magnetic resonance imaging of a healthy adult. The knee joint was represented by a crossing bars linkage to simulate cruciate ligament function, and muscles were represented by spring actuators. The effects of hamstring and quadriceps contractions, in various combinations, were tested on different configurations of hip and knee joint position in the absence of gravity. In the standing posture, with the foot free to move and the pelvis fixed in space, the effect of semimembranosus (SM) contraction was hip and knee flexion. If the foot was fixed to the ground, SM contraction produced hip extension and knee flexion. The addition of quadriceps contraction reduced or abolished the knee flexion and enhanced hip extension. In all other simulations, SM alone produced knee flexion and hip extension and the combination of SM with vastus (VA) and rectus femoris (RF) contractions resulted in knee extension and enhanced hip extension. Our findings suggest that co-contraction of quadriceps and hamstrings may be a strategy to increase the hip extension function of the hamstrings.
    Gait & posture 10/2009; 31(1):100-3. · 2.58 Impact Factor
  • E. Pavan, C. Frigo, A. Pedotti
    Gait & Posture - GAIT POSTURE. 01/2009; 29.
  • Gait & Posture - GAIT POSTURE. 01/2009; 29.
  • E. Pavan, C. Frigo
    Gait & Posture - GAIT POSTURE. 01/2009; 30.
  • E. E. Pavan, P. Taboga, C. Frigo
    Journal of Biomechanics - J BIOMECH. 01/2006; 39.
  • Gait & Posture - GAIT POSTURE. 01/2006; 24.
  • E. E. Pavan, P. Taboga, C. Frigo
    Gait & Posture - GAIT POSTURE. 01/2006; 24.
  • Gait & Posture - GAIT POSTURE. 01/2006; 24.
  • Journal of Biomechanics - J BIOMECH. 01/2006; 39.
  • [show abstract] [hide abstract]
    ABSTRACT: Cited By (since 1996): 4, Export Date: 11 April 2013, Source: Scopus
    01/2005: pages 708-712;
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    ABSTRACT: The purpose of the present work was to develop a tool for preoperatively planning the Total Hip Replacement (THR). Starting from the MR images, the 3D surface model of both the pelvis and the femur was built and the surgical operation was virtually performed. Data coming from gait analysis were added to visualize the physiologic movement of the hip joint. The resulting triangular mesh was sufficiently accurate to allow the building of the stereolithographic model of the joint by means of rapid prototyping technique. The plastic bones allow the user to have an enhanced vision of the surgical procedure to be performed.
    International Congress Series 01/2005; 1281:708-712.
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    ABSTRACT: Spatial and temporal parameters of gait have clinical relevance in the assessment of motor pathologies, particularly in orthopaedics. A new gait analysis system is proposed which consists of (a) an ambulatory device (Physilog) including a set of miniature gyroscopes and a portable datalogger, and (b) an algorithm for gait analysis. The aim of this study was the validation of this system, for accuracy and clinical applicability. Eleven patients with coxarthrosis, eight patients with total hip arthroplasty and nine control subjects were studied using this portable system and also a reference motion analyzer and force plate. The small differences in the stance period (19 +/- ms), stride length and velocity (0.4 +/- 9.6 cm and 2.5 +/- 8.3 cm/s, respectively), as well as thigh and shank rotations (2.4 +/- 4.3 degrees and 0.3 +/- 3.3 degrees, respectively), confirmed good agreement of the proposed system with the reference system. In addition, nearly the same accuracy was obtained for all three groups. Gait analysis based on Physilog was also in agreement with their Harris Hip Scores (HHS): the subjects with lower scores had a greater limp, a slower walking speed and a shorter stride. This ambulatory gait analysis system provides an easy, reproducible and objective method of quantifying changes in gait after joint replacement surgery for coxarthrosis.
    Gait & Posture 09/2004; 20(1):102-7. · 1.97 Impact Factor
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    ABSTRACT: The goal of the present work was to develop and test an innovative system for the training of paraplegic patients when they are standing up. The system consisted of a computer-controlled stimulator, surface electrodes for quadricep muscle stimulation, two knee angle sensors, a digital proportional-integrative-derivative (PID) controller and a mechanical device to support, partially, the body weight (weight reliever (WR)). A biomechanical model of the combined WR and patient was developed to find an optimum reference trajectory for the PID controller. The system was tested on three paraplegic patients and was shown to be reliable and safe. One patient completed a 30-session training period. Initially he was able to stand up only with 62% body weight relief, whereas, after the training period, he performed a series of 30 standing-up/sitting-down cycles with 45% body weight relief. The closed-loop controller was able to keep the patient standing upright with minimum stimulation current, to compensate automatically for muscle fatigue and to smooth the sitting-down movement. The limitations of the controller in connection with a highly non-linear system are considered.
    Medical & Biological Engineering & Computing 06/2002; 40(3):282-9. · 1.79 Impact Factor
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    ABSTRACT: A patient driven control strategy for standing-up and sitting-down was experimentally tested on two paraplegic patients by applying functional electrical stimulation (FES) to the quadriceps muscle. The strategy-also known as “patient-driven motion reinforcement” (PDMR)-was developed by computer simulations reported in a former study. It is based on an inverse dynamic model (IDM) that predicts the stimulation pattern required to maintain the movement as it is initiated by the patient's voluntary effort. For reasons of safety and weight relief, the movement was supported by a seesaw construction. After some practice the patients were able to influence the stimulator output and to control the movement by their voluntary effort. Consequently, no pre-programmed reference trajectory was required. As a positive side effect, upper body effort could be minimized compared to trials without FES. To achieve a satisfactory performance of the PDMR controller a careful parameter identification of the inverse dynamic model was fundamental
    IEEE Transactions on Rehabilitation Engineering 01/2001;
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    ABSTRACT: The surface EMG signal detected from voluntarily activated muscles can be used as a control signal for functional neuromuscular electrical stimulation. A proper positioning of the recording electrodes in relation to the stimulation electrodes, and a proper processing of the recorded signals is required to reduce the stimulus artefact and the non-voluntary contribution (M-wave). Six orientations and six locations of the recording electrodes were investigated in the present work. A comb filter (with and without a blanking windowing) was applied to remove the signal components synchronously correlated to the stimulus. An operative definition of the signal to noise ratio and an efficiency index were implemented. It resulted that when the recording electrodes were located within the two stimulation electrodes the best orientation was perpendicular to the longitudinal line. However the best absolute indexes were obtained when the recording electrodes were located externally of the stimulation electrodes, and in that case the best orientation was longitudinal. Concerning the filtering procedure, the use of a blanking window before the application of the comb filter, gave the best performance.
    Journal of Electromyography and Kinesiology 11/2000; 10(5):351-60. · 1.64 Impact Factor
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    ABSTRACT: In this study different closed-loop control strategies for standing-up (SU) and sitting-down (SD) were experimentally tested on two paraplegics by applying Functional Electrical Stimulation (FES) to the quadriceps muscle. The motion is supported by a seesaw construction. The control strategies studied include on-off control, PID control, PID control with feedforward on the basis of an inverse dynamic model (IDM), and “patient-driven motion reinforcement” (PDMR). Satisfactory control behaviour was observed in the on-off and PID controllers. However, during standing they show a tendency towards instability. The PDMR controller is able to coordinate FES and upper body and significantly reduce upper body effort. A disadvantage of the IDM-based and PDMR controllers is that cumbersome parameter adjustment is required prior to the experiments
    01/1999; 1.
  • Gait & Posture. 35:S34–S35.
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    ABSTRACT: Comprehensive gait analysis usually includes kinematics, kinetics, and electromyography. A complex instrumentation is thus required that only can be installed in a dedicated laboratory. These techniques are valuable to support clinical decisions and to evaluate the results. However, in several instances, a simplified analysis, concentrated on few selected gait parameters, can be valuable as well. One problem, however, is to ascertain that the computed parameters are correct and correspond to what could be measured by other, more complicated methods. A second point is to verify the feasibility of the measurement in pathologic cases. A third point is to understand the validity and the usefulness of the computed parameters to demonstrate the benefit for the clinical practice. In this study we describe an ambulatory system for temporal parameters estimation using gyroscopes. The accuracy of the measurement was assessed using a standard provided by an Elite system. To show the effectiveness of the method, gait parameters were obtained in patients with hip osteoarthrosis and after arthoplasty
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    ABSTRACT: Osteoarthritis is the most frequent joint pathology throughout the world. Obtaining objective, dynamic and quantified data allowing the evaluation of patients’ progress before and after hip arthroplasty is crucial. Gait analysis can be used for evaluating improvement in such patients, since walking is the principal human physical activity. Comprehensive gait analysis usually includes kinematics, kinetics, and electromyography. A complex instrumentation is thus required that only can be installed in a dedicated laboratory. These techniques are valuable to support clinical decisions and to evaluate the results. However, in several instances, a simplified analysis, concentrated on few selected gait parameters, can be valuable as well. Recently, we have proposed a new ambulatory system for gait analysis (Physilog) and validated its performances for normal and abnormal walking (Aminian et al., 2002). The aim of this study is to show the efficacy of Physilog system for clinical gait analysis in orthopaedics