Biomedical subjects

M G Benedetti

Publications and source records attributed to M G Benedetti.

16 recordsLinked to original sources

PubMed2000

Integrated pressure-force-kinematics measuring system for the characterisation of plantar foot loading during locomotion.

Plantar pressure, ground reaction force and body-segment kinematics measurements are largely used in gait analysis to characterise normal and abnormal function of the human foot. The combination of all these data together provides a more exhaustive, detailed and accurate view of foot loading during activities than traditional measurement systems alone do. A prototype system is presented that integrates a pressure platform, a force platform and a 3D anatomical tracking system to acquire combined information about foot function and loading. A stereophotogrammetric system and an anatomically based protocol for foot segment kinematics is included in a previously devised piezo-dynamometric system that combines pressure and force measurements. Experimental validation tests are carried out to check for both spatial and time synchronisation. Misalignment of the three systems is found to be within 6.0, 5.0 and 1.5 mm for the stereophotogrammetric system, force platform and pressure platform, respectively. The combination of position and pressure data allows for a more accurate selection of plantar foot subareas on the footprint. Measurements are also taken on five healthy volunteers during level walking to verify the feasibility of the overall experimental protocol. Four main subareas are defined and identified, and the relevant vertical and shear force data are computed. The integrated system is effective when there is a need for loading measurements in specific plantar foot subareas. This is attractive both in clinical assessment and in biomechanics research.

Biomechanical Phenomena↗

PubMed2000

Analysis of ground reaction forces by means of wavelet transform.

OBJECTIVE: To identify details of clinical relevance in ground reaction forces by means of wavelet transform. DESIGN: A retrospective analysis of gait tests performed by total knee replacement patients and a control population has been performed. METHODS: The ground reaction forces have been processed by means of wavelet transform. Results of the wavelet analysis are represented, in a time-frequency plane, by tiles. These are coloured in different grey levels associated to the values of a suitable energy function of the expansion coefficients, resulting from the wavelet transform. RESULTS: The high frequency tiles revealed the presence of irregularities with clinical significance in the first part of the stance phase. These transients in ground reaction forces are described in a quantitative manner allowing to monitor their evolution during the patient observation time. The heel strike transient has been identified by the tile representation of the vertical component of ground reaction forces and confirmed by its correlation with corresponding irregularities in the other components. CONCLUSIONS: The tile representation allows to detect and to quantify details not easily perceivable by the examiner through traditional techniques. The wavelet transform seems particularly appealing for clinical applications such as outcome assessment or treatment evaluation and can assist in the definition of normative models of ground reaction forces. The effectiveness of the procedure suggest to try to automate it. RELEVANCE: The tile representation allows to identify and to keep the records of ground reaction forces clinically significant details, such as heel strike transient.

Arthroplasty, Replacement, Knee↗

PubMed2000

Muscle performance about the knee joint in patients who had distal femoral replacement after resection of a bone tumor. An objective study with use of gait analysis.

BACKGROUND: The treatment of a malignant bone tumor in the distal aspect of the femur often requires great sacrifice of bone and muscle. The extent of quadriceps removal has been reported to influence the long-term functional efficiency of a patient's gait. The objective of the present study was to determine gait function as it relates to the residual quadriceps strength and to the specific component or components of the quadriceps removed in patients treated with total knee replacement because of a malignant bone tumor in the distal aspect of the femur. METHODS: Sixteen patients were evaluated after implantation of a modular hinged cementless knee prosthesis. The patients were assigned to two groups on the basis of the different components of the quadriceps muscle that were resected. Group 1 consisted of five patients who had removal of the vastus medialis and the vastus intermedius and two who had removal of the vastus medialis only. Group 2 consisted of nine patients who had removal of the vastus lateralis and the vastus intermedius. Residual muscular strength about the treated knee was measured by voluntary maximum contraction isometric testing. Foot-ground reaction forces, kinematic and kinetic findings, and electromyographic activity during free-speed walking were recorded. RESULTS: The kinematic study showed that the patients in Group 1 tended to have a stiff-knee gait during stance, whereas those in Group 2 (in which the vastus medialis was spared) had a more regular flexion-extension knee pattern. Electromyographic findings showed that a higher percentage of patients in Group 1 had reduced or absent rectus femoris activity during the loading response. Compared with the contralateral side, knee-extension strength in the treated limb was decreased in both groups. However, there were no significant differences between the groups with respect to the pattern of strength loss. CONCLUSIONS: Good gait function can be achieved in patients with a distal femoral tumor that is treated with distal femoral resection, partial excision of the quadriceps, and total knee arthroplasty with insertion of a hinged prosthesis. Patients in whom the vastus lateralis and vastus intermedius were removed had better gait performance and a more physiological knee-loading pattern than did patients in whom the vastus medialis was removed.

Adult↗

PubMed1999

Flat foot functional evaluation using pattern recognition of ground reaction data.

OBJECTIVE: Main purpose of this study was to apply quantitative gait analysis and statistical pattern recognition as clinical decision-making aids in flat foot diagnosis and post-surgery monitoring. DESIGN: Statistical pattern recognition techniques were applied to discriminate between normal and flat foot populations through ground reaction force measurements; ground reaction forces time course was assumed as a sensible index of the foot function. BACKGROUND: Gait analysis is becoming recognized as an important clinical tool in orthopaedics, in pre-surgery planning, post-surgery monitoring and in a posteriori evaluation of different treatment techniques. Statistical pattern recognition techniques have been utilized with success in this field to identify the most significant variables of selected motor functions in different pathologies, and to design classification rules and quantitative evaluation scores. METHODS: Ground reaction forces were recorded during free speed barefoot walks on 28 healthy subjects, and 28 symptomatic flexible flat foot children selected for surgical intervention. A new feature selection algorithm, based on heuristic optimization, was applied to select the most discriminant ground reaction forces time samples. A two-stage pattern recognition system, composed by three linear feature extractors, one for each ground reaction force component, and a linear classifier, was designed to classify the feet of each subject using the selected features. The output of the classifier was used to define a functional score. RESULTS: The classifier assigned the ground reaction force patterns performed by each subject into the right class with an estimated error of 15%, corresponding to an assignment error for each subject's foot of 9%. The most discriminant ground reaction forces time samples selected are in full agreement with the pathophysiology of the symptomatic flexible flat foot. The obtained score was utilized to monitor the 1 and 2 years post-operative functional recovery of two differently treated subgroups of 32 flexible flat foot subjects. CONCLUSIONS: Statistical pattern recognition techniques are promising tools for clinical gait analysis; the obtained score provides important functional information that could be used as a further aid in the clinical evaluation of flat foot and different surgical treatment techniques. RELEVANCE: Symptomatic flexible flat foot surgical decision making is frequently difficult because of the lack of objective criteria to assess functional abnormalities of the foot/ankle complex. Gait analysis and statistical pattern recognition can give us parameters with which to characterize "functional" flat foot. Moreover, we can objectively follow up the recovery of the foot/ankle complex function after surgical treatment.

Algorithms↗

PubMed1999

An anatomically based protocol for the description of foot segment kinematics during gait.

OBJECTIVE: To design a technique for the in vivo description of ankle and other foot joint rotations to be applied in routine functional evaluation using non-invasive stereophotogrammetry. DESIGN: Position and orientation of tibia/fibula, calcaneus, mid-foot, 1st metatarsal and hallux segments were tracked during the stance phase of walking in nine asymptomatic subjects. Rigid clusters of reflective markers were used for foot segment pose estimation. Anatomical landmark calibration was applied for the reconstruction of anatomical landmarks. BACKGROUND: Previous studies have analysed only a limited number of joints or have proposed invasive techniques. METHODS: Anatomical landmark trajectories were reconstructed in the laboratory frame using data from the anatomical calibration procedure. Anatomical co-ordinate frames were defined using the obtained landmark trajectories. Joint co-ordinate systems were used to calculate corresponding joint rotations in all three anatomical planes. RESULTS: The patterns of the joint rotations were highly repeatable within subjects. Consistent patterns between subjects were also exhibited at most of the joints. CONCLUSION: The method proposed enables a detailed description of ankle and other foot joint rotations on an anatomical base. Joint rotations can therefore be expressed in the well-established terminology necessary for their clinical interpretation. RELEVANCE: Functional evaluation of patients affected by foot diseases has recently called for more detailed and non-invasive protocols for the description of foot joint rotations during gait. The proposed method can help clinicians to distinguish between normal and pathological pattern of foot joint rotations, and to quantitatively assess the restoration of normal function after treatment.

Adult↗

PubMed1999

Myoelectric activation pattern during gait in total knee replacement: relationship with kinematics, kinetics, and clinical outcome.

Gait usually presents an excellent improvement after total knee replacement. Nevertheless, some abnormalities persist even after a long period of time. The abnormal knee patterns have been attributed to several possible causes, such as implant geometry and surgical technique, posterior cruciate ligament sparing/sacrificing, preoperative "stiff-knee" pattern due to pain and altered biomechanics, weakness of the extensor muscles, preoperative arthritic pattern, proprioceptive deficiency, and multijoint degenerative involvement. Cocontraction of the knee flexors and extensors is a common strategy adopted to reduce strain and shear forces at the joint, but it increases compressive forces and joint loading. Even in patients with an excellent functional score, the duration of the implant may be compromised by an altered neuromuscular control of the knee. In this paper, we report a single case study carried out over two years on a patient that underwent total knee replacement. The aim of this work is to show that quantitative gait analysis is essential to augment the understanding of the mechanisms underlying gait, thus enabling clinicians to adapt the rehabilitation program to the specific patient. Although the limits of single case reports are obvious, we believe that this evaluation methodology could be beneficial for assessing the effectiveness of rehabilitation programs aimed at achieving an active control of the knee during gait through a correct muscular activation pattern.

Biomechanical Phenomena↗

PubMed1999

Analysis of function after intra-articular fracture of the os calcis.

Fractures of the os calcis with intra-articular involvement can cause difficulty in treatment and can result in abnormal function throughout the ankle-foot complex. We evaluated the function of the ankle-foot complex and the overall gait pattern after fracture of the os calcis, and we compared the results of surgical and nonsurgical treatment. Those in whom the geometry of the os calcis and joint was restored by reconstructive surgery had better compensation of gait and a better clinical-functional score. Complex disturbances in gait were found in the group of patients that did not undergo open reduction or internal fixation.

Adult↗

PubMed1999

Gait abnormalities in minimally impaired multiple sclerosis patients.

Subclinical evidence of gait abnormalities were identified in a group of seven patients with multiple sclerosis, EDSS scored 0 - 2, without functional limitations. A movement analysis technique was used to identify gait parameters indicative of impaired motor function during walking. Abnormalities related primarily to time-distance parameters (reduced speed of progression, shorter strides, prolonged double support phase) and muscular function (premature recruitment of gastrocnemius and late relaxation of tibialis anterior during stance phase) were identified regardless the severity of the clinical score. The gait analysis procedure was able to provide the clinician with evidence of motor abnormalities prior to functional disturbance observable by a trained physician. These minimal dysfunctions may have resulted from reflex mechanisms impaired by delayed transmission through long loop pathways or else as a result of a nonspecific protective gait strategy to improve balance control. The technique described in this study may be useful to identify earlier starting points for follow-up and physiotherapy.

Adult↗

PubMed1998

Data management in gait analysis for clinical applications.

OBJECTIVE: To study the reliability of gait analysis data obtained using the Calibrated Anatomical System Technique (CAST) protocol and to verify the suitability and repeatability of the extraction of a number of parameters from the waveforms obtained. DESIGN: The experimental protocol and the parametric analysis technique were applied on a population of able-bodied subjects. BACKGROUND: The clinical interpretation process of gait data still needs a more accurate analysis of the reliability and repeatability of the measurements and a suitable procedure for data reduction useful for data comparison. METHODS: Gait analysis was performed in 20 able-bodied subjects using a stereophotogrammetric system and a forceplate. 124 parameters relative to time-distance, kinematic and kinetic variables were calculated by means of an automatic procedure and statistically analysed. RESULTS: Most of the parameters were found to be normally distributed with relatively small range of variation. Few of them showed poor repeatability, mostly due to the experimental inaccuracies introduced. Correlation of several gait parameters with age, sex, and speed of progression was also identified.

Journal Article↗

PubMed1997

Application of stereophotogrammetry to total body three-dimensional analysis of human tremor.

This work aims at verifying the possibility of investigating joint rotations, with amplitude and frequency ranges typical of pathological human tremor, using commercially available stereophotogrammetric systems together with signal processing techniques. A rotating disk is used as a mechanical tremor simulator to test the ability of the system to track known marker trajectories both in a large and a small calibrated volume. The performances of standard discrete Fourier transform (DFT) and autoregressive techniques are also evaluated and compared in the signal spectrum estimation. Results obtained from a pathological test subject and their dependence on the processing techniques adopted are also presented. The use of stereophotogrammetry and of the proposed signal spectrum estimation technique allow to quantify both frequency and amplitude content of three-dimensional (3-D) rotations of many human joints simultaneously and therefore to isolate the contribution of each joint to the whole body tremor.

Aged↗

PubMed1996

Position and orientation in space of bones during movement: experimental artefacts.

This paper deals with the experimental problems related to the reconstruction of the position and orientation of the lower limb bones in space during the execution of locomotion and physical exercises. The inaccuracies associated with the relative movement between markers and underlying bone are analysed. Quantitative information regarding this movement was collected by making experiments on subjects who had suffered fractures and were wearing either femoral or tibial external fixators. These latter devices provided frames that were reliably rigid with the bone involved, and hence the possibility of assessing the relative movement between markers mounted on the skin and this bone. Anatomical frames associated with thigh and shank were reconstructed using technical frames based on different clusters of skin markers and their rotation with respect to the relevant bone evaluated. Marker movement was also assessed in subjects with intact musculoskeletal structures using digital videofluoroscopy.

Journal Article↗

PubMed1993

Gait analysis in patients after Van Nes rotationplasty.

Gait was analyzed through kinetic, kinematic, and temporal-distance parameters assessment to evaluate the functional performance of ten children treated by the classical Van Nes rotationplasty (VNR). Van Nes rotationplasty is a surgical procedure, which permits the conversion of the ankle joint into a "pseudo-knee" joint. The data were compared with measurements of a normal population of ten healthy subjects. Significant differences with respect to the normal were found in stride duration, stride length, cadence, velocity, and stance-swing ratio, and in ground-reaction forces parameters, which define the propulsive phase in the prosthetic side and the acceptance phase in the sound side. There were differences in some kinematic parameters as well. Van Nes rotationplasty is acceptable from a biomechanical-functional point of view, particularly with respect to the active control of the pseudo-knee, which allows a smooth and coordinate gait pattern.

Adolescent↗

PubMed1992

Kinematic and isokinetic evaluation of patients with flat foot.

In recent years research into joint physiology and biomechanics of movement has employed high-technology instruments to quantify the parameters which determine whether the behavior of a joint or kinematic chain is normal or pathologic. Motion analysis, featuring evaluation of both kinematics and the foot-ground reaction, enables us to measure the temporal and quantitative events of normal and pathologic gaits. The use of motion analysis in the study of flat foot has confirmed the ability to discriminate between "normal" and pathologic. Analysis of these themes has enabled us to follow the temporal evolution of the quantitative parameters both before and after treatment, which can be either surgical or conservative. Evaluation of the kinematic changes and the foot-ground reaction also provides information about the quality and effectiveness of the corrective treatment. For instance, the change in the subtalar alignment following application of an endo-orthotic implant can be targeted for validation by motion analysis. All of the joints comprised in the kinematic chain of the lower limb work together to achieve a symmetrical, rhythmic, and most of all harmonic gait.

Adolescent↗

PubMedDate not supplied

The influence of clinical and biomechanical factors on the results of valgus high tibial osteotomy.

The results of the surgical treatment of valgus high tibial osteotomy were studied based on clinical and radiographic assessment and gait-analysis in 21 patients affected with arthrotic varus knee. Although tibial osteotomy has been in use for some time now, the reasons for its frequent failure are still not fully understood. A statistical analysis of the clinical and biomechanical parameters taken into account in this study have shown that hypercorrection in valgus is required to unload the medial compartment and to prevent the recurrence of deformity in varus and pain. Walking with the limb extrarotated may also be a compensatory mechanism, in order to reduce the adductor moment in the knee and overloading of the medial compartment.

Adult↗

PubMedDate not supplied

The use of bioabsorbable polymers in reconstruction of the anterior cruciate ligament. A preliminary experiment conducted on bioabsorbable interference screws: bovine model vs. ovine model.

The use of interference screws in the reconstruction of the anterior cruciate ligament has increased over the years. Despite doubtless advantages there are some problems, too, some involving method of fixation, others the metallic nature of the screws. With the purpose of overcoming the latter, the authors evaluated the possibility of using interference screws made of bioabsorbable material. This preliminary study was conducted on two animal models (bovine and ovine); as a comparison parameter the torsional pair of screw insertion was used. A substantial similarity in the results thus obtained was observed that, together with the minor difficulties observed in the surgical field, contributes to the indication of the ovine model as preferential, based also on successive tests of functional validation conducted in vivo.

Absorbable Implants↗

PubMedDate not supplied

Functional evaluation in total hip replacement patients.

An evaluation of total hip replacement patients requires objective criteria that allow for the measurement of any changes in the biomechanics of the prosthesis and the effects of these changes on clinical findings. An evaluation of loading and joint movement during walking in these patients has been dealt with by many authors. In this study 15 patients who had undergone total hip replacement for coxarthrosis primary or secondary to congenital dysplasia were examined by kinematic and kinetic gait analysis, clinical evaluation, and radiographic evaluation of the position of the neocenter of prosthetic joint rotation. The patients with prostheses in congenital dysplasia presented with a pattern of walking that was significantly modified. In agreement with what is reported in the literature proximal positioning had less influence on gait parameters as compared to lateral dislocation. Furthermore, changes in positioning observed did not seem to have negative effects on joint loading, measured indirectly by the calculation of joint moments.

Adult↗