Time filter

Source Type

Tura A.,National Research Council Italy | Tura A.,University of Bologna | Rocchi L.,University of Bologna | Raggi M.,Prostheses Center | And 2 more authors.
Journal of NeuroEngineering and Rehabilitation | Year: 2012

Background: Symmetry and regularity of gait are essential outcomes of gait retraining programs, especially in lower-limb amputees. This study aims presenting an algorithm to automatically compute symmetry and regularity indices, and assessing the minimum number of strides for appropriate evaluation of gait symmetry and regularity through autocorrelation of acceleration signals. Methods. Ten transfemoral amputees (AMP) and ten control subjects (CTRL) were studied. Subjects wore an accelerometer and were asked to walk for 70 m at their natural speed (twice). Reference values of step and stride regularity indices (Ad1 and Ad2) were obtained by autocorrelation analysis of the vertical and antero-posterior acceleration signals, excluding initial and final strides. The Ad1 and Ad2 coefficients were then computed at different stages by analyzing increasing portions of the signals (considering both the signals cleaned by initial and final strides, and the whole signals). At each stage, the difference between Ad1 and Ad2 values and the corresponding reference values were compared with the minimum detectable difference, MDD, of the index. If that difference was less than MDD, it was assumed that the portion of signal used in the analysis was of sufficient length to allow reliable estimation of the autocorrelation coefficient. Results: All Ad1 and Ad2 indices were lower in AMP than in CTRL (P < 0.0001). Excluding initial and final strides from the analysis, the minimum number of strides needed for reliable computation of step symmetry and stride regularity was about 2.2 and 3.5, respectively. Analyzing the whole signals, the minimum number of strides increased to about 15 and 20, respectively. Conclusions: Without the need to identify and eliminate the phases of gait initiation and termination, twenty strides can provide a reasonable amount of information to reliably estimate gait regularity in transfemoral amputees. © 2012Tura et al; licensee BioMed Central Ltd.


Tura A.,National Research Council Italy | Tura A.,University of Bologna | Raggi M.,Prostheses Center | Rocchi L.,University of Bologna | And 2 more authors.
Journal of NeuroEngineering and Rehabilitation | Year: 2010

Background. The aim of this study was to evaluate a method based on a single accelerometer for the assessment of gait symmetry and regularity in subjects wearing lower limb prostheses. Methods. Ten transfemoral amputees and ten healthy control subjects were studied. For the purpose of this study, subjects wore a triaxial accelerometer on their thorax, and foot insoles. Subjects were asked to walk straight ahead for 70 m at their natural speed, and at a lower and faster speed. Indices of step and stride regularity (Ad1 and Ad2, respectively) were obtained by the autocorrelation coefficients computed from the three acceleration components. Step and stride durations were calculated from the plantar pressure data and were used to compute two reference indices (SI1 and SI2) for step and stride regularity. Results. Regression analysis showed that both Ad1 well correlates with SI1 (R2 up to 0.74), and Ad2 well correlates with SI2 (R2 up to 0.52). A ROC analysis showed that Ad1 and Ad2 has generally a good sensitivity and specificity in classifying amputee's walking trial, as having a normal or a pathologic step or stride regularity as defined by means of the reference indices SI1 and SI2. In particular, the antero-posterior component of Ad1 and the vertical component of Ad2 had a sensitivity of 90.6% and 87.2%, and a specificity of 92.3% and 81.8%, respectively. Conclusions. The use of a simple accelerometer, whose components can be analyzed by the autocorrelation function method, is adequate for the assessment of gait symmetry and regularity in transfemoral amputees. © 2010 Tura et al; licensee BioMed Central Ltd.


Ferrari A.,Prostheses Center | Ferrari A.,University of Bologna | Cutti A.G.,Prostheses Center | Garofalo P.,Prostheses Center | And 5 more authors.
Medical and Biological Engineering and Computing | Year: 2010

A protocol named "Outwalk" was recently proposed to measure the thorax-pelvis and lower-limb kinematics during gait in free-living conditions, by means of an inertial and magnetic measurement system (IMMS). The aim of this study was to validate Outwalk on four healthy subjects when it is used in combination with a specific IMMS (Xsens Technologies, NL), against a reference protocol (CAST) and measurement system (optoelectronic system; Vicon, Oxford Metrics Group, UK). For this purpose, we developed an original approach based on three tests, which allowed to separately investigate: (1) the consequences on joint kinematics of the differences between protocols (Outwalk vs. CAST), (2) the accuracy of the hardware (Xsens vs. Vicon), and (3) the summation of protocols' differences and hardware accuracy (Outwalk + Xsens vs. CAST + Vicon). In order to assess joint-angles similarity, the coefficient of multiple correlation (CMC) was used. For test 3, the CMC showed that Outwalk + Xsens and CAST + Vicon kinematics can be interchanged, offset included, for hip, knee and ankle flexion-extension, and hip ab-adduction (CMC > 0.88). The other joint-angles can be interchanged offset excluded (CMC > 0.85). Tests 1 and 2 also showed that differences in offset between joint-angles were predominantly induced by differences in the protocols; differences in correlation by both hardware and protocols; differences in range of motion by the Xsens accuracy. Results thus support the commencement of a clinical trial of Outwalk on transtibial amputees. © 2009 International Federation for Medical and Biological Engineering.


Cutti A.G.,Prostheses Center | Ferrari A.,Prostheses Center | Ferrari A.,University of Bologna | Garofalo P.,Prostheses Center | And 4 more authors.
Medical and Biological Engineering and Computing | Year: 2010

A protocol named Outwalk was developed to easily measure the thorax-pelvis and lower-limb 3D kinematics on children with cerebral palsy (CP) and amputees during gait in free-living conditions, by means of an Inertial and Magnetic Measurement System (IMMS). Outwalk defines the anatomical/functional coordinate systems (CS) for each body segment through three steps: (1) positioning the sensing units (SUs) of the IMMS on the subjects' thorax, pelvis, thighs, shanks and feet, following simple rules; (2) computing the orientation of the mean flexion-extension axis of the knees; (3) measuring the SUs' orientation while the subject's body is oriented in a predefined posture, either upright or supine. If the supine posture is chosen, e.g. when spasticity does not allow to maintain the upright posture, hips and knees static flexion angles must be measured through a standard goniometer and input into the equations that define Outwalk anatomical CSs. In order to test for the inter-rater measurement reliability of these angles, a study was carried out involving nine healthy children (7.9 ± 2 years old) and two physical therapists as raters. Results showed RMS error of 1.4° and 1.8° and a negligible worst-case standard error of measurement of 2.0° and 2.5° for hip and knee angles, respectively. Results were thus smaller than those reported for the same measures when performed through an optoelectronic system with the CAST protocol and support the beginning of clinical trials of Outwalk with children with CP. © 2009 International Federation for Medical and Biological Engineering.


Fantozzi S.,University of Bologna | Garofalo P.,University of Bologna | Cutti A.G.,Prostheses Center | Stagni R.,University of Bologna
Journal of Mechanics in Medicine and Biology | Year: 2012

The aim of the present study was to identify the phases of gait and the joints where the "ground reaction vector technique" (GRVT) can represent an acceptable alternative to the use of inverse dynamics (ID), when considering subjects with a lower-limb amputation. First, an analytical investigation of the ID of the three joints of the lower limb is given, distinguishing the gravitational, the inertial and the ground reaction contributions. The first two contributions require inertial parameters estimation; for this purpose, literature anthropometric data are typically used, both for the unimpaired and prosthetic limb, as accurate specific inertial parameters for the prosthetic limb are difficult to obtain from companies or require time consuming estimation. This assumption potentially leads to errors in the three-dimensional (3D) joint moment estimation. Second, the results of two case studies, a trans-femoral amputee with two different prostheses and a trans-tibial amputee, showed that the GRVT can explain the most part of the net joint moment for the ankle and the knee in the whole stance phase, and for the hip in the first part of the stance, leading to a similar clinical evaluation without any assumptions on inertial parameters. © 2012 World Scientific Publishing Company.


de Vries W.H.K.,Technical University of Delft | Veeger H.E.J.,Technical University of Delft | Veeger H.E.J.,VU University Amsterdam | Cutti A.G.,Prostheses Center | And 2 more authors.
Journal of Biomechanics | Year: 2010

Background: Inertial Magnetic Measurement Systems (IMMS) are becoming increasingly popular by allowing for measurements outside the motion laboratory. The latest models enable long term, accurate measurement of segment motion in terms of joint angles, if initial segment orientations can accurately be determined. The standard procedure for definition of segmental orientation is based on the measurement of positions of bony landmarks (BLM). However, IMMS do not deliver position information, so an alternative method to establish IMMS based, anatomically understandable segment orientations is proposed. Methods: For five subjects, IMMS recordings were collected in a standard anatomical position for definition of static axes, and during a series of standardized motions for the estimation of kinematic axes of rotation. For all axes, the intra- and inter-individual dispersion was estimated. Subsequently, local coordinate systems (LCS) were constructed on the basis of the combination of IMMS axes with the lowest dispersion and compared with BLM based LCS. Findings: The repeatability of the method appeared to be high; for every segment at least two axes could be determined with a dispersion of at most 3.8° Comparison of IMMS based with BLM based LCS yielded compatible results for the thorax, but less compatible results for the humerus, forearm and hand, where differences in orientation rose to 17.2° Interpretation: Although different from the 'gold standard' BLM based LCS, IMMS based LCS can be constructed repeatable, enabling the estimation of segment orientations outside the laboratory. Conclusions: A procedure for the definition of local reference frames using IMMS is proposed. © 2010 Elsevier Ltd.


Raggi M.,Prostheses Center | Cutti A.G.,Prostheses Center | Lippi S.,Prostheses Center | Davalli A.,Prostheses Center
Assistive Technology Research Series | Year: 2010

The stance time symmetry has been assessed on a population of monolateral transfemoral amputees (all C-Leg users) and control subjects through baropodometric insoles. Subjects walked at three self-selected speeds on a daily-living environment for 80m. Results were compared by speed and population, showing both higher asymmetry and variability for the amputees. No relation was found between speed and symmetry. © 2010 The authors and IOS Press. All rights reserved.


PubMed | Prostheses Center
Type: Introductory Journal Article | Journal: Medical & biological engineering & computing | Year: 2014

In 2009, the International Shoulder Group (ISG) had the opportunity to propose to the readers of Medical and Biological Engineering and Computing a Special Issue on shoulder biomechanics. At that time, we pointed out that the field was evolving to include more applied research. After 4years, we can confirm that impression: 10 out of 12 papers included in this second Special Issue deal with clinical related questions, through theoretical and experimental methodologies. This demonstrates that the translational research at the base of ISG foundation in 1989 is effective. We think that the papers of this issue will have an impact on clinics in general and on the treatment of work-related injuries and diseases in particular. Based on the statistics of the Italian Workers Compensation Authority (INAIL), injuries at the shoulder are first in terms of average duration of temporary total disability to work. Moreover, occupational diseases at the shoulder in the industrial and services sector represented 16% of all occupational diseases in 2012, i.e., 46% of those related to the upper limb. These data stress the need for specific interventions, with the contribution of both researchers and policy makers. Starting from the papers included here, we would encourage additional efforts on: (1) quantitative analysis of shoulder loading during tasks associated with musculoskeletal injuries, and ways to reduce that loading, (2) simple and effective tools to improve the diagnosis and outcome assessment of motion-related shoulder diseases, and (3) the development of rehabilitation treatments focused on occupational tasks, taking advantage of state-of-the-art biofeedback technologies, and exploiting the power of biomechanical models for muscle force prediction.


PubMed | Prostheses Center
Type: Evaluation Studies | Journal: Medical & biological engineering & computing | Year: 2010

A protocol named Outwalk was developed to easily measure the thorax-pelvis and lower-limb 3D kinematics on children with cerebral palsy (CP) and amputees during gait in free-living conditions, by means of an Inertial and Magnetic Measurement System (IMMS). Outwalk defines the anatomical/functional coordinate systems (CS) for each body segment through three steps: (1) positioning the sensing units (SUs) of the IMMS on the subjects thorax, pelvis, thighs, shanks and feet, following simple rules; (2) computing the orientation of the mean flexion-extension axis of the knees; (3) measuring the SUs orientation while the subjects body is oriented in a predefined posture, either upright or supine. If the supine posture is chosen, e.g. when spasticity does not allow to maintain the upright posture, hips and knees static flexion angles must be measured through a standard goniometer and input into the equations that define Outwalk anatomical CSs. In order to test for the inter-rater measurement reliability of these angles, a study was carried out involving nine healthy children (7.9 +/- 2 years old) and two physical therapists as raters. Results showed RMS error of 1.4 degrees and 1.8 degrees and a negligible worst-case standard error of measurement of 2.0 degrees and 2.5 degrees for hip and knee angles, respectively. Results were thus smaller than those reported for the same measures when performed through an optoelectronic system with the CAST protocol and support the beginning of clinical trials of Outwalk with children with CP.


PubMed | Prostheses Center
Type: Evaluation Studies | Journal: Medical & biological engineering & computing | Year: 2010

A protocol named Outwalk was recently proposed to measure the thorax-pelvis and lower-limb kinematics during gait in free-living conditions, by means of an inertial and magnetic measurement system (IMMS). The aim of this study was to validate Outwalk on four healthy subjects when it is used in combination with a specific IMMS (Xsens Technologies, NL), against a reference protocol (CAST) and measurement system (optoelectronic system; Vicon, Oxford Metrics Group, UK). For this purpose, we developed an original approach based on three tests, which allowed to separately investigate: (1) the consequences on joint kinematics of the differences between protocols (Outwalk vs. CAST), (2) the accuracy of the hardware (Xsens vs. Vicon), and (3) the summation of protocols differences and hardware accuracy (Outwalk + Xsens vs. CAST + Vicon). In order to assess joint-angles similarity, the coefficient of multiple correlation (CMC) was used. For test 3, the CMC showed that Outwalk + Xsens and CAST + Vicon kinematics can be interchanged, offset included, for hip, knee and ankle flexion-extension, and hip ab-adduction (CMC > 0.88). The other joint-angles can be interchanged offset excluded (CMC > 0.85). Tests 1 and 2 also showed that differences in offset between joint-angles were predominantly induced by differences in the protocols; differences in correlation by both hardware and protocols; differences in range of motion by the Xsens accuracy. Results thus support the commencement of a clinical trial of Outwalk on transtibial amputees.

Loading Prostheses Center collaborators
Loading Prostheses Center collaborators