Biomedical subjects

Aurelio Cappozzo

Publications and source records attributed to Aurelio Cappozzo.

10 recordsLinked to original sources

PubMed2005

Human movement analysis using stereophotogrammetry. Part 1: theoretical background.

This paper sets the stage for a series of reviews dealing with the problems associated with the reconstruction and analysis of in vivo skeletal system kinematics using optoelectronic stereophotogrammetric data. Instantaneous bone position and orientation and joint kinematic variable estimations are addressed in the framework of rigid body mechanics. The conceptual background to these exercises is discussed. Focus is placed on the experimental and analytical problem of merging the information relative to movement and that relative to the morphology of the anatomical body parts of interest. The various global and local frames that may be used in this context are defined. Common anatomical and mathematical conventions that can be used to describe joint kinematics are illustrated in a comparative fashion. The authors believe that an effort to systematize the different theoretical and experimental approaches to the problems involved and related nomenclatures, as currently reported in the literature, is needed to facilitate data and knowledge sharing, and to provide renewed momentum for the advancement of human movement analysis.

Biomechanical Phenomena↗

PubMed2005

Human movement analysis using stereophotogrammetry. Part 2: instrumental errors.

This paper reviews the main aspects involved with the management of instrumental errors associated with video-based optoelectronic stereophotogrammetry. Insights on how such errors propagate to kinematic quantities are of great interest in the field of human movement analysis to improve the precision and reliability of measurements. The review focuses on the technical assessment and analytical compensation procedures to cope with instrumental errors. Relevant contributions dealing with intrinsic sources of systematic and random errors, such as the issues concerning camera calibration and filtering and smoothing of marker position data, are presented. Procedures for marker imaged processing, and missing marker recovery are also surveyed. Methods for checking the accuracy and precision of stereophotogrammetric systems are then reviewed. Finally, since the desired outcome of the movement measurements is a reliable estimate of body segment kinematics, state-of-the-art techniques proposed for minimization of error propagation arising from a cluster of external markers are described.

Biomechanical Phenomena↗

PubMed2005

Human movement analysis using stereophotogrammetry. Part 3. Soft tissue artifact assessment and compensation.

When using optoelectronic stereophotogrammetry, skin deformation and displacement causes marker movement with respect to the underlying bone. This movement represents an artifact, which affects the estimation of the skeletal system kinematics, and is regarded as the most critical source of error in human movement analysis. A comprehensive review of the state-of-the-art for assessment, minimization and compensation of the soft tissue artifact (STA) is provided. It has been shown that STA is greater than the instrumental error associated with stereophotogrammetry, has a frequency content similar to the actual bone movement, is task dependent and not reproducible among subjects and, of lower limb segments, is greatest at the thigh. It has been shown that in in vivo experiments only motion about the flexion/extension axis of the hip, knees and ankles can be determined reliably. Motion about other axes at those joints should be regarded with much more caution as this artifact produces spurious effects with magnitudes comparable to the amount of motion actually occurring in those joints. Techniques designed to minimize the contribution of and compensate for the effects of this artifact can be divided up into those which model the skin surface and those which include joint motion constraints. Despite the numerous solutions proposed, the objective of reliable estimation of 3D skeletal system kinematics using skin markers has not yet been satisfactorily achieved and greatly limits the contribution of human movement analysis to clinical practice and biomechanical research. For STA to be compensated for effectively, it is here suggested that either its subject-specific pattern is assessed by ad hoc exercises or it is characterized from a large series of measurements on different subject populations. Alternatively, inclusion of joint constraints into a more general STA minimization approach may provide an acceptable solution.

Adipose Tissue↗

PubMed2005

Human movement analysis using stereophotogrammetry. Part 4: assessment of anatomical landmark misplacement and its effects on joint kinematics.

Estimating the effects of different sources of error on joint kinematics is crucial for assessing the reliability of human movement analysis. The goal of the present paper is to review the different approaches dealing with joint kinematics sensitivity to rotation axes and the precision of anatomical landmark determination. Consistent with the previous papers in this series, the review is limited to studies performed with video-based stereophotogrammetric systems. Initially, studies dealing with estimates of precision in determining the location of both palpable and internal anatomical landmarks are reviewed. Next, the effects of anatomical landmark position uncertainty on anatomical frames are shown. Then, methods reported in the literature for estimating error propagation from anatomical axes location to joint kinematics are described. Interestingly, studies carried out using different approaches reported a common conclusion: when joint rotations occur mainly in a single plane, minor rotations out of this plane are strongly affected by errors introduced at the anatomical landmark identification level and are prone to misinterpretation. Finally, attempts at reducing joint kinematics errors due to anatomical landmark position uncertainty are reported. Given the relevance of this source of errors in the determination of joint kinematics, it is the authors' opinion that further efforts should be made in improving the reliability of the joint axes determination.

Biomechanical Phenomena↗

PubMed2004

Knowledge discovery in databases of biomechanical variables: application to the sit to stand motor task.

ABSTRACT : BACKGROUND : The interpretation of data obtained in a movement analysis laboratory is a crucial issue in clinical contexts. Collection of such data in large databases might encourage the use of modern techniques of data mining to discover additional knowledge with automated methods. In order to maximise the size of the database, simple and low-cost experimental set-ups are preferable. The aim of this study was to extract knowledge inherent in the sit-to-stand task as performed by healthy adults, by searching relationships among measured and estimated biomechanical quantities. An automated method was applied to a large amount of data stored in a database. The sit-to-stand motor task was already shown to be adequate for determining the level of individual motor ability. METHODS : The technique of search for association rules was chosen to discover patterns as part of a Knowledge Discovery in Databases (KDD) process applied to a sit-to-stand motor task observed with a simple experimental set-up and analysed by means of a minimum measured input model. Selected parameters and variables of a database containing data from 110 healthy adults, of both genders and of a large range of age, performing the task were considered in the analysis. RESULTS : A set of rules and definitions were found characterising the patterns shared by the investigated subjects. Time events of the task turned out to be highly interdependent at least in their average values, showing a high level of repeatability of the timing of the performance of the task. CONCLUSIONS : The distinctive patterns of the sit-to-stand task found in this study, associated to those that could be found in similar studies focusing on subjects with pathologies, could be used as a reference for the functional evaluation of specific subjects performing the sit-to-stand motor task.

Journal Article↗

PubMed2004

Estimation of the centre of rotation: a methodological contribution.

The location of the centre of rotation of human joints that can be modelled as a spherical hinge can be estimated using kinematics information about the two adjacent bony segments involved recorded while the subject makes them move one relative to the other (functional method). In order to solve the relevant analytical problem, several algorithms have been proposed. Most recently, two methods, one based on a spherical best-fit approach and another based on the Reuleaux construction, have been presented as being different and submitted to comparative evaluation. This paper modifies the second method taking all information in the data set into account and shows that, having done this, the two methods coincide analytically.

Algorithms↗

PubMed2004

An optimization algorithm for human joint angle time-history generation using external force data.

A mathematical model is presented that estimates joint kinematics and kinetics using measured external resultant loads and readily available parameters. The musculo-skeletal system was represented by a planar three degrees of freedom open kinematic chain. Information extraction was limited to the flexion-extension function of ankle, knee, and hip during quasi-planar motor tasks. Starting from plausible first approximation kinematics, other kinematic functions are iteratively generated by an optimization algorithm and corresponding ground reaction loads are calculated through inverse dynamics. Kinematic coordinates are represented using B-splines and modified by manipulating the control points. The iterative procedure stops and provides the final kinematic and kinetic estimates when a similarity criterion between estimated and measured ground reaction components is satisfied. The model structure was elaborated upon and the algorithm parameters optimized for robustness and accuracy using a benchmark motion in a simulation exercise. The maximal root mean square difference over time between estimated and benchmark quantities was approximately 1% of the peak to peak value for ground reaction components and intersegmental couples, and 6% for joint angles.

Algorithms↗

PubMed2003

Clinical characteristics of flexed posture in elderly women.

OBJECTIVES: To investigate the relationships between the severity of flexed posture (FP), skeletal fragility, and functional status level in elderly women. DESIGN: Cross-sectional study. SETTING: Geriatric rehabilitation research hospital. PARTICIPANTS: Sixty elderly women (aged 70-93) with FP referred to a geriatric rehabilitation department for chronic back pain without apparent comorbid conditions. MEASUREMENTS: Multidimensional clinical assessment included the severity of FP (standing occiput-to-wall distance) demographic (age) and anthropometric (height, weight) data, clinical profile (number of falls, pain assessment, Mini-Mental State Examination, Comorbidity Severity Index, Geriatric Depression Scale, Multidimensional Fatigue Inventory), measures of skeletal fragility (number of vertebral fractures by spine radiograph, bone mineral density (BMD), and T-score of lumbar spine and proximal femur), muscular impairment assessment (muscle strength and length), motor performance (Short Physical Performance Battery, Performance Oriented Mobility Assessment, instrumented gait analysis), and evaluation of disability (Barthel Index, Nottingham Extended Activities of Daily Living Index). RESULTS: The severity of FP was classified as mild in 11, moderate in 28, and severe in 21 patients. Although there were no differences between FP groups on the skeletal fragility measurements, the moderate and severe FP groups were significantly different from the mild FP group for greater pain at the level of the cervical and lumbar spine. The severe FP group was also significantly different from the mild but not the moderate FP group in the following categories: clinical profile (greater depression, reduced motivation), muscle impairment (weaker spine extensor, ankle plantarflexor, and dorsiflexor muscles; shorter pectoralis and hip flexor muscles), the motor function performance-based tests (lower scores in the balance and gait subsets of the Performance Oriented Mobility Assessment), the instrumented gait analysis (slower and wider base of support), and disability (lower score on the Nottingham Extended Activities of Daily Living Index). The total number of vertebral fractures was not associated with differences in severity of FP, demographic and anthropometric characteristics, clinical profile, muscular function, performance-based and instrumental measures of motor function, and disability, but it was associated with reduced proximal femur and lumbar spine BMD. CONCLUSION: The severity of FP in elderly female patients (without apparent comorbid conditions) is related to the severity of vertebral pain, emotional status, muscular impairments, and motor function but not to osteoporosis, and FP has a measurable effect on disability. In contrast, the presence of vertebral fractures in patients with FP is associated with lower BMD but not patients' clinical and functional status. Therefore, FP, back pain, and mobility problems can occur without osteoporosis. Older women with FP and vertebral pain may be candidates for rehabilitation interventions that address muscular impairments, posture, and behavior modification. Randomized controlled trials are needed to support these conclusions.

Aged↗

PubMed2003

Is it feasible to reconstruct body segment 3-D position and orientation using accelerometric data?

The analysis of the mechanics of the musculo-skeletal system during the execution of a motor task requires the determination of the instantaneous position and orientation of the body segments involved in relation to an inertial system of reference. By using adequately assembled uniaxial accelerometric sensors, an easy-to-manage measurement system can be obtained that estimates the three-dimensional position and orientation (P&O) of a body segment through an appropriate analytical model. However, the extent to which experimental errors, in particular accelerometers (ACs) assembly inaccuracies, affect such estimation has never been systematically investigated. This paper systematically analyzes the sensitivity of analytical models of body segment P&O reconstruction through a six-AC system and a nine-AC system to different sources of experimental error. We simulated and statistically assessed the performance of these models in the case of body segment motions typical of movements under muscular control. The results obtained indicated that the inaccuracy in the orientation of the individual AC's active axes and the offset error in the AC responses were the major sources of P&O estimation errors. In particular, no accurate estimation of position was possible with the analytical models analyzed. Under the motion conditions simulated in this study, no substantial advantages were found in using a nine-AC system rather than a six-AC system. Considering that the magnitudes of the simulated experimental errors were quite low (< or = 0.1 deg: AC's orientation; < or = 10(-4) m: uncertainty of the distance between two ACs; < or = 10(-2) ms(-2): random error; 0.5 x 10(-2) ms(-2): offset error), the results indicate that none of the two ACs systems analyzed is suitable for body segment P&O estimation in routine biomechanical applications.

Acceleration↗

PubMed2002

Minimum measured-input models for the assessment of motor ability.

The problem of assessing the physical functional limitation of a given individual and establishing the relationship between impairment/s and disability using a biomechanical approach is addressed. This endeavour was pursued with reference to the locomotor system and in order to address the following specific clinical issues: prognosis, eligibility for health services, measure of the outcome of a therapy, and therapeutic programming. A thorough biomechanical analysis of selected motor tasks would be effective but awkward to apply for subject-specific evaluation in clinical practice by reason of the complexity of both instrumentation and experimental protocols. In addition, as illustrated in the paper, the adequacy of the accuracy with which this type of analysis provides relevant information may be argued. Therefore, different methods were devised in the attempt to join objectivity with field applicability. These entailed the measurement of a minimum number of biomechanical variables during the execution of the selected motor task and these quantities were acquired using a low cost experimental apparatus least perceivable to the test subject, that is a dynamometric plate. However, since data thus obtained do not necessarily lend themselves to straightforward interpretation in terms of function assessment, models of the musculo-skeletal system that embodied the invariant aspects of both the modelled system and the specific motor task were devised. Using such "minimum measured-input models", physiology-related, and thus easier to interpret, information was obtained. Two different sets of mathematical models are presented: one deals with the lowest level of detail and normally aims at assessing a global physical performance score, the other discloses joint function and segmental mechanics and therefore contributes to establishing a relationship between impairment and disability. The validation of these models, carried out in the laboratory, has shown that they possess a potential for application in clinical practice.

Biomechanical Phenomena↗