The Center for Biomedical Informatics
State University of Campinas, Brazil

Research Abstracts

Posturography is an objective instrumental method used to quantify, analyse and document postural stance (static body posture) and sway (dynamical alterations in body posture). It has many applications in Neurology, Orthopedics, Phisiatry and Phisioterapy, Ergometrics, Biomechanics, Occupational and Sports Medicine and Physical Education. Static measurements of spatial data of certain body parts and its relations to one another indicate underlying bone or muscular alterations and diseases, such as escoliosis, defective growth processes, etc. The method of recording spontaneous or reflex dynamic posturographic changes (such as the response to a sudden tilt) is useful to characterize the function of the neuromuscular apparatus, and has been employed to diffentiate CNS lesions, to perform follow-up studies and for the surveillance of therapeutic efficacy. Due to the large number of 2D and 3D spatial data wich must be acquired from the subject, in order to calculate several static and dynamic parameters, the computer has been introduced as a valuable tool some time ago. It offers many advantages, such as an increase in the speed of spatial data acquisition, a decrease in the number of erros, and the possibility of performing complex calculations and graphical output in real time. We describe here a simple microcomputer system used to acquire, display and process 2D static postural spatial data provided by photographs of patient subjected to a standardized situation of measurement. The first application of the system was to quantify, analyse and document static postural defects in school children, and the effect of physical exercise thereon, performed by reseachers at the Faculty of Physical Education. Initially, photographs of subjects in upright supine posture, aligned against a standard frame, are taken in lateral and frontal views. Ca. 20 reference points are marked onto pre-defined body parts using small white round self-adhesive labels. Vertebral spines are marked with 1 cm white adhesive "sticks", so that they can be visualized in lateral view. The computer hardware system consists of a 80386-based 32-bit PC microcomputer (Intellimed, Brazil) with a 80 Mbyte fixed disk, a VGA color video monitor, a digitizing tablet (Digigraf, Brazil) and a matrix graphics printer (Elebra, Brazil). The subject photographs are laid upon the digitizing tablet (or a alternatively a slide is projected onto the tablet's surface), and a hand cursor is used to transmit the sequence of orthogonal (X-Y) coordinates of frame reference points and subject's marked anatomical points to the computer. A data acquisition program was especially developed in compiled Turbo BASIC (Version 1.0, Borland International, USA) to acquire, process and analyse the spatial data. It consists of two modules: 1) the first module is used to setup and calibrate the tablet coordinates, and to acquire anatomical point X-Y coordinates from the subject photographs. It is menu-driven, interactive and easy to use. The entered points are stored into a named linked list, and are simultaneously diplayed onto the graphical screen. 2) the second module converts the spatial data points coordinates from tablet to real-word coordinated and exports them in a suitable format (DIF) for analysis by a commercial spreadsheet program (Quattro Pro, Borland International, USA). A Quattro Pro standard template for computation of several postural formulae (distances, angles and indices) was programmed. Starting with this template, the user loads the file produced by module 2 of data acquisition software and asks for a recalculation. Afterwards, the resulting spreadsheet and associated graphs can be stored and printed out for documentation purposes. The combination af a simple hardware and data acquisition software, plus the capability to export data and analyze them by means of a standard, well-known spreadsheet package has a resulted in a user-friendly and effective system for static posturography. It has been used sucessfully by computer-naive persons to acquire and analyze a large quantity of spatial data on child subjects. Populational comparisons and statistical analyses of the samples and groups collected during a study are easily performed with aid of the spreadsheet program.

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Last Updated: March 2, 1996

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