The Development of a Static Posture Analysis Instrument with Direct Application As an Objective Pre X-Ray Screening Procedure
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The development of a static posture analysis instrument with direct application as an objective pre x-ray screening procedure. G. Reid Hadden DC The development of a relatively inexpensive device to Dans le cadre d'une recherche pr6liminaire, I'article objectively measure and allow photographic recording of traite du d6veloppement d'un appareil relativement peu a patient's static posture and centre of gravity vector is onereux, permettant de mesurer objectivement la posture discussed as a preliminary investigation. The overall statique et le vecteur de centre de gravite d'un patient, et accuracy was found to be ± 4.20 on a 3600 protractor for de les enregistrer photographiquement. La precision the centre of gravity vector and an overall error of + 5.3 globale a ete evaluee comme etant de l'ordre de ± 4.20 millimeters for measuring spinal distortion compared to sur une protractor de 3600 pour le vecteur de centre de x-rays. The device can be used as a pre x-ray screening gravite, avec un marge d'erreur globale de + 5.3 instrument to: 1) determine the static biomechanics, millimetres pour la mesure de distortions de l'epine 2) reduce the clinical need for x-ray examination or dorsale, par comparaison aux rayons X. Cet appareil peut 3) suggest the specific type of x-ray required. By servir d'instrument de filtrage pr6c&dant les rayons X measuring the static posture, immediate evaluation of the pour: 1) determiner les facteurs biom6caniques statiques, effect of orthopaedic appliances on the static posture can 2) reduire le besoin clinique d'examens aux rayons X, ou be seen. (key words: posture, chiropractic, x-ray). 3) suggerer le type particulier de rayons X exig6s. En mesurant la posture statique, I'on peut proceder a une evaluation imm6diate de l'effet d'appareils orthopediques sur la posture statique (mots-cle: posture, chiropractie, rayonsX). Introduction The need to develop an instrument to measure static method of first choice for the chiropractor. Brown5 states that posture becomes important in chiropractic practice when one prior development of postural fatigue renders the back liable considers that each human spine develops as a unique to subsequent injury and that movements with a load which biomechanism, both statically and dynamically." 2'3 This is are not parallel with the plane of central gravity are likely to detennined by his or her internal and external environmental result in injury. In dealing with posture, those activities adaptation in one's own lifetime. which involve a great deal of static effort for the maintenance To diagnose and treat back pain, with or without of posture are also associated with increased rates of energy neurological symptomatology, one must be able to study the expenditure leading to postural fatigue. When studying the statics and dynamics of the spine from a position of greater static posture then, maladaptations or assymmetries will lead objectivity, than by palpation and/or x-ray analysis alone. to postural fatigue rendering the spine more susceptible to The chiropractic profession readily acknowledges that spinal both static and dynamic injury. x-ray examination be performed only to fulfill clinical needs The device under study, allows for the objective analytical as shown from other examination procedures and history. As measurement and photograph of the gross static posture. In well, repeated radiological examinations should be avoided doing this, it overcomes the problems of existing methods of unless they are clinically necessary.4 The Ontario Chiroprac- analysis which are: tic Association in addressing the use of x-ray in diagnosis and 1) there is no method that indicates the centre of gravity chiropractic treatment states the radiological approach to position and static posture together, spinal diagnosis must include pathological, biomechanical 2) there is no objective recording procedure to actually and anatomical considerations.4 show that measurements were taken, Chiropractors utilize x-ray basically for three reasons: 3) incomplete data (some instruments were designed to 1) to satisfy themselves that there are no contraindications perform a specific function), to therapy. 4) others take too long to obtain a complete set of 2) to analyse the areas of structural and/or biomechanical measurements, involvement. 5) some methods are too expensive for use in an every day 3) to assess the direction and force of the adjustment that is clinical setting, going to be required.4 6) some were not designed to fumish all measurements The use of x-rays as a method of analysis for static or with an actual numerical value, dynamics of the spine should not be the only objective 7) or a combination of the above. This device measures: 1) where a patient's centre of gravity vector is relative to presented at the Ontario Chiropractic Association 1982 Convention. the x, y, z axis and most importantly to compare this submitted February 1983. with the spine, (not just what quadrant the centre of approved September 1983. gravity is found), The Journal of the CCA/Volume 27 No. 4/December 1983 139 A static posture analysis instrument 2) pelvic rotation, 3) functional pelvic level, 4) fifth lumbar vertebrae's position, right or left of the vertical plumbline, 5) shoulder rotation, 6) shoulder level, 7) seventh cervical vertebrae's position, right or left of the vertical plumbline, 8) first cervical vertebrae's position, anterior or posterior to the second set of vertical plumblines. The instrument in providing this information enables the practitioner to: 1) clinically study human static biomechanics of the spine frequently and without ionizing radiation, 2) to provide an objective, measurable pre x-ray screening method to assist in determining, a) full spine or sectional x-rays required at the time of initial examination, b) to monitor posture of patients who may or may not require films, due to factors such as age or possible pregnancy, c) to monitor treatments which may change the posture, d) for future reference in acute trauma, or aging of the spine, that may cause permanent postural changes and indicate the clinical need for local x-ray studies, 3) to observe the effectiveness of orthopaedic appliances (heel lifts, sole lifts, corsets) that chiropractors may prescribe. This can be seen immediately and for future Figures 1 and 2: Shows the entire instrument. monitoring of their effectiveness. Method: technical description The instrument that has been developed is visualized in figures 1 and 2. For the technical description, an explanation of the centre of gravity vector indicator is necessary. The components include an accurate digital weight scale at the base, and square aluminum tubing with a 900 bend. The actual indicator is made of a trianglular base with three level adjusting screws, a 360° protractor, a bull's eye level, and a circular slide. The digital weight scale was chosen primarily for its method of mechanical operation and the usefulness of monitoring a patient's weight in the normal course of patient care. Any weight scale has the ability to indicate an individual's weight within an accuracy for that scale. The important aspect of the mechanics, is that by standing on one foot and not two, the scale will read approximately the same weight, (± 2-4 pounds). However the angle of the scale's table surface (the part the patient stands on) changes its angulation relative to the horizon the x axis right or left, and z axis, anterior or posterior. The y axis is not important at this time. This angle directly corresponds to where the one foot is placed. 140 The Journal of the CCA/Volume 27 No. 4/December 1983 A static posture analysis instrument To clarify this point, if a 200 pound (lb) man stands on one foot, he still weighs 200 lbs., but the scale is lower on the side of the weight bearing foot. Now if the 200 lb. man stands on both feet properly positioned around the mechanical centre of the scale, any angle change is directly related to any shift in the centre of gravity. By using a 3600 protractor and a bull's eye level the direction of the bubble can be found and a degree assigned. The distance that the bubble travels from the centre of the level is the result of the patient's weight and the distance his centre of gravity is from the centre of the scale, and should not be confused with the direction the bubble moves, which is the vector for the centre of gravity. The square aluminum tube is attached at one end to the exact mechanical centre of the scale (mechanical centre is different from the physical centre). At the other end is the level indicator (figure 3). The actual two measuring grids for the shoulder and pelvis that indicate right or left shift and functional level, have a right or left centimeter (cm) ruler at the bottom of the grid with zero at the vertical centre (the shoulder rotation, and the Figure 3: Close up of the footplate and centre of gravity Cl grids are similar to this) and a single line running vector indicator. horizontally in the middle of the grid. The slides which indicate the L5 or C7 positions move freely on the grid and are actually pendulums which allow them to remain exactly vertical at all times. The slide has a bull's eye position finder. This works similar to the eyeing of parallel double plumblines, but is much faster. The central dot is viewed so that it is in the centre of the larger circle and when this is in line with the center of the PSIS centimeter bar (explained below) the relative position of L5 can be found and a numerical value assigned.