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. At the right side of the shoulder and pelvic grids are two protractors.These measure in degrees the shoulder level and the functional pelvic level. Attached to the shoulder and pelvis grids at their right side and in the anterior-posterior direction, are the pelvic rotation, shoulder rotation and first cervical vertebra's gravity line grids. These also have slides. The pelvic rotation grid which only measures rotation of the pelvis has a slide which indicates standing static pelvic rotation in millimeters and/or Figure 4: PSIS cm. bar and valcrove markers. degrees. The pelvic main slide has a bull's eye position finder, a protractor, as well as a second sliding centimeter mark (x) or a lead marker on the center. He then palpates the scale (on top of the main slide). A flexible indicator line joins left posterior superior iliac spine (PSIS) and places a valcrove both together. Shoulder rotation grids (one on the right and marker over the position. This marker is held by tape and has left side) have anterior-posterior centimeter scales with zero vertical and horizontal lines which intersect in the centre of in the middle. Both the slides use the bull's eye position the marker. The operator repeats the procedure for the right method. The Cl anterior-posterior grid is identical to the right PSIS. He then places the small PSIS centimeter bar on the shoulder rotation grid and uses the same centimeter scale. valcrove of both sides, so that the point of intersection of the The slide, however, is much longer and again uses the same valcrove marker and the centimeter bar reads the same method to locate the position of Cl. number on the right and left sides of the centimeter bar. The centimeter bar consists of a plastic bar with right and left centimeter scale with zero at the centre, a lead bar and Method: operation vertical post at zero and a second vertical post at the right end The patient stands in front of the operator so that his back of the bar (figure 4). This effectively finds the center of the can be clearly seen. The operator palpates the seventh first sacral segment of the spine to within an accuracy cervical or first thoracic spinous process, and puts an ink equivalent to the operator's expertise in spinal palpation. This The Journal of the CCAIVolume 27 No. 4/December 1983 141 A static posture analysis instrument

is usually plus or minus 5 mm. verified by x-ray evaluation. the highest shoulder points (usually the acromioclavicular The use of valcrove markers and PSIS centimeter bar may joint), if both can be seen clearly. This is relatively accurate appear at first glance cumbersome, but this method was in clinical settings since the shoulders are so distant from the chosen for three reasons: spine. If any practitioner wishes, however, a more accurate 1) to indicate the pelvic rotation in the erect static posture measurement of the shoulder level is possible. In the much better than other methods, described analysis and data, the first method is sufficiently 2) the centimeter bar has a metal center at the zero mark accurate. It should be stated here, that shoulder rotation is not which will show up on any AP lumbar film and allow assigned a numerical value in routine examination, but is fine measurement correction when x-rays are necessary, given a direction of rotation relative to the other side. This is 3) to provide a fixed reference point for the dynamic not an important factor in determining spinal statics, but walking analysis which is the same point for the static again the device is set up to measure this for those who wish posture measurements. it. The patient is then directed to stand on the foot plate The slide on the shoulder grid is moved to line up with the assembly. This is the part of the device that indicates the mark on the C7 spinous process, and the value read on the patient's weight and the vector direction of his/her center of centimeter scale. The shoulder level is again read from the gravity (C.G.). The foot plate is divided into four quadrants protractor at the extreme right on the shoulder grid. This, and has normal foot-stance lines on it (figure 3). then, finds the approximate shoulder level and C7 position. The feet, one at a time, are positioned by the operator so Attached to the pelvic and shoulder grids and in the the proximal head of the fifth metatarsal is on the central line anterior-posterior direction are the pelvic rotation, shoulder which cuts the foot plate into anterior and posterior halves rotation and first cervical vertebra gravity line grids. These (the x axis). The great toe of the same foot is placed on the also have slides. stance line of that side and the heel is placed centrally on the Looking at the pelvic rotation grid which only measures same stance line. This is repeated for the opposite foot. It rotation of the pelvis, a slide is moved along the grid until the should be mentioned here that the normal ideal gravity line is bull's eye position finder is in line with the center post of the from the external auditory meatus and the center of the PSIS centimeter bar,, while holding the scale to prevent odontoid process, through the center of the seventh cervical movement, the top centimeter slide is moved anterior or vertebrae and the third lumbar vertebrae through the anterior posterior until its position finder lines up with the post on the 1/3 of the sacrum just posterior to the femoral head and the right side of the PSIS centimeter bar. The millimeters of anterior to the knee joint to hit the head of the fifth metatarsal rotation are read at the intersection of the main and top slide. between both feet.6'7 This is why the feet are carefully placed The degree is read where the flexible indicator line cuts the using the land marks on the foot plate and the patient's feet. protractor. The operation of the entire assembly is quite simple. The The operator must keep in mind that the zero mark on the operator grasps both sides of the pelvic grid and moves the top sliding scale indicates which direction, anterior or sides up or down, until the middle line on the grid is parallel posterior, the right side of the pelvis is rotated relative to the to the PSIS cm. bar, using the bull's eye position finder if left. necessary. The operator then eyes the vertical double The (atlas) gravity line is determined by moving the Cl plumblines, which cuts the entire device into its right and left slide which is attached to the right shoulder rotation grid, by halves. lining up the most posterior margin of the external auditory This is because, if the grid is not perfectly level it is meatus or actually palpating the right transverse process of actually a hypotenuse of a right angled triangle and dependent Cl and marking it with ink. Then, using the bull's eye on the same geometric laws of the Pythagorean theorem. The position finder of that slide, the exact Cl position relative to grid when evaluating pelvic level in reality, becomes shorter the normal vertical double plumblines can be determined. than the base. The grid is made to become longer as Now moving to the center of gravity (C.G.) vector increased pelvic level is found, so the grid's zero point can be indicator, the bubble in the level is found by the circular slide repositioned, and accurate measurements taken. The slide is which is rotated on a 3600 protractor. When the bubble moved right or left and using the bull's eye position finder is appears in the middle of the two indicator lines, the degree lined up with the center of the PSIS cm. bar, and a numerical which is the patient's C.G. vector line (the line which the value assigned from the centimeter scale. The functional C.G. is found on) is read at the opposite end of the slide. In pelvic level can be found at the extreme right side of the grid. lining up the bubble, care must be taken to line up the dot on The grid's short right-sided horizontal double plumbline is the level with the circle on the slide or an inaccurate reading viewed by lining up the two lines to be seen as one, and then will be obtained. This is exactly the same method as the the degree is read from the protractor that is directly behind bull's eye position finder. the grid. The entire procedure for complete static analysis takes 3-4 The shoulder grid is essentially the same and the identical minutes. When the final slide is in position, an instant method is used. The only difference is in determining the polaroid photo is taken to indicate the measurements were shoulder level. The middle line of the grid is lined up with actually done and for patient identification. With the 142 The Joumal of the CCA/Volume 27 No. 4/December 1983 A static posture analysis instrument

measurements and a photo there is better visualization of the actual measured degree are found by using a 3600 protractor patient's posture. There is a full length mirror at the side of whose zero was the intersection of the x and z axis (figure 5). the device so that in the photograph the patient's profile and This, then, provides the exact figures (real value) which the Cl gravity line as well as the posterior view appears in the device should measure and match using the dead weight same photograph. (Table 1). If the practitioner realizes at the time that frequent repeated The dead weight consists of a 5 foot bar bell, so the weight analysis will be necessary, then all ink markings, including could be varied easily. In one of the plastic cups which cover ones that can be drawn around the valcrove markers, can be the ends of the bar bells, a thumb tack was placed in the made with non-washable ink at the first postural analysis. exact center, so as to protrude from the end and was put back This will ensure that with repeated measurements that all onto the bar bell. The end -of the tack would later be placed reference points will be exactly the same from the first into the footplate holes enabling repeated exact centering of reading to the last, no matter what time frame. the dead weight in each quadrant. A tripod was made to hold Nothing is written down until your entire office the dead weight, first vertical and then at any other position examination is completed. All the slides remain in the proper desired. A bull's eye level with a small metal wire, vertically place for future recording. As many as five patients can be placed at the center was adapted. This is the object the device measured consecutively. However, the numerical values must lines up with, to measure right-left and anterior-posterior be marked with colored pens on the grids, corresponding to displacement, and to make sure the bar bell is perfectly the color coding assigned the five patients. vertical at all times. When the static posture analysis and photograph has been It should be stated here, that there are two sets of vertical completed, and if there is enough spinal and center of gravity double plumblines on the device. One set cuts the entire distortion, the appropriate full spine or sectional x-rays are device into right-left halves and is in line with the foot plate requested. All lead anatomical markers (PSIS centimeter bar, or z axis, which also cuts the footplate into right/left halves. C7 marker) are left on the patient. The leaded portions of the The other set, cuts the device and the footplate or x axis into markers appear on the x-ray films. This allows for fine anterior-posterior halves, so that a 20mm. shift measured on measurement correction on the readings, since placement of the footplate also can be measured at a higher position on the the markers are still subject to the operator's subjective device, using the double plumbline as zero. palpation induced error. Between the photograph, the A weight of 30 pounds (lbs.) was used first. This was measurements and this back up system when films are taken, placed at the end of the bar bell that did not have the tack. there is continuous check to allow accuracy of measurements. The tack at the end of the bar bell was placed in the hole, in the first quadrant (anterior right quadrant). The tripod Method: testing secured, the now. top-heavy bar bell was adjusted so that the bull's eye level which was placed on the top of the bar bell The first portion of testing was to determine the accuracy read zero tilt in any direction. This means that the top center of the center of gravity vector indicator and of the pelvic grid of the bar bell is in exactly the same position in the quadrant system, using dead weight. The pelvic grid system is as the bottom center of the bar bell which is the same as the identical to the shoulder system, the accuracy in one can be drilled hole and has known coordinates. used for the other. For this reason, testing of the shoulder grid was not done. At this time, the degree on the device which indicates the The foot plate had randomly placed 1/16 inch holes drilled, vector direction of the center of gravity was read and one in each quadrant. The exact position (in millimeters) of recorded. The pelvic grid system and slides were moved to each hole was measured using the quadrant lines on the foot line up with the metal marker on the bar bell's bull's eye plate as an x and z axis system (x axis right or left from zero; level and the numerical values of any right-left and z axis anterior or posterior from zero). This gives each hole anterior-posterior shift was recorded. The same procedure two measurements in a coordinate system of mathematics. was followed as the weight was increased by increments of From these, a mathematically calculated degree was also 20 lbs., until 200 lbs. were reached. At that point, the bar found for the same point. This is done by using a bell was moved to the next quadrant, the weight reduced to trigonometric function formula: 30 lbs. and the procedure started over. This method was used Tangent 0 = z for all four quadrants. After the results were obtained x (Table 2) and the error of the device was found to be small enough (accurate positional measurements could be taken), 0 = angle from trigonometric functions for patients were selected to determine placement accuracy of the decimal fractions of a degree tables. PSIS centimeter bar and the C7 marker. z = millimeters on the z axis. Patients were selected in order of their appearance as new x = millimeters on the x axis. patients in my office. The selection criteria for use in the All four points of the foot plate have two numerical values investigation were that: in millimeters (where the two line intersect is the position of 1) the chief complaint be orthopaedically or neurologically the drilled hole). A mathematically calculated degree, and an related to the spine or pelvis, for example chronic low The Journal of the CCA/Volume 27 No. 4/December 1983 143 A static posture analysis instrument

back pain or cervical radiculitis that could be demonstrated with orthopaedic testing to have its origin TRIGONOMETRIC e RELATIONSHIP at the spinal column, FOR DEAO WEIGHT TESTING 2) acute patients were not accepted as part of the study, 3) no x-rays of the spine or pelvis had been taken within the last year, and 4) there were no contraindications to taking sectional pelvic I£11 101 - I AXIS I1' or cervical x-rays, for example children or pregnancy. QUAD 2 1++ The patients who fell into this group had the case history, orthopaedic examination, complete postural meaurements using the device and identification photograph, an AP and lateral lumbar and an AP and lateral cervical films taken after the postural measurements. The films were read in the usual manner. As well, the exact position of the leaded portion of the PSIS centimeter bar and C7 marker were measured to find out how close the center of the markers came to the desired Ill AXIS I', 360 position. The device bases its measurements from lining up with the center of the markers, so if the markers could not be placed close enough by palpation to indicate the center of SI and C7 body, then this error would be transmitted and possibly amplified by the device and decrease the needed accuracy. On the developed AP lumbar film, a mark is made on the ODAl3 1- 4 1+ -I right and left intersection point where the posterior aspect of the iliac crest crosses behind the superior lateral portion of the sacral ala. Two more marks, right and left are placed at the most inferior edge of the articular portion of the sacroiliac joint. Lines are drawn from corner to corner, the intersection point of these lines is taken to be the center of the sacrum. usually at a level of S1. A second method can be used if all four sacral points are not clear, or as a check on the first. One puts marks on both Figure 5: Diagramatic relationship between the quadrant sides of the L5 body at the most lateral but middle border. A test holes and the foot plate. perpendicular line is dropped straight down, until the line hits the sacrum. The distance between the two points on the sacrum is measured and then divided by two. If this point is not in line with the first method, the distance between the two is divided by 2 (average found) and that is taken as SI center. The lead marker that was placed on the spinous process of C7 or Ti can be seen on the AP cervical film. The four corners of C7 are marked, and corner to corner lines are drawn, their intersection point is taken as the center of C7 (figure 6). The distance from SI and C7 center and the lead marker were measured. Table 3 shows the results and total error involved for both SI and C7.

Results Figure 5 illustrates the footplate and relationship of the drilled holes, on the x and z axis. Table I shows the actual measurements of each hole, the calculated degree and the Figure 6: Demonstrates AP lumbar and cervical x-rays measured degree on the footplate. It must be stated here that indicating C7 marker placement error of 3mm. right and PSIS the actual real values for each hole were found only after all cm. bar lead marker placement error of 3mm. right. For test dead weight testing had been completed. This was done so subject 36 which is the patient in figure 7.

144 The Joumal of the CCA/Volume 27 No. 4/December 1983 A static posture analysis instrument

Quadrant 1 Quadrant 2 Quadrant 3 Quadrant 4 lbs. z Axis x Axis 00 z Axis x Axis 00 z Axis x Axis 00 z Axis x Axis 00 mm mm mm mm mm mm mm mm 30 60 65 44 12 43 13 70 65 47 19 75 14 50 56 67 42 10 45 14 72 62 46 20 82 15 70 52 60 45 15 37 12 65 58 42 18 84 17 90 58 62 43 11 38 17 67 63 48 17 83 12 110 62 65 47 8 40 18 68 65 47 18 85 17 130 61 64 43 10 42 12 68 64 46 20 87 15 150 53 64 45 11 38 14 70 67 47 21 78 14 170 55 63 45 12 44 13 72 62 48 24 79 14 190 58 62 46 14 43 15 72 63 48 23 80 15 200 57 64 45 13 42 15 71 64 49 22 81 15 Average Measured Dead Weight Value. 57.9 63.6 44.5 11.6 41.2 14.3 69.5 63.3 46.8 20.2 81.4 14.8 Table 2: Measured dead weight values

Quadrant Table 2 is the measured dead weight values of the device No. and Calcu- Plus or of the x and z axis in millimeters and the measured degrees. Hole x Axis z Axis lated Measured Minus O0 No. mm. mm. 0° 0° Error The average degree error is 1.475° or plus or minus 0.73750 rounding this off to- 0.70. The average mm. error is 1 63.0 56.0 41.60 42.5 0 .450 2 40.0 10.0 14.50 13.750 .750 1.125 mm. or plus or minus 0.5625 mm. rounding this off to 3 63.0 69.0 47.50 46.5° .5° 0.6 mm. Table 3 shows the results and total error involved 4 80.0 18.0 12.70 13.5° .4° for both S1 and C7 between x-ray analysis and the external land marks attached to the patient (PSIS cm. bar and C7 marker). Table 4 shows the results obtained between x-ray Table 1: Real values for drilled holes analysis of the pelvic level and the measured pelvic level by the instrument. Table 5 shows the error of actual x-ray measurements of lead markers from S1, C7 and the pelvic level. Table 6 shows the total instrument error calculations. not to prejudice the testing by knowing the real values beforehand. An example of the real value calculation for Quadrant 1 Sources of Error Drilled holes measured coordinates were: There are other areas that in the clinical operation of the x = 63 mm. Tan. 0 = z device, will increase the operating error slightly. The first is x the center of gravity vector indicator. Since the patient's feet z = 56 mm. = 56.0 mm. must be placed on the footplate and the ability to place the feet on repeat examinations in exactly the same spot as before 63.0 mm. is impossible, an added plus or minus 30 error is calculated = .88888 using trig. table no. into the center of gravity vector degree error. Repeated foot = 41.60 placement by the operator can come close in placing the feet Actual measured degree on the footplate using a protractor. in the same spot by using the appropriate land marks, but is = 42.50 still not the exact spot and thus the 30 added error. This error Even in the calculated degree and the measured degree takes into account patient sway which moves the center of there is an average plus or minus error of 0.50. This is due to gravity slightly. Another area of center of gravity vector error the diameter of 1/16 inch drilled holes and the thickness of is in the scales themselves. At the start of the scale's the lines drawn in order to measure the values and degrees. It weighing capability, namely the 0 to 50 lbs. range, the would be expected if the device was 100% accurate there still weight is small enough that only slight depression of the would be plus or minus error of 0.50. These values then are scale's top takes place and thus only slight bubble movement. what the device had to find and read for the different weights This error is small and is eliminated for greater weights used. (Table 1) involved and in practical application does not affect the

The Journal of the CCA/Volume 27 No. 4/December 1983 145 A static posture analysis instrument

R = Right L= Left R = Right L = Left SI C7 X-ray Pelvis Level Measured Pelvis Level Patient No. Right or Left Error Right or Left Error Patient No. low side in 00 low side in 00 I R5 R3 RI 0 2 L2 R2 2 R3 R2.5 3 0 R4 3 R2 R2 4 R7 R5 4 R3 R3.5 5 RI RO 5 L4 L4 6 RIO LI 6 RI Rl.5 7 L5 L2 7 LI.5 L2 8 L3 R4 8 R2 R2 9 R2 R3 9 R3 R3 10 Rl L6 10 R2 R2.5 II R7 R2 11 Ll L1.5 12 R6 R2 12 Rl.5 R2 13 L5 R3 13 0 RO.5 14 R4 L4 14 RI Rl.5 15 L3 Ll 15 RO.5 0 16 LI RO 16 LO 0 17 R7 L3 17 R3 R3 18 R5 L4 18 R2 R2.5 19 L8 L2 19 Ll Ll 20 R9 R5 20 L1.5 L2 21 RI R5 21 R2.5 R3 22 R4 R4 22 Rl Rl 23 L3 R3 23 R3 R3 24 L2 L5 24 RO R5 25 LO L4 25 0 0 26 LI R2 26 L2 L2 27 R8 R5 27 Rl R1.5 28 L7 L4 28 Rl.5 R2 29 R5 L3 29 0 RI 30 R4 RI 30 LI L2 31 L4 RO 31 R3 R3 32 L3 R4 32 L2 L2 33 R2 R4 33 R2 R2 34 RI R3 34 L2.5 L3 35 RO L2 35 Rl Rl.5

Table 3: Actual x-ray measurements of lead markers for SI, Table 4: X-Ray and measured functional pelvic level C7 (mm.) overall accuracy significantly, but should be mentioned. The here than for the rest of the device. One of the main factors in grid scales for the clinical device are in quarter (1/4 cm.) changing pelvic level (measuring the static posture, figure 7) division, unlike the testing device which had the full is any shifting of L5 and S1 right or left due mainly to millimeter scale, so the operator can only measure to the movement of the pelvis on the femoral heads as a response to nearest 1/4 centimeter value. This will increase the plus or static posture adaptation, and to a lesser degree the right or minus millimeter error by plus or minus 1.25 mm. left shift being due to a short leg. This in some cases can Another area of error is in determining functional pelvic increase or decrease spinal distortion and pelvic level, level. The device always had the low side of the pelvis the depending on firstly, the direction and rotation of the shift, same as the x-ray analysis, but due to factors of palpation, and secondly the reason for this type of response by the body. x-ray and the ability of the body to use the hip joints to This does not seem to hamper the overall accuracy of the change its static posture and pelvic level, the error is greater device. The overall actual operating error for the device is:

146 The Journal of the CCA/Volume 27 No. 4/December 1983 A static posture analysis instrument

pelvic level = + 0.830 Error of Actual X-ray Measurements of Lead Markers from grid mm. error = ± 5.3mm. S1, C7 and Pelvic Level. center of gravity vector 0° = ± 4.20 A + 5.3mm. error is equal to 3/16 of an inch. SI Right = 4.684 mm. Discussion Left = 3.615 mm. For the chiropractor to provide complete spinal biomecha- Average Total Right-Left Error = 3.9 mm. nical evaluation he must include three phases of analysis: 1). gross static posture (including center of gravity), C7 2). gross dynamic posture, Right = 3.368 mm. 3). intervertebral statics and dynamics, Left = 3.153 mm. and this should be done when possible without ionizing Average Total Right-Left Error = 3.0 mm. radiation. This device provides a solution to phase 1 only. I Total millimeter error for am confident that in the future, instruments for phases 2 and SI and C7 = 3.45 mm. right or left 3 can be developed to aid the practitioners palpation, and Pelvic Level Error increase his diagnostic expertise. Average Error = + 0.580 The overall error for the device must be sufficiently high to T allow for general daily postural changes due to factors such as fatigue and emotion, which would not greatly or permanently Table 5: Error calculation from Tables 3 and 4 change the patient's previously measured posture. If this instrument were made to be technologically extremely accurate, which it can be, not only will the cost of such a Dead Weight mm. Error for device be prohibitive, but each time the patient was Spinal Distortion ± 0.6 mm. remeasured new values would be obtained. If a slightly Dead Weight Center of temporary change was detected each time by the instrument, Gravity Vector Error ± 0.7 ° this would make it of limited clinical value and only suitable Dead Weight Measured from Real Values ± 0.5 0 in a research setting. Lead Marker Error Right or Left ± 3.45 mm. There is a constant compromise between accuracy, the Pelvic Level Error = + 0.580 final marketing cost of such a device, repairability and cost, operator control and involvement. This instrument has an Total Plus or Minus, Right and Left Millimeter Error for excellent balance between all of these parameters. By Spinal Distortion. = -+- mm. obtaining this balance, this device with its overall accuracy of 0.6 + ± 3.45 mm. + mm. ± is than actual 5.3 and 4.2° (which slightly larger + error found due to certain deliberately introduced features in 4.05 mm. the instrument) is accurate enough to allow its use for total Total Center Of Gravity Vector Error. analysis of the static posture as a routine office procedure. = + 0.70 The static posture of a patient is as important as the dynamic + ± 0.50 Static is the neutral posture. posture patient's acquired + 1.20 position from which all dynamics start. For this reason static position, gross or segmental will have some effect on the Pelvic Level Error dynamics, and until the static posture for each patient can be = + 0.580 measured and analyzed routinely the dynamics, gross or + 0.250 (added error due to type of scales used) segmental for that patient in a clinical setting can not be fully + 0.830 appreciated. By having the ability to measure the gross static posture, Table 6: Total instrument error calculations one also has an objective pre x-ray screening procedure. In other words in dealing with complete spinal care it can be demonstrated now that more patients should have full spine x-rays due to their spinal distortion, but only every 3-4 years, films would be required to provide the necessary information. not yearly. Subsequent films at a later date would not be This would effectively reduce over-exposure of patients to taken unless the need could be objectively demonstrated by x-ray radiation, by annual or semi-annual x-ray postural any permanent static change, and then usually only sectional studies. The Journal of the CCA/Volume 27 No. 4/December 1983 147 A static posture analysis instrument

L5 10 mm. left 10 low right, 0.50 anterior right rotation, C7 12 mm. right 10 low right, Cl 15.0 mm. anterior. Note the posterior right center of gravity vector of 350° from his measurements, and the anterior placement of Cl in the anterior right quadrant, indicating that Cl or the gravity line associated with Cl does not apply to this patient. He does not have an anterior center of gravity which might be assumed by Cl's position.

Other areas that might require films after the initial full spine, that may or may not change the static posture are high risk pathology patients, mainly cancer, and most of these patients are already under active care for this problem. Figure 7: This is a typical patient posture analysis as it The onset of acute symptoms differing from the chief would appear in his files. Note the lateral deviation to the complaint usually produces a postural change which can be right of L5 S 1 of 30 mm. and C6 lateral deviation to the right observed and monitored for days or weeks if necessary to see of 32.5 mm. This movement takes place on the hip joints. if the changes are transient or permanent, before films are The patient's full movements are: taken. Even normal aging of the spine can be monitored and Center of gravity 325° at some future date, when enough permanent change has L5 30 mm. right, 2° low right 2° anterior right rotation, taken place, sectional films can be taken to assess the effect C7 32.5 mm. right 10 low right, on the spinal motor segments. The need can be demonstrated Cl 6 mm. posterior. This patient's x-rays appear in flgure 6. and permanently recorded before the films are taken. Equally as important this device can objectively demonstrate the static biomechanical need to take full spine or sectional x-rays on new patients at -the time of the initial examination. As an instrument to initially observe and later monitor the effectiveness of orthopaedic appliances it is invaluable. By having an objective non ionizing method of postural analysis that can be repeated frequently, the chiropractor can have the patient use the orthopaedic appliance prescribed immediately, while still on the instrument and measure the effect. This allows the practitioner to observe that the patient is responding in the desired manner, with the proper direction of change and the proper amount of change induced by the appliance. This decreases the therapeutic trial time now required to assess the appliance. There is presently no way to accurately tell the patient's response, except by directly observing and measuring the total spinal change with this instrument or by re-xraying, which is not always practical or reasonable. The chiropractor may assess the static posture and observe the role it plays in the total spinal health picture for that patient. The practitioner will be better able to determine from a weight bearing static posture aspect whether the patient's posture is irritating the chief complaint, rendering the spine more susceptible to static Figure 8: Represents a postural analysis to illustrate the weight bearing stress, or producting little static biomechanical unique postural difference found when measurements can be insult on the spine and chief complaint. taken. This again is a posture analysis which would appear in Depending on the observation based on measurements, the this patient's file. chiropractor could decide to temporarily or permanently C6 3500 posterior right quadrant, change the static posture as part of the prescribed treatment. 148 The Joumal of the CCA/Volume 27 No. 4/December 1983 A static posture analysis instrument

By observing the spinal change one will increase the accuracy sary depending on the degree of spinal distortion, regardless and ability to normalize the static posture of the spine and of whether symptoms are present, thus promoting thus increase therapeutic effectiveness. preventative care. By having the ability to actually photograph the patient, to record measurements, and to institute corrective measures if References necessary, before x-rays are taken, this instrument lends itself I. Johnston L. The paradox of the functional spine. JCCA 1966; 10(4). well to control making it an effective diagnostic tool for the 2. Johnston L. The relation of AP postural deficiency to articular stress. chiropractic profession. JCCA 1962; 6(2):8. In conclusion then, with each patient not only adapting to 3. Gleeson GM. A report of findings and observations regarding the use of the posturometer and posturizer. JCCA 1964; 8(6):10-13. his or her internal and external environment in a unique 4. Holmes RB. X-ray safety in Ontario - report of the advisory committee manner, but responding in different ways and in different on radiology. March 1980. Ontario Ministry of Health Toronto, magnitudes to the same stimuli it is necessary for the Ontario. chiropractor to observe these adaptations, and accurately 5. Brown JR. Manual lifting and related fields - an annotated measure the changes, before and during therapy. When a bibliography: Toronto 1972. Toronto Ontario: Labour Safety Council of Ontario; Ontario Ministry of Labour. chiropractor can completely determine one or all of the three 6. Grice AS. Posture and postural mechanics. JCCA 1970; 14(2):12-19. steps by objective instrumentation and palpation, he can 7. Caillet R. Foot and ankle pain. Philadelphia: FA Davis Company, better determine whether chiropractic intervention is neces- 1968.

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The Journal of the CCA/Volume 27 No. 4/December 1983 149