Number 13
however, as we began to plan a series of observations relating to the question of balance, it became evident that the field was so large that we could hope to cover for the present only some one small phase of the subject, and after a survey of the whole field of inquiry opened by our physiologic research we decided to limit ourselves for this first paper to a study of the very suggestive question of why such backache was in our clinical experience frequently improved or relieved by the use of corsets or high-heeled shoes.
No one realizes more fully than ourselves how very small a portion of the whole field we have here covered, and our present contribution is regarded by us rather as a report of progress, possibly of therapeutic value, than as a final settlement of even the management of static backache. It is our intention to pursue the lines of investigation already undertaken further as opportunity may permit.[1]
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Fig. 4.—Position Induced by bad corset in dotted outline; normal in solid line. In this Instance the shoulders are thrown back of the normal a little, but not so much as the hips. On this and all following records, the solid vertical indicates the original position of the centre of gravity, the dotted vertical the induced position.
Fig. 5.—Position induced by bad corset in dotted outline; normal in solid line. In this instance the shoulders are thrown forward of the normal and the hips back.
Fig, 7.—Position induced by good corset in dotted outline. Normal in solid line. The apparent flattening of the lumbar curve in the dotted line is due to the bulging of the soft tissues through the open space at the back of the corset.
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Fig. 9.—Record of the normal position and that induced by high-heeled shoes, the normal in solid line, the induced position in dotted line.
Fig. 10.—Record of normal position in solid line, corset position in dotted line and position of shoes and corsets in black line broken at longer intervals.
Fig. 11.—Record of Patient 4. whose backache was relieved by corset and Cook bark splint. Original position in solid line; position of relief in dotted line.
PRELIMINARY CONSIDERATION OF PHYSICS RELATING TO BALANCE
For the proper comprehension of the practical application of our experimental work to clinical conditions, it is necessary at this place to introduce certain elementary points in mechanics which are familiar to every one, for the preliminary problem under consideration resolves itself into an analysis of the mechanism of the standing position.
These points are the following:
- The base of support of the upright human figure consists of a trapezoid formed by the outer borders of the feet and lines connecting the back of the heels and the front of the toes.
- The center of support lies perpendicularly under the center of gravity and must always lie within this trapezoid.
- For the purpose of studying the mechanism by which any weight is borne by a solid body in unstable equilibrium, the entire weight may be regarded as concentrated in the center of gravity, and the determination of the relation between the center of gravity and the bearing points determines the lines of stress.
Our observations show that in the erect position the center of gravity of the body lies in front of the ankle-joints, which are held from dorsal flexion in this position by the gastrocnemius muscles. The center of gravity lies also in front of the knees, which are similarly held in position by the hamstring and quadriceps extensor muscles. The center of gravity lies also anterior to the sacra-iliac joints and most of the vertebral joints. The position of the acetabula cannot be determined in the erect position in the living individual because we have no means of locating them from any available landmark. If we were able to determine the position of the acetabula in the antero-posterior plane it would be posible to state definitely, from the relation of the center of gravity to them, whether the trunk in the erect position would tend to fall forward or backward at their level. But from the impossibility of obtaining definite
- ↑ Other lines of investigation at once suggest themselves as likely to prove of value, especially from the point of view of the orthopedic surgeon. (a) The establishment of a "normal" for the standing position and, the formulation of the normal position of the center of gravity is possible with a sufficient number of observations. (b) The relation of the line of weight to the foot may be of much importance. It is obvious that the further forward this line falls the greater will be the strain on the tissues supporting the arch. It may in the future aid in the diagnosis and treatment of static disorders of the feet. (c) The attitude of round shoulders is a vicious position of the entire body and not of the shoulders alone, and its treatment by gymnastics would be made more exact and efficient if the attitude were analyzed. (d) Some incidental experiments showed that the effect of corrective gymnastics must be studied by some more exact apparatus than the eye if they are to be correctly and efficiently prescribed. (e) The static conditions evidently underlying the ptoses of the various abdominal viscera form a most promising field of study.
