Surgery – Diagnostic testing – Measuring anatomical characteristic or force applied to or...
Reexamination Certificate
2002-06-06
2004-01-06
Hindenburg, Max F. (Department: 3736)
Surgery
Diagnostic testing
Measuring anatomical characteristic or force applied to or...
Reexamination Certificate
active
06673027
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a posture measurement and feedback instrument designed to prevent the slumped or immobile sitting postures that cause dysfunction and pain such as head, neck, and back pain. Especially effected are those who sit for hours every day on a regular basis, which due to the rapid computerization of society is an ever increasing group.
In order to prevent these posture dependent ailments successfully a posture measurement and feedback instrument needs to alert users when they slump or become immobile in an inexpensive, valid, reliable, and user-friendly manner.
Cost
An informal survey of potential consumers revealed that they may be willing to spend about $200 for a personal posture feedback instrument.
Validity
Validity would require that the instrument is able to differentiate healthy from unhealthy posture. The postures identified by the literature to be most harmful for the spine are prolonged episodes of slumped sitting, heavy stoop lifting, and prolonged episodes of immobility regardless of spinal curvature. Therefore a valid posture feedback instrument needs to be able to distinguish upright sitting from slumped sitting, squat lifting from stoop lifting and mobile from immobile posture.
Reliability
Reliability would require that the posture sensor—body interface of the posture feedback instrument be stable enough to prevent measurement error due to displacement. The sensor should in other words not slip or come loose with the regular daily activities of the users. Nor should the posture readings be subject to variability by extraneous forces such as the earth's magnetic field or extremity movement.
User-friendliness
A user-friendly posture feedback instrument requires that (a) it may be applied independently without much ado by a user, (b) one simple calibration of thresholds covers the entire range of postures a user goes through (e.g. alternating between sitting, standing, and lifting), (c) it does not restrict normal activities such as leaning back against a backrest, (d) it may be used inconspicuously, and (e) it is portable.
While the high prevalence of posture dependent back pain has motivated the invention of a number of posture feedback instruments designed to facilitate healthy posture, they have to this point not managed to become a common consumer item, because none of the instruments has to this point succeeded in being cost efficient, valid, reliable and user-friendly. Rather, the prior art suffers from a number of disadvantages:
(a) U.S. Pat. Nos. 5,425,378 (1995), 5,402,107 (1995), and 5,474,083 (1995) only measure body position relative to gravity and in the case of U.S. Pat. No. 5,474,083 (1995) electromyographic activity, both of which are not suited to measure the spinal curvature that differentiates erect from slumped spinal posture.
(b) U.S. Pat. Nos. 5,553,531 (1996), 4,730,625 (1988), 5,522,401 (1996), and 4,007,733 (1977) are integrated in garments, belts, or suspenders, all of which may easily slip relative to the spine or be regarded unfashionable.
(c) U.S. Pat. Nos. 5,143,088 (1992), 5,012,819 (1991), 5,398,697 (1995), and 4,527,982 (1985) are bulky or require to be worn outside the clothing, both of which precludes an inconspicuous application.
(d) Donning and doffing U.S. Pat. Nos. 5,243,998 (
1993
) requires a user to undress, making it user-unfriendly.
(e) The application of the sensing means of U.S. Pat. Nos. 5,400,800 (1995), 5,146,929 (1992), 5,143,088 (1992) 5,012,819 (1991), and the Spinoscope® (see copy of flyer) to the back of a user requires the help of a second person, making it user-unfriendly. Mounting the sensing means to the back also causes discomfort and displacement of the sensing means when using a back rest thus excluding an application by seated occupations.
(f) U.S. Pat. Nos. 5,400,800 (1995), 5,146,929 (1992), 5,143,088 (1992), 5,012,319 (1991), 4,660,829 (1987), 4,527,982 (1985), 5,398,697 (1995), 4,665,928 (1987), and 5,469,861 (1995) attempt to measure joint motion directly. As opposed to the indirect method of 5,433,201 (1995), where measurement is based on joint movement dependent skin dilation and contraction, the direct method requires an attachment of the sensing means to either of the articulating members of a joint. The sensing means can however only be attached to the skin which displaces relative to the articulating bones with movement. The resulting displacement of the sensing means relative to the joint causes measurement error. Tightening the attachment can only partially solve this problem and causes discomfort and soft tissue dysfunction. Furthermore, the mechanical linkages of U.S. Pat. Nos. 5,400,800 (1995), 5,146,929 (1992), 5,143,088 (1992), 5,012,819 (1991), 4,660,829 (1987), and 4,527,982 (1985) require rotation and sliding of numerous parts relative to one another. Such elaborate hardware arrangement drives up the cost, makes the instrument bulky, and causes friction which in turn reduces measurement sensitivity.
(g) The more elegant solution of U.S. Pat. No. 5,433,201 (1995) avoids all the above-mentioned disadvantages. Rather than trying to obtain a direct measure of joint motion by attaching to either joint member, U.S. Pat. No. 5,433,201 (1995) measures the amount of joint motion dependent skin dilation and contraction as is commonly done with the Schober method of the German physician Paul Schober (1865-1943). The preferred embodiment of U.S. Pat. No. 5,433,201 (1995) with ultrasonic sensing means has been marketed as “OrthoSon” posture trainer (see copy of flyer) at a cost of $600, definitively above what might be paid by an average consumer. Other than cost, other disadvantages of using an ultrasonic transmitter and receiver are that both need to be powered with a separate cable and that the evaluation of the signal is complicated. When the distance between two points on the skin above the spine changes with movement, the travel time of the ultrasound between the transmitter and receiver changes only minutely, requiring a very sensitive microprocessor to measure and subtract subsequent travel times. A Hall signal on the other hand is easily processed and can be fed directly into standard telemetry systems such as the one offered by the company Conrad Electronic. Developing a cost efficient, valid, reliable and user-friendly slump and immobility guard for seated occupations was part of the applicant's doctoral work in physical therapy. This development included the testing of an alternate embodiment of U.S. Pat. No. 5,433,201: the method of measuring joint dependent skin dilation with a simpler and more cost efficient Hall sensor rather than an ultrasonic sensor. Realizing the skin dilation method of U.S. Pat. No. 5,433,201 with Hall sensor technology comprises the application of a magnet to a fist position on the skin and a Hall sensor to a second position on the skin. When choosing a user-friendly application of the magnet and the Hall sensor on the chest rather than the back, the chest's skin with the magnet and Hall sensor on it approximates with slumping and stretches when the spine is straightened. In theory this should change the Hall reading accordingly. Upon testing however, slumping was found to not merely shorten, but to also fold the chest's skin. Accordingly, slumping did not only approximate the magnet and the Hall sensor as the skin shortened and lengthened. Rather, the skin folding also caused a multidimensional rotation of the magnet and the Hall sensor relative to one another. The problem this created was that the approximation of the magnet and the Hall sensor changed the Hall readings one way, while at the same time the associated rotation changed the readings another way. The result was that during a continuous slumping motion, the Hall readings would often begin to reverse midway. Thus, the method of attaching the magnet and the Hall sensor separately as suggested by U.S. Pat. No. 5,433,201 did not allow for valid measures of slumping and had to be abandoned.
Other drawbacks of attaching the magnet an
Hindenburg Max F.
Szmal Brian
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