Surgery – Diagnostic testing – Sensitivity to vibration
Reexamination Certificate
2000-02-04
2001-05-22
Winakur, Eric F. (Department: 3736)
Surgery
Diagnostic testing
Sensitivity to vibration
C600S587000
Reexamination Certificate
active
06234975
ABSTRACT:
BACKGROUND
1. Technical Field
This disclosure relates to the diagnosis of bone loss, more particularly, to a method of diagnosing osteoporosis, osteopenia and sarcopenia at an early stage.
2. Description of the Related Art
Osteoporosis is a pernicious disorder usually, but not exclusively, afflicting elderly women. The osteoporotic state can also be manifest by those who are confined to bed and even to astronauts who are subjected to weightlessness. Osteoporosis occurs through a decrease in bone mass which makes the afflicted bones more fragile and more susceptible to breaking.
The fractures resulting from osteoporosis can cause death, require extended hospital stays and sometimes involve expensive and painful surgery. Health care costs in this area range in the billions of dollars per year in the United States alone. In addition, osteoporosis severely diminishes the mobility and vitality of those afflicted with the disease.
The reduction in bone mass from osteoporosis results when destruction outpaces bone formation. The balance between destruction and formation is affected by hormones, calcium intake, vitamin D and its metabolites, weight, smoking, alcohol consumption, exercise and many other factors.
Osteoporosis is not easily determined in its early phases as physical deformity is not yet evident. Because osteoporosis develops progressively, early diagnosis and appropriate treatment may help to delay, if not avoid a serious condition. Appropriate diet and exercise can be used in early years to prevent the damaging effects of osteoporosis later in life. Methods for maintaining or promoting bone growth are described in numerous patents. For example, McLeod and Rubin, U.S. Pat. Nos. 5,103,806, 5,191,880, 5,273,028 and 5,376,065 collectively describe non-pharmacological means and methods for promoting bone growth and preventing bone loss. The method described in the above referenced patents describes a mechanical vibrational loading of bones to promote growth in a non-invasive procedure. McLeod and Rubin, U.S. Pat. Nos. 5,103,806, 5,191,880, 5,273,028 and 5,376,065 are all incorporated herein by reference.
The existing technology for predicting fracture risk and osteoporosis exposes the patient to cumulative doses of X-rays. The invasive nature of X-ray radiation is compounded by multiple exposures whenever the patient is to be reevaluated. Typical X-ray scanners are very expensive and require extensively trained technicians to operate. Further, these methods report only bone density, and do not directly indicate bone strength or tendency for bone loss.
Another method of diagnosing osteoporosis is to estimate bone mass through ultrasound velocity measurements. Unfortunately, these tests are limited to bones, such as the calcaneus and patella, which do not suffer from osteoporosis and are only weakly indicative of risk of fracture. Traditional bone mass measurements, by their very nature, are unable to predict bone loss prior to its occurrence and can only chart the course of bone loss over an extended period of time. Further, these diagnostics only consider bone mass, and fail to consider other factors such as tendency to fall, or ability to protect yourself during falling.
Since it is desirable to institute treatment for osteoporosis early on, a need exists for an inexpensive, non-invasive technique for diagnosing osteoporosis in its early stages.
SUMMARY
The present disclosure describes a method of determining the onset of osteoporosis by measuring, non-invasively, the vibrational characteristics of the musculoskeletal system. These measurements can be taken during both voluntary and involuntary muscle stimulation. Risk of fracture of bones due to osteoporosis is mainly determined by three risk factors: muscle strength, bone mass and postural stability. Because these three risk factors for fractures are interrelated and dependant on muscle function, they can be determined by quantifying physiologic vibration non-invasively. This quantification can be done either with or without external stimulus to the patient. For example, all people sway during quiet standing, thereby stimulating muscle activity. Alternately, the patient may be subjected to perturbation to stimulate muscle activity. For example, under the influence of an upper body perturbation on a standing patient, a younger patient will typically exhibit a fluid “sway” away from and then back toward the source whereas, in an older patient, the response is more stiff and resistant. External stimulation can be accomplished by, e.g., using a vibration generating device such as, a shaker table.
Muscle vibrations are produced by the normal force fluctuations of unfused motor units during contraction and are expressed by the lateral expansion of muscle fibers during both quiet standing and/or gait. Musculoskeletal vibrational characteristics span a broad (0-100 Hz) frequency regime, directly reflecting the types of muscle fibers being utilized and the nature of the dynamic mechanical milieu experienced by the skeleton during postural or locomotory muscle activity. Muscle vibrational characteristics have been shown to be reflective of muscle mechanical activity correlating to muscle strength but they also are an important determinant of bone mass. While muscle vibrations less than 25 Hz correlate with muscle strength, we have shown that a specific frequency component of the muscle vibration spectrum (25-50 Hz) represents the contribution of fast-oxidative fibers which are well correlated to the bone mineral density of humans. In addition, we have shown that postural sway measurements can be simultaneously obtained with the muscle vibration measurement when using an accelerometer to obtain the latter. Thus, all three of the major risk factors of osteoporotic fracture are measured by a simple measurement of the musculoskeletal vibration spectrum using physiologic vibration quantification. This can be an important early marker for the tendency to develop osteoporosis and/or susceptibility to bone fracture with age.
A non-invasive method for evaluating musculoskeletal tissue includes the steps of connecting one or more vibration measurement devices to an external location(s) on a body. For locations over a muscle, the vibrational characteristics of the muscle and skeletal system can be obtained, given measurement over a predetermined period of time. A frequency decomposition or other time series analysis (fractal techniques, diffusion techniques, etc.) approach can be used to quantify the vibrational spectrum to evaluate muscle strength, postural stability and bone density.
In other methods, the step of determining bone mineral density by evaluating the vibrational response in a frequency range of between about 25 Hz and about 50 Hz may be included. The step of determining postural stability by evaluating the vibrational response in a frequency range of below about 5 Hz may also be included. The vibrational response may be measured concurrent with inducing vibrations within the muscle by an external stimulation device. The vibration measurement device may include a low-mass cantilever beam accelerometer. The step of analyzing the vibrational spectrum may further include the step of comparing the vibrational spectrum to vibrational spectrums of a same category. The same category may include individuals having at least one of age, sex and body type in common. The predetermined amount of time may be about 0.5 to about 5 minutes.
A non-invasive physiologic vibration quantification system for evaluating a musculoskeletal system may include vibration means for externally transferring vibrations or other displacements to the musculoskeletal system. A vibration measurement device is included for mounting externally to a body over a muscle, the vibration measurement device for measuring a response by the muscle in accordance with the vibrations/displacements transferred by the vibration means, the vibration measurement device for forming signals representative of the musculoskeletal response. An analyzer is coupled to the vibration measur
Huang Robert
McLeod Kenneth J.
Rubin Clinton T.
Dilworth & Barrese
Marmor II Charles
Research Foundation of State University of New York
Winakur Eric F.
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