Isometric strength testing method and equipment for disability evaluation

• US 4,882,677 A
• Filed: 09/03/1987
• Issued: 11/21/1989
• Est. Priority Date: 09/03/1987
• Status: Expired due to Fees

• Current Assignee: Thomas M. Curran
• Original Assignee: Thomas M. Curran
• Inventors: Curran, Thomas M.
• Primary Examiner(s): Jablon, Clark A.
• Application Number:
  US07/092,432
• Time in Patent Office: 810 Days
• Field of Search: 128/782, 73/379, 364/413, 364/415, 364/551, 364/413.27, 364/413.02, 364/551.01, 358/107
• US Class Current: 600/587
• CPC Class Codes: A61B 5/103 Detecting, measuring or recording devices for testing the shape, pattern, colour, size or movement of the body or parts thereof, for diagnostic purposes A61B5/08 takes precedence; measuring aids for tailors A41H1/00; measuring instruments specially adapted for dentistry A61C19/04
• CPC Class Codes: A61B 5/22 Ergometry; Measuring muscular strength or the force of a muscular blow exercising apparatus A63B21/00 ; measuring of work or force in general G01L
• CPC Class Codes: A61B 5/4528 Joints A61B5/4533, A61B5/4538 take precedence
• CPC Class Codes: A61B 5/4561 Evaluating static posture, e.g. undesirable back curvature A61B5/1116 takes precedence
• CPC Class Codes: Y10S 128/923 by comparison of patient data to other data
• CPC Class Codes: Y10S 482/902 Employing specific graphic or video display

Abstract

New disability testing and evaluation software combined with an isometric strength testing machine provides a very complete and standardized means of determining disability in comparison with the norms of the general population. The software utilizes not only the machine but also the digitization of photographs taken of the subject person during each strength test. Combining the digitized photographic data, the force monitor information from the load cell of the machine and extensive anthropomorphic data the software calculates for loading of the weakest joint in the subject person and compares this loading to normative values from the general population. In this manner a percentage disability for a subject person can be calculated with reasonable assurance of the validity and reproducibility of the result. New specialized hand grips for an isometric strength testing machine are disclosed to test grip strength and torsional strength of the hand.

Claims

1. In an isometric strength testing system which includes a disability analysis computer program, an isometric strength test unit comprising a vertical column and a horizontal arm of the vertical column, a load sensor on the arm and grip means on the arm connected to the load sensor to enable a subject person to apply an isometric load to the load sensor, means to electrically monitor the load sensor as a function of time and means to record the load applied to the load sensor as a function of time, the steps of,

having an unrestrained subject person apply an isometric load at least one time to the grip means on the arm,

photographing the subject person during the application of the load to the arm,

entering the subject person'"'"'s height, weight, and sex into the program, digitizing the photograph to measure body angles and entering the measurements into the program,

in the program calculating the subject person'"'"'s anthropometric data including body link lengths, centers of gravity and weights from the subject person'"'"'s height, weight, sex and digitized body angles,

into the program entering the subject person'"'"'s actual load exerted, direction of exertion and number of hands from the application of the isometric load to the grip means,

in the program calculating the subject person'"'"'s joint compression expressed as a population percentage capability at each selected joint from the calculated anthropometric data, direction of exertion, number of hands and actual load exerted,

in the program reiteratively recalculating the joint compression at each selected joint by repeatedly adjusting the value of load exerted until the value of joint compression at one of the joints substantially equals a predetermined value expressed as a specified percentage of population capability to thereby determine an expected load exerted, and

comparing the subject person'"'"'s expected load exerted to the subject person'"'"'s actual load exerted.

2. The strength testing system of claim 1 including the steps of,

averaging the actual loads exerted over the number of tests,

averaging the expected loads exerted over the number of tests,

dividing the averaged actual loads exerted by the average expected loads exerted and,

if less than 0.95, multiplying by 100 to obtain a result,

subtracting the result from 95% to determine strength impairment, and

multiplying the result by specified weights to determine male and female weight restrictions for the subject person, and

if greater than 0.95, then indicating no impairment.

3. The strength testing system of claim 2 wherein the specified weights for male and female are respectively 35 lbs. and 20 lbs.

4. The strength testing system of claim 1 wherein the specified percentage of the population capability is 75%.

5. The strength testing system of claim 1 including the steps of,

averaging the actual loads exerted over the number of tests,

averaging the expected loads exerted over the number of tests,

dividing the averaged actual loads exerted by the average expected loads exerted and,

if less than a specified value, subtracting from the specified value and multiplying by 100 to determine percentage strength impairment.

6. An isometric strength testing apparatus comprising an isometric strength test unit having a vertical column and a horizontal arm on the vertical column, a load sensor on the arm and grip means on the arm connected to the load sensor to enable a subject person to apply an isometric load to the load sensor, means to electrically monitor the load sensor as a function of time and means to record the load applied to the load sensor as a function of time, and

a disability analysis computer including a program comprising:

means to input anthropometric data from published human surveys and a subject person'"'"'s height, weight, and sex to the computer,

means to digitize a subject person'"'"'s unrestrained testing configuration and enter the digitized configuration information including body angles, direction of exertion and number of hands into the computer,

means to input a subject person'"'"'s actual load exerted from the application of the isometric load,

means to calculate the subject person'"'"'s anthropometric data including body link lengths, centers of gravity and weights from the subject person'"'"'s height, weight, sex and digitized body angles,

means to calculate the subject person'"'"'s joint compression expressed as a population percentage capability at each selected joint from the calculated anthropometric data, direction of exertion, number of hands and actual load exerted,

means to reiteratively recalculate the joint compression at each selected joint by repeatedly adjusting the value of load exerted until the value of joint compression at one of the joints substantially equals a predetermined value expressed as a specified percentage of population capability to thereby determine an expected load exerted, and

means to compare the subject person'"'"'s expected load exerted (limit) to the subject person'"'"'s actual load exerted.

7. The isometric strength testing apparatus of claim 6 including the additional means to:

average the actual loads exerted over a number of tests,

average the expected loads exerted over the number of tests,

divide the averaged actual loads exerted by the average expected loads exerted and,

if less than 0.95, multiply by 100 to obtain a result,

subtract the result from 95% to determine strength impairment, and

multiply the result by specified weights to determine male and female weight restrictions for the subject person.

8. The isometric strength testing apparatus of claim 7 wherein the specified weights for male and female are respectively 35 lbs. and 20 lbs.

9. The isometric strength testing apparatus of claim 6 wherein the specified percentage of the population capability is 75%.

10. The isometric strength testing apparatus of claim 6 including additional means to:

average the actual loads exerted over a number of tests,

average the expected loads exerted over the number of tests,

divide the averaged actual loads exerted by the average expected loads exerted and,

if less than a specified value, subtract from the specified value and multiply by 100 to determine percentage strength impairment.

11. In a disability analysis isometric strength testing system which includes a computer program, an isometric strength testing unit comprising means to support a load sensor, a load sensor on the support means and grip means on the support means connected to the load sensor to enable a subject person to apply an isometric load to the load sensor, means to monitor the load sensor as a function of time and means to record the load applied to the load sensor as a function of time, the steps of, p1 measuring and recording a subject person'"'"'s height, weight, and sex,

having an unrestrained subject person apply an isometric load to the grip means,

measuring and recording the subject person'"'"'s actual load exerted, direction of exertion and number of hands from the application of the isometric load,

photographing the subject person during application of the load and digitizing the photograph to measure and record body angles,

calculating the subject person'"'"'s anthropometric data including body link lengths, centers of gravity and weight from the subject person'"'"'s height, weight, sex and digitized body angles,

calculating the joint compression for several selected joints of the subject person from the calculated anthropometric data, direction of exertion, number of hands, sex and actual load exerted,

reiteratively recalculating the joint compression at each selected joint by repeatedly adjusting the value of load exerted until the value of joint compression at one of the joints substantially equals a predetermined value to thereby determine an expected load exerted, and

comparing the subject person'"'"'s expected load exerted to the subject person'"'"'s actual load exerted to determine the subject person'"'"'s disability.

12. An isometric strength testing apparatus comprising means to support a load sensor, a load sensor on the support means and grip means on the support means connected to the load sensor to enable a subject person to apply an isometric load to the load sensor, means to monitor the load sensor as a function of time and means to record the load applied to the load sensor as a function of time, means to record and digitize the posture of an unrestrained subject person during loading of the sensor, said means to record and digitize providing measurements of body angles, direction of exertion and number of hands of the subject person during isometric loading of the sensor, and

computer means to calculate the expected load exerted by the subject person and compare with the subject person'"'"'s actual load exerted to determine the subject person'"'"'s disability, said means to calculate including means to input the subject person'"'"'s height, weight, and sex for the calculation of anthropometric data including body link lengths, centers of gravity and weight, and means to input the actual load exerted, the body angles, direction of exertion and number of hands for the calculation of joint compression at several selected joints of the subject person, and

means to reiteratively recalculate the joint compression at each selected joint by repeatedly adjusting the value of load exerted until the value of joint compression at one of the selected joints substantially equals a predetermined value to thereby determine an expected load exerted for comparison with the actual load exerted.