The present invention relates generally to the field of physical therapy and more particularly to the objective testing of muscle strength.
In the field of physical therapy a proper physical examination is of utmost importance in determining the type of therapy a patient will receive and, further, on how well that patient is responding to his or her therapy. In addition, muscle testing is an important and integral part of a physical examination as it provides information, not otherwise obtained, useful in differential diagnosis, prognosis, and treatment of neuromuscular and musculoskeletal disorders. Since, many neuromuscular conditions are characterized by muscle weakness, it becomes very important to determine which muscles are weak and the extent of that weakness.
In performing a muscle test, it is the standard procedure to position the patient in the proper position for the desired muscle response. The position is important in relation to the test in two respects: (1) In so far as practical, the position of the body should permit function against gravity for all muscles in which gravity is a factor in grading, and (2) the body should be in such a position that parts not being tested will be held as firm and stable as possible.
After the patient is in proper position, the physical therapist or tester administers the muscle test by applying gradually increasing pressure to the muscle under test. The term "pressure" as used herein denotes the outside force applied by the examiner to the muscle. Although the place where pressure is applied is significant to the accuracy of the testing, a very important aspect of the test is the evaluation of the amount of pressure applied by the tester. The amount of applied pressure varies according to the size of the patient and the muscle being tested. The patient must be allowed to "set" or contract his muscles against the tester's pressure. The tester cannot gauge the degree of strength unless pressure is applied gradually because slight pressure applied suddenly can "break" or over come the pull of the muscle.
It is standard procedure for therapists or examiners to grade the strength of a tested muscle. By conventional standards the ability of a patient to hold his muscle in a test position against the force of gravity establishes a grade factor of 50% or fair. The examiner then applies pressure to determine grades above 50%. The amount of pressure applied by the examiner in testing is the determining factor in grading above 50%. Under present testing procedures and due to the subjectiveness of measuring the applied pressure, the muscle strength of a patient can only be expressed as the ability of a muscle to hold against a minimum, moderate, or maximum amount of applied pressure. A minimum amount is given a grade of 60% to 70%, a moderate amount indicates a grade of 80% to 90% and a maximum amount results in a grade of 100%. Strong pressure is necessary to reach the 100% grade and because to much applied pressure can result in injury to the muscle, testers are justifiably reluctant to continue the muscle strength test to the maximum or 100% point.
During the course of the muscle testing procedure, a point, termed the breaking point, is reached at which the muscle can no longer counteract the external forces of gravity plus the tester's applied pressure and the muscle being tested moves in a direction which does not oppose the applied forces. Because muscle injury can occur to the muscle if the breaking point is reached, testers base their diagnoses and prognoses of muscle condition on the amount of the applied pressure at a point of muscle reaction just prior to the breaking point called the pre-breaking point. It is at this pre-breaking point that the muscle is "graded".
As is evident by the above description of conventional muscle testing the current testing procedures involve two subjective determinations made by the tester during the course of the test:
(1) the instant of time at which the pre-breaking point is reached and PA1 (2) the evaluation of the amount of pressure being applied at the instant the pre-breaking point is reached.
The present invention is directed to eliminating the subjective nature of the evaluation of the amount of pressure being applied at the instant the pre-breaking point is reached.