Surgery – Diagnostic testing – Measuring anatomical characteristic or force applied to or...
Patent
1997-09-29
1999-06-15
Hindenburg, Max
Surgery
Diagnostic testing
Measuring anatomical characteristic or force applied to or...
600595, A61B 5103
Patent
active
059116935
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a device for measuring the force applied to an object, especially a person's limb, and more particularly to a force-sensing mitt or cuff to be worn or grasped by an evaluator e.g. a clinician, when applying force to a limb. In particular, the invention relates to a mitt or cuff to be worn by an evaluator, with which the evaluator grasps the limb and imposes force on the limb, with the mitt or glove measuring the resultant or net force applied to the limb. The device is particularly intended for use by neurologists, sports clinicians, physiotherapists, occupational therapists and sports trainers to quantify limb force and stiffness as part of an evaluation of motor function. The device could be used elsewhere, where an object is gripped and the force applied is to be monitored.
BACKGROUND OF THE INVENTION
Several known systems use force transducers of different types to monitor force applied manually to a limb. In most cases, force is measured uni-directionally i.e. the push-force or the pull-force is measured, but not both, through a pad or plate applied to a limb. This type of clinical device does not allow the force to be measured during both the push and pull phases of testing cycles characteristic of a clinical evaluation. Some myometers allow for push or pull measurement but this requires the use of either a pad for push or a hook for pull. Numerous laboratory-based systems have been described in which limbs are held in a cast or cradle, and a force transducer measures push-pull forces applied to the cast. Methods of measuring the dynamic characteristics of muscle rigidity, strength and tremor in the upper extremity are described by J. Ghika et al in IEEE Trans. Biomed. Eng. 40, pages 276-283 (1993) and by M. P. Caligiuri in Movement Disorder, Vol. 9, pages 57-63 (1994). Several myometers incorporate bulbs or pads inflated with air or fluid. Force applied to the bulb or pad is measured indirectly by a pressure transducer sensing pressure in a port or tube leading from the bulb.
U.S. Pat. No. 4,337,780 discloses an evaluator's glove having pads attached to the fingertip and palm areas. The evaluator operates a valve to selectively connect one or the other of the pads to a pressure transducer. The force applied to the selected pad is evaluated. IEEE Transactions on Biomedical Engineering 35 (1988) December p. 1091-1093, discloses a plurality of force-sensing elements attached to the fingertips of a clinician performing vaginal delivery of babies. The contribution of the individual fingers to the total grasping force is monitored.
None of these devices allow a clinician to grasp the limb between thumb and fingers and apply cyclical push and pull forces. This is a crucial difference, because in order to evaluate limb stiffness, it is important for the evaluator to cycle the limb back and forth through the full range of motion, while supporting it in a manual grasp. To our knowledge, no myometer exists which ignores the internal force of the grasp while registering the resultant force exerted on the limb.
SUMMARY OF THE INVENTION
A device has now been found which permits a clinician to evaluate limb stiffness.
According to an aspect of the present invention, a device in the form of a mitt or cuff is provided which electronically senses the net force applied to a limb or other object grasped by a person wearing the mitt or cuff.
Another aspect of the present invention provides a force-sensing mitt or cuff which may be used to grasp a limb or other object, said mitt or cuff comprising pressure measuring means at at least two locations on said mitt or cuff to provide quantitative information on pressure applied to said limb or object.
In preferred embodiments of the mitt or cuff of the invention, the pressure is measured by at least two pressure transducers, especially in which the difference in pressure is measured.
A further aspect if the invention provides a device in the form of a garment having a first pressure transducer and a second pressur
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J. Ghika et al, Portable System for Quantifying Motor abnormalities in Parkinson's Disease, IEEE Transactions on Biomedical Engineering, vol. 40, No. 3, Mar. 1993.
Bennett David
Prochazka Arthur
Hindenburg Max
Marmor II Charles
University of Alberta
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