An assessment of a system to monitor the activity of patients in a rehabilitation programme
J. Holden *
G. R. Fernie *
M. Soto *
This project was funded by The Ontario March of Dimes and The National Sanitarium Association.
Abstract
The need for an objective quantitative method of monitoring performance in the natural environment for use in a rehabilitation programme is discussed. A system of monitoring the number of steps taken has been developed for an amputee programme as a first attempt towards this goal. Instrumentation consists of an inexpensive foot switch, a storage unit and a retrieval unit. Early clinical experience indicates this system may be of value in the rehabilitation programme by (1) indicating low or unusual activity and alerting clinical staff to identify the cause. (2) Restricting the over-anxious patient when excessive activity is contra-indicated. (3) Identifying poor use of the prosthesis in the home environment. (4) Providing motivation for patients to set personal goals. (5) Acting as a base line for the evaluation of research and development of new techniques.
Introduction
The assessment of progress in gait training is an essential component of many rehabilitation programmes. Analysis procedures range from simple observations made by a physiotherapist to complex multiparameter analyses using sophisticated instrumentation (Smidt, 1974). Therapists' clinical assessments have some value but they tend to be limited in terms of reliability and consume valuable clinical time. A technical approach can improve precision, however, it is often expensive, cumbersome, and difficult to interpret (Dubo et al., 1976).
Typically either of these approaches involves the examination of a patient's ability to walk a short distance (Skorecki, 1966). It is questionable whether analysis of such a small segment of performance in artificial circumstances is representative of a patient's progress.
An objective quantitative method of monitoring performance in a natural environment is needed. This paper describes the authors' first attempt towards this goal.
One parameter indicating progress in a gait training programme is the level of activity attained. A simple inexpensive method of counting the number of steps taken has been developed to follow progress by the lower limb amputee. The system consists of a foot switch fitted into a prosthetic foot, a small storage unit and a retrieval unit. A similar method of storing events was used to evaluate a peroneal stimulator and a myoelectric prosthesis (Há'gg, 1975).
Equipment
Foot switch
The foot switch assembly (Fig. 1 ) consists of a push button momentary action switch with a metal spring attached to the button. The switch is mounted on the end of a threaded brass rod. A
hole is drilled in the heel of the SACH foot and a brass threaded insert is glued in place. The switch assembly is then screwed into place. When the heel is compressed the switch is closed. Its sensitivity can be adjusted simply be turning the brass rod.
Storage unit
The storage unit (Fig. 1 ) is an integrated memory chip housed in a small cylinder which clips on to the tubular pylon of a modular limb. The storage unit is powered by three small cells of the type used in hearing aids which have a life of approximately one year.
Retrieval unit
During the early stages of this research project a Swedish readout unit was used.* A more sophisticated portable pocket retrieval system for inpatient clinical use and a higher capacity system for use in outpatient clinics (capacity: 8,388,608 events) have now been developed at the Amputee Research Centre and are in current use.
Clinical procedures
Thirty-five patients of various ages and amputation levels have been monitored to date. Counters were fitted to each patient when they began using their artificial limb. The total number of prosthetic steps was read once a day. The counters were left on when the patients visited home for the weekend. On two occasions patients were discharged with a storage unit hidden inside a cosmetic cover. The storage unit was read when the patients returned to the clinic for review.
Results
Six graphs of patient progress are presented for discussion (Fig. 2, Fig. 3, Fig. 4, Fig. 5, Fig. 6,and Fig. 7 ).
Two patients were discharged with hidden storage units and the total step count was retrieved on return to the hospital clinic. One patient (H.A.) walked an average of 76 steps per day in the 19 days following discharge. Technical problems prevented collection of data from the second patient.
Discussion
The use of these storage systems is now routine in our Centre. The stored data can assist the clinical team in assessing the amount of walking done by each patient. The equipment is inexpensive and does not depend on the presence of a therapist.
Data reflecting activity level can assist the clinical team in several ways. If activity is consistently lower than expected for a patient or if he exhibits an abrupt decrease in steps taken a clinician is alerted to identify the cause. This parallels the typical use of a thermometer in acute care medicine. Examine, for example, the graph of patient E.S. (Fig. 2 ). He progressed well until the second week of training when a decrease in activity occurred. He was suffering from stress related cardiac problems and was restricted to rest for two days. Return to previous activity level followed within a few days. E.S. likely attempted too much exercise in the early stages of training. Patients eager to return to an active life often do not accept the restrictions indicated in early stages of training.
Another overanxious patient, F.G., showed signs of overshooting his tolerance limits (Fig. 3 ). His first burst of activity resulted in blister formation and a drastic reduction in activity. A subsequent attempt to increase activity caused the blister to burst and restricted activity for several days.
E.G. had delayed healing. Notice that every peak above 500 steps per day was followed by increased pain and restricted walking (Fig. 4 ). The patient was finally discharged home for healing.
Many other patients monitored showed high peaks of activity followed by opposite rebounds. There appears to be a tolerance level which might coincide with the patient's medical condition and training level. If this could be identified the clinician may be able to prevent set-backs in training caused by overshooting physical limitations. This could reduce the duration of hospital stay and limit patient discomfort. Collection of data from a larger sample may provide some guidelines as to a desirable range of activity.
One concern of the clinical team is the actual use of a prosthesis in the discharge environment. Patient M.M. spent the weekend at home (Fig. 5 ). His monitor revealed that he had done no walking during his visit. His goals regarding rehabilitation were discussed on his return and he improved his performance at home the following weekend. If a patient is not using his limb it is a waste of resources to continue training and prosthetic assessment. Unnecessary fitting of an expensive final limb could be avoided if this was identified during the temporary limb fitting stage.
Patient H.A. who was discharged with a storage unit used her limb an average of 76 steps per day. The patient has multiple health problems and was not expected to be very active. She used the limb in transferring and it offered her some independence in activities of daily living. The storage data provided valuable information for the assessment by the prosthetist in final fitting.
Patients have frequently been motivated to set their own personal goals for improvement. They are generally more aware of their activity and show great interest in progression. Subject O.R. (Fig. 6 ), for example, became keenly interested in her step count part way through her training. She looked forward to being told of results of her practice and setting goals for the next day. Conclusive evidence of the effect of step counting as a motivator would of course require extensive data collection, however, experience to date is encouraging.
A system of monitoring the results of a rehabilitation programme by counting steps can act as a base measurement for the evaluation of new treatment of training techniques. In our unit a biofeedback knee trainer is being evaluated (Fernie, 1978). This device provides feedback of a patient's knee position to assist in learning control of the above-knee prosthesis. The number of steps taken and the number of errors made are stored in two event counters. An example of a progress chart is shown in Fig. 7 where errors each day are expressed as a percentage of the total number of steps.
Conclusions
Preliminary experience with the step storage system revealed several uses which may improve the level of efficiency of an amputee programme :
Indicate low or unusual activity and alert clinical staff to identify the cause.
Restrict the overanxious patient when excessive activity is contra-indicated.
Identify low activity while wearing the prosthesis in the home environment.
Provide motivation for patients to set personal goals.
Act as a base line for the evaluation of research and development of new techniques.
* Electroline A B, Stockholm, Sweden.
References:
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Ferme, G. R. Holden, J. M. and Soto, M. (1978) Biofeedback training of knee control in the above-knee amputee. Am. J. Phys. Med., 57:4, 161-166.
Hägg, G. M. Hayes, W. C. Klasson, B. and Ljungquist, D. P. (1975). Miniaturized electronic event counter. Proc. 5th Int. Symp. on External Control of Human Extremities, ETAN, Yugoslavia, Dubrovnik, 183-186.
Skorecki, J. (1966). The design and construction of a new apparatus for measuring the vertical forces exerted in walking: A gait machine. Strain Analysis, 1:5,429-438.
Smidt, G. L. (1974). Methods of studying gait. Phys. Ther, 54:1, 13-17.
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