A LOW COST GONIOMETER FOR CLINICAL GAIT ASSESSMENT IN REHABILITATION

Carmen P.L. Sy 1, Daniel H.K. Chow 2, Eric W.C. Tam 2, Yvonne H.M. Leung 2 1 Physiotherapy Department, MacLehose Medical Rehabilitation Center 2 Rehabilitation Engineering Center, The Hong Kong Polytechnic University Hong Kong

ABSTRACT

The movement of a joint during walking is of particular importance in clinical gait assessment. In most clinical settings, pathological conditions were usually described in a non-quantitative and subjective manner. Modern instrumentation, especially electrogoniometer, has provide clinicians with a portable device for objective measurement in joint motion. However, such device is still relatively expensive and clinicians who are busy with their routine assessments and treatments cannot afford extra time to download any collected data onto the computer. In view of that, this project aims to develop a low cost and simple mechanical device which can allow direct read out of the measured joint range during daily activities.

BACKGROUND

The study of human locomotion has been performed by many researchers over the past decades. Modern instrumentation, such as computerized motion analysis system, force platform and pedobarography, allows the capture of both kinetic and kinematic information during gait. These types of instrumentation are usually complex and expensive, and frequently require highly trained operators to devote relatively long time for data processing even though this process can be done by commercially available computer software. In fact, the most difficult part of a complete "instrumented" gait analysis is in the interpretation of the physiological meanings of the gait parameters. As most of the clinicians were not trained in their basic training to use such sophisticated and expensive instrument, application of instrumented gait analysis in conventional clinical settings is still not common. It is thought that a low cost and simple gait analysis device will be of utmost importance for instrumented gait analysis to become part of the routine clinical gait assessment procedures.

RATIONALE OF THE STUDY

During the clinical assessment procedures, observational gait analysis is frequently used in knowing the movement pattern of the body segments during walking. This technique is subjective and cannot easily be used to document pathological changes especially when the changes are subtle. Early recognition of gait deviations and continuous monitoring of changes in gait patterns are essential for rehabilitation specialists to select and implement an appropriate rehabilitation protocol.

Among various gait parameters, ranges of motion of various joints of the lower limbs are likely to be the most commonly used parameters for clinicians to document the functions of the joints. In clinical practice, the ranges of motion of a joint can be measured in terms of the differences between either physiological limits or functional limits. For the physiological range of motion measure, it refers to the maximum range of motion that a joint can reach either by passive or active action. For the functional range of motion measure, it refers to the "useful" arc, within the physiological range of motion, that a joint moves during walking activities. Moreover, different functional measures can be obtained when the subject is walking on a level surface or a non-leveling walking condition such as stair climbing, or up and down a slope. In principle, the physiological range of motion can be measured with a higher accuracy than the functional range of motion, as the former range is measured with the limb segments in static postures while the latter one has to be measured when the limbs are in dynamic motion. Additionally, from the clinical view point, the functional range of motion is of higher clinical significance than the physiological range of motion as it describes the actual performance of a joint. Although there is now commercially available electronic device such as electrogoniometer, which can provide a fairly accurate measure of the functional range of motion, its application in clinical assessment is still not popular in most clinical settings in Hong Kong. Besides the fact that such device is relatively expensive, most clinical settings in Hong Kong are very busy in their daily duties. Clinicians really need a device which is even more simple to apply and will not take them much time to learn. This is the primary motive of this project to develop a low cost and simple mechanical measuring device which can serve this particular function.

DESIGN CONSIDERATIONS

The objective of this project is to develop a low cost and simple mechanical goniometer which could be used to measure quantitatively the functional ranges of motion of various joints of the lower limbs. Instead of recording continuous changes in the joint angle during a gait cycle, we focused on 3 essential parameters which were believed to be able to represent and differentiate the gait deviations of a subject from normal. These parameters included the maximum flexion and extension of the joint during walking activities and the neutral position of the joint in relaxed standing posture. In addition, if this new goniometer should gain acceptance in clinical practice, the following criteria need to be incorporated: 1. low cost; 2. easy to use; - no particular training is required - no calibration is required 3. able to provide a direct read out of the measurements; 4. measurements need to be accurate, repeatable and easy to access/record; and 5. maintenance free.

EVALUATION

To validate the performance of the new mechanical goniometer, the accuracy of the device was evaluated under different alignment situations. Moreover, the functional ranges of motion of hips, knees and ankles of 10 normal volunteers (age ranged from 22 to 52 years old) were measured during level walking, and climbing up and down a stair. The results were with those obtained by commercially available electrogoniometer (Penny & Giles, U.K.). The accuracy of the new device for measuring functional range of motion was found to be within ( 1(.

CLINICAL APPLICATIONS

The evaluation of treatment efficacy is a common goal of gait assessment conducted in clinical situation. Usually, normal data are required as references for outcome measures in gait evaluation for patients where both legs are affected. This would involve a lot of work and time to establish a "normal" database which can represent our daily activities. The newly developed mechanical goniometer can be used to document the functional ranges of motion of various joints of the lower limbs for different age groups and sex. The measurement can be conducted in any clinical settings and even in outdoor environment.

In most clinical situations encountered with patients suffered from neurological disorders, such as stroke and tumor, or other sports or orthopaedic injuries, such as fracture, joint replacement and ACL injuries, etc., it is often to have only one side of the lower limbs affected. As information regarding pre-injury is rarely available, the unaffected limb is frequently used as the reference or control for documenting the progression of the gait improvement during the rehabilitation period. The assessment of symmetry of the movement is also commonly used in the evaluation of hemiplegic gait pattern. As this new mechanical goniometer can easily be used bilaterally to document the symmetry of the gait of a subject, the progress during rehabilitation, as part of the outcome measures, will be very useful for investigating the effectiveness of various types of treatment prescribed. Further experimental studies have also been initiated to validate the reliability of the device in clinical application.

The new device has also been applied by clinicians during prosthetic socket alignment process. In conventional clinical practice, the ranges of motion of the joints of an amputee are "observed" by the prosthetist for adjusting the prosthesis alignment. However, the time required for establishing a proper alignment would highly depend on the skill and experience of the clinician in correlating the observed joint angles with the necessary adjustments that are required. This new goniometer has been used to assist the prosthetist in extracting joint angles information in a quantitative manner, which can be documented with the necessary adjustment procedures. The result gathered would be valuable for enhancing the techniques in achieving an optimum prosthesis alignment in meeting various demand encountered during daily activities.

DISCUSSION

It should be noted that this new mechanical goniometer is designed to measure the functional range of motion of a joint. However, the user should take note of the joint angle at its initial (neutral) posture. If the joint is in hyperextension initially, there could exist chances that the functional range of motion of the joint during walking may not reach the initial limit. In this case, the corresponding functional range of motion obtained should be considered carefully.

CONCLUSION

A new simple mechanical goniometer has been designed and developed to allow clinicians to perform quantitative clinical gait analysis at an affordable cost. The measurement of the functional range of motion of joint angles provides an objective way to document normal and pathological gait patterns and can be used as references for outcome measures after clinical treatment. In addition, this simple device also allow clinicians to collect essential information of joint movement due to different function deficiency resulting from injuries or diseases. This also helps to establish a reference database for joint range of motion in different conditions of normal gait, including level walking, stair climbing and slope walking.

REFERENCES

R.K. Begg, R. Wytch and R.E. Major, Instrumentation used in clinical gait studies: a review, J. Med. Eng. and Tech., Vol. 13(6), 1989, pp. 290-295.

R.L. Gajdosik and R.W. Bohannon, Clinical measurement of range of motion. Review of goniometry emphasizing reliability and validity, Phy. Ther. Vol. 67(12), 1987, pp. 1867-1872.

A.C. Nicol, Measurement of joint motion, Clin. Rehab. Vol. 3, 1989, pp. 1-9.

ACKNOWLEDGMENTS

This work is supported by the Royal Hong Kong Jockey Club (Charitable) Ltd. and the Hong Kong Polytechnic University.

Daniel H.K. Chow Rehabilitation Engineering Center The Hong Kong Polytechnic University Hunghom, Kowloon Hong Kong Email: RCDANIEL@PolyU.EDU.HK

Low Cost Goniometer