Influence of examiner experience and gender on interrater reliability of KT-1000 arthrometer measurements.

[Bauantyne BT, French AK, Heinsoth SL, et al. Influence of examiner experience and gender on interrater reliability of KT-1000 arthrometer measurements. Phys Ther. 1995; 75.-898-906.]

Key Words: Knee, Ligaments, Reliability.

The most commonly used devices available to assess ligament integrity are designed to assess the cruciate ligaments because they are accessible for testing and because they are important in maintaining knee stability. Several manual tests are also available to determine whether the anterior cruciate ligament (ACL) has been injured.[1] Of these, only the Lachman's test has been investigated for reliability and validity.[2] Results suggested relatively poor reliability within and between examiners and questionable validity for predicting the presence of an ACL injury.

More recently, testing of knee ligament integrity with devices such as the KT-1000 arthrometer(*) has gained increasing popularity. The most common uses of these devices have been (1) to confirm the presence of cruciate ligament disruption, (2) to document the degree and type of injury, and (3) to evaluate the success of treatment, both surgical and therapeutic. For example, if during the course of rehabilitation following knee ligament reconstruction periodic testing revealed a progressive increase in laxity, a more conservative treatment approach or bracing may be indicated. Conversely, if anterior displacement of the involved knee remained substantially less than that of the normal knee, a more aggressive regimen of mobilization and exercise could be initiated. This kind of clinical decision making requires reproducible, quantified data about cruciate ligament integrity or laxity.

Use of the KT-1000 arthrometer for discriminating injured from uninjured knees has been documented by numerous investigators.[3-8] Daniel and colleagues[3] tested 338 subjects without ACL injuries and 89 subjects with arthroscopically confirmed unilateral ACL deficiency. Comparing measures of absolute anterior tibial displacement with an applied force of 89 N (20 lb) through the KT-1000, the authors reported means of 5.7 and 13.0 mm of tibial translation for uninjured and ACL-deficient knees. They also reported that 96% of the subjects with unilateral ACL deficiencies had an anterior displacement difference of greater than 2 mm between their injured and uninjured knees. Ninety-two percent of subjects without ACL injuries had a difference of 2 mm or less.[3] Using the same 2-mm side-to-side difference in the 89-N test as a basis for diagnosis, Sherman et al[5] Correctly detected 90% to 95% of ACL-deficient knees when the posterior cruciate ligament was intact. Steiner et al[6] differentiated 80% to 90% of subjects without ACL injuries from those with ACL deficiency using 89-N and 133-N (30-1b) anterior forces.

Bach et al[7] have suggested that the maximum manual test is superior to the 89-N test force in discriminating between a normal knee and a knee with an ACL tear. Diagnostic criteria established by these investigators require a difference between knees of 3 mm or more and 10 mm or more of absolute anterior displacement on the involved side. Based on a sample of 401 subjects, sensitivity of this test was reported to be 99%.[7]

To be clinically useful, reliability of arthrometer measurements should be established. Intrarater reliability studies have been completed with the KT-1000 arthrometer, but all have been done on knees without any pathology. Highgenboten et al[9] compared three knee laxity measuring devices, the test being completed by an experienced examiner on 30 subjects with no reported knee pathology. Three trials were performed on each knee using all three devices, and the process was subsequently repeated. The intraclass correlation coefficient (ICC) (version unreported) between the two testing sessions was .87 when using an 89-N anterior displacement force. The intertrial reliability across the three trials within a testing session had an ICC of .97.[9]

Wroble et al[10] investigated the intrarater reliability of one experienced examiner using only the KT-1000 arthrometer. The examiner conducted three test sessions per day for 6 consecutive days on six subjects with no reported knee injury. Each test consisted of three trials using 89-N and 134-N anterior forces. Using an analysis of variance (ANOVA), they found differences in measurements taken on different days for a given knee, but right-to-left differences did not change across days.[10] Torzilli et al[11] studied the intrarater reliability of a single trained physical therapist using the KT-1000 arthrometer and the Genucom system[dagger] on 20 male subjects with no reported knee pathology. Tests were repeated on the same day and 1 week later. The investigators found no difference between measurements taken on the 2 different test days. Therefore, they concluded that the KT-1000 was intrafater reliable within the limitations of the study.[11]

Research on interrater reliability of knee arthrometer testing is limited to only two studies. Hanten and Pace[12] studied intrarater and interrater reliability for experienced examiners using the KT-1000 arthrometer in 43 asymptomatic male athletes. Two 67-N anterior force measurements were taken on the right knee only, with the arthrometer removed between the two measurements. The authors reported an ICC (2,k) value of .92 for intrarater reliability using the KT-1000 arthrometer. The first anterior measurement from the initial examiner was also compared with a second experienced examiner's single anterior measurement. An ICC (2, 1) value of .92 was obtained for these comparisons.[12]

The only study of interrater reliability on a clinically relevant population (ie, using knees with pathology) was reported by Forster et al,[13] who used the KT-1000 arthrometer on 4 subjects with no known knee injuries and 6 other subjects with ACL injuries. Examiners were two experienced and two inexperienced persons who were instructed according to the manufacturer's specifications. The first examiner tested the right leg and then the left leg of each subject using 67-N (15 lb) and 89-N anterior forces. These tests were followed by the second, third, and fourth examiners consecutively testing all 10 subjects. The process was then repeated. Based on frequency tallies for various magnitudes of displacements measured, the authors questioned the reliability of the arthrometer because there was great variability among all measurements regardless of experience.[13]

The literature relative to the intrarater reliability of the KT-1000 arthrometer suggests that measurements are reliable when one examiner collects them. All studies, however, have been done on knees without pathology. One of only two studies that have addressed interrater reliability demonstrated good results but did not include subjects with knee pathologies. The other study included only six knees with ACL injuries, and the authors questioned whether one examiner's results for a single subject could be compared with the results of another examiner. Given the protracted course of treatment for most ACL injuries, the possibility that a patient might be discharged from the care of one practitioner to the care of another seems likely. Additional studies that establish intertester reliability are essential, therefore, if testing of a knee or multiple knees by a number of practitioners is to be credible. Further, the factors that influence reproducibility of these measurements, such as gender and examiner experience, need to be identified so that we can determine how much of a change in anterior tibial displacement must be measured before we can conclude that a real change has occurred. Therefore, we designed this study to further investigate the effects on interrater reliability of measurements obtained using the KT-1000 arthrometer of experience, gender of tester, and leg tested (with versus without ACL injury).

Method and Materials

Subjects

Tests were performed on 22 subjects with unilateral ACL injury. Subjects were selected from patient records at the Iowa Medical Clinic (IMC) in Cedar Rapids, Iowa. Descriptive characteristics for the subjects are summarized in Table 1. All subjects signed a consent form after the test procedure was thoroughly explained.

[TABULAR DATA 1 OMITTED]

Subjects had unilateral knee pathology confirmed by previous arthroscopy or by usual clinical evaluation by their physician. The subjects had no reported history of ACL pathology in their uninvolved knees. There was no involvement of the posterior cruciate ligament, as determined by a negative posterior sag test that was administered prior to each test session.[14]

Examiners

Four examiners, two experienced and two inexperienced, participated in this study. The two experienced examiners were physical therapists from IMC with prior training and clinical experience with the KT-1000 arthrometer. The female experienced examiner reported using the KT-1000 arthrometer on more than 120 patients, and the male experienced examiner reported using the device on more than 80 patients over a period of a year and a half. The two inexperienced examiners were physical therapist students with no previous experience with the KT-1000 arthrometer. The novices were matched, by generally less than 100/o, by gender, height, and weight with the experienced examiners. Training of the novices replicated the initial training of the experienced examiners by mimicking their original 1-hour training in-service that consisted of reading the manufacturer's training manual,[15] observing the technique performed by one of the experienced therapists, and practicing on asymptomatic subjects for three or four trials while under supervision of one of the experienced therapists.

Procedure

Each subject was arbitrarily assigned to a testing area (a booth) to which a data recorder had been assigned. Each booth contained a KT-1000 arthrometer Figure), which remained in that booth to be used by the four examiners. The arthrometers were not calibrated for two reasons: (1) The user's manual states that "barring component failure the force level audio indicators and the displacement gauge will remain within calibration throughout the instrument's lifetime,"[15] and (2) all displacements for each subject were collected using the same arthrometer. The examiners were randomly assigned to each testing area to minimize an ordering effect. Upon entering the testing area, the examiner presented the recorder with a datacollection form. The knee on which testing was begun was randomly determined by drawing a card specifying left or right. This procedure eliminated bias, which might result from always testing the injured or uninjured leg first.

Each subject was instructed to lie supine on the table with the knees flexed 90 degrees. Completion of the posterior sag test ensured an intact posterior cruciate ligament, while also allowing for determination of the neutral position of the knee.[5] This neutral position has not been defined in the literature, but is the position in which neither a posterior nor anterior displacement of the tibia on the femur exists. Measurements in this and other studies need to establish a "zero"[4] or neutral position from which displacements are quantified. Procedures provided by the manufacturer[15] specified that the examiner locate the support provided with the arthrometer under the subject's thighs to reposition the knees between 20 and 35 degrees of flexion. The lateral (external) aspect of the foot rested against a foot-support platform, and heel placement was noted to be symmetrical on the platform scale. The function of the foot-support platform was to partially constrain lateral rotation of the tibia and to ensure symmetrical initial tibial rotation. A loose-fitting circumferential Velcro[R][3] strap around the thighs prevented excessive lateral rotation at the hip.[15]

The knee joint line was palpated and marked both medially (internally) and laterally with removable adhesive strips to allow proper alignment of the arthrometer. At the end of each test session, the examiner removed these strips and rubbed the area to obscure any residual markings that may have influenced subsequent examiners. Knee angle measurements were then taken with a goniometer to ensure that knee flexion was within the appropriate range (ie, 20[degrees]-35[degrees]).

The arthrometer was placed on the anterior aspect of the leg aligning the medial and lateral arrows on the arthrometer with the joint lines marked on the subject. The two circumferential Velcro[R][double dagger] straps on the arthrometer's case were secured with the distal strap being loosely applied and then the proximal strap being secured tightly. The arthrometer had two sensor pads, a proximal one in contact with the patella and a distal one over the tibial tubercle. These sensors monitored the relative anterior-posterior (AP) motion between the tibial plateau and the femur. Because AP forces were applied through the patellar sensor pad, tightness of the proximal strap was important.

Anterior and posterior tibial displacement loads were applied through the force-sensing handle. Tibial displacement (in millimeters) was indicated by a dial needle on the arthrometer case and was visually interpreted by each tester to the nearest 0.25 mm during the application of the load. The arthrometer remained on a leg until the testing by one examiner was completed.

To begin the data collection, the examiner applied a downward pressure on the patellar sensor pad until no further deflection of the dial needle was noted. This pressure was then held constant throughout the test to sustain the patella within the trochlear groove. Initial zeroing of the machine was done by applying an 89-N posterior force through the force-sensing handle. The examiner then released the posterior force and adjusted the dial needle to zero.

The examiner applied an anterior force by pulling slowly and smoothly on the force-sensing handle until two consecutive audible tones indicated the 67-N and 89-N anterior forces had been reached. Three trials of each measurement were completed. These trials were followed by three trials of a manual maximum anterior drawer test in which the examiners placed their free hand just distal to the joint line on the posterior surface of the leg and applied a maximum anteriorly directed force. The greatest excursion of the dial needle was noted by the examiner and recorded by the recorder. Testing concluded with three active drawer trials in which the subject was instructed to "gently raise your heel slightly off the table." The excursion of the dial needle was again recorded for each trial, and the subject was instructed to relax between trials. Following each trial, the affluometer was rezeroed using a posterior 67-N force with the dial returning to zero [+ or -] 1 mm). At this time, the arthrometer was removed and placed on the contralateral leg, and the testing procedure was repeated. No conferring or sharing of data was done between examiners at any time. All tests on one subject were completed in one session by each of the two examiners, one experienced and one inexperienced.

Data Analysis

Intraclass correlation coefficients (2,k)[16] were calculated to describe the degree of interrater agreement for each of the measurements taken in this study. The formula used was chosen because ratings from each examiner represented the mean of three trials for each measurement.

In addition, standard errors of measurement (SEMs)[17] were calculated for all data to aid in the interpretation of our reliability coefficients. The SEM is an estimate of the magnitude of the error associated with obtaining a measurement and reflects the range of scores that can be expected when measurements are repeated. The SEM was calculated for all data using the formula:

SEM=SDX(1-r)1/2

where SD is the standard deviation of the set of observed test scores, and r is the reliability coefficient for that data. All procedures were performed using SAS software[sections] on The University of Iowa's (Iowa City, Iowa) mainframe computer.

Results

The values of anterior displacement obtained in this study (Tab. 2) were expected, given the variation in level of force applied and the differences in involved-uninvolved extremities. Specifically, the higher loads applied by the examiners produced greater displacements. In addition, anterior displacement values for the injured leg were always greater than for the uninjured leg. The ICCs and SEMs are also shown in Table 2, reflecting the influence of gender of the tester on the reliability of measurements taken from injured and uninjured knees. The ICCs for measurements taken by male and female therapists with comparable levels of experience ranged from .77 to .88. Measurement errors ranged from 0.7 to 1.5 mm. The errors in the 67-N and 89-N tests did not exceed 1 mm for either the injured or uninjured leg. The data presented in Table 3 reflect the influence of therapist experience rather than gender. On average, these reliability coefficients are slightly lower than those in Table 2, suggesting that therapist experience may be a more important factor influencing reliability than gender.

[TABULAR DATA 2 OMITTED]

[TABULAR DATA 3 OMITTED]

Results of the analyses for data using between-leg difference values are resented in Tables 4 and 5. In Table 4, reliability coefficients are presented that indicate the influence of gender, whereas the results in Table 5 reveal the influence of therapist experience. The ICCs in Table 4 range from .68 to .84, and SEMs range from 0.8 mm in the 67 N and 89 N tests to 1.3 mm in the maximum manual and active anterior drawer tests. In Table 5, ICCs range from .12 to .78, and measurement errors range from 1 mm to 2.2 mm.

[TABULAR DATA 4 & 5 OMITTED]

Discussion

That greater loads produced greater anterior displacement was an expected finding and held true across all examiners. The 89-N load is the most commonly applied for testing of ligament integrity[3-13] and provides a "standard" to which the other values can be compared. The anterior displacement values for 89-N loading obtained in our study (Tab. 2) compare favorably with those reported for injured and uninjured knees (injured knees/ uninjured knees) by Daniel et al3 (13/5.7), Sherman et al[5] (12.1/6.2), Steiner et al6 (7.8/3.9), Forster et al[13] (8.3/5.3), and Staubli and Jakob[18] (11.9/6.2) and with results when only uninjured knees were tested by High-genboten et al[9] (4.6) and Wroble et al[10] (7. 1). The higher values found in some of the studies by orthopedic surgeons may reflect the severity of injury in their samples or the acute stage of the injury, or a combination of the two factors. The general comparability across all studies for a standardized load indicates that the same test was being performed.

Because height, weight, strength, and hand size of the examiner are all possible factors contributing to the actual displacement values obtained, we anticipated that therapist gender would influence the variability of test results, particularly for the maximum manual anterior drawer test. Based on the ICCs reported in Tables 2 and 4, however, arthrometer measurements obtained by therapists of similar experience show moderate to good reliability for all tests regardless of gender. These results are in general agreement with those reported by Hanten and Pace,[12] who declared the KT-1000 arthrometer to be intertater reliable. Although our estimates are lower, the difference can be explained by the fact that the findings of Hanten and Pace[12] were based on the testing of 43 male college athletes without knee injuries, whereas our study investigated male and female subjects with unilateral ACL injury.

In contrast, intertater reliability was reduced considerably when therapists were not matched for experience (Tabs. 3 and 5). These findings are consistent with the interrater reliability results reported by Forster et al,[13] who tested knees without injuries compared with knees with ACL injuries. Those investigators found that variable displacement values were obtained by

two experienced and two less experienced examiners. They concluded, therefore, that interrater reliability was poor when using the KT-1000 arthrometer. Their conclusions, however, were based on percentage of agreement among examiners rather than inferential statistics.

For assessing reliability with respect to changes in individual patients, a more meaningful estimate of the magnitude of the error associated with taking a measurement is the SEM. An advantage of the SEM is that values are expressed in the units of the measurement rather than as a ratio. Knowing the magnitude of the error allows us to estimate the range of values that can be expected on retesting. For example, if a clinician obtains a value of 6 mm of anterior displacement on the 89-N test and the SEM is 1.5 mm, then there is a 95% chance that the patient's "true" score lies within [+ or -] 2 SEM, or between 3 and 9 mm (ie, [+ or -] 3 mm). A measurement taken on the same patient by a different therapist would represent a clinically meaningful change only if the second score fell outside the range of scores estimated from the first measurement. in this example, a fairly large difference is required.

Measurement errors of [+ or -] 1.6 mm for tests conducted by the same examiner in asymptomatic subjects have been reported by Wroble et al.[10] The results of our study indicate that a measurement error of [+ or -] 2 mm (Tab. 2, worst-case SEM = 1 mm) is required for 67-N and 89-N tests in ACL-deficient knees when the measurements are taken by two examiners of comparable experience (both inexperienced or both experienced). Maximum manual and active drawer tests require a measurement error of [+ or -] 3 mm (worst-case SEM=1.5 mm) under these conditions. When considering between-leg difference values (Tab. 4), 67-N and 89-N tests require a measurement error of [+ or -] 1.8 mm (SEM=0.9 mm), whereas maximum manual and active drawer tests require a measurement error of [+ or -] 2.6 mm.

Somewhat larger differences are required to be considered meaningful if single-leg measurements are taken by two examiners of vastly different experience (Tab. 3, [+ or -] 2.2 mm for 67-N and 89-N tests, [+ or -] 3.6 mm for maximum manual tests). Similar results were found when considering between-leg difference values. When therapists are not matched for experience (Tab. 5), the conservative ranges are [+ or -] 3.6 mm for 67-N and 89-N tests and [+ or -] 4.4 mm for maximum manual and active drawer tests. These results serve to illustrate the importance of the SEM in interpreting ICCs with this kind of measurement. Because the error of the measurement was greater when therapist experience differed, the reliability coefficients suffered. The SEM, however, still provides useful information about the range of acceptable scores.

Reliability in using the KT-1000 arthrometer may be influenced by numerous confounding factors. Lack of muscle relaxation has often been cited as a factor increasing inaccuracy.[3,5,9,10,12-14,19,20] Markolf et al[21] reported that active muscle tension can increase stiffness two to four times the normal value and thus decrease knee laxity by 25% to 50%. In our study, muscle guarding was monitored by the examiners during the testing procedure. If the arthrometer failed to rezero, indicating that muscle guarding was occurring, the subject was then encouraged to relax. If necessary, the examiner gently oscillated the knee to promote muscle relaxation, allowing the dial to rezero.

Proper identification of the tibial-femoral joint line is also an important component of the testing procedure. Failure to properly identify the joint line or misalignment of the arthrometer by 10 mm can alter measurements by 15% to 20%.[15] In our study, the examiners minimized this effect by palpating and marking the joint line before testing began.

Maintaining contact between the flat patellar sensor pad and the rounded surface of the patella is awkward and may influence measurements.[5,13] Another difficulty with the testing protocol is that a constant stabilization pressure must be maintained throughout the test so the patella remains fixed within the trochlear groove.[3,5,13,19] The manufacturer of the KT-1000 affluometer states that if constant pressure on the patella is not maintained throughout the test, a 1- to 2-mm displacement error may result.[15] Our protocol required the arthrometer needle to return to within [+ or -] mm following each application of force, thus ensuring maintenance of constant pressure on the patella.

The KT-1000 arthrometer minimally constrains lateral rotation of the tibia while allowing free medial rotation.3,22 Medial rotation of the tibia accompanies anterior displacement.[23] If the

tibia is not allowed to medially rotate freely, anterior tibial displacement is decreased by 30% at all flexion angles.[24] Therefore, initiating the tests in varying degrees of initial medial rotation may mask true anterior displacement measurements. To decrease this confounding factor, the examiners in our study ensured that foot placement was symmetrical.[15]

Numerous authors[5,15,24,25] recommend that when testing anterior displacement, the subject's knees be maintained within 20 to 35 degrees of flexion to obtain the greatest amount of anterior displacement. Failure to do so results in structures other than the ACL restricting anterior displacement (ie, medial and lateral collateral ligaments, iliotibial tract, and the middle one third of the medial and lateral capsules).[26] Because knee angle was standardized within our study, variations in knee flexion angle should not be a factor that influenced reliability.

Another factor that could influence reliability is soft tissue approximation under the tibial reference pad. This may occur when the Velcro[R] straps are secured, especially if the leg is very fleshy or obese.[15] A nonuniform rate and direction of displacement forces may also add to the variability of the measurement.[3,5,19,20] Our examiners were instructed to use a 1-second count when applying anterior and posterior forces to keep the rate of force application uniform between examiners. In addition, examiners were instructed to apply forces to the force handle without incurring medial or lateral rotation of the arthrometer on the leg. The influence of each of these factors limits our ability to make accurate measurements.

Physical therapists routinely utilize the results of instrumented testing of knee ligament integrity in treatment planning and as an aid in determining whether a patient should be referred to a physician. Wide ranges of anterior tibial displacement values have been reported for knees with and without pathology.[7,13,19] Therefore, clinicians often do not emphasize the individual displacement values of a given leg, but rather the difference between legs.3,5,10,13,19,22 The rationale behind this method is that because intersubject variability is high, the between-leg differences are used to minimize between-subject variation, including the patient who exhibits general ligamentous laxity.[21,27,28] In our discussions with several experienced clinicians, a commonly expressed opinion was that injured-uninjured leg differences minimize the variability in individual displacement values obtained by the examiners (eg, if one examiner obtains an uninjured leg displacement value of 3 mm and a 7-mm displacement on the injured leg, whereas a second examiner obtains measurements of 5 mm and 9 mm, respectively, both examiners have difference values of 4 mm). Therefore, it is assumed that variability between examiners had been reduced. Using the results of our study, a clinically meaningful change would be indicated if during the course of treatment a patient's between-leg difference value increased by 2.6 mm when evaluated by two therapists of comparable experience.

Our study was conducted using a small number of examiners on a limited number of patients with nonacute knee injuries. We believe, therefore, that our results must be interpreted with caution, thus limiting generalizability. Further, we recognize that lack of calibration is a limitation. Although we did not calibrate the instrument, how the device is mechanically constructed, manufacturer's testing, use of the same arthrometer on each subject, and comparability with data sets of other investigators all support the ability of the device to take repeated measures. Because instrumented testing has gained greater acceptance and more frequent clinical usage, however, we feel that information regarding the influence of gender and experience on measurement reliability is important. Based on these results, it appears that experience has a greater influence on reliability than does gender for these results obtained from a mean of three measurements. Three explanations for this finding can be offered. First, the experienced examiners possessed greater confidence in testing, which may have resulted in a more uniform rate of loading and increased patient trust leading to greater relaxation. Second, the experienced examiners may have had superior ability in detecting and responding to subject muscle guarding. Third, experienced examiners may have been more proficient in maintaining a constant firm pressure over the patellar sensor pad without causing discomfort.

Conclusion

The experimental design of our study allowed us to evaluate the reliability of anterior displacement measurements obtained with the KT-1000 arthrometer when considering the gender and level of experience of the examiner. In general, therapist experience was a more important factor influencing reliability than gender. Given the magnitude of the errors obtained for many of the tests routinely conducted in the clinic, we recommend that repeated measurements should be taken by the same examiner whenever possible. Evaluation of test results obtained by different therapists when necessary must include these errors.

BT Ballantyne, PT, is Physical Therapy Clinical Coordinator, Arizona Movement and Balance Laboratory, Rehab institute of Tucson, Tucson, AZ 85726. When this study was completed, Mr Ballantyne was Associate Instructor, Physical Therapy Graduate Program, The University of Iowa, Iowa City, IA 55242-1008.

AK French, IT, is Staff Physical Therapist, St Luke.'s Hospital, Cedar Rapids, IA 52402.

SL Heimsoth, PT, is Staff Physical Therapist, St Luke's Hospital.

AF Kachingwe, PT, is Contract Physical Therapist, Northern Illinois University Physical Therapy Clinic, De Kalb, IL 60115.

JB Lee, PT, is Staff Physical Therapist, University of Iowa Hospital and Clinics, lowa City, TA 52242.

GL Soderberg, Phd, PT, FAPTA, is Professor, Department of Physical Therapy, Creighton University, 2500 California Plaza, Omaha, NE 68178 (USA) ([e-mail]). When this study was completed, he was Director, Physical Therapy Graduate Program, The University of lowa. Address all correspondence to Dr Soderberg.

Ms French, Ms Heimsoth, Ms Kachingwe, and Mr Lee were students in the Physical Therapy Graduate Program, The University of Iowa, when this study was complete in partial fulfillment of the requirements for their Master of Physical Therapy degrees.

This study was approved by the Human Subjects Review Committee at The University of lowa and by the Iowa Medical Clinic review committee.

This article was submitted May 1 7, 1994, and was accepted May 8, 199-5.

[dagger] Faro, Far Orthopaedics Inc, Montreal, Quebec, Canada.

[double dagger] Velcro USA Inc, 406 Brown Ave, PO Box 5218, Manchester, NH 03108.

[sections] Institute Inc, PO Box 8000, Cary, NC 27511.

References

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