VALID AND RELIABLE MEASUREMENT tools are essential

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1 396 Intra- and Intertester Reliability and Criterion Validity of the Parallelogram and Universal Goniometers for Measuring Maximum Active Knee Flexion and Extension of Patients With Knee Restrictions Lucie Brosseau, MSc, PhD, Suzanne Balmer, PT, Michel Tousignant, MA, PhD, Joseph P. O Sullivan, MD, Calina Goudreault, Mélanie Goudreault, Sonia Gringras, PT ABSTRACT. Brosseau L, Balmer S, Tousignant M, O Sullivan JP, Goudreault C, Goudreault M, Gringras S. Intraand intertester reliability and criterion validity of the parallelogram and universal goniometers for measuring maximum active knee flexion and extension of patients with knee restrictions. Arch Phys Med Rehabil 2001;82: Objective: To examine the intra- and intertester reliability of the universal goniometer (UG) and parallelogram goniometer (PG), and to assess the criterion validity of the same instruments on subjects with knee restrictions. Design: Reliability and validation study. Setting: Radiology department at university hospital. Participants: Sixty subjects (34 men, 26 women; mean age, 52yr) with various knee restrictions. Interventions: Sixteen goniometric measurements were collected per patient by 2 physical therapists. Subjects were evaluated in knee flexion and knee extension positions. To serve as a gold standard, radiographs were taken in both positions. Main Outcome Measures: Active knee flexion and knee extension on 2 goniometers, radiographs. Maximum active range of motion (AROM). Results: The UG intratester reliability (intraclass correlation coefficients [ICCs]) was.997 in flexion and.972 to.985 in extension. The results were also high with the PG (ICC.996, ) for flexion and extension, respectively. The intertester reliability was high for flexion (ICC ) and for extension (ICC ) when using the UG. For the PG, ICC results ranged from.959 to.970 for flexion and from.856 to.898 for extension. Criterion validity (r) varied from.975 to.987 for flexion and from.390 to.442 for extension with the UG, and from.976 to.985 for flexion and.423 to.514 for extension with the PG. From the Physiotherapy Program, School of Rehabilitation Sciences, University of Ottawa (Brosseau, Tousignant); Rehabilitation Centre (Balmer); Department of Radiology, Ottawa Hospital, General Campus (O Sullivan), Ottawa, Ont; and physiotherapy private practice (Goudreault, Goudreault, Gringras), Ontario and Quebec, Canada. Accepted April 21, Supported by the Institute of Rehabilitation Research and Development of The Rehabilitation Centre (Ottawa), by the Institute of Functional and Active Rehabilitation, and by the Physiotherapy and the Radiology Departments of the Ottawa Hospital. Presented in part at the 67th Annual Congress of ACFAS in Ottawa, Ont, May 12, No commercial party having a direct financial interest in the results of the research supporting this article has or will confer a benefit upon the authors or upon any organization with which the author(s) is/are associated. Reprint requests to Lucie Brosseau, PhD, Physiotherapy Program, School of Rehabilitation Sciences, Faculty of Health Sciences, University of Ottawa, 451 Smyth Rd, Ottawa, Ont K1H 8M5, Canada, [email protected] /01/ $35.00/0 doi: /apmr Conclusion: Intra- and intertester reliability were high for both goniometers. The results for the criterion validity varied. Our study also revealed that it is preferable to use goniometry rather than visual estimations when measuring AROM. It is recommended that the same therapist take all the measurements when assessing AROM for UG and PG goniometric measurements on patients with knee restrictions. Key Words: Goniometry; Knee joint; Radiology; Range of motion articular; Rehabilitation; Reproducibility of results by the American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation VALID AND RELIABLE MEASUREMENT tools are essential to health care professionals. Because physical therapists use outcome measures to justify their practice and the effectiveness of their interventions, clinically validated and reliable instruments are vital in practice. 1 The universal goniometer (UG) is a frequently used instrument, and it permits physical therapists to quantify restrictions in range of motion (ROM), to guide treatment interventions, and to document the efficacy of their approach. 2 Goniometers also allow patients to appreciate their own progress and achievements. The standard goniometer is commonly used, but without the proper placement of its fulcrum over the center of rotation of the joint, it can provide unreliable results. 3 For this reason, the Rehabilitation Centre (Ottawa) designed a new parallelogram goniometer (PG) (fig 1). Its advantage is its capacity to measure a joint angle without using a point representing the joint s center of rotation. Because of the parallelogram design, the range obtained is always represented by the angle between the 2 goniometric arms. 3,4 In a clinical setting, limited ROM is a common impairment. Various pathologies or injuries may result in restrictions of knee ROM. These limitations prevent normal function, and so it is imperative that physical therapists assess with valid and reliable tools to treat these restrictions adequately. Reliability and validity of the PG has only been studied on knee joints of healthy subjects, 5 therefore, we examined the psychometric properties of this new instrument on subjects with knee restrictions. LITERATURE REVIEW Over the years, several published studies have addressed the reliability and validity of goniometric measurements. Studies 6-8 have shown that goniometric measurements are more reliable than visual estimates. In addition, research studies have found the UG to have a good overall intra- and intertester reliability. However, most studies found the intratester reliability to be better than the intertester reliability. 5,8-12 Overall

2 VALIDATION STUDY OF THE PARALLELOGRAM GONIOMETER, Brosseau 397 METHOD Fig 1. The parallelogram goniometer. reliability of the UG was found to be high, though it varied from 1 articulation to another and among physiologic movements. 11,13,14 Reliability and validity studies on universal goniometry of knee measurements have been summarized. 5 Results on the reliability and validity of goniometry on the knee joint varied. Many studies found a high intratester reliability for the knee joint, 5,8-11 and, in general, most observed that the intratester reliability was higher than the intertester reliability. 5,8-12 Some studies 5,8,11 have also shown higher reliability measurements for larger but not smaller angles. Results for intra- and intertester reliability varied from good to excellent (r.87.99) and (r.50.98) for knee flexion and extension. Generally, reliability was greater for knee flexion than for knee extension ROM. Another important characteristic that affects objective goniometric measurements is validity. Although there has not been extensive research on the validity of goniometry, a few studies 10,15,16 have examined the criterion validity for goniometry by using radiographs as the gold standard. All of these studies showed a significantly high correlation between the 2 methods of measurement for knee ROM. In a recent study by Brosseau et al, 5 the intra- and intertester reliability along with the criterion validity of the UG and PG were assessed. The validity of both goniometers was studied by comparing the goniometric data with radiographs. This study was performed on 60 university students with no history of knee injuries. Results showed a good intratester reliability for the UG in a small angle position (intraclass correlation coefficient [ICC].86.94) and a large angle position (ICC.95.97) and the PGs also showed good intratester reliability for the small angle (ICC.85.87) and large angle (ICC.91.96) positions, respectively. The results also showed a good intertester reliability for the PG (small angle position ICC.43.52; large angle position ICC.82.88), however, the correlation coefficient was slightly lower than that of the UG (small angle position ICC.62.71; large angle position ICC.91 1). Validity results showed low correlation coefficients for the UG (r.33.48) and for the PG (r.33.41) in the small angle position. However, the correlation coefficients were higher in the large angle knee position, for both the UG (r.73.78) and the PG (r.73.77). This study sought to examine: (1) the intratester reliability of the UG and PG; (2) the intertester reliability of the same 2 instruments; (3) the criterion validity of both goniometers; and (4) the criterion validity of visual estimations, for active knee flexion and extension on subjects with knee restrictions. Subjects Sixty subjects (34 men, 26 women; mean age, 52yr) with a residual musculoskeletal impairment at the right or left knee were recruited from discharged patient lists obtained from the physiotherapy departments of different institutions: the Ottawa Hospital, General Campus; The Rehabilitation Centre (Ottawa); the Health Care Center of the Canadian Forces Support Unit of Ottawa; the Clinique de physiothérapie l Envolée; the Physio Sports Care Centre; and the Centre Hospitalier des Vallées de l Outaouais (CHVO). All subjects were recruited within a year after their discharge date. Only patients with residual reduction of active ROM (AROM) of knee flexion or knee extension were eligible to participate. A questionnaire was used to screen all potential subjects. Subjects with a history of neuromuscular pathologies, back problems, or ipsilateral impairments at the hip or ankle joints were excluded. Subjects unable to understand verbal and written instructions in English or in French, as well as pregnant women, were excluded. In the case of bilateral knee impairments, the knee joint without limitations at the hip and ankle joints was evaluated. However, in the presence of bilateral impairments with no hip or ankle problems, the most limited knee joint was chosen. Our study sample was composed of subjects with the following diagnoses: 31 arthritis (including total knee replacements), 23 meniscal/ligamentous injuries, and 6 patellofemoral conditions. All the subjects recruited from the participating institutions were contacted by mail or by phone to invite them to participate. Each candidate who agreed received an information letter and signed a consent form. Research approval was obtained by the ethics committees of the Ottawa Hospital: General Campus, The Rehabilitation Center, and the CHVO. Instrumentation To conduct this study, 3 quantitative clinical measuring tools were used: (1) a UG; (2) a PG; and (3) radiographs. The UG, a is a 360 plastic goniometer with 2 25-cm movable arms and a scale marked in 1 increments. The PG a looks similar to a UG, however, the instrument has been modified by including a parallelogram, joining 1 of the arms to the center of the fulcrum (fig 1). This goniometer, incorporating the parallelogram principle, was developed and field tested by The Rehabilitation Centre in Ottawa. 3 Radiographs of the restricted knees were taken at the department of radiology of the Ottawa Hospital, General Campus. Tester Qualitative clinical data were collected by 2 physiotherapists. The information taken was: (1) visual estimations of maximum AROM of the hip, knee, and ankle of both lower extremities; (2) identification of the end-feels (amount of passive ROM limited by unique structure of the joint being tested at the end of passive movement) of the previously mentioned joints; (3) identification of the presence of pain in both lower extremities; and (4) identification of bony landmarks. The purpose of collecting such information was to ensure that the candidate was eligible for the study and to determine which knee joint would be evaluated. Before the actual testing, a practice session on normal subjects was conducted for the physiotherapists to test the end-feels of both lower extremities. This practice session assured the effective proceedings of the formal testing. The goniometric measurements were taken by 2 other physiotherapists with different levels of experience (testers 1, 2).

3 398 VALIDATION STUDY OF THE PARALLELOGRAM GONIOMETER, Brosseau Two fourth-year physiotherapy students from the University of Ottawa (recorders 1, 2) made the recording of those goniometric measurements. A practice session was conducted before the first actual testing session. During this 45-minute practice session, both physiotherapists measured maximum AROM of knee extension and flexion with both goniometers on normal subjects. This practice session was followed up with a pilot study, which was completed when 90% agreement was achieved between each goniometric measurement of the 2 testers. Overall, this preparation for the formal testing took an hour. The preparation session and the actual testing were both conducted at the radiology department of the Ottawa Hospital, General Campus. Throughout the study, recorder 1 was always teamed up with tester 1 and recorder 2 with tester 2. The angles measured by each tester were collected by their respective recorder on distinct record sheets. Fig 2. PG measurement for the knee in flexion. Fig 3. PG measurement for the knee in extension. Procedure For the qualitative data collection, the subject laid supine on a hospital bed with both legs resting on the bed. The physiotherapists then visually estimated the AROM of the hip, knee, and ankle joints of both lower extremities. In the same position, the physiotherapists verified the end-feels of the hip, knee, and ankle joints of both legs, as well as for the presence of pain. The final step was to identify and mark the bony landmarks on the subjects to standardize the goniometric placement and to facilitate the measurements. The bony landmarks identified by an independent, and trained physiotherapist were the greater trochanter, the lateral femoral condyle, and the lateral malleolus. Sticky markers were put over these body landmarks that remained and were used by both testers. The next step was to collect quantitative data. All the candidates chosen for the study were tested in knee flexion and in knee extension (fig 2). While maintaining a supine position, the subject s affected knee was placed in maximum knee flexion (fig 3). For standardization purposes, a Velcro strap attached to the stretcher fixed the subject s foot. This position was maintained for both goniometric and radiographic measurements. To measure extension (fig 3), the subject remained in the supine position and was asked to extend maximally his/her knee. When full extension was not achieved, a roll was placed underneath the knee to standardize the position, with different sizes of rolls made to accommodate the different knee extension positions. This position was maintained for goniometric measurements. As for the radiographic measurement, the same position was maintained; however, the nontested lower extremity was flexed at the hip joint, instead of lying on the bed, and the foot was elevated on a box to prevent interference with the radiograph of the evaluated leg. Throughout the procedure, the subjects were instructed to maintain the required positions as stated earlier. Two different radiographic rooms were used to evaluate 2 subjects at once. Each pair of subjects were tested simultaneously in different positions, one in flexion and the other in extension. Before taking any measurements, the testers took a visual estimate of the AROM. Measurement of the knee joint followed and the data were collected by the recorder. Once the first measurement was complete, goniometers were exchanged and the testers alternated rooms. This procedure was repeated until each tester had taken 4 goniometric measurements (2 UG, 2 PG) on each of the 2 subjects. A radiology technician then obtained a radiograph of the knee joint of each subject. The subject positioned in knee flexion in the first testing step was switched to a knee extension position and vice versa. The second phase of the quantitative data collection was conducted in the same fashion as the first, resulting in the collection of 4 more measurements by each tester for each subject. The second radiograph was then obtained, finalizing the testing session for the 2 participants. Overall, 4 visual estimations and 18 quantitative data were collected, of which 16 were goniometric measurements and 2 were radiographic pictures. All goniometric measurements taken with the UG were performed according to the technique described by Norkin and White. 17 The center of the fulcrum was positioned over the lateral condyle of the femur. The proximal fixed arm of the UG was aligned with the axis of the femur by using the greater trochanter as a reference point. The distal mobile arm was aligned by using the lateral malleollus as the reference point. The landmarks used to measure the AROM with the PG were the same as the ones used with the UG. However, because the PG measures joint angle without requiring a center of rotation, the fulcrum of the goniometer was not placed over the lateral condyle of the femur. 3 To minimize information biases, pairs of subjects were evaluated simultaneously in different rooms and testers alternated rooms for every measure. Furthermore, each recorder always collected the data from the same tester and all of the testers and the recorders were informed not to discuss any measures once they were collected. An acceptable dosage of 10mrad, with the use of a gonadal shield, was approved by a radiologist of the Ottawa Hospital, General Campus. The radiograph s beam was centered on the

4 VALIDATION STUDY OF THE PARALLELOGRAM GONIOMETER, Brosseau 399 Fig 4. Radiologic readings. knee s joint line and was placed perpendicular to the sagittal plane (fig 4). To obtain the quantitative information on the radiographs, a fourth-year physiotherapy student drew lines parallel to the axes of the femur and the tibia. For the lines to be representative of the axes of both bones, they were drawn joining points marked in the middle of the width of each diaphysis. These lines were prolonged passed the joint, forming an angle that represented the AROM. This angle was measured with a protractor. Statistical Analysis The statistical data was computed by using the SPSS software b on a personal IBM computer. c ICCs obtained by using the analysis of variance procedure 18 were chosen to calculate the intra- (1:1) and intertester (2:1) reliability of both goniometers. To calculate the intratester reliability, the first and second goniometric measurements of each tester were compared to determine the ICCs for each goniometer in both positions. The intertester reliability was calculated by comparing the pairs of goniometric measurements for each tester in active knee flexion and extension with the UG and PG. To establish the criterion validity, Pearson s product-moment correlation coefficients (r) were used by comparing the UG and PG measurements with radiographic data. The calculation of these correlations was obtained by using the results of intratester measurements for each goniometer in full knee flexion and extension. A level of significance of.05 was selected for all statistical tests. RESULTS Table 1 presents descriptive results obtained from the goniometric measurements for active knee flexion and extension. In addition, radiographic measurements and visual estimations are presented (table 1). The intratester reliability of goniometric measurements was high for the UG and PG when measuring active knee flexion with ICCs of.997 and.996, respectively (table 2). The ICCs for intratester reliability of active knee extension were.972 and.985 for the UG and.953 and.955 for the PG (table 2). The intertester reliability was also high for active knee flexion for both goniometers, with ICCs ranging from.977 to.982 for the UG and from.959 to.970 for the PG (table 3). The intertester reliability was found to be slightly lower for knee extension, however, the results were still good. The ICCs ranged from.893 to.926 for the UG and from.856 to.898 for the PG (table 3). The intra- and intertester reliability of both goniometric measurements were higher for the active knee flexion compared with the active knee extension position (tables 2, 3). In addition, the intratester reliability was found to be higher than the intertester reliability. As for the criterion validity, the r values for the knee flexion position varied from.975 to.987 for the UG and from.976 to.985 for the PG (table 4). In the extension position, results were fair for both the UG (r ) and the PG (r ) (table 4). The results obtained comparing visual estimation and radiographic measurements are also presented in table 4. The overall mean scores did not differ significantly (p.05) between testers for goniometric (UG, PG) and visual measurements for knee flexion and extension. No statistically significant differences (p.05) were found between goniometric measurements and visual estimation for flexion and extension of the knee. No statistically significant differences (p.05) were observed between goniometric and radiologic measurements for knee flexion. Statistically significant differ- Table 1: Goniometric and Radiographic Measurements for Flexion and Extension Measurement Measurement Measurement Measurement Measurement Measurement Measurement Measurement Visual estimation Radiographic Measurements NOTE. Values are presented as mean standard deviations, and are expressed in degrees. UG PG

5 400 VALIDATION STUDY OF THE PARALLELOGRAM GONIOMETER, Brosseau Table 2: Intratester Reliability for Knee Flexion and Extension (n 60) PMS RMS EMS K r UG PG NOTE. ICCs were calculated by comparing the first and the second measurements by each tester for both goniometers in both positions. Abbreviations: PMS, patients mean square; RMS, raters mean square; EMS, error mean square; K, number of measurements; r, random ICCs. ences (p.05) were established, however, between goniometric and radiologic measurements for knee extension. DISCUSSION Intratester Reliability The intratester reliability obtained in this study was high for the PG and the UG when measuring active knee flexion and extension on subjects with knee restrictions. The high intratester reliability of the UG supports findings of previous studies. 5,8-11 The results for the PG correlate with those of a recent study, assessing the reliability of the PG on the knee joint. The differences between the ICCs for the UG and the PG, between testers and positions, were minimal. As previously mentioned, both goniometers showed minimally lower ICCs with active knee extension than flexion for both examiners. 5,8,9,11 From a clinical perspective, the PG is as reliable as the UG when used by the same physiotherapist. Therefore, whenever possible, measurements should be taken by the same physiotherapist with either instrument. Intertester Reliability The examination of intertester reliability of the UG and PG revealed high correlations when assessing active knee flexion and extension on subjects with knee restrictions. Once again, the differences between the UG and the PG were minimal. This finding does not correlate with the study by Brosseau et al 5 on healthy subjects, which found higher results with the UG. Furthermore, patients with knee restrictions have more variability (patients mean square [PMS] Table 3: Intertester Reliability for Knee Flexion and Extension (n 60) PMS RMS EMS K r Intertester (1, 2) reliability using the UG Measurements 1 and Measurements 1 and Measurements 2 and Measurements 2 and Measurements 1 and Measurements 1 and Measurements 2 and Measurements 2 and Intertester (1, 2) reliability using the PG Measurements 1 and Measurements 1 and Measurements 2 and Measurements 2 and Measurements 1 and Measurements 1 and Measurements 2 and Measurements 2 and

6 VALIDATION STUDY OF THE PARALLELOGRAM GONIOMETER, Brosseau 401 Table 4: Criterion Validity for Knee Flexion and Extension r VE r UG r PG Visual estimation and x-ray.912 Measurement 1 and x-ray Measurement 2 and x-ray Visual estimation and x-ray.943 Measurement 1 and x-ray Measurement 2 and x-ray Visual estimation and x-ray.246 Measurement 1 and x-ray Measurement 2 and x-ray Visual estimation and x-ray.367 Measurement 1 and x-ray Measurement 2 and x-ray Abbreviation: VE, visual estimation. values) in their maximum ROM than healthy subjects. The reliability coefficients in this study tended to be higher for both positions and goniometers compared with the previous study with healthy subjects. 5 The results show a slightly higher reliability when measuring active knee flexion compared with extension for both goniometers. The review of literature shows similar results for the UG 5,8,11 and the PG. 5 This could be explained by the fact that there are more limitation variations (PMS values) among patients for flexion than for extension. The study also showed that the intratester reliability of the UG was slightly higher than the intertester reliability for both positions and examiners. Such findings were also shown in other studies. 5,8,9,11,12 Our study also found similar results with the PG, establishing an intratester reliability greater than intertester reliability for the 2 positions used and the 2 examiners participating in the research. The data analysis suggests that, from a clinical perspective, the PG is a reliable tool in measuring AROM on pathologic knee joints, among physiotherapists. However, it is important to remember that like the UG, the PG is more reliable when used by the same physiotherapist. Furthermore, health professionals using a goniometer as a measuring tool need to consider that the PG as well as the UG are more reliable when measuring angles of knee flexion than extension, within and among physiotherapists. The sample of patients was well balanced in terms of the heterogeneity of limitations in ROM. Approximately half of the patients, those with arthritis (including total knee replacements), exhibited larger restrictions in knee ROM than the other half, with meniscal/ligamentous injuries or patellofemoral conditions. Although this study was designed to eliminate the greatest sources of error, 19,20 some instances remained and could have affected the results. The lack of experience and familiarity in the use of the PG could have been a potential source of error, as well as changes in the position of the subjects regardless of the attempt to standardize these positions. Furthermore, some error could have been introduced by faulty readings of goniometric or radiographic measurements. Finally, as suggested by some investigators, 9,11 the knee joint s long lever arms (femur and tibia) could have occasioned errors in the reliability. Criterion Validity To examine criterion validity, this study compared the results obtained with the UG and the PG with radiographs. The PG revealed high validity when measuring active knee flexion on subjects with knee restrictions. However, with the knee in the extension position, only moderate results were revealed. The study by Brosseau et al 5 also showed such data, because they obtained better results with large angles of knee flexion compared with smaller ones. Similar results were obtained by using the UG the validity was high in the flexion position, whereas in the extension position it was poor. These findings correlate with other study results. 5,15,16 Even though validity results in the extension position were not conclusive, it is important to note that the PG showed slightly higher correlation (r) values for this position compared with the UG. In a clinical setting, health care practitioners often visually estimate joint ROM instead of using standardized tools like the goniometer to quantify properly measures and progress. 21,22 The comparison of visual estimations with the gold standard used in our study showed high validity with the flexion position and poor validity with the extension position, and that was for both examiners. In general, the data obtained from visual estimations revealed lower r values with the PG or the UG. Therefore, the use of visual estimations is less valid than goniometric measurements. Consequently, in clinical settings, goniometric tools give more accurate measures and, therefore, offer a more precise approach to the evaluation of ROM and the patient s progress. In this study, certain factors could have influenced the results of the criterion validity for the PG, the UG, and the visual estimations. Potential errors could have been introduced by the use of radiographs. These include diminished visibility secondary to darker shadows and lack of experience interpreting radiographs. Variations in the placement of the radiographic beam, sometimes showing more diaphysis of the femur compared with the tibia and vice versa, might have also contributed to the potential errors in calculating the validity. CONCLUSION Goniometric measurements taken on subjects with impaired knee ROM were found to be very reliable when using either the PG or the UG. However, it is recommended that the same therapist take all the measurements when assessing AROM on a pathologic knee. The PG has been found to be as reliable and valid as the UG, especially when assessing active knee flexion compared with active knee extension. The current study also revealed that it is preferable to use goniometry rather than visual estimations when measuring knee AROM, particularly for the measurement of extension. Considering its adequate psychometric properties and reported ease of application, we recommend the PG. However, it is imperative that further validation studies of the PG be conducted on subjects with impairments involving more complex joints (shoulder, ankle). Establishing reliability and validity of different measurement tools is an important part of research, especially considering the increasing need for precise and accurate outcome measures in physiotherapy practice. Acknowledgments: The authors thank Lynn Moore and Marie- Josée Trudel from the Ottawa Hospital, General Site, Department of Radiology, for their dedication to the project. Special thanks to Julie Budd, Simon Bougie, and Shayne O Donoghue, the therapists in-

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