Intratester and Intertester Reliability and Validity of Measures of lnnominate Bone Inclination

Transcription

1 Intratester and Intertester Reliability and Validity of Measures of lnnominate Bone Inclination Richard D. Crowell, MS, PT' Cordon S. Cummings, MA, PT2 /. Randy Walker, PhD, PT3 larry I. Tillman, PhD4 t is estimated that up to 80% of patients with low back pain have no diagnosed pathology for their pain (33). Nonpathological causes of pain include possible biomechanical factors such as disturbed stress patterns at the sacroiliac joint and lumbar spine. One asymmetry that is commonly thought to be associated with disturbed stress patterns is unequal innominate bone inclination in the sagittal plane (7,10,11,16,28), often described as a pelvic asymmetry. Pelvic symmetry is often evaluated as part of the examination for postural deviations and leg length discrepancies (3,8,11,16,28). The credibility of postural assessments has been hampered by the fact that many clinical tests/measures for assessing pelvic asymmetry have been shown to lack precision, or the methods are unreliable (19,29). Given these facts, an instrument and method that yields precise and reliable measures of innominate bone inclination would enhance credibility for physical therapists as they evaluate and treat problems involving pelvic tilt angle or asymmetrical innominate bone inclination. Such a method would yield a determination of pelvic asymmetry by comparing measures of inclination of both innominate bones. Determination of innominate bone inclination in standing is frequently assessed in postural analysis of subjects. Currently, no goniometer for objective assessment of innominate bone inclination in standing is commercially available. The purpose of this study was to determine the intratester and intertester reliability and validity of measures taken with a pelvic inclinometer. The intraclass correlation coefficient (KC) for repeated measures of the pelvic inclinometer fixed to a mechanical model was The intertester reliability of using the hand-held pelvic inclinometer to determine inclination on a mechanical model was ICC = In measures of 20 male subjects by three testers, the K C for intertester reliability was 0.95 and the range of lccs for intratester measures was Measures by the inclinometer had a high degree of reliability compared with the criterion roentgenographic measure, ICC = Measurement of the inclination of both left and right innominate bones of a subject required only 2 minutes, indicating clinical applicability. Key Words: innominate bone, inclinometer, palpation ' Assistant Professor, Department of Physical Therapy, The College of St. Scholastics, 1200 Kenwood Ave., Duluth, MN Associate Professor, Department of Physical Therapy, Ceorgia State University, Atlanta, CA 'Associate Professor, Department of Physical Therapy, University of Tennessee at Chattanooga, Chattanooga, TN Associate Professor, Department of Physical Therapy, University of Tennessee at Chattanooga, Chattanooga, TN Since 1936, clinicians have attempted to measure innominate bone inclination by developing instruments that are sufficiently precise and methods that are sufficiently reliable to meet their need to document clinical theories (6,17,18,20). Precision of instruments to measure innominate bone inclination is important because of the relatively small amount of excursion of the pelvis as a whole and the even smaller movement available between the two innominate bones. Alviso et al reported ranges of total pelvic tilt between 10.9 and 17.1 " (1). Gajdosik et al reported a total range of motion of to " for pelvic tilt (1 5). Precision is critical to measure asymmetrically inclined innominate bones which may differ in position only from 1 to 1 1 " (9.1 8) or a few mm (2.12,14,29,32). This excursion becomes even smaller after the third decade of life (26.30). It is clear, therefore, that clinical measures must achieve very small ranges of variability to detect changes in 88 Volume 20 Number 2 August 1994 JOSPT

2 innominate bone inclination associated with dysfunction or in response to treatment. Radiographic studies are generally accepted as providing the most accurate data on innominate bone inclination, but this method is generally regarded as "expensive and potentially harmful" (1 5). Repeated radiographic studies are not feasible for ongoing clinical assessments of treatment effects. Most visual and palpatory assessment methods, although widely used by physical therapists, are supported by little objective and verifiable data (1 1). Visual assessment of the anterior superior iliac spine (ASIS), posterior superior iliac spine (PSIS), and crest height used in combination were found acceptable to detect qualitative but not quantitative pelvic asymmetry (29). Potter and Rothstein demonstrated that testers agreed on ASIS and PSIS levels only 3.538% of the time (1 9). A system of trigonometric measurement has been introduced to provide a more reliable method for measuring innominate bone inclination. Sanders and Stavrakas (20) and Smidt et al (24) combined palpation, visual observation, and external measuring devices to calculate the degree of innominate bone inclination. Alviso et al investigated intertester reliability of Sanders and Stavraka's method and reported an ICC of 0.95 (I). This finding indicates that the process is quite reliable. The chief limitation of this process is that it is reported to take about 10 minutes to measure one side of the pelvis. To measure both sides and determine pelvis asymmetry would, therefore, require about 20 minutes, which is excessive for many clinical situations. A goniometric device for measuring innominate bone inclination was first introduced in 1936 (1 8). and variations have since been reported (1 7,24,3 1). The original device, called an inclinometer, consisted of holding each end of a cali- per against the ASIS and PSIS and reading the angle of inclination from a gravity goniometer. Although the use of inclinometers for measuring innominate bone inclination has been reported in the literature, neither intertester reliability nor validity for these inclinometers has been reported. Walker et al reported "excellent" intratester reliability of their inclinometer, with an r value of 0.84 (3 1). Although this is considered statistically acceptable, the absence of descriptive statistics makes it difficult to assess the clinical applicability of their method. The purpose of this study was to determine whether a method of measurement including a modified inclinometer would provide valid The range of intratester and intertester measures was 0-10 and 1-2", respectively. and reliable measures of innominate inclination with a clinically acceptable degree of precision. To achieve this, we had to minimize sources of variation in measurement due to differences between subjects and changes in position of the subject between measures. Specifically, we determined the intratester and intertester reliability and concurrent validity for our method of measurement of pelvic inclination. METHOD Subjects The subjects for the reliability phase of the study consisted of 26 male volunteers. All were over the age of 40, with a mean age of 45 years, a mean weight of 78.2 kg, and a mean height of cm. Two subjects reported that they were currently experiencing low back pain but could stand for the required 15 minutes. Each subject read and signed a consent form prior to testing. Instrumentation The pelvic inclinometer is a hand-held instrument designed to measure innominate bone inclination. It consists of two freely moveable arms, two finger braces to allow for concurrent palpation of the ipsilateral ASIS and PSIS of an innominate bone, a spirit level, and an electronic level (SPI Protracto Level, Swiss Precision Instruments, Inc., Los Angeles, CA) (Figure 1). We modified the original inclinometer described by Pitkins and Pheasant (18) in three ways that we felt would help to reduce error. To minimize slipping of the caliper ends on the skin over the bony landmarks, we replaced the metal ends of the inclinometer with finger braces. The investigator placed his fingertips through the braces, allowing palpation of the exact landmark to confirm accurate placement concurrent with the moment of reading the inclination. Secondly, we found that if the inclinometer was allowed to pivot around the fingertips so that the bar with the electronic level was held above or below the finger contact point. an error of ' occurred. To prevent this error, we placed a spirit level on one moving arm so that we could hold that arm and, therefore, the inclinometer level with the finger contact point. Lastly, the accuracy of the gravity goniometer was difficult to establish secondary to small lettering on the output scale, undamped oscillations of the pendulum, and the possibility of parallax reading. Therefore, we substituted an electronic level, which included a liquid crystal display and a hold button with a temporarily attached flap to blind the tester to the output (Fig- JOSPT * Volume 20 * Number 2 * August 1994

3 FIGURE 1. The pelvic inclinometer, with attached protracto level and spirit level, has adjustable arms and finger rings for palpation. A flap was attached to blind all testers from viewing the degree of inclination. FIGURE 2. The pelvic inclinometer adjusted over the anterior superlor 111ac spine and posterior superior iliac spine (ASlSIPSlS). The recorder depresses the hold button for determining innominate bone inclination. ure 2). To measure innominate inclination, the investigator placed his fingertips, stabilized in the finger braces, over the ASIS and PSIS, leveled the inclinometer in the frontal plane, and read the degree of inclination from the liquid crystal display of the electronic level. The electronic level was chosen for the precision reported by the manufacturer. The manufacturer's reported specifications for the level are: measurement range-f 45" ; accuracy-0-lo0, +.l; 10-45". 1.5% of the reading. Procedure The study was conducted in three phases. Phase I consisted of two steps. The repeatability of measures was established with the inclinometer clamped to an incline board that was randomly positioned at 10 different angles between 0 and 45". Secondly, the reliability of measures with the hand-held inclinometer was established with various inclinations on an incline board. In phase 11, we determined the reliability of measuring innominate bone inclination in standing subjects, ie., pelvic tilt angles. In phase 111, we established the validity of measurements using the pelvic inclinometer by comparing radiographic data with data obtained with the inclinometer. Phase I An incline board was designed to provide various fixed angles that could be measured with the pelvic inclinometer. The pelvic inclinometer was clamped to the incline board, and the incline board was set in 10 randomly assigned numbered positions from 0-45 " (Figure 3). The tester placed the incline board and attached pelvic inclinometer in a numbered position, the electronic level was turned on, and the hold button was depressed. The angle was recorded three times for each of the 10 different positions. Reliability of measures with the hand-held inclinometer was established on the incline board with 5- mm wood buttons placed 15 mm apart to simulate ASIS and PSIS landmarks (Figure 4). Three physical therapists with 5 or more years of experience in outpatient orthopaedic practice randomly tested different positions on the incline board. A recording assistant was used for blind data collection. Upon completion of the 10 readings, the cycle was immediately repeated twice using the same positions, yielding a total of three measurements for each position. The next two testers followed the above procedure, resulting in a total of 90 selected positions on the incline board. Phase II Data collection on the subjects was scheduled for six sessions over a 4-week period. The order in which testers measured subjects was randomized to control for subject fatigue during repeated testing and to control any effect of subject familiarity with the instructions, inclinometer placement, and palpation. A printed instruction sheet was placed so that each tester was able to repeat the same instructions and procedures for each subject. Testers were not allowed to view the recorded data until all data from all subjects had been collected. A recording assistant read and recorded the innominate inclination from the pelvic inclinometer and noted subjects who were deemed unacceptable by any of the testers so that additional subjects could be scheduled. Six subjects were rejected from the Volume 20 Number 2 August 1994 JOSPT

4 FIGURE 3. The pelvic inclinometer fixed to the incline board. i.- - FIGURE 4. The pelvic inclinometer used to determine inclinations of a wood model. study because one or more of the testers reported difficulty with palpating the bony landmarks. To begin data collection for measuring innominate bone inclination, the subject stepped onto a level platform, placing his bare feet on marked footprints that were 6 inches apart (Figure 5). Placement of the footprints was adjusted until the subject felt that he was standing in a relaxed posture and that his thighs were gently touching the thigh pad. The subject was asked to stand comfortably on the platform with his thighs touching the stabilizing bar while the upper part of his pelvis was exposed for the purpose of palpating the ASIS and PSIS. The tester located the most prominent aspect of the ASIS and PSIS and placed a 10- mm adhesive dot over each bony landmark. The dots were used to allow the tester to quickly approximate his finger placement prior to palpation of the landmarks for repeated measurements. The subject was then asked to comfortably straighten his knees and make certain that his anterior thighs were in contact with the stabilizing pad. After assuming this position, the subject was instructed to maintain visual contact with his own eyes in a mirror positioned at his eye level during the data collection to minimize postural sway (Figure 5). The tester manipulated the inclinometer in the same manner as previously described. The assistant read the output of the electronic level, and the tester removed his fingers from the subject to rest for 15 seconds. The short time period between repeated measures was chosen in a further attempt to reduce the chance of the patient changing pelvic or innominate positions between measures. This process was repeated to achieve a total of three readings from each subject. Once the readings were recorded, the subject was instructed to relax but not to move his feet. The adhesive dots were removed, the first tester left the testing area, and the second and third tester entered the area in sequence to repeat the process described above. Data collection by all three testers for each subject required approximately 12 minutes. Phase III We investigated the validity of measurements from the pelvic inclinometer by comparing measures determined by radiographic studies with those obtained with the pelvic inclinometer. The subjects for the validity phase of the study were five healthy male volunteers from the 20 subjects described above. Only one tester was involved with recording the readings from the pelvic inclinometer. Data were collected approximately 1 month after phase I1 of the study, and all subjects were tested on the same day. Each session required approximately 10 minutes. The data collection procedure using the pelvic inclinometer was implemented exactly as described for testing the subjects in phase 11. Immediately following the measurements with the pelvic inclinometer, 5-mm lead markers were placed over the adhesive dots on the ASIS and PSIS. The lead markers were used JOSPT Volume 20 Number 2 August 1994

5 ers were fixed effects; that is, trained in using this device and not representative of individuals who are unfamiliar with the pelvic inclinometer (22). The ICC (I, 1) was calculated to determine the concurrent validity of the inclinometer measures vs. roentgenogram measures of subjects' innominate bone inclination. In addition, the means and standard deviations for all of the measurements were computed, and agreement among testers was determined (5.22). RESULTS FIGURE 5. The testing stand provided a level surface, consistent foot placement, a mirror, and a thigh pad for reducing postural sway. to identify the bony landmarks as palpated with the pelvic inclinometer. Each subject maintained the test position while an X-ray technician centered the X-ray beam over the superior surface of the greater trochanter and took a lateral roentgenogram with a Semens Poly Phase 50 X-ray unit (Semens Inc., Insbruck, NJ). The roentgenograms were immediately developed and placed on a view box to verify that there was adequate film resolution. Innominate bone inclination was determined on the film by extending a line between the center of the two lead marker images over the ASIS and PSIS to intersect with a horizontal reference line imposed on the film from a lead marker attached to the test platform (Figure 6). The angle of inclination was determined and recorded by another tester using a standard goniometer. Data Analysis We used the intraclass correlation coefficients (ICC 3,l) to determine the reliability of measures for FIGURE 6. Drawing from lateral pelvic roentgenogram with A) a line drawn parallel to the test platform and intersected with 8) a line projected between the center of the lead marker images located over the anterior superior iliac spine and the posterior superior iliac spine (ASIS/PSIS). A standard goniometer was used to measure the degree of inclination. the inclinometer fixed to the incline board, the intratester and intertester reliability of measures of the simulated pelvis, and subjects' innominate bone inclination (5.22). The ICC (3,l) model was used to determine intratester and intertester reliability because it was assumed that the test- Concurrent palpation of the landmarks prevented error due to skin slippage away from the landmarks at the moment of reading the inclination. The ICC of the three repeated measures with the inclinometer fixed to the incline board was The ICC intertester reliability coefficients for the three testers measuring the wood buttons on the model was also The range of intratester and intertester measures was 0-1 " and 1-2", respectively, in all 10 of the angles measured. The ICC (3,l) for intratester reliability for each of the three testers measuring innominate bone inclination in 20 subjects ranged from and the intertester coefficient was The range of intratester measures was 0-2" in all but one trial when it was 3". The mean, standard deviation, and ICC values for the wood model and subjects' innominate bone inclination are given in Tables 1 and 2, respectively. Intertester measures on subjects varied 2-5". with the 5" difference occurring four times out of 20 (Table 3). The validity of the pelvic inclinometer for measuring innominate bone inclination in humans was determined by comparing the values obtained with the pelvic inclinometer and values obtained from the criterion method (roentgenogram measures) (4,lS). The ICC (I, 1 ) of the pelvic inclinometer for measuring innominate bone inclination in humans compared with the criterion was 0.93 (Table 4). Table 3 shows the range of Volume 20 Number 2 August 1994 JOSPT

6 Trials - X SD ICC(3,l) Tester A 8.5' 8.8' 8.3" 3.3" 2.9' 2.8".92 Tester B 8.8" 8.8" 8.6" 3.9" 4.3" 4.3".96 Tester C 8.9" 9.2" 9.3" 2.9' 3.3" 3.1'.95 TABLE 1. Mean, standard deviation, and intraclass correlation coefficient of intratester reliability estimates for repeated measures on human subjects-inclinometer handheld (Figure 5). Testers TT SD ICC(3,l) TABLE 2. Mean, standard deviation, and intraclass correlation coefficient of intertester reliability estimates for repeated measures on human subjects-inclinometer hand-held (Figure 5). Subiect Tester Trials (Degrees) Range in Degrees Inhatester Intertester 1 RC BH MM MM B H RC Table continued on next pane TABLE 3. Raw data for three testers determining three measures on 20 subjects' innominate bone inclination. JOSPT Volume 20 Number 2 August 1994

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8 Inclinometer 12.4" 4.5'.93 X-ray 11.0' 4.4" TABLE 4. Mean, standard deviation, and intraclass correlation coefficient of criterion reliability estimate for comparing hand-held inclinometer to X-ray (Figure 6). measures, including the method of palpation of the landmarks, the use of concurrent palpation, the use of the electronic inclinometer, and the control for changes in innominate inclination between measures from postural sway and lower extremity movement. The Inclinometer Potter and Rothstein reported poor intertester agreement for palpation of PSIS and ASIS in standing (19). In our study, the use of wood buttons on the incline board allowed for precise location of the measurement landmarks. With this model, we knew that the positions were precisely reproduced and that all variance in measures could be ascribed to error in placement or in reading the inclinometer. The high degree of reliability found with this model indicates that these two sources of error are minimal when the target is readily identified. The liquid crystal readout provided much less error than previous attempts to read a traditional gravity goniometer. The hold button on the instrument is very helpful since it allows time to record the number and to check back with the instrument to make sure that no numbers are transposed or misread. The lack of variability of measures in phase I suggests that a major source of error in clinical measures is inaccurate identification of precise landmarks. Method of Palpation Identification of the PSIS and the ASIS involves identification of the most prominent aspects of the iliac crests. In our opinion, this is best determined through palpation involving several fingers at once, yielding relative positions of the target. When palpation is performed with one finger alone, as done with the inclinometer, the tester cannot determine whether he is on the most prominent aspect of the bony landmark. Therefore, in our clinical procedure, we always mark the general landmark with a skin marker after multiple finger palpation prior to the use of the inclinometer. Our system of first identifying the general landmark with three-finger palpation and, subsequently, identifying the exact highest point with palpation concurrent with reading of the inclinometer is associated with excellent intertester precision and reliability. Concurrent palpation of the landmarks prevented error due to skin slippage away from the landmarks at the moment of reading the inclination. Instability of Target Vs. Inconsistent Measures In a pilot study, we found variations in measures within subjects when they were allowed to walk about a room and return to the same test position for retesting. Changes in position of the pelvis between measures as a source of variance a p pears not to have been addressed in previous studies, making it impossible to determine how much of the variation in measures reflected instability of innominate position and how much was caused by imprecision or inaccuracy in the measurement procedure. One of our major concerns was to control for changes of innominate bone position of the subject between measures and testers. To facilitate this, we controlled for postural sway and lower extremity movement. We chose to have each tester wait only 15 seconds between measures and to allow the subject to relax on the test platform but not to move his feet between testers. Natural standing posture was encouraged by having the subject look into a mirror and gaze into his own eyes (23). In addition, we used thin paper dots, which are easily palpated through, to help the investigator reposition his contact when the inclinometer was used for data collection. We believe that the final position chosen was determined by concurrent palpation of a specific point on the landmark rather than by the initial finger placement or paper dot. While analysis of our data indicates that interrater reliability is statistically significant, it is not clinically strong enough to encourage assessment of patient outcomes by multiple testers. The total amount of movement at each sacroiliac joint has been reported to range between 1 and 1 1 " (2 1.25,27). Other authors reported sacroiliac joint mobility in terms of a few mm of movement (32). Walker (30) concluded from her histological study of the sacroiliac joint that "the potential for a p preciable motion in the sacroiliac joint appears severely limited after the third decade of life." Changes of 3 or 4" in innominate bone inclination with such treatments as manipulations, heel lifts, and soft tissue techniques may be beyond the realm of objective measurement devices such as the inclinometer and the method proposed by Sanders and Stavrakas (20). In this study, agreement between the three testers was within 3" in 60% of the measurements and within 4" in 85% of the measurements. The range of measures was between 1 and 5". A range of 5" between three testers on any given measure is still not sensitive enough to identify small changes in innominate bone inclination that are reported to occur with treatment. Conversely, the range of 1 and 2" found within testers (Table 3) indicates that the instrument and measurement method is sensitive enough to detect small changes attributed to treatment intervention. JOSPT Volume 20 Number 2 August 1994

9 Limitations The pelvic inclinometer was tested only for male subjects' innominate bone inclination in the sagittal plane in singleday trials. Intratester and intertester reliability of the pelvic inclinometer appears to be partly dependent upon tester familiarity with the goniometer, strict standardization of testing procedures, and control of postural sway. Our pilot study indicated that small variations in innominate bone inclination may normally occur when subjects move from a standardized test position and return to the test position. However, individuals with musculoskeletal dysfunction may be obese or have indistinct osteal landmarks. These limitations will likely result in less reliable measurements with the pelvic inclinometer. CLINICAL IMPLICATIONS The results of this study clearly indicate that an experienced physical therapist can make reliable measurements of innominate bone inclination with the inclinometer. The pelvic inclinometer offers promise as a useful measurement device for the clinician who treats postural problems related to pelvic tilt angle and pelvic asymmetry. The precision of the instrument and procedure will allow for normative data collection. Clinicians must have knowledge of how much normal variation in measures may occur from day to day, what percent of asymmetry can be expected in both the normal and patient populations, and whether measured changes are significant enough to be attributed to treatment intervention. Our study suggests that clinicians can learn to use the device with a few hours of practice and can achieve sufficient precision in measures to detect the small changes that we expect in pelvic position or innominate inclination. Testers familiar with the pelvic inclinometer were able to determine the inclination of both left and right innominate bones of a subject in less than 2 minutes. It is proposed that this type of inclinometer and procedure is applicable to the patient pop ulation with low back pain. If a client has palpable landmarks and can stand for 2-4 minutes, then an objective assessment of his or her innominate bone inclination can be determined. Standardization of objectively assessing pelvic tilt, ie., innominate bone inclination, should be accepted practice and be an integral part of goniometric measurements of the musculoskeletal system. SUMMARY Objective and reliable measures of innominate bone inclination can be achieved when concurrent palpation, digital readout instrumentation, and detailed measurement procedures are utilized with a pelvic inclinometer. It appears that 1-2" of variability in measures can be expected within testers and 3-5" with multiple testers. The design of the study does not allow for positive identification of factors leading to the high reliability. However, several aspects of our method and instrument design can be identified. Variability may occur due to difficulty in palpating specific points on osteal landmarks and movement of the subject during testing. The high intratester and intertester reliability is attributed to concurrent palpation, control of postural sway, instrument design, and specific palpation and testing methodology. The time efficiency of this method makes it feasible for collection of baseline data and quantification of treatment outcome measures. Utilization of this type of instrument and measurement procedure will allow collection of normative data on the incidence of asymmetrically inclined innominate bones in the normal and patient pop ulations. Compared with previous methods, it has been shown to have significantly less variability, especially for intratester measures. Clinicians should adapt strict measurement procedures to enhance confidence and accuracy. This study implies that when small changes < 3" are detected, it cannot be attributed to treatment intervention alone. Further research is needed to identify sources of variability and day-to-day repeatability and determine reliability in the low back pain population. JOSPT REFERENCES Alviso Dl, Dong CT, Lentell CL: Intertester reliability for measuring pelvic tilt in standing. Phys Ther 68: , 1988 Cibulka MT, Delitto A, Koldehoff RM: Changes in innominate tilt after manipulation of the sacroiliac joint in patients with low back pain. An experimental study. Phys Ther 68: , 1988 Cibulka MT, Koldehoff RM: Leg length disparity and its effect on sacroiliac joint dysfunction. Clin Management Phys Ther 6(5):10-11, 1986 Clayson FC, Newman IM, Debevec DF, Anger RW, Skowlund HV, Kottke F/: Evaluation of mobility of hip and lumbar vertebrae of normal young women. Arch Phys Med Rehabil43: 1-8, 1962 Currier DP: Elements of Research in Physical Therapy, pp Baltimore: Williams & Wilkins, 1979 Day lw, Smidt CL, Lehamann T: Effect of pelvic tilt on standing posture. Phys Ther 64: , 1984 Denslow IS, Chace /A: Mechanical stresses in the human lumbar spine and pelvis. / Am Osteopath Assoc 61: , 1962 DonTigny RL: Anterior dysfunction of the sacroiliac joint as a major factor in the etiology of idiopathic low back pain. Phys Ther 70: , 1990 DonTigny RL: Function and pathomechanics of the sacroiliac joint: A review. Phys Ther 65:35-44, 1985 DonTigny RL: Measuring PSIS movement. Clin Management 10:43-44, 1990 DonTigny RL: Dysfunction of the sacroiliac joint and its treatment. / Orthop Sports Phys Ther 1:23-35, 1979 Egund N, Olsson TH, Schmid H, Selvik C: Movements in the sacroiliac joints demonstrated with roentgen sterophotogrammetry. Acta Radio1 53: , 1978 Volume 20 Number 2 August 1994 JOSPT

10 13. Flint MM: Lumbar posture: A study of roentgenographic measurements and the influence of flexibility and strength. Res Q Exerc Sport 34: , Frigerio NA, Stowe RR, Howe /W: Movement of the sacroiliac joint. Clin Orthop 1 OO: , Cajdosik R, Simpson R, Smith R, DonTigny RL: Pelvic tilt intratester reliability of measuring the standing position and range of motion. Phys Ther 65: , Grieve CP: The sacro-iliac joint. Physiother 62: , Loebl WY: Measurement of spinal postures and range of spinal movements. Ann Phys Med 9: , Pitkins HC, Pheasant HC: Sacrarthrogenetic telalgia. 11. A study of sacral mobility. 1 Bone loint Surg 28A: , Potter NA, Rothstein /M: Intertester reliability for selected clinical tests of the sacroiliac joint. Phys Ther 65: , Sanders C, Stavrakas P: A technique for measuring pelvic tilt. Phys Ther 6 1 :49-50, Sashin D: A critical analysis of the anatomy and the pathological changes of the SI joints. / Bone loint Surg 1 2A: , Shrout PE, Fleiss /L: lntraclass correlations: Using rater reliability. Psycho1 Bull 86: , Siersbaek-Nielsen 5, Solow 6: Intraand inter-examiner variability in head posture recorded by dental auxiliaries. Am / Orthod Dentofacial Orthop 82:50-57, Smidt CL, Day /W, Cerleman DC: Iowa anatomical position system: A method of assessing posture. Eur Appl Physiol52: , Solen KA: The sacroiliac joint in light of anatomical roentgenological and clinical studies. Acta Orthop Scand Suppl22: 1-127, Stewart TD: Pathologic changes in aging sacroiliac joint: A study of dissecting room skeletons. Clin Orthop 183: , Sturresson B, Selvik C, Uden A: Movements of the sacroiliac joints: A roent- genstereophotogrammetric analysis. Spine 14: , Subotnick 51: Limb length discrepancies of the lower extremity: The short leg syndrome. / Orthop Sports Phys Ther 3: , US Department of Health and Human Services: NlOSH Low Back Atlas of Standardized TestslMeasures, Springfield, VA: National Technical Information Services, Walker /M: Age-related differences in the human sacroiliac joint: A histological study; implications for therapy. 1 Orthop Sports Phys Ther 7: , I Walker ML, Rothstein /M, Finucane SD, Lamb RL: Relationship between lumbar lordosis, pelvic tilt, and abdominal muscle performance. Phys Ther 67: , Weisl H: The movements of the 511. Acta Anat 23:80-9 1, White AA, Cordon SL: Synopsis: Workshop on idiopathic low back pain. Spine 7: , 1982 JOSPT Volume 20 Number 2 August 1994