OBJECTIVE AND ACCURATE measurements of lumbar

Transcription

1 99 Strapped Versus Unstrapped Technique of the Prone Press-Up for Measurement of Lumbar Extension Using a Tape Measure: Differences in Magnitude and Reliability of Measurements William D. Bandy, PhD, PT, SCS, ATC, Nancy B. Reese, PhD, PT ABSTRACT. Bandy WD, Reese NB. Strapped versus unstrapped technique of the prone press-up for measurement of lumbar extension using a tape measure: differences in magnitude and reliability of measurements. Arch Phys Med Rehabil 2004;85: Objectives: To determine (1) the reliability of the prone press-up to measure lumbar extension using a strap and not using a strap to control pelvic movement in experienced clinicians and students and (2) if a difference exists between the magnitude of lumbar extension range of motion between the strapped and unstrapped condition. Design: Prospective study. Setting: Academic laboratory. Participants: Convenience sample of 63 unimpaired volunteers (mean age standard deviation, y). Interventions: Not applicable. Main Outcome Measures: Lumbar extension was measured in the prone position by using a tape measure to measure the perpendicular distance of the sternal notch to the support surface while using a strap and not using a strap to control pelvic movement. All measurements were performed independently by 2 groups of examiners (1 experienced group, 1 student group) and repeated to determine intrarater and interrater reliabilities. Results: Intrarater and interrater reliability were good or excellent for all methods and all measurement group comparisons (intraclass correlation coefficient range,.82.91). Additionally, the amount of lumbar extension, as measured by the prone press-up, during the strapped condition was significantly greater than with the unstrapped condition. Conclusion: Use of a tape measure while the subject performs a prone press-up appears to be a reliable method for the measurement of lumbar extension. This technique is reliable whether the examiner is experienced or inexperienced and whether or not the subject has the pelvis secured with a strap. Key Words: Back; Range of motion; Rehabilitation; Reliability and validity; Spine by the American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation OBJECTIVE AND ACCURATE measurements of lumbar spine mobility are fundamental to the evaluation of the patient with potential spinal dysfunction. 1 This examination of From the Department of Physical Therapy, University of Central Arkansas, Conway, AR; and the Department of Anatomy and Neurobiology, University of Arkansas for Medical Sciences, Little Rock, AR. No commercial party having a direct financial interest in the results of the research supporting this article has or will confer a benefit on the author(s) or on any organization with which the author(s) is/are associated. Correspondence to William D. Bandy, PhD, PT, SCS, ATC, Dept of Physical Therapy, PTC Ste 300, University of Central Arkansas, 201 S Donaghey, Conway, AR , billb@mail.uca.edu /04/ $30.00/0 doi: /s (03) range of motion (ROM) of the lumbar spine is important, not only for assessment of spinal function, but also for selection of appropriate intervention and monitoring of the patient s response to treatment. 1-3 Although radiographs may be considered the criterion standard for the examination of lumbar mobility, frequent measurement over time is hazardous to the patient. Therefore, clinicians have attempted to quantify ROM in the lumbar spine with a variety of techniques and instruments such as the tape measure, 4-6 goniometer, 7,8 inclinometer, 8-12 and a back range of motion (BROM) device. 13,14 Use of these nonradiologic tools is quicker, less costly, and less hazardous than repeated radiographs. Although these nonradiologic tools are frequently used in the clinical setting to measure flexion, extension, lateral flexion, and rotation of the lumbar spine, historically, measurement of lumbar flexion ROM has received the most attention in the literature. Not until the late 1980s and early 1990s has information been consistently provided on the measurement of lumbar extension ROM. The majority of these early studies quantified lumbar extension in the standing position. Problems that were reported in having subjects perform lumbar extension while standing included difficulty in controlling motion at the pelvis, hips, and knees; inability of the patient to maintain the extended position long enough for measurements to be taken; poor balance; and a fear of falling backward that prevented the subject from obtaining full extension. Additionally, these measurement techniques in standing require palpation of bony landmarks that are somewhat difficult to locate (ie, lumbosacral junction), especially in the obese patient. As early as 1968, Troup et al 15 suggested measuring lumbar extension in the prone position using a protractor attached to 24-in (61-cm) arms, which were maintained on an adjustable, upright bracket. Troup did not provide a detailed description of the technique and did not describe methods of controlling movement of the pelvis. Given the lack of literature reporting on the use of this procedure, this technique did not appear to gain popularity as a measurement tool. Later, Clarkson and Gilewich 16 provided a detailed description of the prone press-up and added a stabilization belt to control pelvic motion (fig 1). Additionally, they suggested measuring the perpendicular distance from the sternal notch to the support surface. This technique had an advantage over the standing measurement of lumbar extension because it eliminated pelvic, hip, and knee movement; it eliminated balance problems and fear of falling; and it provided a bony landmark that was easy to palpate. However, no information was provided as to the reliability of the measurement technique. Alternatively, Stokes et al 17 indicated that the prone press-up was an appropriate method for the examination of lumbar extension ROM but suggested that the technique could be appropriately performed without a stabilization strap (fig 2). Stokes suggested that the movement of the pelvis could be controlled by the patient, confirmed by verbal cues provided by

2 100 MEASUREMENT OF LUMBAR EXTENSION, Bandy Equipment A standard metal tape measure, with a centimeter scale on 1 side and no measurement scale on the other side, was used for all measurements. During data collection, the examiner placing the measurement device was not allowed to see the centimeter side of the tape measure. Fig 1. Prone press-up with a stabilization belt to control pelvic motion. the clinician. Again, no data on the reliability of this suggestion was provided. Given the suggestion that the prone press-up may be an easier and more efficient method for measuring lumbar extension ROM, more information is needed as to the appropriate methods for performing this technique, as well as its accuracy. Therefore, there were 3 primary purposes of this study. The first was to determine the intrarater reliability (accuracy of the same examiner) of the prone press-up while using or not using a strap to control pelvic movement. The second was to determine the interrater reliability (accuracy of 2 examiners) of the measurement technique, strapped and unstrapped. The third was to determine if the prone press-up is, as suggested, an easy technique by comparing the reliability obtained by experienced clinicians with that of students with minimal training. If appropriate reliability was established, then another purpose of the investigation was to determine if a difference existed in the magnitude of lumbar extension ROM between the strapped and unstrapped conditions. METHODS Procedure Data were collected during 2 sessions in which measurements were taken by both groups. Each subject was randomly assigned to begin the first measurement session with group 1 or group 2. Once the participants were assigned to the initial measurement group of the initial measurement session, their lumbar extension was measured using the tape measure method for the prone press-up described by Reese and Bandy. 18 The subjects were positioned prone with hands placed directly under their shoulders. Landmarks used during measurement were the sternal notch and perpendicular to, and in contact with, the support surface. Before data collection for the initial measurement session, each subject performed 5 prone press-ups as a warm-up. Each session consisted of measuring the prone press-up with and without the pelvis stabilized with a strap. Random procedures were used to determine the order of the type of prone press-up (strapped, unstrapped) within each group and during each measurement session. Whether the subject was strapped or unstrapped, the procedure for performing the prone press-up was the same. Subjects were instructed to extend their elbows and raise their trunk as high as possible while muscles of the lumbar spine remained relaxed. Before performing the technique using the stabilization strap, each subject was positioned prone and strapped tightly, at the level of the anterior superior iliac spines (ASIS) of the pelvis, to the support surface with a mobilization belt. After a subject performed a press-up against the stabilization belt, examiner 1 aligned the tape measure (with the blank side of the tape measure facing the examiner) and measured the perpendicular distance between the sternal notch and the support surface (fig 3). Examiner 2 palpated the paraspinal muscles to ensure that these muscles remained relaxed. Participants Sixty-three subjects (43 women, 20 men) with a mean age standard deviation (SD) of years (range, 21 38y) were recruited for this study. All subjects underwent an initial screening to ensure that they were pain free and did not have musculoskeletal or neurologic dysfunction of the spine or lower extremities at the time of data collection. Subjects were told the purpose of the study and the procedures to be used and signed an institutionally approved informed consent form before data collection. Examiners Two groups of 2 examiners participated in the measurement of the prone press-up. Group 1 (experienced) consisted of an examiner with 20 years of experience in measuring joint ROM, a second examiner with 20 years of experience in orthopedic physical therapy, and a third person who recorded data. Group 2 (inexperienced) consisted of 3 graduate students in physical therapy who were trained for 1 hour in the measurement procedure used in this study. Fig 2. Prone press-up performed without stabilization strap. Note the examiner palpating to ensure that the bilateral ASIS remained against the support surface.

3 MEASUREMENT OF LUMBAR EXTENSION, Bandy 101 Table 1: Measurements (cm) on Day 1 and Day 2 for Strapped and Unstrapped Prone Press-Up ROM in Experienced and Inexperienced Groups Fig 3. To measure the amount of lumbar extension, the examiner then measured the perpendicular distance between the sternal notch and the support surface. Note that the examiner who is placing the tape measure is blinded to the actual number measured and recorded. To measure the amount of lumbar extension without the stabilization strap, the subject was instructed to maintain the pelvis against the support surface as the press-up was performed. Examiner 1 then measured the perpendicular distance between the sternal notch and the support surface. Examiner 2 palpated to ensure that the bilateral ASIS remained against the support surface and to ensure relaxation of lumbar paraspinal muscles. Once the subject was in the full press-up position (with or without the strap), examiner 1 maintained the alignment of the tape measure, while examiner 2 read from the centimeter scale the distance between the sternal notch and the support surface and passed this information on to examiner 3, the recorder. Examiner 1 did not see the tape measure distance or hear the information that was passed from examiner 2 to examiner 3. Each measurement (strapped, unstrapped) was repeated twice during the initial measurement session in both groups. An average of the 2 measurements was used for later analysis. One day later, both groups used the same procedures to measure strapped and unstrapped prone press-ups again. The researchers did not have information about the measurements collected on the first day when measurements were taken on the second day. Data Analysis Means and SDs were calculated for all of the measurements. Intrarater reliability of the measurements was assessed by using 4 separate intraclass correlation coefficients (ICC 3,2 ): (1) group 1: strapped day 1 versus strapped day 2, (2) group 1: unstrapped day 1 versus unstrapped day 2, (3) group 2: strapped day 1 versus strapped day 2, and (4) group 2: unstrapped day 1 versus unstrapped day 2. Additionally, the ICC 2,2 was used to examine interrater reliability between group 1 and group 2 for the strapped and unstrapped conditions. Data collected during the first measurement day by the experienced and inexperienced groups were used for the comparison. Finally, a dependent t test was used to determine whether a significant difference existed between the ROM of lumbar Mean SD Range Group 1 (experienced) Strapped Day Day Unstrapped Day Day Group 2 (not experienced) Strapped Day Day Unstrapped Day Day extension performed while strapped versus unstrapped. The level of significance was accepted at P less than.05. RESULTS Descriptive statistics for all measurements for both the strapped and unstrapped techniques are presented in table 1. The ICC values calculated for the intrarater reliability of the repeated measurement for each technique for each group are presented in table 2. Interrater reliability comparing the first measurement between the experienced and inexperienced groups for strapped was.87 and for unstrapped was.85. Follow-up analysis of variance (ANOVA) found no significant differences between measurements of either the strapped or unstrapped prone press-up for any condition (including intrarater and interrater calculations). Results of the dependent t test indicated that the amount of prone press-up ROM measured by group 1 while strapped (mean, 32.36cm) was significantly greater than while unstrapped (mean, 28.38cm). The calculated t value was 6.05, indicating a probability of P equal to.001. The actual difference between strapped and unstrapped was 3.98cm. DISCUSSION This study is the first to quantify the measurement of lumbar extension using the prone press-up. Several researchers have suggested that intratester reliability in a test-retest design needs to be above.80 to be considered acceptable. More recently, Youdas et al 22 suggested the following scheme for defining reliability based on the ICC:.90 to.99 is high reli- Table 2: ICC Values Calculated for the Intrarater Reliability of the Repeated Measurement Across Day 1 and Day 2 for Each Technique for Each Group Group ICC Experienced Strapped.91 Unstrapped.90 Inexperienced Strapped.86 Unstrapped.82

4 102 MEASUREMENT OF LUMBAR EXTENSION, Bandy ability,.80 to.89 is good reliability,.70 to.79 is fair reliability, and.69 and below is poor reliability. Finally, Portney and Watkins 23(p565) write, As a general guideline, we suggest that values above.75 are indicative of good reliability, and those below.75 poor to moderate reliability. For many clinical measurements, reliability should exceed.90 to ensure reasonable validity. These are only guidelines, however, and we urge our readers not to use these as absolute standards. Judgments must be made within the context of each individual study. In our clinical judgments, the correlation coefficients for intrarater and interrater reliability achieved in this study (table 2), as well as the fact that the ANOVA showed no significant difference between the measurements, whether strapped or unstrapped, or the experience of the tester, indicate that acceptable reliability was achieved. The intrarater reliability reported in the study compares well with the measurements of lumbar extension in standing that have been reported in the literature, and the interreliability is better than in most previously reported investigations, irrespective of the measurement device used. Intrarater reliability of more than.90 for the experienced testers and more than.82 for the inexperienced testers is comparable to intrarater reliability for measurement of lumbar extension using a tape measure in standing reported by Frost et al 5 (.78), Beattie et al 4 (.90,.95; 2 testers), and Williams et al 6 (.69.91; multiple testers). The interrater reliability reported in this study of.87 for strapped and.85 for unstrapped is higher than the interrater reliability reported by Frost 5 (.79) but lower than that reported by Beattie 4 (.94). Only 2 studies have examined the reliability of the goniometer in measuring lumbar extension in standing, with Nitschke et al 8 reporting intrarater reliability of.81 and interrater reliability of.63 and Burdett et al 7 reporting interrater reliability of.76. Again, the results of our study indicate comparable intrarater reliability and higher interrater reliability than has been reported previously in relation to measurement of lumbar extension with a goniometer. The most extensive research into the measurement of lumbar extension has been done using an inclinometer with the subject standing. The intrarater reliability reported was.28 to.66, 6.71, 8.79, 11 and Interrater reliability ranged from.35 to ,12 Finally, the correlations calculated in this study for intrarater reliability were higher than those calculated using the BROM to measure lumbar extension in standing, as has been reported by Breum et al 13 (.63) and Madson et al 14 (.78). Additionally, the interrater reliability was higher than the correlation of.35 that was reported by Breum. 13 Although appropriate reliability was reported by both the experienced and inexperienced groups, slightly higher reliability was reported by the experienced group (table 2). This finding is consistent with one of the first major studies on the reliability of measurement of joint ROM performed by Hellebrandt et al 24 in Examining the reliability of the goniometer to measure a variety of upper-extremity motions, Hellebrandt reported that a highly skilled tester was more reliable than an average tester. Specific to measurement of the spine, only Chiarello and Savidge 9 actually attempted to compare measurement between different levels of experience. They compared the measurements obtained by testers with 1, 10, and 12 years of clinical experience and reported that the least trained tester was different from the trained therapist but that the difference was not clinically relevant. Although the experienced group had higher reliability than the inexperienced group, it should be emphasized that both groups achieved appropriate intrarater reliability. Additionally, the interrater reliability of greater than.85 between groups suggests that the prone press-up technique for the measurement of lumbar extension yields accurate results and in addition, is easy to use, regardless of experience. This study is the first to compare the amount of lumbar extension during a prone press-up in a strapped and unstrapped condition. That more lumbar extension was achieved during the strapped condition was expected. During the strapped press-up, subjects were able to concentrate more on achieving the greatest possible ROM and fully extend the spine by pushing with the arms. During the unstrapped press-up, subjects had the additional concern of maintaining the pelvis against the support surface and, therefore, were not able to attain full range of lumbar extension. However, given that the accuracy of the measurement of lumbar extension was not affected by performing the press-up strapped or unstrapped (as indicated by similar reliability correlations reported for each technique [table 2]), both the strapped and unstrapped pressups appear to be appropriate for use in the clinic. However, given that a significant difference was found between the amount of ROM between the strapped and unstrapped prone press-ups, for optimal accuracy, the 2 techniques should not be used interchangeably. In other words, when measuring ROM of lumbar extension using the prone press-up, clinicians should choose either the strapped or the unstrapped technique and then use that technique for repeated measurements. CONCLUSION Use of a tape measure while the subject performs a prone press-up appears to be a reliable method with which to measure lumbar extension. This technique is reliable whether the examiner is experienced or inexperienced and whether or not the subject s pelvis is secured with a strap. References 1. Dillard J, Trafimow J, Andersson GB, Cronin K. Motion of the lumbar spine. Reliability of two measurement techniques. Spine 1989;16: Gill K, Krag MH, Johnson GB, Haugh LD, Pope MH. Repeatability of four clinical methods for assessment of lumbar spinal motion. Spine 1988;13: Mayer TG, Kondraske G, Beals SB, Gatchel RJ. Spinal range of motion. Spine 1997;22: Beattie P, Rothstein JM, Lamb RL. Reliability of the attraction method for measuring lumbar spine backward bending. Phys Ther 1987;67: Frost M, Stuckey S, Smalley LA, Dorman G. Reliability of measuring trunk motions in centimeters. Phys Ther 1982;62: Williams R, Binkley J, Bloch R, Goldsmith CH, Minuk T. Reliability of the modified-modified Schober and double inclinometer methods for measuring lumbar flexion and extension. Phys Ther 1993;73: Burdett RG, Brown KE, Fall MP. Reliability and validity of four instruments for measuring lumbar spine and pelvic positions. Phys Ther 1986;66: Nitschke J, Nattrass C, Disler P. Reliability of the American Medical Association guides model for measuring spinal range of motion. Its implication for whole-person impairment rating. Spine 1999;24: Chiarello CM, Savidge R. Interrater reliability of the Cybex EDI- 320 and fluid goniometer in normals and patients with low back pain. Arch Phys Med Rehabil 1993;74: Mellin GP. Measurement of thoracolumbar posture and mobility with a Myrin inclinometer. Spine 1986;11: Mellin G, Kiiski R, Weckstrom A. Effects of subject position on measurements of flexion, extension, and lateral flexion of the spine. Spine 1991;16:

5 MEASUREMENT OF LUMBAR EXTENSION, Bandy Newton M, Waddell G. Reliability and validity of clinical measurement of the lumbar spine in patients with chronic low back pain. Physiotherapy 1991;77: Breum J, Wiberg J, Bolton JE. Reliability and concurrent validity of the BROM II for measuring lumbar mobility. J Manipulative Physiol Ther 1995;18: Madson TJ, Youdas JW, Suman VJ. Reproducibility of lumbar spine range of motion measurements using the back range of motion device. J Orthop Sports Phys Ther 1999;29: Troup JD, Hood CA, Chapman AE. Measurements of the sagittal mobility of the lumbar spine and hips. Ann Phys Med 1968;9: Clarkson HM, Gilewich GB. Musculoskeletal assessment: joint range of motion and manual muscle strength. Baltimore: Williams & Wilkins; Stokes IA, Bevins TM, Lunn RA. Back surface curvature and measurement of lumbar spinal motion. Spine 1987;12: Reese NB, Bandy WD. Joint range of motion and muscle length testing. Philadelphia: WB Saunders; Currier DP. Elements of research in physical therapy. 2nd ed. Baltimore: Williams & Wilkins; Elveru RA, Rothstein JM, Lamb RL. Goniometric reliability in a clinical setting. Subtalar and ankle joint measurements. Phys Ther 1988;68: Fleiss JJ, Cohen J. The equivalence of weighted kappa and intraclass correlation coefficient as measures of reliability. Educ Psychol Meas 1973;33: Youdas JW, Suman VJ, Garrett TR. Reliability of measurements of lumbar spine sagittal mobility obtained with the flexible curve. J Orthop Sports Phys Ther 1995;21: Portney LG, Watkins MP. Foundations of clinical research: applications to practice. 2nd ed. Upper Saddle (NJ): Prentice Hall Health; Hellebrandt FA, Duvall EN, Morris ML. The measurement of joint motion: part III. Reliability of goniometry. Phys Ther Rev 1949;29:302-7.