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Interexaminer Reliability of the Hip Extension Test for Suspected Impaired Motor Control of the Lumbar Spine
INTEREXAMINER RELIABILITY OF THE HIP EXTENSION TEST FOR SUSPECTED IMPAIRED MOTOR CONTROL OF THE LUMBAR SPINE Donald R. Murphy, DC,a David Byfield, DC,b Peter McCarthy, PhD,c Kim Humphreys, DC, PhD,d Amy A. Gregory, DC,e and Ryan Rochon, DCf
ABSTRACT Objective: The hip extension test may be a clinical sign of impaired motor control in the lumbar spine, which may have a negative impact on spine stability. The purpose of this study is to evaluate the interexaminer reliability of the hip extension test for suspected dynamic instability of the lumbar spine in patients with chronic low back pain. Methods: Forty-two patients with chronic low back pain participated in this interexaminer reliability study. Chronic low back pain was defined as pain of greater than 7 weeks duration in the area between T12 and the buttocks, with or without leg pain. Two doctors of chiropractic simultaneously observed and independently assessed the left and right prone hip extension test on all 42 patients. Results for both examiners were given to an independent recorder. Each examiner was blinded to the results of the other examiner. Results: The mean age of subjects was 38 years (SD 12.35); 73.8% were female. Sixty-eight percent (SD 1.72) reported current back pain intensity greater than 5 on an 11-point numerical rating scale. The mean score for the Roland-Morris Low Back Pain and Disability questionnaire was 5.8 (SD 4.34). The j measure of agreement was 0.72 for the left leg and 0.76 for the right leg. This indicated a substantial strength of agreement between examiners for both left and right hip extension tests. For the 8 cases of disagreement, rater 1 generally rated the tests as positive, whereas rater 2 consistently rated the tests as negative. Conclusions: The hip extension test appears to have good reliability in detecting deviation of the lumbar spine from the midline. Validity with regard to the test’s ability to distinguish patients with chronic low back pain from normal individuals and its relation to lumbar spine stability remains to be determined. (J Manipulative Physiol Ther 2006;29:374-377) Key Indexing Terms: Reproducibility of Results; Low Back Pain; Hip
I
n the area of nonsurgical treatment of low back pain (LBP), there is increasing recognition of the importance of various dysfunctions as causative and perpetuating factors of pain. A difficulty encountered by practitioners is
a
Department of Community Health, Brown University School of Medicine, Providence, RI; and Rhode Island Spine Center, Providence, RI. b Welsh Institute of Chiropractic, University of Glamorgan, Wales, UK. c Welsh Institute of Chiropratic, University of Glamorgan, Wales, UK. d Department of Research, Canadian Memorial Chiropractic College, Toronto, ON, Canada. e Rhode Island Spine Center, Providence, RI. f Rhode Island Spine Center, Providence, RI. Submit requests for reprints to: Donald R. Murphy, DC, DACAN, Rhode Island Spine Center, 600 Pawtucket Avenue, Pawtucket, RI 02860 (e-mail: [email protected]). Paper submitted November 15, 2005; in revised form November 28, 2005. 0161-4754/$32.00 Copyright D 2006 by National University of Health Sciences. doi:10.1016/j.jmpt.2006.04.012
374
clinically identifying these dysfunctions using tests wherein the trained clinician can feel confident. Clinicians need access to clinical tests that have acceptable reliability and validity with regard to their clinical significance as a screening procedure or diagnostic test. They also need to know the sensitivity or specificity of the test in question. One type of dysfunction, recognized recently as important in patients with LBP, is that of disruption of the stability system of the spine or what will be referred to here as dynamic instability. The purpose of the spinal stability system is to properly monitor and compensate for common perturbations to the spine that have the potential to cause tissue irritation or injury.1,2 Fine motor control is required to ensure that the stability responses required to maintain intersegmental control, control of spinal orientation, and maintenance of postural stability occur in a way that ensures maximum protection to the spine. It has been shown that these motor control responses do not function properly in patients with chronic LBP,3 - 5 leading to the suggestion that improper and inefficient stabilization responses may serve as a perpetuating factor in these patients. It therefore would be beneficial for clinicians to have at their disposal one or
Journal of Manipulative and Physiological Therapeutics Volume 29, Number 5
several simple, reliable, and valid tests that are capable of detecting the disturbance of these automatic motor control responses and of monitoring the effectiveness of rehabilitative measures designed to correct this dysfunction. The hip extension test was originally developed by Janda6 as a test of the coordination of the muscles involved in extending the hip in the prone position. It has been (and still is) taught that when using this test, the examiner should look for an border of contractionQ in which the hamstring is suppose to activate first, followed in order by the gluteus maximus, contralateral lumbosacral erector spinae (ES), ispilateral lumbosacral ES, contralateral thoracolumbar ES, ipsilateral thoracolumbar ES, and finally by the thoracic ES (Janda, personal communication with the author 19892002). Any deviation from this bnormalQ pattern was deemed to represent a bfaulty movement pattern.Q However, recent evidence suggests that the normal pattern assumed with this use of the test is incorrect. Vogt and Banzer 7 assessed 15 healthy college students using the hip extension test and, using 16-channel electromyography, found that the ES consistently activated before the gluteus maximus, and that the gluteus maximus consistently activated after elevation of the leg. Prince et al 8 showed that during gait, the muscular response occurs in an above-down order of contraction rather than the below-up order suggested by the classical interpretation of the hip extension test. Most recently, Lehman et al 9 used electromyography to measure the timing of activation of the latissimus dorsi, hamstrings, gluteus maximus, and lower ES muscles during the hip extension test in 14 normal subjects. They found no consistent recruitment patterns in these subjects, but that the gluteus maximus activity was consistently delayed compared with the first muscle to activate. In spite of this evidence that argues against the traditional use of the hip extension test, the test may still be useful for other purposes. It has been the clinical experience of the first author that, in using this test, a common finding in patients with chronic LBP is that of deviation of the lumbar spine from the neutral position during the raising of the leg. This typically took 1 of 3 forms: (1) rotation of the lumbar spine such that the spinous processes appeared to move toward the side of hip extension; (2) lateral shift of the lumbar spine toward the side of hip extension; or (3) extension of the lumbar spine. Furthermore, it was commonly found that when the patient was taught to perform a maneuver designed to co-contract the deep segmental stabilizing muscles (primarily transverse abdominis and multifidis) 10 and hold this maneuver during the performance of the hip extension test, the lumbar deviation would appear to decrease. If this did not improve the test, teaching the patient to superimpose the contraction of the larger stabilizing muscles of the trunk (ES, rectus abdominis, external oblique) on the contraction of the deeper muscles would usually bring about reduced deviation. This raised the question as to whether the finding of deviation of the lumbar
Murphy et al Hip Extension Test Interexaminer Reliabilty
spine on the hip extension test may be a sign of impaired motor control, or dynamic instability, in the lumbar spine. It was hypothesized that perhaps the deviation of the lumbar spine that often occurs during the hip extension test represents inability of the stabilizing system of the spine to properly perform its function in automatically ordering co-contraction of the stabilizing muscles in response to perturbation, here in the form of the raising of the leg. This study investigates whether the finding of deviation of the lumbar spine during the hip extension test could be detected reliably by clinicians trained in the performance of the test.
METHODS Consecutive patients with chronic LBP were recruited from the patient population of the Rhode Island Spine Center. Informed consent was obtained from each subject, and the study protocol was reviewed and approved by the New York Chiropractic College Institutional Review Board. The inclusion criteria were chronic (z7weeks) pain between T12 and the buttocks, with or without leg pain; ability to perform hip extension in the prone position without pain; and ability to understand English. Exclusion criteria were visceral pathology; spinal infection or spinal fracture as the cause of the patient’s LBP; inability to understand English; and pain when performing hip extension. The examiners were 2 chiropractic physicians, one with 13 years of experience and the other with less than 1 year of experience. Criteria for identifying a test as positive were developed based on the clinical observations of the first author. These criteria were discussed at length between the 2 examiners, and a training period lasting approximately 1 hour was undertaken to ensure that the examiners agreed on the findings that were being observed and recorded. The criteria for a positive test were rotation, lateral shift (interpreted as movement either in a lateral translational direction or lateral flexion), or hyperextension of the lumbar spine upon performing hip extension. The test was negative if the lumbar spine remained in its neutral position during performance of the test. The other findings that have been reported to be important in the hip extension test 6,11 were not included for the purpose of the study. It is the first author’s clinical experience that repetition of the test more than 3 to 4 times can sometimes alter the findings. Thus, both examiners observed the performance of the test at the same time. For each examination, the patient lay prone on the examining table with an examiner on each side. A research assistant was also in the examining room to record the findings. The patient was asked to raise 1 leg into extension while keeping the knee straight (Fig 1). The examiners recorded their findings on a piece of paper. Each examiner was allowed to ask the patient to repeat the maneuver, but no more than 3 repetitions were allowed. The patient would then raise the other leg in the same fashion as
375
376
Murphy et al Hip Extension Test Interexaminer Reliability
Journal of Manipulative and Physiological Therapeutics June 2006
sex of the patient may have affected the findings. The only noticeable trend was possibly between sex of the patient and disagreement between examiners. In the case of patients where there was a single disagreement (n = 4), there were equal numbers of males and females represented. In the total disagreement category (n = 4), all the patients were female. This means there was a 3:1 ratio of female to male in respect to the patients where there was either total or partial disagreement, which approximates to the ratio of females to males in the entire cohort (31:11). These numbers are too small, however, to perform any meaningful statistics.
DISCUSSION Fig 1. The hip extension test. Reprinted with permission from
Murphy.11
the first, and the examiners would again record their findings. Each examiner then handed the piece of paper with the findings to the research assistant, who recorded them on a chart with the patient’s age, sex, duration of pain, and score on the Roland-Morris Low Back Pain and Disability scale. As the examiners were standing on opposite sides of the examination table, each was unable to see the other’s findings as recorded on the piece of paper. The examiners were not to discuss the findings of any current or previous examinations until data were collected on all 42 patients. After data collection was complete, inferential statistical analysis was performed using the j coefficient 12-14 to determine examiner concordance beyond chance. Although the data were not normally distributed, they will be presented as mean F 1 SD and range to give some indication of data distribution.
RESULTS Forty-two patients with chronic LBP were recruited. The mean age was 37.8 years (F 12.4, range 19-60), with 31 of the 42 patients being female. Sixty-eight percent reported current back pain intensity of greater than 5 on an 11-point numerical rating scale (mean 5.2 F 1.7, range 2-10). For disability, the mean score for the Roland-Morris Low Back Pain and Disability questionnaire was 5.8 F 4.3 (range 1-16). The j measure of agreement was 0.72 for the left leg and 0.76 for the right leg. This indicates a substantial concordance between examiners beyond chance for both left and right hip extension tests. For the 8 cases of disagreement, rater 1 generally rated the tests as positive, whereas rater 2 consistently rated the tests as negative. No significant trend was seen with respect to the disagreement and age, sex, numerical rating scale, or Roland Morris scores. The
This study showed that 2 examiners can reliably detect deviation of the lumbar spine from the resting position using the hip extension test. It did not assess the validity of the finding with regard to lumbar spine motor control or stability nor did it assess the reliability of any other conclusion that one could draw from the test. Further study is required to evaluate these factors. But this study is a first step in evaluating the attributes of this clinical test in patients with chronic LBP. Various dysfunctions have been increasingly recognized as important in the development and perpetuation of LBP. The difficulty that nonsurgical spine clinicians encounter is assessing function and dysfunction using a battery of reliable and valid tests, particularly those that do not require a great deal of time and equipment. One of the more important types of dysfunction that has been discussed in recent years is that of what is referred to here as dynamic instability. However, few methods have been developed that allow the clinician to reliably assess this disorder. In the pelvis, the active straight leg raise test has been shown to be reliable and valid. 15 Hicks et al16 found good interexaminer reliability of the bprone instability test,Q originally developed by McGill, 17 which shows promise in assessing the stability response to shear forces. The validation of simple clinical tests such as these would be useful to clinicians managing patients with chronic LBP as it would assist in decision making with regard to the implementation of spinal stability training. 10,17 The hip extension test has potential for being useful for this purpose, and experiments are presently being designed to compare the findings of this test in patients with chronic LBP and in sex- and agematched controls. This study did not assess the hip extension test as it was originally described by Janda 6 (personal communication with the author 1989-2002), which involved observing order of contraction of various muscles in the lower extremity, pelvis, and spine. Rather, it assessed only the finding of deviation of the lumbar spine during the test procedure. Thus, comment cannot be made on the reliability of the original test, but, as discussed earlier, the validity of the
Journal of Manipulative and Physiological Therapeutics Volume 29, Number 5
order of contraction interpretation of the test has been called into question. A weakness of this study is that the mean score on the Roland-Morris Low Back Pain Disability scale was rather low (5.8 F 4.3). However, this is because some of the patients in the study had been receiving treatment for a period of time before the hip extension testing. These patients all had higher scores at intake. It was felt that this would not affect the study because the study’s purpose was to assess interexaminer reliability, not validity. As the examiners assessed the hip extension test at the same time in all patients, the reduced disability status of some patients was not likely to affect the assessment of the level of agreement between the examiners. Future studies will evaluate other attributes such as, validity, responsiveness, sensitivity, and specificity.
CONCLUSION The hip extension test appears to have reliability in detecting deviation of the lumbar spine from the midline during the performance of hip extension in the prone position. Validity with regard to the ability of this test to distinguish patients with chronic LBP from normal individuals and its relation to lumbar spine stability remains to be determined.
ACKNOWLEDGMENT The authors thank Tovah Reis of the Brown University School of Medicine library and Mary Ott of the New York Chiropractic College library for help with gathering information.
REFERENCES 1. Panjabi MM. The stabilizing system of the spine. Part I: function, dysfunction, adaptation and enhancement. J Spinal Disord 1992;5:383-9.
Murphy et al Hip Extension Test Interexaminer Reliabilty
2. McGill SM. Linking latest knowledge of injury mechanisms and spine function to the prevention of low back disorders. J Electromyogr Kinesiol 2004;14:43-7. 3. Hodges PW, Richardson CA. Inefficient muscular stabilization of the lumbar spine associated with low back pain a motor control evaluation of transversus abdominis. Spine 1996; 21:2640-50. 4. O’Sullivan P, Twomey L, Allison GT, Sinclair J, Miller K, Knox J. Altered pattern of abdominal muscle activation in patients with chronic low back pain. Aust J Physiother 1997; 43:91-8. 5. Silfies SP, Squillante D, Maurer P, Westcott S, Karduna AR. Trunk muscle recruitment patterns in specific chronic low back pain populations. Clin Biomech 2005;20:465-73. 6. Janda V. Evaluation of muscular imbalance. In: Liebenson C, editor. Rehabilitation of the spine: a practitioner’s manual. Baltimore7 Williams and Wilkins; 1996. p. 97-112. 7. Vogt L, Banzer W. Dynamic testing of the motor stereotype in prone hip extension from the neutral position. Clin Biomech 1997;12:122-7. 8. Prince F, Winter DA, Stergiou P, Walt SE. Anticipatory control of upper body balance during human locomotion. Gait Posture 1994;2:19-25. 9. Lehman GJ, Lennon D, Tresidder B, Rayfield B, Poschar M. Muscle recruitment patterns during the prone leg extension. BMC Musculoskel Disord 2004;3:3. 10. Richardson C, Jull G, Hodges P, Hides J. Therapeutic exercise for spinal segmental stabilization in low back pain. Scientific basis and clinical approach. Edinburgh7 Churchill Livingstone; 1999. 11. Murphy DR. Evaluation of posture and movement patterns. In: Murphy DR, editor. Conservative management of cervical spine syndromes. New York7 McGraw-Hill; 2000. p. 307-28. 12. Cohen JA. A coefficient of agreement for nominal scales. Educ Psychol Meas 1960;20:37-46. 13. Haas M. Statistical methodology of reliability studies. J Manipulative Physiol Ther 1991;14:119-32. 14. Haas M. The reliability of reliability. J Manipulative Physiol Ther 1991;14:119-32. 15. Mens JMA, Vleeming A, Snijders CJ, Koes BJ, Stam HJ. Reliability and validity of the active straight leg raise test in posterior pelvic pain since pregnancy. Spine 2001;29:1167-71. 16. Hicks GE, Fritz JM, Delitto A, Mishock J. Interrater reliability of clinical examination measures for identification of lumbar segmental instability. Arch Phys Med Rehab 2003;84:1858-64. 17. McGill S. Low back disorders. Evidence-based prevention and rehabilitation. Champaign (Ill)7 Human Kinetics; 2002.
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ABSTRACT Objective: The hip extension test may be a clinical sign of impaired motor control in the lumbar spine, which may have a negative impact on spine stability. The purpose of this study is to evaluate the interexaminer reliability of the hip extension test for suspected dynamic instability of the lumbar spine in patients with chronic low back pain. Methods: Forty-two patients with chronic low back pain participated in this interexaminer reliability study. Chronic low back pain was defined as pain of greater than 7 weeks duration in the area between T12 and the buttocks, with or without leg pain. Two doctors of chiropractic simultaneously observed and independently assessed the left and right prone hip extension test on all 42 patients. Results for both examiners were given to an independent recorder. Each examiner was blinded to the results of the other examiner. Results: The mean age of subjects was 38 years (SD 12.35); 73.8% were female. Sixty-eight percent (SD 1.72) reported current back pain intensity greater than 5 on an 11-point numerical rating scale. The mean score for the Roland-Morris Low Back Pain and Disability questionnaire was 5.8 (SD 4.34). The j measure of agreement was 0.72 for the left leg and 0.76 for the right leg. This indicated a substantial strength of agreement between examiners for both left and right hip extension tests. For the 8 cases of disagreement, rater 1 generally rated the tests as positive, whereas rater 2 consistently rated the tests as negative. Conclusions: The hip extension test appears to have good reliability in detecting deviation of the lumbar spine from the midline. Validity with regard to the test’s ability to distinguish patients with chronic low back pain from normal individuals and its relation to lumbar spine stability remains to be determined. (J Manipulative Physiol Ther 2006;29:374-377) Key Indexing Terms: Reproducibility of Results; Low Back Pain; Hip
I
n the area of nonsurgical treatment of low back pain (LBP), there is increasing recognition of the importance of various dysfunctions as causative and perpetuating factors of pain. A difficulty encountered by practitioners is
a
Department of Community Health, Brown University School of Medicine, Providence, RI; and Rhode Island Spine Center, Providence, RI. b Welsh Institute of Chiropractic, University of Glamorgan, Wales, UK. c Welsh Institute of Chiropratic, University of Glamorgan, Wales, UK. d Department of Research, Canadian Memorial Chiropractic College, Toronto, ON, Canada. e Rhode Island Spine Center, Providence, RI. f Rhode Island Spine Center, Providence, RI. Submit requests for reprints to: Donald R. Murphy, DC, DACAN, Rhode Island Spine Center, 600 Pawtucket Avenue, Pawtucket, RI 02860 (e-mail: [email protected]). Paper submitted November 15, 2005; in revised form November 28, 2005. 0161-4754/$32.00 Copyright D 2006 by National University of Health Sciences. doi:10.1016/j.jmpt.2006.04.012
374
clinically identifying these dysfunctions using tests wherein the trained clinician can feel confident. Clinicians need access to clinical tests that have acceptable reliability and validity with regard to their clinical significance as a screening procedure or diagnostic test. They also need to know the sensitivity or specificity of the test in question. One type of dysfunction, recognized recently as important in patients with LBP, is that of disruption of the stability system of the spine or what will be referred to here as dynamic instability. The purpose of the spinal stability system is to properly monitor and compensate for common perturbations to the spine that have the potential to cause tissue irritation or injury.1,2 Fine motor control is required to ensure that the stability responses required to maintain intersegmental control, control of spinal orientation, and maintenance of postural stability occur in a way that ensures maximum protection to the spine. It has been shown that these motor control responses do not function properly in patients with chronic LBP,3 - 5 leading to the suggestion that improper and inefficient stabilization responses may serve as a perpetuating factor in these patients. It therefore would be beneficial for clinicians to have at their disposal one or
Journal of Manipulative and Physiological Therapeutics Volume 29, Number 5
several simple, reliable, and valid tests that are capable of detecting the disturbance of these automatic motor control responses and of monitoring the effectiveness of rehabilitative measures designed to correct this dysfunction. The hip extension test was originally developed by Janda6 as a test of the coordination of the muscles involved in extending the hip in the prone position. It has been (and still is) taught that when using this test, the examiner should look for an border of contractionQ in which the hamstring is suppose to activate first, followed in order by the gluteus maximus, contralateral lumbosacral erector spinae (ES), ispilateral lumbosacral ES, contralateral thoracolumbar ES, ipsilateral thoracolumbar ES, and finally by the thoracic ES (Janda, personal communication with the author 19892002). Any deviation from this bnormalQ pattern was deemed to represent a bfaulty movement pattern.Q However, recent evidence suggests that the normal pattern assumed with this use of the test is incorrect. Vogt and Banzer 7 assessed 15 healthy college students using the hip extension test and, using 16-channel electromyography, found that the ES consistently activated before the gluteus maximus, and that the gluteus maximus consistently activated after elevation of the leg. Prince et al 8 showed that during gait, the muscular response occurs in an above-down order of contraction rather than the below-up order suggested by the classical interpretation of the hip extension test. Most recently, Lehman et al 9 used electromyography to measure the timing of activation of the latissimus dorsi, hamstrings, gluteus maximus, and lower ES muscles during the hip extension test in 14 normal subjects. They found no consistent recruitment patterns in these subjects, but that the gluteus maximus activity was consistently delayed compared with the first muscle to activate. In spite of this evidence that argues against the traditional use of the hip extension test, the test may still be useful for other purposes. It has been the clinical experience of the first author that, in using this test, a common finding in patients with chronic LBP is that of deviation of the lumbar spine from the neutral position during the raising of the leg. This typically took 1 of 3 forms: (1) rotation of the lumbar spine such that the spinous processes appeared to move toward the side of hip extension; (2) lateral shift of the lumbar spine toward the side of hip extension; or (3) extension of the lumbar spine. Furthermore, it was commonly found that when the patient was taught to perform a maneuver designed to co-contract the deep segmental stabilizing muscles (primarily transverse abdominis and multifidis) 10 and hold this maneuver during the performance of the hip extension test, the lumbar deviation would appear to decrease. If this did not improve the test, teaching the patient to superimpose the contraction of the larger stabilizing muscles of the trunk (ES, rectus abdominis, external oblique) on the contraction of the deeper muscles would usually bring about reduced deviation. This raised the question as to whether the finding of deviation of the lumbar
Murphy et al Hip Extension Test Interexaminer Reliabilty
spine on the hip extension test may be a sign of impaired motor control, or dynamic instability, in the lumbar spine. It was hypothesized that perhaps the deviation of the lumbar spine that often occurs during the hip extension test represents inability of the stabilizing system of the spine to properly perform its function in automatically ordering co-contraction of the stabilizing muscles in response to perturbation, here in the form of the raising of the leg. This study investigates whether the finding of deviation of the lumbar spine during the hip extension test could be detected reliably by clinicians trained in the performance of the test.
METHODS Consecutive patients with chronic LBP were recruited from the patient population of the Rhode Island Spine Center. Informed consent was obtained from each subject, and the study protocol was reviewed and approved by the New York Chiropractic College Institutional Review Board. The inclusion criteria were chronic (z7weeks) pain between T12 and the buttocks, with or without leg pain; ability to perform hip extension in the prone position without pain; and ability to understand English. Exclusion criteria were visceral pathology; spinal infection or spinal fracture as the cause of the patient’s LBP; inability to understand English; and pain when performing hip extension. The examiners were 2 chiropractic physicians, one with 13 years of experience and the other with less than 1 year of experience. Criteria for identifying a test as positive were developed based on the clinical observations of the first author. These criteria were discussed at length between the 2 examiners, and a training period lasting approximately 1 hour was undertaken to ensure that the examiners agreed on the findings that were being observed and recorded. The criteria for a positive test were rotation, lateral shift (interpreted as movement either in a lateral translational direction or lateral flexion), or hyperextension of the lumbar spine upon performing hip extension. The test was negative if the lumbar spine remained in its neutral position during performance of the test. The other findings that have been reported to be important in the hip extension test 6,11 were not included for the purpose of the study. It is the first author’s clinical experience that repetition of the test more than 3 to 4 times can sometimes alter the findings. Thus, both examiners observed the performance of the test at the same time. For each examination, the patient lay prone on the examining table with an examiner on each side. A research assistant was also in the examining room to record the findings. The patient was asked to raise 1 leg into extension while keeping the knee straight (Fig 1). The examiners recorded their findings on a piece of paper. Each examiner was allowed to ask the patient to repeat the maneuver, but no more than 3 repetitions were allowed. The patient would then raise the other leg in the same fashion as
375
376
Murphy et al Hip Extension Test Interexaminer Reliability
Journal of Manipulative and Physiological Therapeutics June 2006
sex of the patient may have affected the findings. The only noticeable trend was possibly between sex of the patient and disagreement between examiners. In the case of patients where there was a single disagreement (n = 4), there were equal numbers of males and females represented. In the total disagreement category (n = 4), all the patients were female. This means there was a 3:1 ratio of female to male in respect to the patients where there was either total or partial disagreement, which approximates to the ratio of females to males in the entire cohort (31:11). These numbers are too small, however, to perform any meaningful statistics.
DISCUSSION Fig 1. The hip extension test. Reprinted with permission from
Murphy.11
the first, and the examiners would again record their findings. Each examiner then handed the piece of paper with the findings to the research assistant, who recorded them on a chart with the patient’s age, sex, duration of pain, and score on the Roland-Morris Low Back Pain and Disability scale. As the examiners were standing on opposite sides of the examination table, each was unable to see the other’s findings as recorded on the piece of paper. The examiners were not to discuss the findings of any current or previous examinations until data were collected on all 42 patients. After data collection was complete, inferential statistical analysis was performed using the j coefficient 12-14 to determine examiner concordance beyond chance. Although the data were not normally distributed, they will be presented as mean F 1 SD and range to give some indication of data distribution.
RESULTS Forty-two patients with chronic LBP were recruited. The mean age was 37.8 years (F 12.4, range 19-60), with 31 of the 42 patients being female. Sixty-eight percent reported current back pain intensity of greater than 5 on an 11-point numerical rating scale (mean 5.2 F 1.7, range 2-10). For disability, the mean score for the Roland-Morris Low Back Pain and Disability questionnaire was 5.8 F 4.3 (range 1-16). The j measure of agreement was 0.72 for the left leg and 0.76 for the right leg. This indicates a substantial concordance between examiners beyond chance for both left and right hip extension tests. For the 8 cases of disagreement, rater 1 generally rated the tests as positive, whereas rater 2 consistently rated the tests as negative. No significant trend was seen with respect to the disagreement and age, sex, numerical rating scale, or Roland Morris scores. The
This study showed that 2 examiners can reliably detect deviation of the lumbar spine from the resting position using the hip extension test. It did not assess the validity of the finding with regard to lumbar spine motor control or stability nor did it assess the reliability of any other conclusion that one could draw from the test. Further study is required to evaluate these factors. But this study is a first step in evaluating the attributes of this clinical test in patients with chronic LBP. Various dysfunctions have been increasingly recognized as important in the development and perpetuation of LBP. The difficulty that nonsurgical spine clinicians encounter is assessing function and dysfunction using a battery of reliable and valid tests, particularly those that do not require a great deal of time and equipment. One of the more important types of dysfunction that has been discussed in recent years is that of what is referred to here as dynamic instability. However, few methods have been developed that allow the clinician to reliably assess this disorder. In the pelvis, the active straight leg raise test has been shown to be reliable and valid. 15 Hicks et al16 found good interexaminer reliability of the bprone instability test,Q originally developed by McGill, 17 which shows promise in assessing the stability response to shear forces. The validation of simple clinical tests such as these would be useful to clinicians managing patients with chronic LBP as it would assist in decision making with regard to the implementation of spinal stability training. 10,17 The hip extension test has potential for being useful for this purpose, and experiments are presently being designed to compare the findings of this test in patients with chronic LBP and in sex- and agematched controls. This study did not assess the hip extension test as it was originally described by Janda 6 (personal communication with the author 1989-2002), which involved observing order of contraction of various muscles in the lower extremity, pelvis, and spine. Rather, it assessed only the finding of deviation of the lumbar spine during the test procedure. Thus, comment cannot be made on the reliability of the original test, but, as discussed earlier, the validity of the
Journal of Manipulative and Physiological Therapeutics Volume 29, Number 5
order of contraction interpretation of the test has been called into question. A weakness of this study is that the mean score on the Roland-Morris Low Back Pain Disability scale was rather low (5.8 F 4.3). However, this is because some of the patients in the study had been receiving treatment for a period of time before the hip extension testing. These patients all had higher scores at intake. It was felt that this would not affect the study because the study’s purpose was to assess interexaminer reliability, not validity. As the examiners assessed the hip extension test at the same time in all patients, the reduced disability status of some patients was not likely to affect the assessment of the level of agreement between the examiners. Future studies will evaluate other attributes such as, validity, responsiveness, sensitivity, and specificity.
CONCLUSION The hip extension test appears to have reliability in detecting deviation of the lumbar spine from the midline during the performance of hip extension in the prone position. Validity with regard to the ability of this test to distinguish patients with chronic LBP from normal individuals and its relation to lumbar spine stability remains to be determined.
ACKNOWLEDGMENT The authors thank Tovah Reis of the Brown University School of Medicine library and Mary Ott of the New York Chiropractic College library for help with gathering information.
REFERENCES 1. Panjabi MM. The stabilizing system of the spine. Part I: function, dysfunction, adaptation and enhancement. J Spinal Disord 1992;5:383-9.
Murphy et al Hip Extension Test Interexaminer Reliabilty
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