NECK PAIN IS A COMMON complaint in the general

ORIGINAL ARTICLE The Immediate Effects of Mobilization Technique on Pain and Range of Motion in Patients Presenting With Unilateral Neck Pain: A Randomized Controlled Trial Rotsalai Kanlayanaphotporn, PhD, Adit Chiradejnant, PhD, Roongtiwa Vachalathiti, PhD ABSTRACT. Kanlayanaphotporn R, Chiradejnant A, Vachalathiti R. The immediate effects of mobilization technique on pain and range of motion in patients presenting with unilateral neck pain: a randomized controlled trial. Arch Phys Med Rehabil 2009;90:187-92. Objective: To determine the immediate effects on both pain and active range of motion (ROM) of the unilateral posteroanterior (PA) mobilization technique on the painful side in mechanical neck pain patients presenting with unilateral symptoms. Design: Triple-blind, randomized controlled trial. Setting: Outpatient physical therapy, institutional clinic. Participants: Patients (N 60), 2 physical therapists, and 1 assessor involved in this study. Interventions: The patients were randomly allocated into either preferred or random mobilization group by using an opaque concealed envelope. The first therapist performed the screening, assessing, prescribing the spinal level(s), and the grade of mobilization. The second therapist performed the mobilization treatment according to their allocated group stated in an envelope. The assessor who was blind to the group allocation conducted the measurements of pain and active cervical ROM. Main Outcome Measures: Pain intensity, active cervical ROM, and global perceived effect were measured at baseline and 5 minutes posttreatment. Results: After mobilization, there were no apparent differences in pain and active cervical ROM between groups. However, within-group changes showed significant decreases in neck pain at rest and pain on most painful movement (P 0.001) with a significant increase in active cervical ROM after mobilization on most painful movement (P 0.002). Conclusions: The results of this study did not provide support for the preference of the unilateral PA mobilization on the painful side to the random mobilization. Key Words: Clinical trial; Manual therapy; Mobilization; Neck pain; Rehabilitation. 2009 by the American Congress of Rehabilitation Medicine 187 NECK PAIN IS A COMMON complaint in the general population with the lifetime prevalence of approximately 50%. 1,2 Its exact pathology remains obscure, but the source of symptoms has been asserted to involve mechanical dysfunction of the cervical spine, 3,4 particularly the zygapophysial joints. 5-7 Among the diversity of neck pain, mechanical neck pain is the most common type, with the pain primarily confined in the area on the posterior aspect of the neck that can be exacerbated by neck movements or by sustained neck postures. 8,9 The usual clinical presentation of this mechanical neck pain is a reduction in mobility of either a single segment or multiple segments of the cervical spine in association with pain. 8,10 Recent evidence 11-16 suggests manipulation and mobilization to be the effective therapies for mechanical neck pain. Manipulation is defined as a high-velocity and small-amplitude movement applied at the end or just beyond an available joint ROM, whereas mobilization is defined as a low-velocity and small- or large-amplitude movement applied anywhere within a joint ROM. 3 For an immediate effect, cervical spine manipulation was shown to be more effective in reducing pain and increasing cervical ROM than cervical spine mobilization with muscle energy or sustained manipulated position. 17,18 The muscle energy technique was executed by asking the patients to repeatedly contract their hypertonic muscles statically against the manual resistance provided by the therapist. 17 On the other hand, the sustained manipulated position was performed by holding the patients head for 30 seconds in the position ready for manipulation but with no additional tension and thrust. 18 In a longer duration, the mobilization technique in the form of an oscillatory movement targeted at a cervical segment yielded similar mean reductions in pain and disability as cervical spine manipulation. 19 Nevertheless, adverse effects are more likely to be reported after cervical spine manipulation than mobilization. 20,21 Therefore, it is suggested that the cervical spine manipulation should be used as a progression of the treatment when the cervical spine mobilization provides no further improvement. 3 Among various cervical spine mobilization procedures, the manifestation of an oscillatory movement targeted at a cervical segment is widely used. With this mobilization procedure, an empiric guideline for the selection of the cervical mobilization technique is based on the distribution of the patient s symptoms. 3 For patients whose symptoms are situated either in the From the Department of Physical Therapy, Faculty of Allied Health Sciences, Chulalongkorn University (Kanlayanaphotporn, Chiradejnant), Bangkok; and Faculty of Physical Therapy and Applied Movement Science, Mahidol University (Vachalathiti), Nakhon Pathom, Thailand. Supported by the Thailand Research Fund and the Commission on Higher Education (grant no. MRG4980001). Correspondence to Rotsalai Kanlayanaphotporn, PhD, Dept of Physical Therapy, Faculty of Allied Health Sciences, Chulalongkorn University, 154 Rama 1 Rd, Pathumwan, Bangkok 10330, Thailand, e-mail: rotsalai.k@chula.ac.th or rotsalai@gmail.com. Reprints are not available from the author. 0003-9993/09/9002-00310$36.00/0 doi:10.1016/j.apmr.2008.07.017 ANOVA CROM ICC PA RCT ROM VAS List of Abbreviations analysis of variance cervical range of motion intraclass correlation coefficient posteroanterior randomized controlled trial range of motion visual analog scale

188 CERVICAL MOBILIZATION FOR NECK PAIN, Kanlayanaphotporn midline or distributed evenly to each side of the neck, the central PA mobilization technique over the spinous process of the cervical spine is recommended. 3 For the patients whose symptoms are unilaterally distributed, the ipsilateral unilateral PA mobilization technique over the zygapophysial joint of the cervical spine on the side of the symptoms is of most benefit. 3 The aim of this RCT was to establish in patients suffering from unilateral mechanical neck pain whether the preferred ipsilateral unilateral PA mobilization technique showed greater immediate effects on neck pain and active cervical ROM than a randomly assigned mobilization. METHODS Research Design A triple-blind, RCT was used for examining the immediate effects of the cervical spine mobilization techniques on neck pain and active cervical ROM. Two physical therapists and 1 assessor were involved in this study. This study was conducted at the outpatient physical therapy, institutional clinic. Ethical clearance was obtained from the university s Human Research Ethics Committee. The testing procedures were fully explained, and written informed consent was obtained from all subjects before participating in the study. Subjects Patients suffering from mechanical neck pain that was unilaterally distributed for at least 1-week duration were recruited. They were included in the study if their symptoms were primarily confined in the area between the superior nuchal line and the tip of the first thoracic spinous process and were provoked by neck movements or by sustained neck postures. 9,10 To permit a clinically worthwhile effect to be shown, their neck pain at rest had to be greater than 20 on a 0- to 100-mm VAS. 22 Patients were excluded if they had (1) any contraindications to mobilization (eg, disease of spinal cord and/or cauda equina, inflammatory arthropathy of unknown causes, presence of malignancy), 3 (2) previous history of a significant trauma to and fracture of the cervical spine, (3) history of cervical spine surgery, (4) undergone spinal manipulative therapy within the past month before the study, and (5) a positive neurologic examination. Outcome Measures Pain intensity. Neck pain was measured via the VAS. It was a 100-mm line with pain descriptors marked no pain at 1 end and the worst pain imaginable at the other. The patients were asked to report their perceived pain level, both at rest and on most painful movement, by marking the VAS with a perpendicular line. This has been found to be a reliable and valid measure of pain. 22,23 Active CROM. Neck mobility was assessed with a CROM device a that consisted of a magnetic neck brace and 3 inclinometers that were located in the sagittal, frontal, and horizontal planes. The patients were measured while sitting with feet rested on the ground, their hips and knees positioned at a right angle, and their back against a chair. The CROM was set on the patients head so that all 3 inclinometers for 3 cardinal planes read zeroes. Six conventional movements of the cervical spine were measured in order from flexion, extension, left lateral flexion, right lateral flexion, left rotation, and right rotation. The patients were instructed to perform a maximally active Fig 1. A flow diagram of the patients in this study.

CERVICAL MOBILIZATION FOR NECK PAIN, Kanlayanaphotporn 189 movement in each direction twice in which the second value was recorded for further analysis. This instrument has been shown to be a valid cervical ROM measure when being compared against the radiograph and the optoelectric system (r range,.82.98). 24-26 The intratester reliability was reported to be high (ICCs range,.76.98). 27,28 In the present study, an excellent test-retest reliability with ICC 2,1 values ranging from.86 to.98 was established before commencing the experiment. A group of 20 patients who suffered from mechanical neck pain was measured twice with a 5-minute rest in between. During this time, the CROM was removed, and the patients were allowed to move around in the laboratory. The SEs of measurements for all cervical ROMs were found to be within 4. Body chart pain location. A body chart showing the anterior and the posterior views of the upper body part was used for recording the location and distribution of patients neck pain both before and 5 minutes after the treatment. This was to provide evidence whether there were any changes in the location and the distribution of patients symptoms after the treatment. Global perceived effect. An ordinal 7-point scale with responses ranging from 1 (completely recovered) to 7 (worse than ever) was used to reflect the patients assessment of their improvement. This scale has been shown to be a valid measure for the patients perceived satisfaction from the treatment. 29 To be considered as a clinically important change, the subjects should rate this scale after the treatment to be either less than 3 or more than 5. 22 Procedure Two physical therapists each with greater than 10 years of clinical experience in manual therapy and 1 assessor were involved in this study. Initially, the patients were asked to fill out the demographic and the Thai version of the Neck Disability Index questionnaires. 30 The pretreatment data, which included the body chart pain location, neck pain at rest, pain on most painful movement, and active cervical ROM, were collected by an assessor. Next, the first physical therapist who was blind to the pretreatment data performed all screening examinations to establish the intervertebral joint level(s). The level(s) that were found to be hypomobile or painful in the manner that matched the characteristics in which the patients were affected were deemed responsible for the patients symptoms. 3 Treatment details including the spinal level(s) to be treated, the grade of movement to be applied, and the most appropriate technique of mobilization were noted. In general, there are 4 major grades of movement (I IV) that indicate the depth of the mobilization. The small grades are used to treat the pain dominant problems, whereas the high grades are used to treat the stiffness dominant problems. 3 Once the examination had been completed, patients were randomly allocated to the preferred or random mobilization groups (fig 1). The preferred mobilization group received the unilateral PA pressure on the side of the symptoms (ipsilateral). The random mobilization group received 1 of the following 3 mobilization techniques that could be applied in the clinic as a placebo intervention: the central PA, ipsilateral unilateral PA, or contralateral unilateral PA pressure. For both groups, all patients were asked to lay face downward on a plinth that provided a hole for their face to rest comfortably. The therapist stood at the head of the patients with his thumbs held back to back and in opposition. The tips of their thumb pads were placed on the articular process and the spinous process of the cervical vertebra to be mobilized when performing the unilateral PA and the central PA, respectively. The unilateral PA pressure was performed by applying an oscillatory pressure through the thumbs directed posteroanteriorly against an articular process of the cervical vertebra to be mobilized. This similar procedure was also performed for the central PA pressure except the therapist s thumbs were placed on the spinous process of the cervical vertebra. The randomization was performed in blocks of 6 patients by using a computer-generated random-sequence table that was created before the beginning of the study. The mobilization technique was sealed in a sequentially numbered opaque envelope. The second therapist, who was blind to the pretreatment data and the examination findings, was then asked to perform the mobilization treatment by using the treatment details noted by the first therapist. The mobilization technique stated in the concealed envelope was applied as two 1-minute repetitions. A slight adjustment was possible in accordance with the patients symptoms. Finally, the posttreatment data, which were the same as those for the pretreatment data and the global perceived effect, were taken 5 minutes after completing the mobilization treatment by the same assessor who remained blind to the patients group allocation. Any adverse effects caused by the mobilization, such as dizziness and neurologic problems, were asked and recorded. Data Analysis Data were analyzed with the SPSS b for Windows. Means and SDs were calculated for each variable. Pretreatment data were compared between groups by using the independent t tests. The neck pain at rest, pain on most painful movement, and active cervical ROM between the pretreatment and post- Table 1: Means SDs of Patients Clinical and Demographic Data of Each Group at Baseline Variables Preferred Mobilization Group Random Mobilization Group Sex (male/female) 13/17 11/19 Symptomatic side (left/right) 15/15 16/14 Direction of worst movement Flexion 5 3 Extension 8 5 Ipsilateral lateral flexion 2 4 Contralateral lateral flexion 8 10 Ipsilateral rotation 6 5 Contralateral rotation 1 3 Age (y) 39.7 10.0 44.8 13.6.109 Duration of neck pain (d) 804.3 149.4 999.6 182.5.688 Neck Disability Index (%) 22.9 10.0 26.5 10.5.172 Pain intensity (mm) At rest 47.4 15.9 48.3 22.2.868 On most painful movement 59.5 16.6 61.6 23.0.682 Active CROM (degrees) Flexion 44.0 8.5 42.7 9.8.575 Extension 63.4 12.8 61.8 11.5.613 Ipsilateral lateral flexion 36.7 10.2 35.6 8.9.669 Contralateral lateral flexion 37.0 9.4 35.6 9.0.551 Ipsilateral rotation 66.3 8.4 64.4 9.8.414 Contralateral rotation 66.9 9.8 65.2 6.7.442 On most painful movement 52.1 19.2 46.8 19.3.288 P

190 CERVICAL MOBILIZATION FOR NECK PAIN, Kanlayanaphotporn Table 2: Means SDs of the Difference Scores Between Pretreatment and Posttreatment Data for Each Outcome Measure Variables Preferred Random Pain intensity (mm) At rest 10.8 11.4 12.3 12.5 On most painful movement 16.7 17.6 16.9 16.0 Active CROM (deg) Flexion 1.9 4.1 0.7 4.5 Extension 1.8 6.3 0.8 4.6 Ipsilateral lateral flexion 0.3 6.3 1.2 4.9 Contralateral lateral flexion 0.8 4.8 1.3 4.1 Ipsilateral rotation 0.5 5.5 0.6 6.9 Contralateral rotation 1.1 4.2 0.8 6.0 On most painful movement 2.7 5.5 1.4 4.3 ROM on most painful movement (degrees) 50 45 40 35 30 Pretreatment Preferred mobilization group Random mobilization group Posttreatment Fig 2. An interaction plot of the means of the change in active cervical flexion between the preferred mobilization and the random mobilization groups. treatment measures were compared between groups by using separate 2-way repeated measures ANOVAs. Where significant interaction existed between groups for each outcome measure, a post hoc analysis was examined by drawing an interaction plot. 31 For all comparisons, P less than.05 was considered as statistically significant. RESULTS Sixty patients (24 males and 36 females) participated in this study, and none reported any adverse effects from mobilization. The majority of patients had subacute or chronic neck pain, and only 13 patients suffered from acute neck pain with the complaint of less than 3 weeks (4 in the preferred group and 9 in the random group). No significant differences between groups in demographic details and pretreatment data were found (P 0.05) as shown in table 1. The number of spinal levels mobilized for both groups were similar, and they varied from 2 to 4 levels. The patients in both groups also received a similar grade of movement for the mobilization. Approximately 90% of the patients in each group were treated with grades IV and IV. Irrespective of the mobilization groups, most patients reported a reduction in neck pain area identified by pain drawing on the body chart. The means SDs of the change scores of each outcome measure for both groups are shown in table 2. In general, the changes in active cervical ROM in all 6 movements were less than 3. After mobilization, 2-way repeated-measures ANOVAs showed significant decreases in neck pain at rest and pain on most painful movement (P 0.001) with a significant increase in active cervical ROM after mobilization on most painful movement (P 0.002) as presented in table 3. No significant interaction effects between group and session were found for all outcome measures except for cervical flexion (P 0.024). Post hoc analysis revealed different effects of mobilization groups on the cervical flexion ROM (fig 2). The preferred mobilization group showed an increase in cervical flexion ROM, whereas the random mobilization group showed a decrease. For both groups, a similar number of patients rated their global perceived effect in each category (table 4). DISCUSSION The results of the current study suggest that, in patients suffering from unilateral mechanical neck pain, the preferred mobilization or the ipsilateral unilateral PA mobilization is no more effective than the random mobilization. These findings do not support the empirical guideline that recommends using the unilateral PA mobilization on the painful side as a preferred mobilization for treating patients presenting with unilateral neck pain. Comparing these results with other research findings Table 3: Results of 2-Way Repeated-Measures ANOVA Testing for Effects of Group, Session, and Interaction Between Group and Session Group (preferred vs random mobilization) Session (pretreatment vs posttreatment) Interaction *P.05. P.001. Variables F 1,58 P F 1,58 P F 1,58 P Pain intensity (mm) At rest 0.000.984 56.363.001 16.133.227 On most painful movement 0.151.699 60.008.001 0.003.957 Active CROM (deg) Flexion 1.369.247 1.249.268 5.410.024* Extension 0.497.484 3.373.071 0.568.454 Ipsilateral lateral flexion 0.024.879 0.416.521 1.028.315 Contralateral lateral flexion 0.253.617 3.260.076 0.217.643 Ipsilateral rotation 0.681.413 0.465.498 0.000.984 Contralateral rotation 0.799.375 2.036.159 0.076.784 On most painful movement 1.488.227 10.795.002* 1.051.310

CERVICAL MOBILIZATION FOR NECK PAIN, Kanlayanaphotporn 191 Table 4: The Number of Patients Who Rated Their Global Perceived Effect in Each of the 7-Point Scale Categories Global Perceived Effect Preferred Random 1 (completely recovered) 2 2 2 (much improved) 9 11 3 (slightly improved) 13 11 4 (no change) 5 6 5 (slightly worse) 1 0 6 (much worse) 0 0 7 (worse than ever) 0 0 is difficult because of the identified lack of studies that used the same mobilization procedure. However, the clinical merits of these mobilization techniques could be established by comparing the outcomes of this study with previous relevant studies. Because of the statistically nonsignificant differences in pain intensity between groups as well as in most active cervical ROM between groups and sessions, retrospective statistical power analysis was conducted. This was to determine the degree of power achieved by the sample size of this study. The magnitudes of the minimum clinically significant difference between group means and between session means were set at 20mm for pain intensity 22 and 4 for active cervical ROM. The power of greater than 90% was found for all comparisons. This suggests that the statistically nonsignificant differences found in this study can be confidently accepted. It is surprising to find nonsignificant differences between the preferred and the random mobilizations in neck pain at rest and on most painful movement because it is believed that the underlying pathology of the unilateral neck pain is originated from the dysfunctions of the zygapophysial joint(s) on the painful side. 3 Therefore, the mobilization that directly targets on altering the kinematic behavior of the affected joint(s) should result in greater pain relief. For the study that used sustained manipulated position as the mobilization procedure, this insignificant effect of the mobilizing side was also reported. 18 Nevertheless, these unexpected findings might relate to the anatomic relationship of the zygapophysial joints by which an alteration in kinematic behavior of the joints on 1 side also influences the kinematic behavior on the other side. Consequently, the zygapophysial joints on the opposite side to those being mobilized would also be mobilized inevitably. Moreover, the underlying pathology of the unilateral neck pain patients in this study might not be unilaterally confined; it was reported in a previous study 5 that approximately 72% of patients suffering with chronic neck pain developed bilateral pathology in their zygapophysial joints. The findings of the present study imply that the mobilization on both sides of the cervical spine would be more beneficial in these patients. However, further study is required to prove this speculation. The insignificant effects of the specific tailoring mobilization technique on the patients outcomes found in this study correspond with the findings of previous studies for nonspecific low back pain. An RCT found that the patients who received the mobilization technique selected by the treating physical therapist showed similar pain reduction and change in lumbar ROM to those who received a randomly selected mobilization technique. 32 A recent meta-analysis study 33 also suggested that the tailoring manual therapy techniques did not improve the outcomes of pain and activity limitation for nonspecific low back pain. Regardless of the mobilization techniques, a slightly greater reduction in neck pain on most painful movement than neck pain at rest was found. No previous studies have reported the change in neck pain on most painful movement after mobilization. For neck pain at rest, the magnitudes of pain reduction agreed with the 10.5-mm reduction for mobilization with muscle energy technique 17 but differed from the 4-mm reduction for sustained stretching in manipulated position. 18 Notably, these reductions were less than the 20-mm value deemed to provide clinical significance. 22 However, these findings must be interpreted with care and should not be taken as an ineffectiveness of these mobilization procedures. As discussed earlier of the possibility of bilateral pathology in chronic unilateral neck pain patients, a greater pain reduction might have been shown if the mobilization had been applied bilaterally. For both groups, the most notable improvement in active cervical ROM after mobilization was on most painful movement (see table 3). These values were also found to be in the same ranges reported by previous studies. 17,18 Because all of the changes were less than 3, which were within the range of the measurement error of this study, this indicated that there were no apparent differences in cervical ROM between the preferred and the random mobilization techniques. These negligible changes in cervical ROM might reflect the trivial changes in the intervertebral segmental ROM during the oscillatory mobilization. 34 More than 36% of patients reported their pain as much improved and completely recovered. In both groups, a similar number of patients rated an immediate improvement in their neck pain in each of the 7-point scale categories. This further supports the comparable effects of the preferred and the random mobilization techniques. Nevertheless, the low proportion of the improved patients might suggest the use of additional modalities for treating these patients. Study Limitations The results of the current study should be interpreted with some potential limitations. First, this study investigated the immediate effects of the preferred mobilization technique. Studies examining the effects of this mobilization technique for a longer duration are required. Second, the majority of the patients included in this study suffered from subacute or chronic neck pain. Different results might be shown if all patients have acute neck pain. Third, the patients were deemed to have unilateral neck pain based on the distribution of their symptoms. Thus, they could not be confidentially claimed to have their pathology localized only on the painful side. Fourth, this study did not assess the patients disability because of neck pain after the treatment. As a result, the effect of mobilization on function was not evaluated. CONCLUSIONS The present study provides evidence that the use of unilateral PA mobilization on the painful side in subacute or chronic unilateral neck pain patients seems unimportant. Nevertheless, all mobilization techniques used in this study could reduce pain at rest and pain on most painful movement. References 1. Fejer R, Kyvik KO, Hartvigsen J. The prevalence of neck pain in the world population: a systematic critical review of the literature. Eur Spine J 2006;15:834-48. 2. Côté P, Cassidy JD, Carroll L. The Saskatchewan health and back pain survey. The prevalence of neck pain and related disability in Saskatchewan adults. Spine 1998;23:1689-98.

192 CERVICAL MOBILIZATION FOR NECK PAIN, Kanlayanaphotporn 3. Maitland GD, Hengeveld E, Banks K, English K. Maitland s vertebral manipulation. 7th ed. Edinburgh: Elsevier Butterworth Heinemann; 2005. 4. Ahn NU, Ahn UM, Ipsen B, An HS. Mechanical neck pain and cervicogenic headache. Neurosurgery 2007;60(1 Suppl 1):S21-7. 5. Manchukonda R, Manchikanti KN, Cash KA, Pampati V, Manchikanti L. Facet joint pain in chronic spinal pain: an evaluation of prevalence and false-positive rate of diagnostic blocks. J Spinal Disord Tech 2007;20:539-45. 6. Cooper G, Bailey B, Bogduk N. Cervical zygapophysial joint pain maps. Pain Med 2007;8:344-53. 7. Manchikanti L, Boswell MV, Singh V, Pampati V, Damron KS, Beyer CD. Prevalence of facet joint pain in chronic spinal pain of cervical, thoracic, and lumbar regions. BMC Musculoskelet Disord 2004;5:15. 8. Fernandez-de-las-Penas C, Downey C, Miangolarra-Page JC. Validity of the lateral gliding test as tool for the diagnosis of intervertebral joint dysfunction in the lower cervical spine. J Manipulative Physiol Ther 2005;28:610-6. 9. Merskey H, Bogduk N. Classification of chronic pain. Descriptions of chronic pain syndromes and definition of pain terms, 2nd ed. Seattle: IASP Pr; 1994. 10. Bogduk N. The neck. Best Pract Res Clin Rheumatol 1999;13: 261-85. 11. Bronfort G, Haas M, Evans RL, Bouter LM. Efficacy of spinal manipulation and mobilization for low back pain and neck pain: a systematic review and best evidence synthesis. Spine J 2004;4: 335-56. 12. Costello J, Jull G. Australian Physiotherapy Association. Neck pain position statement. In: Musculoskeletal Physiotherapy Australia, a national special group of the APA 2002:1-5. 13. Gross AR, Hoving JL, Haines TA, et al. A Cochrane review of manipulation and mobilization for mechanical neck disorders. Spine 2004;29:1541-8. 14. Vernon H, Humphreys BK. Manual therapy for neck pain: an overview of randomized clinical trials and systematic reviews. Eur Medicophys 2007;43:91-118. 15. Sarigiovannis P, Hollins B. Effectiveness of manual therapy in the treatment of non-specific neck pain: a review. Phys Ther Rev 2005;10:35-50. 16. Pikula JR. The effect of spinal manipulative therapy (SMT) on pain reduction and range of motion in patients with acute unilateral neck pain: a pilot study. J Can Chiropr Assoc 1999;43:111-9. 17. Cassidy JD, Lopes AA, Yong-Hing K. The immediate effect of manipulation versus mobilization on pain and range of motion in the cervical spine: a randomized controlled trial. J Manipulative Physiol Ther 1992;15:570-5. 18. Martinez-Segura R, Fernandez-de-las-Penas C, Ruiz-Sáez M, López-Jiménez C, Rodriguez-Blanco C. Immediate effects on neck pain and active range of motion after a single cervical high-velocity low-amplitude manipulation in subjects presenting with mechanical neck pain: a randomized controlled trial. J Manipulative Physiol Ther 2006;29:511-7. 19. Hurwitz EL, Morgenstern H, Harber P, Kominski GF, Yu F, Adams AH. A randomized trial of chiropractic manipulation and mobilization for patients with neck pain: clinical outcomes from the UCLA neck-pain study. Am J Public Health 2002;92:1634-41. 20. Hurwitz EL, Morgenstern H, Vassilaki M, Chiang LM. Frequency and clinical predictors of adverse reactions to chiropractic care in the UCLA neck pain study. Spine 2005;30:1477-84. 21. Ernst E, Canter PH. A systematic review of systematic reviews of spinal manipulation. J R Soc Med 2006;99:192-6. 22. Ostelo RW, de Vet HC. Clinically important outcomes in low back pain. Best Pract Res Clin Rheumatol 2005;19:593-607. 23. Kelly AM. Does the clinically significant difference in visual analog scale pain scores vary with gender, age, or cause of pain? Acad Emerg Med 1998;5:1086-90. 24. Tousignant M, de Bellefeuille L, O Donoughue S, Grahovac S. Criterion validity of the cervical range of motion (CROM) goniometer for cervical flexion and extension. Spine 2000;25:324-30. 25. Tousignant M, Duclos E, Laflèche S, et al. Validity study for the cervical range of motion device used for lateral flexion in patients with neck pain. Spine 2002;27:812-7. 26. Tousignant M, Smeesters C, Breton AM, Breton E, Corriveau H. Criterion validity study of the cervical range of motion (CROM) device for rotational range of motion on healthy adults. J Orthop Sports Phys Ther 2006;36:242-8. 27. Youdas JW, Carey JR, Garrett TR. Reliability of measurements of cervical spine range of motion comparison of three methods. Phys Ther 1991;71:98-106. 28. Capuano-Pucci D, Rheault W, Aukai J, Bracke M, Day R, Pastrick M. Intratester and intertester reliability of the cervical range of motion device. Arch Phys Med Rehab 1991;72:338-40. 29. Fischer D, Stewart AL, Bloch DA, Lorig K, Laurent D, Holman H. Capturing the patient s view of change as a clinical outcome measure. JAMA 1999;282:1157-62. 30. Luckumnueporn T. Cross-cultural adaptation and validation of the Thai version of the Neck Disability Index in patients with mechanical neck pain [dissertation]. Bangkok: Chulalongkorn Univ; 2007. 31. Portney LG, Watkins MP. Foundations of clinical research. Applications to practice, 2nd ed. Upper Saddle River: Prentice Hall Health; 2000. 32. Chiradejnant A, Maher CG, Latimer J, Stepkovitch N. Efficacy of therapist-selected versus randomly selected mobilisation techniques for the treatment of low back pain: a randomised controlled trial. Aust J Physiother 2003;49:233-41. 33. Kent P, Marks D, Pearson W, Keating J. Does clinician treatment choice improve the outcomes of manual therapy for nonspecific low back pain? A meta-analysis. J Manipulative Physiol Ther 2005;28:312-22. 34. McGregor AH, Wragg P, Bull AM, Gedroyc WM. Cervical spine mobilizations in subjects with chronic neck problems: an interventional MRI study. J Back Musculoskeletal Rehabil 2005;18: 21-8. Suppliers a. Performance Attainment Associates, PO Box 528, Lindstrom, MN 55045. b. Version 10; SPSS Inc, 233 S Wacker Dr, 11th Fl, Chicago, IL 60606.