Manual Therapy 16 (2011) 141e147. Contents lists available at ScienceDirect. Manual Therapy. journal homepage:

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1 Manual Therapy 16 (2011) 141e147 Contents lists available at ScienceDirect Manual Therapy journal homepage: Original article The effectiveness of thoracic manipulation on patients with chronic mechanical neck pain e A randomized controlled trial Herman Mun Cheung Lau a, Thomas Tai Wing Chiu a, *, Tai-Hing Lam b a Department of Rehabilitation Sciences, The Hong Kong Polytechnic University, Hung Hom, Hong Kong b Department of Community Medicine, The University of Hong Kong, Hong Kong article info abstract Article history: Received 21 October 2009 Received in revised form 20 July 2010 Accepted 9 August 2010 Keywords: Spinal manipulation Thoracic spine Neck pain The aim of our study was to assess the effectiveness of thoracic manipulation (TM) on patients with chronic neck pain. 120 patients aged between 18 and 55 were randomly allocated into two groups: an experimental group which received TM and a control group without the manipulative procedure. Both groups received infrared radiation therapy (IRR) and a standard set of educational material. TM and IRR were given twice weekly for 8 sessions. Outcome measures included craniovertebral angle (CV angle), neck pain (Numeric Pain Rating Scale; NPRS), neck disability (Northwick Park Neck Disability Questionnaire; NPQ), health-related quality of life status (SF36 Questionnaire) and neck mobility. These outcome measures were assessed immediately after 8 sessions of treatment, 3-months and at a 6-month follow-up. Patients that received TM showed significantly greater improvement in pain intensity (p ¼ 0.043), CV angle (p ¼ 0.049), NPQ (p ¼ 0.018), neck flexion (p ¼ 0.005), and the Physical Component Score (PCS) of the SF36 Questionnaire (p ¼ 0.002) than the control group immediately post-intervention. All these improvements were maintained at the 6-month follow-ups. This study shows that TM was effective in reducing neck pain, improving dysfunction and neck posture and neck range of motion (ROM) for patients with chronic mechanical neck pain up to a half-year post-treatment. Ó 2010 Elsevier Ltd. All rights reserved. 1. Introduction Neck pain is a common musculoskeletal disorder in the general population. In Saskatchewan, Canada, Cote et al. (2000) reported that the age-standardized lifetime prevalence of neck pain was 66.7%. In a telephone survey performed in Hong Kong, Chiu and Leung (2006) reported that the lifetime prevalence of neck pain was 65.4% and the 12-month prevalence was 53.6% (41.0% in male, 59.0% in female). Neck pain is costly in terms of treatment, individual suffering, and time lost to work absentee (Rempel et al., 1992). Growing evidence has confirmed that the use of manipulation with exercise or the use of mobilization with exercise in treating neck pain has better clinical outcomes than other major and common modalities (Greenman, 1996; Gross et al., 2002; Flynn et al., 2007). Owing to the intrinsic biomechanical linkage with the cervical spine, disturbances in the biomechanics of the thoracic spine could * Corresponding author. Tel.: þ ; fax: þ address: rstchiu@polyu.edu.hk (T.T. Wing Chiu). be a primary contributor to neck pain (Flynn et al., 2007). Flynn et al. (2007) reported that with the use of thoracic manipulation (TM), there was immediate improvement in neck pain. However the lack of comparative group in this trial renders the cause-andeffect relationship inconclusive (Flynn et al., 2007). Many clinicians have intuitively adopted the use of TM to treat neck pain patients, although there is a lack of scientific evidence. Cleland et al. (2005) reported that thoracic spine is the area that is most often manipulated. There are studies investigating the effect of TM in treating acute and subacute mechanical neck pain (Cleland et al., 2005, 2007a,b; Fernandez-de-las-Penas et al., 2007; Gonzalez-Iglesias et al., 2009a,b), but to date, no studies have investigated the effect in patients with chronic neck pain. In a randomized controlled trial, Cleland et al. (2005) demonstrated an immediate analgesic effect in patients with mechanical neck pain. However the study was limited to a short-term follow-up and the effects on disability and physical impairments e.g. cervical range of motion (ROM) was not evaluated (Cleland et al., 2005). In contrast, Parkin-Smith and Penter (1998) demonstrated that the combination of cervical and TM did not result in any significant benefit than cervical manipulation alone. Another trial comparing the effect of TM and instructed exercise in the management of neck X/$ e see front matter Ó 2010 Elsevier Ltd. All rights reserved. doi: /j.math

2 142 H.M.C. Lau et al. / Manual Therapy 16 (2011) 141e147 shoulder pain revealed that there was a statistically significant reduction in the level of perceived worst pain after 12-months follow-up (Savolainen et al., 2004). As there is a lack of general consensus on the efficacy of TM for patients with neck pain, a well designed trial studying the clinical effects of TM in treating mechanical neck pain with substantial period of follow-up is necessary. 2. Methodology 2.1. Subjects A sample of 120 patients with a diagnosis of chronic mechanical neck pain by a primary care physician were recruited from an outpatient clinic of the Prince of Wales Hospital and randomly allocated to a TM group (Group A) and a control group (Group B). Patients whose age ranged between 18 and 55 with a diagnosis of mechanical neck pain for more than 3 months were recruited. Patients who had one or more of the following conditions such as: contraindication to manipulation (Gonzalez-Iglesias et al., 2009a,b), history of whiplash or cervical surgery, diagnosis of fibromyalgia syndrome (Wolfe et al., 1990), having undergone spinal manipulative therapy in the previous 2 months or loss of standing balance were excluded from the current study. Explanation and informed consent were obtained from each subject. This study was approved by the ethical review board of the university Randomization Patients were randomly allocated to the TM group or the control group by using computer-generated minimization method (Jenson, 1991) taking into account of their age, gender, and degree of disability resulting from neck pain. A computer program for randomization was installed in a notebook computer. After a senior physiotherapist keyed in the patients particulars, the program automatically allocated the grouping of the patient according to the minimization theory that yielded the smallest imbalance between the two groups. The computer-based randomization also helps establish allocation concealment, which is an essential part of a randomized trial. The senior physiotherapist then notified the physiotherapist in-charge for the group allocation of individual patient through a sealed envelope in the patients bed-notes Outcome measures For the baseline examination and the subsequent follow-ups, each subject reported his/her intensity of neck pain by the verbal Numeric Pain Rating Scale (NPRS) (Jensen et al., 1986) (scale: 0 ¼ no paine10 ¼ worst pain), which was the primary outcome, and completed two sets of questionnaires [Northwick Park Questionnaire (NPQ) (Chiu et al., 2001) and SF36 health-related quality of life questionnaire (SF36)] as subjective measurements. For objective measurements, subjects cervical ROM was measured by the Hanoun Multi-Cervical Unit (MCRU) (Chiu and Lo, 2002). The craniovertebral (CV) angle of these subjects was also measured by an Electronic Head Posture Instrument (EHPI) (Lau et al., 2009) Sample size calculation The rationale for calculating the sample size was as follows: From a related study (Chiu et al., 2001) (N ¼ 90) using the same questionnaire (NPQ), it was found that the mean and standard deviation of the neck pain score were and 5.823, respectively. Assuming that the TM group would improve by 50% and the control group would improve by 25%. Assuming a 0.5 correlation between the pre- and post-measurement, and the standard deviations in the pre- and post-intervention measurement would be about the same, the standard deviation for their difference would be about the same as that of the original measurement (or smaller if the correlation is higher). Using 5% alpha, 90% power, 2-sided alternative test on the difference between pre- and post-measurement, it was estimated that 60 subjects should be required for each group Study design Group A received TM including 8 sessions (2/week) of infrared radiation therapy (IRR) for 15 min over the painful site. TM (anterioreposterior approach in supine lying) (Gibbons and Tehan, 2000) was given and the level of TM was determined according to clinical assessment (which includes movement analysis and palpation) by an experienced physiotherapist who had post-graduate training in spinal manipulative therapy and with at least 5 years of clinical experience in the management of neck pain patients with manual procedures (Appendix 1). A standard set of educational materials illustrating the simple pathology of neck pain and general advice on neck care was also given. Neck exercises prescribed in the educational pamphlet mainly involve active neck mobilization, isometric neck muscle contraction for stabilization, stretching of upper trapezius and scalene muscles and postural correction exercise. For the mobilization exercises, subjects were instructed to perform 10 repetitions of movement in flexion, extension, side flexion and rotation. For the isometric muscle contractions, subjects were instructed to sustain a contraction in flexion, extension, side flexion and rotation for 5 s and repeat this for 10 repetitions. For the stretching exercise, subjects were instructed to hold a stretched position for 5e8 s for 10 repetitions. All exercises were to be performed daily. Group B was the control group and received 8 sessions (2/week) of the same IRR treatment together with the same set of educational materials. IRR was suitable as a control intervention as it gives only superficial heating (almost all energy is absorbed at a depth of 2.5 mm) and the effect is not long lasting (Chiu et al., 2005). All subjects were evaluated and assessed at baseline, immediately after 8 sessions of treatment, at 3-months and at a 6-month follow-up by a blinded assessor Data analysis Data was analysed with the SPSS package (Version 16.0). The TM group was compared with the control group at the baseline by independent t-tests. After the intervention, statistical analysis for the difference (i.e. difference between the pre- and postmeasurement) of all outcome measures in both groups were compared by using repeated-measures analysis of variance (ANOVA). The mean difference and their standard deviation were calculated. Moreover, repeated-measures ANOVA was used to investigate whether there was any change after the intervention in each group. Paired t-tests with Bonferroni adjustment were adopted for the post-hoc analysis. Between-group effect size was calculated using Partial Eta squared. A p value of less than 0.05 was considered statistically significant Missing data Some subjects did not return for the follow-up assessments. All of these subjects were contacted again by phone to identify the reason and to determine the treatment effect. The present study adopted the following methods to impute the missing data: (1) For those subjects who failed to attend the follow-up because of

3 H.M.C. Lau et al. / Manual Therapy 16 (2011) 141e dissatisfaction of the intervention effect or worsening of symptoms after treatment, a mean percentage of worsening of symptoms was calculated from all the observed subjects of both groups whose condition had become worse and the missing data was replaced by the product of the mean percentage and the baseline measurement. (2) For those subjects whose condition was improving but they could not attend because of time constraints, a mean percentage of improvement was calculated from all the observed subjects of both groups whose condition had been better, and the missing value was replaced by the product of the mean percentage and the baseline measurement. (3) For those subjects whose treatment effect was unknown, the baseline value was used for imputation. 3. Results 3.1. Baseline descriptive statistics A total of 120 patients (60 in each group with 30 male and 30 female) were recruited and followed up in the study from June 2007 to June There was no significant difference in gender between the control and the TM group. [t (118) ¼ 0.000; p ¼ 1]. The age range of the patients was between 18 and 55 with a mean age of (SD ¼ 9.25) and (SD ¼ 9.27) in the control and the TM group respectively. There was no significant difference in age between the two groups [t (118) ¼ 0.227; p ¼ 0.821]. All patients completed the 4 week, 8 sessions of treatment, and they all completed most of the follow-up evaluations up to 6-months posttreatment. No discomfort or any other adverse conditions were reported after the TM or other treatment procedures. The participants flow of follow-up evaluation from immediately post-treatment till the 6-month follow-up is illustrated in Fig Baseline measurement There was no significant difference in any of the parameters between the control and the TM group at the baseline measurement. The p value ranges from 0.11 to 0.91 (Table 1) Post-treatment measurements The mean values, 95% CI and standard deviation of all parameters in both the control and treatment group and the 95% CI of between-group comparison and the interaction effect between time and groups are listed in Tables 2e4 respectively Northwick Park Neck Disability Questionnaire (NPQ) Both groups demonstrated a decrease in NPQ immediately post treatment which remained decreased up to 6-months post-treatment. The TM group showed a significantly greater decrease in NPQ compared to the control group from immediately post-intervention up to the 6-month follow-up (p ¼ 0.018, and respectively). Details of NPQ in both groups during the entire study are shown in Tables 2e CV angle The CV angle was increased in both groups right after treatment and up to the 6-month post-treatment period. A statistically significant difference was detected up to 6-months post-treatment (p ¼ 0.049, and respectively). Details of the CV angle in both groups throughout the study are shown in Tables 2e Numeric Pain Rating Scale (NPRS) Patients in the TM group showed a significantly greater reduction in pain than that of the control group from immediate posttreatment (p ¼ 0.043) to the 6-month follow-up (p ¼ and p ¼ respectively). Details of the NPRS in both groups throughout the study are shown in Tables 2e Cervical ROM Flexion Flexion increased in both groups immediately after 4 weeks of treatments and continued to increase 6-months post-treatment (p values are 0.005, <0.001 and <0.001 respectively) Extension (E), left side flexion (LSF) and right side flexion (RSF) Both groups showed improvement in E, LSF and RSF immediately after the 4-week intervention and up to the 6-month followup. Yet the improvement shown in the TM group became significantly better than that of the control group from the 3-month follow-up onwards up to 6 months (p values for E from 3-month to 6-month follow-up are and respectively; p values for LSF are and and p values for RSF are and respectively). Details of changes in E, LSF and RSF in both groups are listed in Tables 2e Left rotation (LR) and right rotation (RR) LR and RR improved in both groups immediately after treatment and was maintained at 6 months. Although statistically not significant, the TM group showed a greater increase than the control group. Details of the cervical ROM in both groups during the entire study are shown in Tables 2e SF36 e PCS and Mental Component Score (MCS) There was an increase in PCS and MCS 6-months post-treatment. The TM group showed a greater increase than the control group in PCS and MCS. However, only the difference shown in PCS was statistically significant throughout the study (p values ¼ 0.002, <0.001 and <0.001 respectively at different follow-up assessments). Details of changes in PCS and MCS in both groups during the entire study are shown in Tables 2e4. 4. Discussion 4.1. Subjects/populations selected for the study Patients in the present study came from one of the largest typical physiotherapy outpatient departments in Hong Kong, thus the population should be a reasonably representative sample of patients with chronic mechanical neck pain. In addition, their displayed pain intensity and disability were comparable to those of typical patients with chronic mechanical neck problems listed in many previous studies (Ylinen et al., 2003; Chiu et al., 2005). Hence, the results of the present study could be generalized to patients with chronic mechanical neck pain Change in NPQ Improvement in NPQ was significantly better in the TM group than that of the control group up to 6 months. A randomized clinical trial by Gonzalez-Iglesias et al. (2009a,b) also demonstrated that TM in patients with acute mechanical neck pain showed a greater improvement in perceived neck disability (NPQ) with a between-group difference of 8.5 points where the current study

4 144 H.M.C. Lau et al. / Manual Therapy 16 (2011) 141e147 Enrollment Assessed for elgibility (n=198) Excluded (n=78) Eligible but refused to particiate (n=12) Not meeting inclusion criteria (n=66) Randomised (n=120) Allocation (Manipulation Group) Allocated to intervention (n=60) Received allocated intervention (n=60) Did not receive allocated intervention (n=0) (Control Group) Allocated to intervention (n=60) Received allocated intervention (n=60) Did not receive allocated intervention (n=0) Baseline Assessment Discontinued follow up (n=0) Not enough time to attend =0 Dissatisfied with treatment effect =0 Worsening of symptoms=0 Other reason =0 Discontinued follow up (n=0) Not enough time to attend =0 Dissatisfied with treatment effect =0 Worsening of symptoms =0 Other reason =0 Immediate follow up Discontinued follow up (n=3) Not enough time to attend =2 Dissatisfied with treatment effect=1 Worsening of symptoms =0 Other reason =0 Drop out rate=5% of the manipulation group Discontinued follow up (n=6) Not enough time to attend =1 Dissatisfied with treatment effect =2 Worsening of symptoms=2 Other reason =1 Drop out rate=10% of the control group Post 3 months follow up Discontinued follow up (n=5) Not enough time to attend =2 Dissatisfied with treatment effect =1 Worsening of symptoms=1 Other reason= 1 Drop out rate=8.33% of the manipulation group Discontinued follow up (n=11) Not enough time to attend =3 Dissatisfied with treatment effect =3 Worsening of symptoms =4 Other reason= 1 Drop out rate=18.33% of the control group Post 6 months follow up Discontinued follow up (n=6) Not enough time to attend =3 Dissatisfied with treatment effect=1 Worsening of symptoms =1 Other reason =1 Drop out rate=10% of the manipulation group Discontinued follow up (n=11) Not enough time to attend =2 Dissatisfied with treatment effect =4 Worsening of symptoms =4 Other reason =1 Drop out rate=18.33% of the control group Analysis Analyzed (n=60) Excluded from analysis by intention to treat (n=0) Analyzed (n=60) Excluded from analysis by intention to treat (n=0) Fig. 1. Participant flow and follow-up evaluation. showed similar results of 6.0e8.9 points. However, their study terminated at 1 week post-treatment with no longer follow-up evaluation Changes in CV angle The TM group showed a significantly better improvement than the control group up to 6-months post-treatment. However, the control group failed to demonstrate any significant change to the CV angle for the rest of the study after completion of treatment. To the best of the author s knowledge, the current study is the first to investigate the effect of TM on the CV angle. This study provides evidence that TM could lead to an improvement in head posture as a result of the significant increase in the CV angle.

5 H.M.C. Lau et al. / Manual Therapy 16 (2011) 141e Table 1 Baseline characteristics of patients. Intervention Control P* n Age (yr) Mean/SD 44.17/ / Range 18e55 19e55 Gender (n) Male a Female NPQ Mean/SD 39.15/ / Range 9.38e e71.88 CV Mean/SD 44.27/ / Range 9.38e e55.40 NPRS Mean/SD 5.02/ / Range 1e10 2e8 F Mean/SD 48.99/ / Range 26.77e e65.10 E Mean/SD 47.30/ / Range 24.40e e67.07 LSF Mean/SD 33.20/ / Range 14.57e e49.63 RSF Mean/SD 34.00/ / Range 15.73e e50.02 LR Mean/SD 54.57/ / Range 27.10e e81.80 RR Mean/SD 56.16/ / Range 34.77e e80.32 MCS Mean/SD 43.92/ / Range 19.18e e70.87 PCS Mean/SD 38.35/ / Range 9.11e e51.59 *P values of comparison of baseline characteristics using independent T-test. MCS ¼ Mental Component Score; PCS ¼ Physical Component Score; NPQ ¼ Northwick Park Neck Disability Questionnaire; CV ¼ Craniovertebral angle; NPRS ¼ Numeric Pain Rating Scale; F ¼ Flexion; E ¼ Extension; LSF ¼ Left Side Flexion; RSF ¼ Right Side Flexion; LR ¼ Left Rotation; RR ¼ Right Rotation. a As determined by chi square test for independence Changes in NPRS Both groups showed improvement in NPRS after completion of a 4-week intervention up to the 6-month follow-up. In addition, the improvement shown (reduction in NPRS) in the TM group was better than the reduction in NPRS in the control group throughout the entire study period. Hence TM was shown to have a positive influence in NPRS reduction with an effect lasting up to 6-months posttreatment. It is important to note that between-group differences for pain achieved by the thoracic spine thrust manipulation group in this present study was not only statistically significant but also clinically meaningful as the improvement exceeded the clinically important benefit (15%) as suggested by the Philadelphia Panel (2001) (decrease in NPRS ranged from 34.4% to 40.6% in the TM group). In a prospective study on the efficacy of different treatments for chronic mechanical neck pain patients (Muller and Giles, 2005), results showed that TM significantly decreased mean NPRS from 6 to 2.3 (reduction of 3.7) whereas the present study showed an average reduction of 1.20 in NPRS. However, the total treatment sessions were 9 weeks as compared with only 4 weeks in the current study. In an RCT study comparing the short-term effect of a single TM and mobilization in patients with neck pain by Cleland et al. (2007a,b), the results showed similar findings as the present study with a significantly greater reduction in NPRS by TM than mobilization 2e4 days after the intervention Changes in cervical ROM Except for rotation, improvement in cervical ROM was significantly better in the TM group at 3-months and 6-months posttreatment. Moreover, flexion ROM was significantly greater immediately post-treatment in the TM group. A case study on the effect of TM on neck pain and ROM (Fernandez-de-las-Penas et al., 2007) showed there was a significant decrease in neck pain and a trend toward an increase in cervical ROM after a single TM. In a randomized controlled trial on the treatment of mechanical neck disorders, cervical ROM improvement was better immediately following a single high velocity, low-amplitude manipulation than following regular physiotherapy treatment (Martinez-Segura et al., 2006). Yet both studies were only evaluating the immediate effect (with 48 h) and there was no comparison with a control. Similar results were demonstrated by Flynn et al. (2007). They reported that TM resulted in an immediate increase in cervical ROM in patients with primary neck dysfunction. However, owing to the Table 2 Results at post-treatment immediate follow-up. Outcome Measures Control Intervention P value for Mean (95%Cl) SD Mean (95%Cl) SD interaction effect between time and group Between-group comparison by ANOVA (95%CI) NPQ (32.11e40.71) (22.60e30.78) * 28.58e34.52* CV (42.91e45.81) (45.80e48.56) * 44.77e46.77* NPRS 4.37 (3.89e4.93) (2.49e3.47) * 3.33e4.05* F (46.85e51.40) (54.79e59.12) * 51.47e54.61* E (47.21e51.74) (50.31e54.63) e52.54 LSF (32.96e38.26) (36.95e42.00) * 35.71e39.37 RSF (33.89e38.63) (38.06e42.58) * 36.65e39.93 LR (54.76e61.13) (59.18e65.24) e62.27 RR (54.03e61.86) (59.02e66.48) * 57.65e63.06 MCS (43.80e49.43) (42.88e48.24) e48.03 PCS (32.98e37.90) (39.45e44.14) e40.32* *P < MCS ¼ Mental Component Score; PCS ¼ Physical Component Score; NPQ ¼ Northwick Park Neck Disability Questionnaire; CV ¼ Craniovertebral angle; NPRS ¼ Numeric Pain Rating Scale; F ¼ Flexion; E ¼ Extension; LSF ¼ Left Side Flexion; RSF ¼ Right Side Flexion; LR ¼ Left Rotation; RR ¼ Right Rotation.

6 146 H.M.C. Lau et al. / Manual Therapy 16 (2011) 141e147 Table 3 Results at 3-months follow-up. Outcome Measures Control Intervention P value for Mean (95%Cl) SD Mean (95%Cl) SD interaction effect between time and group Between-group comparison by ANOVA (95%CI) NPQ (31.12e39.69) (23.40e31.57) e34.40* CV (42.28e44.87) (45.16e47.63) * 44.09e45.88* NPRS 4.41 (3.89e4.93) (2.74e3.74) * 3.46e4.19* F (45.54e50.24) (53.56e58.04) * 50.22e53.47* E (44.93e49.39) (51.73e55.98) e52.05* LSF (34.85e39.25) (41.45e45.64) * 38.78e41.82* RSF (34.46e38.30) (39.05e42.70) * 37.30e39.95* LR (54.68e61.00) (58.81e64.84) e62.02 RR (50.96e58.19) (57.70e64.59) * 55.36e60.36 MCS (43.52e50.00) (42.85e49.02) e48.59 PCS (31.91e36.76) (39.25e43.87) e39.62* *P < MCS ¼ Mental Component Score; PCS ¼ Physical Component Score; NPQ ¼ Northwick Park Neck Disability Questionnaire; CV ¼ Craniovertebral angle; NPRS ¼ Numeric Pain Rating Scale; F ¼ Flexion; E ¼ Extension; LSF ¼ Left Side Flexion; RSF ¼ Right Side Flexion; LR ¼ Left Rotation; RR ¼ Right Rotation. lack of comparison group in the study, no conclusion about the cause-and-effect relationship could be drawn. In addition, only the short-term positive effect was investigated in their study while the present study showed improvement in cervical ROM up to 6-months post-treatment. More importantly, the significant improvement in cervical ROM after TM in the present study gives good support to the biomechanical implications associated with thoracic spine manipulation in patients with neck pain. Our results suggest that TM could help restore normal biomechanics to the cervical-thoracic motion segment, leading to a decrease in mechanical stress to the cervical spine and thus improve neck pain Adverse effects from the present study The types of benign, self-limiting adverse events from TM have been prospectively and systemically described in different studies (Leboeuf-Yde et al., 1997; Sentad et al., 1997; Barrett and Breen, 2000; Cagnie et al., 2004; Hurwitz et al., 2004; Rubinstein et al., 2007). Generally, those events are mild to moderate in intensity, have little to no influence on activities of daily living, and spontaneous recovery, typically lasting not more than a few days (Rubinstein, 2008). However, no adverse effect was reported from the TM group throughout the entire study period (up to 6-months post-treatment) in the present study Changes in MCS, PCS (SF36) Although a statistically significant result was shown only in the PCS domain, the TM group had improvement in the health-related quality of life in both MCS and PCS. Results reported by Muller and Giles (2005) showed that spinal manipulation significantly improved neck disability and SF36 after a 1-year follow-up. However, the total treatment sessions were 9 weeks as compared with only 4 weeks in the present study. In addition, cervical manipulation instead of TM was performed in their study Limitations of present study As the present study only recruited patients with chronic nonspecific neck pain, the results of the study may not apply to patients with acute neck pain conditions such as whiplash injury. In addition, the sample size of the present study did not allow subgroup analysis of the effects of TM on patients of different genders or age groups. Furthermore, the time spent in the TM in the treatment group was higher than the control group. The cost effectiveness of the TM for treating neck pain needs to be evaluated in future studies. Table 4 Results at 6-months follow-up. Outcome Measures Control Intervention P value for Mean (95%Cl) SD Mean (95%Cl) SD interaction effect between time and group Between-group comparison by ANOVA (95%CI) NPQ (30.35e39.25) (24.53e33.01) e34.86* CV (42.18e44.80) (45.38e47.87) e45.96* NPRS 4.24 (3.69e4.80) (2.46e3.51) * 3.23e3.99* F (47.06e52.37) (52.03e57.09) * 50.30e53.97* E (46.85e51.76) (50.76e55.44) e52.90* LSF (34.46e40.15) (39.59e45.01) * 37.84e41.77* RSF (32.28e37.59) (37.87e42.92) * 35.83e39.50* LR (52.39e59.79) (58.84e61.90) e59.79 RR (49.80e56.36) (57.08e63.33) * 54.38e58.91 MCS (43.60e49.49) (42.55e48.16) e47.99 PCS (33.11e38.22) (38.81e43.67) e40.21* *P < MCS ¼ Mental Component Score; PCS ¼ Physical Component Score; NPQ ¼ Northwick Park Neck Disability Questionnaire; CV ¼ Craniovertebral angle; NPRS ¼ Numeric Pain Rating Scale; F ¼ Flexion; E ¼ Extension; LSF ¼ Left Side Flexion; RSF ¼ Right Side Flexion; LR ¼ Left Rotation; RR ¼ Right Rotation.

7 H.M.C. Lau et al. / Manual Therapy 16 (2011) 141e Conclusion The effect of TM was shown to be positive in reducing neck pain, improving dysfunction and neck posture, and neck ROM up to half a year post-treatment. In treating patients with chronic mechanical neck pain, TM could be a choice for effective management. Appendix 1. Procedure of TM 1. The subject lay supine with the arms crossed over the chest and hands passed around the shoulder with the thoracic spine was in neutral position. 2. The hand of the therapist contacted with a neutral hand position over the spinous process of the selected thoracic level (inferior vertebra of the motion segment). 3. The other hand stabilized the head, neck, and upper thoracic spine of the subject. 4. Gently, flexion of the thoracic spine was introduced until slight tension was palpated in the tissues at the therapist s contact point. 5. Then, a high velocity, low-amplitude technique downward toward the couch and in a cephalad direction was applied (Fig. 1). 6. A cracking or popping sound accompanied all manipulations. 7. If no popping sound was heard on the first attempt, the therapist repositioned the subject, and the therapist performed a second manipulation over the same selected thoracic level(s). 8. A maximum of 2 attempts was performed on each subject at each session. References Barrett AJ, Breen AC. Adverse effects of spinal manipulation. Journal of the Royal Society of Medicine 2000;93:258e9. Cagnie B, Vinck E, Beernaert A, Cambier D. How common are side effects of spinal manipulation and can these side effects be predicted? Manual Therapy 2004;9:151e6. Chiu TW, Lam TH, Hedley AJ. Subjective health measure used on Chinese patients with neck pain in Hong Kong. Spine 2001;26:1884e9. Chiu TW, Lam TH, Hedley AJ. A randomized controlled trial on the efficacy of exercise for patients with chronic neck pain. Spine 2005;30:E1e7 [Miscellaneous Article]. Chiu TW, Leung SL. Neck pain in Hong Kong: a telephone survey on prevalence, consequences and risk groups. Spine 2006;31:E540e4. Chiu TW, Lo SK. Evaluation of cervical range of motion and isometric neck muscle strength: reliability and validity. Clinical Rehabilitation 2002;16:851e8. Cleland JA, Childs JD, Fritz JM, Whitman JM, Eberhart SL. Development of a clinical prediction rule for guiding treatment of a subgroup of patients with neck pain: use of thoracic spine manipulation, exercise and patient education. Physical Therapy 2007a;87:9e23. Cleland JA, Glynn P, Whitman JM, Eberhart SL, MacDonald C, Childs JD. Short-term effects of thrust versus nonthrust mobilization/manipulation directed at the thoracic spine in patients with neck pain: a randomized clinical trial. Physical Therapy 2007b;87(4):431e40. Cleland JA, Childs JD, McRae M, Palmer JA, Stowell T. 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