The effects of high-velocity low-amplitude thrust manipulation by Qualified Physio

International Journal of Osteopathic Medicine 12 (2009) 56–62

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Research report

The effects of high-velocity low-amplitude thrust manipulation and mobilisation techniques on pressure pain threshold in the lumbar spine Oliver Thomson a, b, c, *, Lesley Haig b, Hazel Mansﬁeld c a

Stockholm College of Osteopathic Medicine, Stockholm, Sweden School of Human Sciences, St Mary’s University College, Twickenham, UK c British College of Osteopathic Medicine, London, UK b

a r t i c l e i n f o

a b s t r a c t

Article history: Received 8 February 2008 Received in revised form 30 June 2008 Accepted 18 July 2008

Objective: To compare changes in pressure pain threshold (PPT) following spinal high-velocity lowamplitude thrust manipulation (HVLAT) and spinal mobilisation.

Keywords: Osteopathy Algometry Pain Hypoalgesia

Design: Fifty asymptomatic subjects (mean age 27 (6) years; 29 males and 21 females) volunteered to participate in a randomised controlled, singled blinded design study. Subjects were screened for suitability and were randomly allocated into one of three intervention groups where they received either a unilateral spinal HVLAT or a spinal mobilisation of the lumbar spine, or a sham ‘laser’ procedure (control). PPT measurements were made immediately pre- and post-intervention, using a hand-held algometer which was positioned directly over the lumbar spinous process. A two-way ANOVA with repeated measures was conducted to determine PPT changes between the groups. Statistical significance was set at the 0.05 level. Results: There were no significant differences in PPT across time for each of the groups (P ¼ 0.584). The mobilisation group displayed a small increase, though not a significant change in the mean pressure pain threshold (0.434(0.55) kg/cm2), although effect size was considered to be large (ES ¼ 0.78). The HVLAT group demonstrated a decrease in the mean PPT ( 0.173(0.48)) (ES ¼ 0.36, small), and a smaller decrease was noted for the control group (0.105(0.425) kg/cm2) (ES ¼ 0.25, small). Conclusion: Neither spinal HVLAT nor mobilisation had a significant effect on PPT of the lumbar spine in asymptomatic subjects. Only spinal mobilisation appeared to have a greater mean increase in PPT and effect size than the control group. Further investigation into the hypoalgesic effects of these techniques on symptomatic subjects is suggested. Ó 2008 Elsevier Ltd. All rights reserved.

1. Introduction Spinal manipulative therapy (SMT) such as mobilisation and manipulation techniques are commonly used by osteopaths, chiropractors and physiotherapists for the treatment of low back pain and dysfunction. Spinal manipulation has been studied frequently in randomised clinical trials1–4 with mobilisation receiving relatively less attention. Both techniques have been subject to structured reviews and meta-analyses which suggest that their use leads to clinically signiﬁcant improvements in pain and function.5–14 Mobilisation involves oscillatory repetitive movements against a restrictive barrier, and can be applied to a single articulation or multiple spinal segments.15 Mobilisation techniques are performed at relatively low velocities, where the force and amplitude can be

controlled.16–18 Manipulation, as opposed to mobilisation, involves a high-velocity low-amplitude thrust (HVLAT) directed to a synovial joint within a very short amplitude.19 There is commonly an associated ‘pop’ or ‘cracking’ noise which has been termed ‘cavitation’ and is thought to occur as a result of the formation and collapse of gas bubbles within the joint.17–20 It has been proposed that SMT has a number of therapeutic effects, including the stretching of thickened peri articular soft tissue, improving the range of motion, reducing oedema around a joint and reducing pain.15,17,21,22 A large body of research has investigated the effect of HVLAT on the modulation and reduction in pain levels.15,23–25 The mechanisms by which these effects are achieved are not yet fully understood, with a large number of possible theories suggested.19,26–33 1.1. Spinal HVLAT manipulation

* Corresponding author. Stockholm College of Osteopathic Medicine, Kronobergsgatan 49 (1 tr), 112 33 Stockholm, Sweden. Tel.: þ46 (0)738 529 119. E-mail address: oliver.thomson@hotmail.com (O. Thomson). 1746-0689/$ – see front matter Ó 2008 Elsevier Ltd. All rights reserved. doi:10.1016/j.ijosm.2008.07.003

A large proportion of the studies investigating the neurophysiological aspect of spinal HVLAT demonstrates a hypoalgesic effect

O. Thomson et al. / International Journal of Osteopathic Medicine 12 (2009) 56–62

that is significantly different from placebo, with a large number of studies initiating pain via the application of pressure on spinal tissues, termed pressure pain threshold (PPT).15,21,24,34,36–39 Terrett and Vernon34 carried out a study looking at changes in the cutaneous receptive field following an HVLAT of the thoracic spine of 53 asymptomatic subjects. The results showed a significantly higher threshold to cutaneous pain over the paraspinal tissue of the manipulation group compared to the control group. As the control group received the same degree of manual contact and joint motion as the HVLAT group, but did not receive a manipulation resulting in a cavitation, it is possible that the critical aspect which provided a hypoalgesic effect was the rapid thrust which occurred in an HVLAT. Similar results have been seen following manipulation of the cervical spine.39–42 In a small study investigating subjects with neck pain, PPT values were shown to increase by an average of 40– 56% for up to 5 min following the manipulation. There was no significant change in PPT in any of the control group subjects. However, due to the small sample size (n ¼ 9), the results of this study must be treated with caution. More recently, Fryer et al15 reported that both manipulation and mobilisation had a significant effect of increasing the threshold to pain when compared to a control group. It appeared that mobilisation was more effective for reducing PPT, producing a greater immediate improvement. These results were in contrast to those of Cassidy et al35 who demonstrated an immediate reduction in almost 85% of the subjects following manipulation, which was greater than that reported by the mobilisation group, suggesting that both techniques may have an immediate hypoalgesic effect. These results are in accordance with those observed by Vernon et al.21 Other studies have failed to show a significant decrease in pain following spinal HVLAT.36,37,43 A large body of evidence has suggested that hypoalgesia observed following SMT is a result of the activation of endogenous descending pathways in the brain inhibitory systems, mediated through the midbrain dorsal periaqueductal grey region (dPAG).23,24,31,41,44 It has been suggested that stimulation of dPAG produces profound selective analgesia.23,24,31,41,44,45 It is known that excitation of the sympathetic nervous system results from stimulation of the dPAG46 and as such has received a considerable amount of attention in the literature. It is possible that these mechanisms play a part in the short and long term relief in symptomatic patients but may not be relevant to hypoalgesia following HVLAT in pain free patients.26,37 Sterling et al41 investigated the neurophysiological mechanisms of spinal mobilisation in subjects with neck pain by looking at the associated sympathetico-excitatory effects. Following mobilisation of the cervical spine, a hypoalgesic effect was demonstrated by way of a reduction in PPT and a mean decrease in VAS score. A sympathetic-excitatory effect was demonstrated by way of a reduction in skin temperature and increase in skin conductance. There have been other suggestions for the hypoalgesia seen following spinal HVLAT. One such theory proposes that the reduction in pain is due to the activation of the endogenous antinociceptive system subserved by plasma b-endorphins.42,47,48 Vernon et al42 investigated this theory by measuring plasma bendorphin levels in 21 subjects following a cervical spine HVLAT. Only the HVLAT group displayed a small though significant increase in b-endorphin levels following the intervention. Subsequent studies into the b-endorphin system failed to show any significant effect.47,48 However, Vernon29 identified methodological flaws used by the investigators including a low sensitivity of assay levels used to detect b-endorphin levels and also the region of the spine receiving the manipulative procedure. It is speculated that the gate control theory, as proposed by Melzack and Wall,27 may also play a role in hypoalgesia following

HVLAT. It is believed that large diameter myelinated neurons from mechanoreceptors modulate and inhibit the smaller diameter nociceptive input at the level of the spinal cord. Both joint HVLAT and mobilisation procedures would have the effect of stimulating joint mechanoreceptors through movement of the peri articular tissues, and thus inhibiting pain.26 1.2. Spinal mobilisation Whilst spinal manipulation has undergone intense scrutiny, mobilisation has received relatively little investigation. A large proportion of studies looking at the effects of lumbar mobilisation has incorporated other treatments. For example, Farrell and Twomey49 found that a combination of manipulation and mobilisation produced a more rapid recovery of low back pain patients when compared to a ‘control’ group receiving microwave diathermy, abdominal exercises and ergonomic education. This is in agreement with Koes et al50,51 who, over two studies, compared four different interventions; combined manipulation and mobilisation, physiotherapy and treatments by the patients medical physician (consisting of medication and advice), and a placebo group. There was the greatest improvement in both the manipulation/mobilisation group and physiotherapy group, compared to the medical physician and placebo groups. To date, only a handful of studies have examined the effects of spinal manipulation and mobilisation separately.25,45,52–54 Hadler et al53 directly compared the effect of manipulation and mobilisation on patients with acute low back pain. The group who received manipulation had a greater improvement than the group who received mobilisation without a ‘rotatory thrust’. However, Goodsell et al25 found no measurable improvement in the mechanical behaviour of the lumbar spine following anteriorposterior mobilisation in symptomatic subjects, but an improvement in pain free active movements of the spine was seen. Similarly, Petty54 observed no difference in flexion and extension ranges following posterior-anterior mobilisations to the lumbar spine. However, numerous studies do show an improvement in spinal mechanics following mobilisation techniques.55–57 A number of authors have examined the influence of spinal mobilisation on the function of the sympathetic nervous system, with the aim to investigate the possible role the descending pathways, projecting from the PAG, have in hypoalgesia.24,45,58–69 A preliminary study by Peterson et al45 looked at the effect of a grade III posterioanterior mobilisation to the C5/6 joint of the cervical spine in non-symptomatic subjects. The outcome measures of skin temperature and conductance of the finger tips were recorded as a measure of sudomotor and vasomotor activity. Compared to the placebo group, skin conductance rose by 60%, whilst skin temperature decreased significantly. The authors concluded that mobilisations to the cervical spine have an immediate excitatory effect on the sympathetic nervous system, and a potential role in hypoalgesia. Similar results have been observed during mobilisation of the cervical spine in subjects with lateral epicondylitis.24 1.3. Pressure algometry An aim of SMT is to attenuate the nociceptive component of spinal pain, and there are a number of methods, with proven reliability, of assessing intervention-induced changes in nociceptive pain. Methods include verbal or numerical rating scales and visual analogue scales61 and pain questionnaires such as the McGill Pain Questionnaire.62 The measurement of PPT via pressure algometry is another method used to quantify a patient’s perception of a painful experience63 and has been shown to be a very reliable and relatively inexpensive method of measuring soft tissue tenderness64–72

O. Thomson et al. / International Journal of Osteopathic Medicine 12 (2009) 56–62

and it is frequently used to measure the effect of SMT on soft and bony tissue.12,15,21,24,36–39,41,44 PPT can be defined as the least stimulus intensity at which a subject perceives pain upon the application of pressure or force.63 A large proportion of investigations have established that bone displays a lower average PPT compared to muscle68,70,72; however, some authors dispute this and have reported no difference between PPT values over bone or muscle.71 A number of researchers have shown regional differences of spinal PPT, and that threshold values increase in the caudal direction64,70,72 and may be due to a higher density of nociceptors and mechanoreceptors in the cervical than lumbar spine.64 There also appears to be gender differences in PPT, with females exhibiting a significantly lower PPT in the first dorsal interosseous muscle than males.73 A number of studies have confirmed the reliability of pressure algometry15,64,67,69 finding good intraobserver reliability for the location of unmarked myofascial trigger points. However, a number of methodological issues have been identified with the use of pressure algometry in previously published research.64,71,74–76 Numerous researchers have attempted to explain the hypoalgesic effects of SMT15,21,24,34–37,41,77 though to date, none have directly compared the hypoalgesic effects of manipulation and mobilisation on the lumbar spine. The aim of this study is to investigate and compare the effect that manipulation and mobilisation has on PPT in the lumbar spine in asymptomatic subjects. 2. Methods 2.1. Subjects Fifty male (n ¼ 29) and female (n ¼ 21) subjects (mean age 27 (6) years) were recruited and were randomly assigned into either a mobilisation group (n ¼ 18, 12 males, five females), an HVLAT group (n ¼ 19, 10 males, 10 females) or a control group (n ¼ 13, seven males, six females). All participants were recruited from the student and teaching population at the British College of Osteopathic Medicine (BCOM). Subjects were screened via a questionnaire for any contraindication to SMT.78 Participants were excluded if they had received spinal manipulation or mobilisation techniques within the last three days, or had any contraindications to spinal manipulation. Both the BCOM and St Mary’s University College ethics committees granted ethical approval for the study. 2.2. Measurement of pressure pain thresholds

measure soft tissue pain associated with trigger points67–69 and has more recently, during a randomised control trial, been used to measure pressure pain thresholds at the sacro-iliac joint.79 A pilot study was conducted prior to the main study to assess the reproducibility of the examiner using the algometer. Three subjects, who were not involved in the main study, received three PPT measurements before and after a 1 min interval. The intraclass correlation coefﬁcient (ICC) was 0.78, indicating good (ICC > 0.75) reproducibility of PPT measurements. The algometer was calibrated by the manufacturer, and a 1 cm2 rubber tip was used as this has been found to stabilise the algometer on a spinous process increasing reliability.15 In the present study, the operator of the algometer undertook over 5 h of practice in the device before data collection began. It has been suggested that training in the device improves the reliability of the operator, in particular the rate of pressure application and cessation of pressure once a verbal demand is given by the subject.76 The procedure used to measure PPTs was similar to that used by Keating et al72 and Fryer et al.15 The subjects received three ‘practice’ measurements on the dorsal aspect of their hand before testing began. The subject lay prone on an adjustable plinth, and the algometer was orientated perpendicular to the spinous process of a marked lumbar vertebra (Fig. 2). Subjects were asked to say ‘now’ at the exact moment when the sensation of pressure changed to one of pain. The researcher then immediately ceased the pressure, and the maximal pressure applied was recorded as the PPT value. Pressure was applied to the algometer at a rate of 1 kg/s, using protocols developed by Fischer.69 Three measurements were taken per subject, with a 20 s break between each one, and the average calculated as the PPT for that participant. It has been demonstrated in previous studies that repeated application of the algometer does not alter the sensitivity of the tissue being measured.65 2.3. Procedure Subjects were asked to undress to expose their spines and lay prone on the plinth. There were two researchers involved in testing. To identify the most-tender lumbar spinous process, researcher 1 used a springing technique in a posterioanterior direction, applying pressure twice to each lumbar spinous process, and the most tender was marked with a skin pencil. Researcher 1 then proceeded to take three PPT measurements of the marked segment, with a 20 s break between each measurement. Researcher 1 then exited

PPT was measured by using a hand-held manual pressure algometer (pain test model FPK, Wagner Instruments, Greenwich, CT) (Fig. 1). This particular algometer model has been used to

Fig. 1. The algometer.

Fig. 2. PPT measurement.

O. Thomson et al. / International Journal of Osteopathic Medicine 12 (2009) 56–62

the room and researcher 2 entered the room to perform the selected intervention. Immediately after the intervention, researcher 1 re-entered the room to measure the post-intervention PPT. Researcher 1 was blinded to the intervention received and researcher 2 was blinded to the pre- and post-intervention PPT values. 2.4. Manipulation intervention The HVLAT group received a single HVLA thrust to the identified lumbar segment (Fig. 3). The thrust delivered was a right sided rotational thrust technique. The subject was instructed to lie on the right side and researcher 2 (a registered osteopath) added components of rotation and side-bending, using the upper torso and pelvis as leverage. The thrust was delivered to the inferior joint of the marked segment. For example, if L3 was identified and marked as the most-tender segment, then the joint between L3 and L4 received the HVLA thrust. These techniques are described in numerous osteopathic texts.78,80 2.5. Mobilisation intervention Subjects in the mobilisation group received a mobilisation into right rotation for 30 s (Fig. 4). This was achieved by the subjects lying prone on the plinth, and researcher 2 standing on their left side. The researcher firmly contacted the transverse process (through the paravertebral soft tissue) of the marked segment, and initiated a rotational movement by pulling on the anterior surface of the pelvis with the other hand. These techniques are described in spinal manipulative texts.81,82 2.6. Sham laser treatment (control) A sham group was employed instead of a non-intervention group as a control group, in order to ensure a similar expectation bias in all groups. The sham intervention was designed to control for any placebo effect. The control group received 30 s of ‘laser acupuncture’, with a laser pointer. Prior to receiving the intervention the subjects were shown the laser being applied to the dorsum of their hand. The subjects lay prone on the plinth, with the laser pointer directed at the marked lumbar segment. Subjects were informed that this technique was a commonly employed modality practiced by acupuncturists. The laser was turned off throughout the treatment.

Fig. 4. Experimental mobilisation technique.

2.7. Statistical analysis All data collected were analysed using the statistical package SPSS version 11. To establish the reliability of the PPT measurement procedure, the intraclass correlation coefficient (ICC, based on a one-way ANOVA) was calculated for the PPT readings obtained from the pilot study. To determine if differences existed between the changes produced by the three interventions, a two-way ANOVA with repeated measures was conducted, and the pre-post effect sizes (Cohen’s d) calculated. Statistical significance was set at the 0.05 level. 3. Results Mean(SD) PPT values are shown in Fig. 5. The ANOVA revealed there were no significant differences across time for each of the groups (P ¼ 0.584). The mobilisation group displayed a small increase, though not a significant change in the mean pressure pain threshold (0.434(0.55) kg/cm2), although effect size was considered to be large (d ¼ 0.78). The HVLAT group showed a decrease in the mean PPT ( 0.173(0.48)) (d ¼ 0.36, small), and a smaller decrease was noted for the control group (0.105(0.425) kg/cm2) (d ¼ 0.25, small). The ANOVA further revealed that there was a non-significant interaction between time and the treatment groups. This can be 3.000

Mean SD

PPT (Kg/cm2)

2.500 2.000 1.500 1.000 0.500 0.000 Pre Mob

Post Mob

Pre Man

Post Man Pre CTRL Post CTRL

Group Fig. 3. Experimental HVLAT technique.

Fig. 5. Mean PPT changes with SD.

O. Thomson et al. / International Journal of Osteopathic Medicine 12 (2009) 56–62 Table 2 ANOVA: mean ages between groups

Between groups Within groups Total

2.5

Kg/cm2

2 Mob Man Control

1.5

0.5

Pre

Post

Time Fig. 6. Pre- and post-PPT measurements across the three groups.

seen in Fig. 6, where the mobilisation group displayed a rise in PPT over time, and both the manipulation and control groups had a marginal decline in PPT values over time. Mean group ages were calculated (Table 1) and an ANOVA was performed, which showed no significant difference between the ages of the subjects either within or between groups (Table 2). 4. Discussion Both HVLAT manipulation and mobilisation techniques are used by a range of manual therapists to treat lower back pain and spinal dysfunction. This was the first study of its kind to directly compare the effects of both techniques on lumbar spine PPT values. This study failed to demonstrate any significant difference in the PPT of the lumbar spine following either technique (P ¼ 0.584). The mobilisation group displayed a slight increase in the mean PPT (0.434(0.55) kg/cm2), and the HVLAT group showed a minor decrease in PPT ( 0.173(0.48)), with the respective effect sizes being large (d ¼ 0.78) and small (d ¼ 0.36). A number of studies have shown that such techniques have a positive effect on pain reduction.15,21,24,34–38,83 The results obtained in this study are in contrast with those of Fryer et al15 who found significant increases in PPT in subjects receiving either an HVLAT or mobilisation of the thoracic spine, with mobilisation appearing more effective. However, the results from the present study do suggest that mobilisation may have a stronger effect on PPT compared to HVLAT. It is thought that PPT values increase with age.84 The mean ages of each group were calculated (Table 1), and an ANOVA was performed, which showed that there was no significant difference

Table 1 Mean group ages with SD

Control Mobilisation Manipulation

Mean

Std. deviation

Effect size (d)

13 18 19

24.38 26.00 29.53

4.46 6.95 8.91

0.25 0.78 0.36

Sum of squares

Mean square

227.87 2487.81 2715.68

2 47 49

113.93 52.93

2.15

0.13

(P ¼ 0.13) in subject ages between and within groups (Table 2), suggesting that subject age was not a significant factor in this study. Uneven group numbers and male to female ratios within each intervention group may also have had an impact on the results obtained, particularly with regard to gender, as females tend to exhibit a lower PPT than males.73 A number of studies have found that PPT values increase in a caudal direction64,69,70,72,85 and it has been suggested that this is due to a lower mechanoreceptor and nociceptor density in the lumbar spine.64 This could offer a theory behind the non-significant results obtained in this study, and why a large number of studies have displayed increases in PPT following SMT applied to the cervical spine.21,35,37–39,41 When considering the gate control theory,27 which relies on large, myelinated neurons from mechanoreceptors to modulate and inhibit nociceptive input from small diameter neurons, a lack of mechanoreceptor activity following SMT to the lumbar spine would be unable to ‘close’ the pain gate and create a hypoalgesic effect. One possible theory of hypoalgesia following SMT involves the release of endorphins which are thought to participate in antinociception, with a number of studies measuring plasma bendorphin levels following SMT.42,47,48 It has been suggested that plasma b-endorphin is derived from pituitary gland secretion, and depends on central hypothalamic activation, which would not occur following SMT performed on the lumbar spine29 and may account for the non-significant change in PPT seen in this study. The absence of clinically or statistically significant results may be attributed to a number of factors and limitations of this study. The choice of the mobilisation technique used may have had a bearing on the results obtained. A rotational mobilisation technique was employed in this study, which was preferred for two main reasons; it involved the subject remaining in the prone position pre- and post-testing, and secondly it was performed in a different position from the sidelying manipulation technique used, which was considered to be important to ensure that both techniques differed sufficiently from each other. However, the limitation with this technique performed on this area of the spine is the very small amount of rotation available in the lumbar spine.86,87 It may be theorized that if a flexion mobilisation had been used, which allows almost five times greater motion than rotation,86 the results may have been different, due to a greater mechanical and neurological effect. Three of the subjects in the HVLAT group did not produce an audible cavitation when the manipulation was applied, which may have contributed to the relative decrease in PPT in the HVLAT group. Conversely studies have suggested that there is little to no relationship between the manipulative ‘pop’ and improved outcome.88,89 Furthermore it has been demonstrated that when audible cavitation does arise during an HVLAT we cannot be certain from which joint the cavitation occurred.90 All of the subjects were osteopathic students, and although it was explained that laser acupuncture was a genuine intervention, it is believed by the researchers that the control subjects may have been aware of the sham procedure; however no follow-up study was conducted to ascertain if this was the case. There was a small mean decrease in PPT in the control group (0.105(0.425) kg/cm2), with a small effect size (d ¼ 0.25) suggesting that there was little to

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no placebo effect. Time constraints of the study meant that only a relatively small sample size of 50 subjects could be recruited, resulting in uneven group numbers. A small sample size may not be representative of the general population, and may reduce the power of the study, increasing the likelihood of non-significant results. The measurement of pain is difficult and there are numerous methods used to quantify a subject’s painful experience.61,62,91 A number of studies have reported good reliability of pressure algometry15,64,65,69; however there are reported methodological flaws with pressure algometry64,71,74,75 and this study is no different. The present study used a mechanical algometer, which does not possess the facility to control the rate of pressure application. Electronic algometers are considered to be more accurate and produce better reliability due to the non-reliance on investigator reaction time.76 This study looked at two techniques in isolation; however in clinical practice these techniques are applied differently, usually more than once within a treatment session, in conjunction with other techniques and on symptomatic patients. As such, further research should incorporate the application of SMT techniques on symptomatic patients in a way in which they would be used in a clinical setting. Additionally, only the immediate hypoalgesic effects of SMT were investigated during the present study; further research could highlight PPT changes which may only be observable minutes or even hours after treatment. It has been established that minor adverse events, such as a worsening of the present symptoms or the onset of new symptoms, are common during the 24–48 h following spinal manipulation.92 This occurrence is often termed a ‘treatment reaction’ or ‘rebound reaction’, and has been identified in osteopathic texts as a relatively common and predictable response.93 For this reason, it may be of no surprise that the HVLAT group displayed a slight reduction in PPT following the intervention. As such, further follow-up measurements taken beyond this period may have revealed an increase in PPT. 5. Conclusion This was the first study to compare the effects of spinal mobilisation and HVLAT manipulation on PPT over the lumbar spine, in asymptomatic subjects. Neither technique significantly produced changes in PPT, with the mobilisation group displaying a greater mean increase in PPT than both the HVLAT and control groups, which may indicate that spinal mobilisation has a greater immediate effect on PPT than spinal HVLAT. Future research would involve comparing the pain relieving properties of different combinations of SMT techniques on symptomatic subjects. It is recommended that PPT be measured and monitored over a longer period of time following the application of both these SMT techniques to account for rebound reactions resulting in hyperalgesia. Acknowledgements I would like to thank Dr Ian Drysdale for his valuable comments and Dr Conor Gissane for his assistance in the study design and statistical support. References 1. Koes BW, Assendelft WJJ, van der Hejden GJMG, Bouter LM, Knipschild PG. Spinal manipulation and mobilization for back and neck complaints: a blinded review. Br Med J 1991;303:1298–303. 2. Koes BW, Bouter LM, van der Heijden GJMG. Methodological quality of randomized clinical trials on treatment efficacy in low back pain. Spine 1995;17:28–35. 3. Assendelft WJJ, Koes BW, Knipschild PG, Bouter LM. The relationship between methodological quality and conclusions in reviews of spinal manipulation. J Am Med Assoc 1995;274:1942–8.

4. Andersson GB, Lucente T, Davis AM, Kappler RE, Lipton JA, Leurgrans S. A comparison of osteopathic spinal manipulation with standard care for patients with low back pain. N Engl J Med 1999;341:1426–31. 5. Hurwitz EL, Morgenstern H, Harber P, Kominski GF, Yu F, Adams AH. A randomized trial of chiropractic manipulation and mobilisation for patients with neck pain: clinical outcomes from the UCLA neck-pain study. Am J Public Health 2002;92:1634–41. 6. Aker PD, Gross AR, Goldsmith CH, Peloso P. Conservative management of mechanical neck pain: systematic overview and meta-analysis. Br Med J 1996;313:1291–6. 7. Gross AR, Aker PD, Quartly C. Manual therapy in the treatment of neck pain. Rheum Dis Clin North Am 1996;22:579–98. 8. Hurwitz ELDC, Aker PD, Adams AH, Meeker WC, Shekelle PG. Manipulation and mobilisation of the cervical spine. A systematic review of the literature. Spine 1996;21:1746–60. 9. Gross AR, Hoving JL, Haines TA, Goldsmith CH, Kay T, Aker P, et al. A Cochrane review of manipulation and mobilisation for mechanical neck disorders. Spine 2004;29:1541–8. 10. Wright A, Sluka KA. Nonpharmacological treatments for musculoskeletal pain. Clin J Pain 2001;17:33–46. 11. Bronfort G, Haas M, Evans RL, Bouter LM. Efﬁcacy of spinal manipulation and mobilisation for low back pain and neck pain: a systematic review and best evidence synthesis. Spine 2004;4:355–6. 12. Vernon H, Humphreys K, Hagino C. Chronic mechanical neck pain in adults treated by manual therapy; a systematic review of change scores in randomized clinical trials. J Manipulative Physiol Ther 2007;30:215–27. 13. Anderson R, Meeker WC, Wirick BE, Mootz RD, Kirk DH, Adams A. A metaanalysis of clinical trials of spinal manipulation. J Manipulative Physiol Ther 1992;15:181–94. 14. Shekelle PG, Adams AH, Chassin MR, Hurwitz EL, Brook RH. Spinal manipulation for low back pain. Ann Intern Med 1992;117:590–8. 15. Fryer G, Carub J, McIver S. The effect of manipulation and mobilisation on pressure pain thresholds in the thoracic spine. J Osteopath Med 2004;7:8–14. 16. Tucker C, Deoora T. Fundamental osteopathic techniques. Melbourne: Research Publications; 1995. 17. Greenman PE. Principles of manual medicine. 2nd ed. Lippincott: Williams and Wilkins; 1996. 18. Maitland GD, Hengeveld E, Banks K, English K. Maitland’s vertebral manipulation. 6th ed. Oxford: Butterworth-Heinemann; 2001. 19. Evans DW. Mechanisms and effects of spinal high-velocity, low-amplitude thrust manipulation; previous theories. J Manipulative Physiol Ther 2002;25:251–62. 20. Young FR. Cavitation. London: Imperial College Press; 1999. 21. Vernon H, Aker P, Burns S, Viljakaanen S, Short L. Pressure pain threshold evaluation of the effect of spinal manipulation in the treatment of chronic neck pain: a pilot study. J Manipulative Physiol Ther 1990;13:3–16. 22. DeVocht JW, Pickar JG, Wilder DG. Spinal manipulation alters electromyographic activity of paraspinal muscles: a descriptive study. J Manipulative Physiol Ther 2004;28:465–71. 23. Wright A. Hypoalgesia post-manipulative therapy: a review of a potential neurophysiological mechanism. Man Ther 1995;1:11–6. 24. Vincenzino B, Collins D, Wright A. The initial effects of a cervical spine manipulative physiotherapy treatment on the pain and dysfunction of lateral epicondylalgia. Pain 1996;68:69–74. 25. Goodsell M, Lee M, Latimer J. Short-term effects of lumbar posterioanterior mobilisation in individuals with low back pain. J Manipulative Physiol Ther 2000;23:332–42. 26. Fryer G. Intervertebral somatic dysfunction: a discussion of the manipulable spinal lesion. J Osteopath Med 2003;6:264–73. 27. Melzack R, Wall PD. Pain mechanisms; a new theory. Science 1965;150:971–9. 28. Cramer G, Budgell B, Henderson C, Khalsa P, Pickar J. Basic science research related to chiropractic spinal adjusting: the state of the art and recommendations revisited. J Manipulative Physiol Ther 2006;11:9. 29. Vernon H. Qualitative review of studies of manipulation-induced hypoalgesia. J Manipulative Physiol Ther 2000;23:134–8. 30. Shacklock MO. Central pain mechanisms: a new horizon in manual therapy. Aust J Physiother 1999;45:83–92. 31. Potter L, McCarthy C, Oldham J. Physiological effects of spinal manipulation: a review of proposed theories. Phys Ther Rev 2005;10:163–70. 32. Halderman S. Neurological effects of the adjustment. J Manipulative Physiol Ther 2000;23:112–4. 33. Pickar JG. Neurophysiological effects of spinal manipulation. Spine 2002;2:357–71. 34. Terrett AC, Vernon H. Manipulation and pain tolerance. A controlled study of the effect of spinal manipulation on paraspinal cutaneous pain tolerance levels. Am J Phys Med 1984;63:217–25. 35. Cassidy DJ, 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. 36. Schiller L. Effectiveness of spinal manipulative therapy in the treatment of mechanical thoracic spine pain: a pilot randomized clinical trial. J Manipulative Physiol Ther 2001;24:394–401. 37. Hamiliton L, Boswell C, Fryer G. The effects of high-velocity, low-amplitude manipulation and muscle energy technique on suboccipital tenderness. Int J Osteopath Med 2007;10:42–9. ˇ as CF, Cerro LP, Blanco CR, Conesa AG, Page JC. Changes in neck pain and 38. Pen active range of motion after a single thoracic spine manipulation in subjects

39.

40.

41.

42.

43.

44.

45.

46.

47.

48.

49. 50.

51.

52. 53.

54. 55. 56. 57. 58.

59. 60.

61. 62.

63.

O. Thomson et al. / International Journal of Osteopathic Medicine 12 (2009) 56–62 presenting with mechanical neck pain; a case series. J Manipulative Physiol Ther 2007;30:312–20. ˇ as CF, Blanco CR, Martıńez-Segura R, Garcıá-Leoń R. Changes Ruiz-Saéz M, Pen in pressure pain sensitivity in latent myofascial trigger points in the upper trapezius muscle after a cervical spine manipulation in pain-free subjects. J Manipulative Physiol Ther 2007;30:578–83. Vernon HT, Aker P, Aramenko M, Battershill D, Alepin A, Penner T. Evaluation of neck muscle strength with a modified sphygmomanometer dynamometer: reliability and validity. J Manipulative Physiol Ther 1992;15:34–9. Sterling M, Jull G, Wright A. Cervical mobilisation: concurrent effects on pain, sympathetic nervous system activity and motor activity. Manual Ther 2001;6:72–81. Vernon HT, Dhami MS, Howley TP, Annett R. Spinal manipulation and bendorphin: a controlled study of the effect of a spinal manipulation on plasma b-endorphin levels in normal males. J Manipulative Physiol Ther 1986;9:115–23. Cote P, Mior SA, Vernon HT. The short-term effect of a spinal manipulation on pain/pressure threshold in patients with chronic mechanical low back pain. J Manipulative Physiol Ther 1994;17:36–48. Vincenzino B, Collins D, Benson H, Wright A. An investigation of the interrelationship between manipulative therapy-induced hypoalgesia and sympathoexcitation. J Manipulative Physiol Ther 1998;21:448–53. Peterson NP, Vincenzino B, Wright A. The effects of a cervical mobilisation technique on sympathetic outflow to the upper limb in normal subjects. Physiother Theory Pract 1993;9:149–56. Morgan MM. Differences in antinociception evoked from dorsal and ventral regions of the caudal periaqueductal grey matter. In: Depacclis A, Bandlier R, editors. The midbrain periaqueductal grey matter. New York: Plenum Press; 1991. p. 139–50. Christian GH, Stanton GJ, Sissons D, How HY, Jamison J, Alder B, et al. Immunoreactive ACTH, b-endorphin and cortisol levels in plasma following spinal manipulation therapy. Spine 1988;13:141–7. Saunders GE, Reinnert O, Tepe R, Maloney P. Chiropractic adjustive manipulation on subjects with acute low back pain; visual analogue scores and plasma b-endorphin levels. J Manipulative Physiol Ther 1990;13:391–5. Farrell JP, Twomey LT. Acute low back pain. Comparison of two consecutive treatment approaches. Med J Aust 1982;1:160–4. Koes BW, Bouter LM, van Mameren H, Essers AH, Verstegen GM, Hofhuizen DM, et al. A blinded randomized clinical trial of manual therapy and physiotherapy for chronic back and neck complaints: physical outcome measures. J Manipulative Physiol Ther 1992;15:16–23. Koes BW, Bouter LM, van Mameren H, Essers AH, Verstegen GM, Hofhuizen DM, et al. The effectiveness of manual therapy, physiotherapy, and treatment by the general practitioner for non-specific back and neck complaints: a randomized control trial. Spine 1992;17:28–35. Moss A, Sluka K, Wright A. The initial effects of knee joint mobilization on osteoarthritic hyperalgesia. Manual Ther 2007;12:109–18. Hadler NM, Curtis P, Gilling DB, Stinnett S. A benefit of spinal manipulation as adjunctive therapy for acute low back pain: a stratified controlled trial. Spine 1987;12:703–6. Petty NJ. The effect of posteroanterior mobilisation on sagittal mobility of the lumbar spine. Manual Ther 1995;1:25–9. McCollan RL, Benson CJ. Effects of posterior-anterior mobilisations on lumbar flexion and extension. J Manipulative Physiol Ther 1993;1:142–7. Beattie AJ. The effectiveness of spinal mobilisation in the treatment of low back pain: a single case study. Physiother Theory Pract 1991;7:57–62. Nwuga VC. Relative therapeutic efficacy of vertebral manipulation and conventional treatment in back pain management. Am J Phys Med 1982;61:2738. Slater H, Vincencino B, Wright A. ‘Sympathetic slump’: the effects of a novel manual therapy technique on peripheral sympathetic nervous system function. J Manual Manipulative Ther 1994;2:156–62. Mulligan BR. Manual therapy. ‘‘Nags’’, ‘‘snags’’, MWMS etc. 3rd ed. New Zealand: Plane View Services Ltd; 1999. Paungmali A, O’Leary S, Souvlis T, Vincenzino B. Hypoalgesic and sympathoexcitatory effects of mobilization with movement for lateral epicondylalgia. Phys Ther 2003;83:374–83. VonKorff M, Jensen M, Karoly P. Assessing global pain severity by self-report in clinical and health services research. Spine 2000;25:3140–51. Triano J, McGregor M, Cramer G, Emde E. A comparison of outcome measures for use with back pain patients: results of a feasibility study. J Manipulative Physiol Ther 1993;16:67–73. International Association for the Study of Pain. Classification of chronic pain, description of chronic pain syndromes and definitions of pain terms. Pain supplement 3. Amsterdam: Elsevier Science Publishers; 1986.

64. Vanderweee¨n L, Oostendorp R, Vaes P, Duquet W. Pressure algometry in manual therapy. Manual Ther 1996;1:258–65. 65. Nussbaum EL, Downes L. Reliability of clinical pressure-pain algometric measurements obtained on consecutive days. Phys Ther 1998;78:160–9. 66. Ylinen J, Nyka¨nen M, Kautiainen H, Ha¨kkinen A. Evaluation of repeatability of pressure algometry on the neck muscles for clinical use. Manual Ther 2007;12:192–7. 67. Reeves JL, Jaeger B, Graff-Radford SB. Reliability of the pressure algometer as a measure of myofascial trigger point sensitivity. Pain 1986;24:313–21. 68. Ohrbach R, Gale EN. Pressure pain thresholds, clinical assessment, and differential diagnosis: reliability and validity in patients with myogenic pain. Pain 1989;39:157–69. 69. Fischer AA. Pressure algometry over normal muscles. Standard values, validity and reproducibility of pressure threshold. Pain 1990;30:115–26. 70. Hogeweg A, Langereis MJ, Bernards ATM, Faber J, Helders PJM. Algometry: measuring pain threshold, method and characteristics in healthy subjects. Scand J Rehabil Med 1992;24:99–103. 71. Kosek E, Ekholm J, Nordemar R. A comparison of pressure-pain thresholds in different tissues and body regions. Scand J Rehabil Med 1993;25:257–63. 72. Keating L, Lubke C, Powell V, Young TR, Souvlis T, Jull GA. Mid-thoracic tenderness: a comparison of pressure pain threshold between spinal regions, in asymptomatic subjects. Manual Ther 2001;6:34–9. 73. Chesterton L, Barlas P, Foster N, Baxter D, Wright C. Gender differences in pressure pain threshold in healthy humans. Pain 2002;101:259–66. 74. Antonaci F, Sand T, Lucas G. Pressure algometry in healthy subjects: interexaminer variability. Scand J Rehabil Med 1998;30:3–8. 75. Vantine J-J, Shapira S, Magora F, Adler D, Magora A. Electronic pressure algometry of deep pain in healthy volunteers. Arch Phys Med Rehabil 1989;25:117– 24. 76. Vaughan B, McLaughlin P, Gosling C. Validity of an electronic pressure algometer. Int J Osteopath Med 2007;10:24–8. 77. van Schalkwyk R, Parkin-Smith GF. A clinical trial investigating the possible effect of the supine cervical rotatory manipulation and the supine lateral break manipulation in the treatment of mechanical neck pain: a pilot study. J Manipulative Physiol Ther 2000;23:324–31. 78. Gibbons P, Tehan P. Manipulation of the spine, thorax and pelvis: an osteopathic perspective. London: Churchill Livingstone; 2006. 79. Shearar KA, Colloca CJ, White HL. A randomized clinical trial of manual versus mechanical force manipulation in the treatment of sacroiliac joint syndrome. J Manipulative Physiol Ther 2005;28:493–501. 80. Stoddard A. Manual of osteopathic techniques. 3rd ed. London: Hutchinson and Co; 1980. 81. Walton WJ. Textbook of osteopathic diagnosis and technique procedures. 2nd ed. The American Academy of Osteopathy; 1970. 82. Byfield D. Chiropractic manipulative skills. 2nd ed. London: Churchill Livingstone; 2005. 83. Glover JR, Morris JG, Khosla T. Back pain: a randomised clinical trial of rotational manipulation of the trunk. Br J Ind Med 1974;31:59–64. 84. Bek N, Uygur F, Bayar B, Armutlu K. Analysis of age and gender related differences in pressure pain threshold and pressure pain tolerance levels. Pain Clinic 2004;14:309–14. 85. Potter L, McCarthy C, Oldham J. Algometer reliability in measuring pain pressure threshold over normal spinal muscles to allow quantification of antinociceptive treatment effects. Int J Osteopath Med 2006;9:113–9. 86. Pearcy M, Portek I, Sheperd J. Three-dimensional x-ray analysis of normal movement in the lumbar spine. Spine 1984;9:294–7. 87. Hickey DS, Hukins DW. Relation between the structure of the annulus fibrosus and the function and failure of the intervertebral disc. Spine 1980;5:106–16. 88. Flynn TW, Fritz JM, Wainner RS, Whitman JM. The audible pop is not necessary for successful spinal high-velocity thrust manipulation in individuals with low back pain. Arch Phys Med Rehabil 2003;84:1057–60. 89. Flynn TW, Childs JD, Fritz JM. The audible pop from high-velocity thrust manipulation and outcome in individuals with low back pain. J Manipulative Physiol Ther 2006;29:40–5. 90. Beffa R, Mathews R. Does the adjustment cavitate the targeted joint? An investigation into the location of cavitation sounds. J Manipulative Physiol Ther 2004;27:2. 91. Strong J. Assessment of pain perception in clinical practice. Manual Ther 1999;4:216–20. 92. Thiel HW, Bolton JE, Docherty S, Portlock JC. Safety of chiropractic manipulation of the cervical spine: a prospective national survey. Spine 2007;32:2375–8. 93. Nelson K, editor. Somatic dysfunction in osteopathic family medicine. Lippincott Williams and Wilkins; 2007.