Summary

Introduction

Most of the research into mechanical diagnosis and therapy that has been conducted to date has involved patients with back pain. There is a considerable body of evidence that has been published regarding efficacy, reliability, mechanically determined directional preference and centralisation relating to the lumbar spine (McKenzie and May 2003, Chapter 1 1). Since the publication of the second edition of The Lumbar Spine: Mechanical Diagnosis & Therapy, more literature has appeared. Of particular importance are a systematic review about centralisation (Aina ^et al. 2004), a systematic review about the efficacy of the McKenzie approach (Clare ^et al. 2004b), and an efficacy study that established mechanically determined directional preference prior to randomisation (Long ^et al. 2004). This study is briefly described below. However, it is still the case that most of this literature relates to back pain, not neck pain, patients.

This chapter covers the literature that is directly relevant to the practice of mechanical diagnosis and therapy in the cervical spine, which at this point is limited. More literature, however, continues to emerge and the following website, which is regularly updated, is recommended to maintain an up-to-date knowledge of the available evidence base:

www.mckenziemdt.org/research.

This chapter contains the following sections:

• efficacy studies

• mechanically determined directional preference centralisation

reliability

prevalence of mechanical syndromes in neck pain patients.

Efficacy studies

A systematic review (Clare ^et al. 2004b) into the efficacy of McKenzie therapy [or spinal pain, with strict inclusion and exclusion criteria, included six randomised controlled studies, one of which involved

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patients with neck pain (Kjellman and Oberg 2002) In this trial the McKenzie group had less pain and disability in the short- and me­

dium-term; however, the effect sizes were small and not statistically significant. The effects on pain were a difference of minus eight and minus two at the different outcome points and the effects on the Neck Disability Index were a difference of minus five and minus two respectively on 100-point scales, favouring the McKenzie group. As there was only one study with data on cervical spine patients, the review (Clare ^et al. 2004b) concluded there is insufficient data to determine efficacy for cervical pain.

Kjellman and Oberg (2002) randomly allocated seventy-seven patients to general exercise, McKenzie therapy or a control group, 9 1 % of whom were followed-up at twelve months. Pain intensity and frequency and neck-related disability improved in all groups with no significant differences in a three-group analysis (Figure 7. 1). However, in a two-group analysis there was Significantly greater improvement in McKenzie compared to the control group in pain intensity and Neck Disability Index, and after treatment the McKenzie group had im­

proved by thirty-four points compared to twenty-nine and twenty-six in the exercise and control groups respectively Significant improve­

ments were noted for The Distress and Risk Assessment Method in the McKenzie group only, and whilst 70% of the two active groups were normal according to this measure, only 42% of the control group were normal. With a definition of clinically important change as five or more points on the Neck Disability Index, 60 - 63% of patients in the exercise and McKenzie groups achieved this compared to 37% in the control group. The exercise group had conSiderably more treatment during the intervention period (mean number of sessions thirteen compared to seven or eight for McKenzie and control groups), and during the follow-up year (102 visits to a health care profeSSional compared to 46 and 140 respectively).

LITERATURE R.EVIEW

Figure 7.1 Pain intensity changes: 0

-

¹⁰⁰ scale over weeks

60

50

;; 40 0

� 30

.OJ c: 20

0-10

0 o

- McKenzie --Exercise

Control Group

---3 Weeks

Source: Kjelltnan and Oberg (2002)

-

--6 26 52

Secondary analysis of this trial involved objective measures of range of movement and muscle endurance and strength (Kjellman and Oberg 2004) Although there were improvements in the other groups, only the McKenzie group improved on all objective measures.

Rasmussen ^et al. (2001) reported on an uncontrolled cohort of sixty patients with neck and arm pain, with many demonstrating signs and symptoms of cervical radiculopathy that were followed-up at one year after McKenzie evaluation and management. Of the forty-five not receiving compensation, thirty were much better, eleven somewhat better, two were unchanged and two were lost to follow-up. Of the fifteen receiving compensation, two were much better, one somewhat better, nine were unchanged and three were worse. The differences were highly significant, and the authors concluded that with a low level of intervention after careful instruction, the McKenzie method was effective for treatment of cervical radiculopathy in patients not receiving compensation.

Regarding patients with symptoms from whiplash, early active move­

ment augmented by mechanical diagnosis and therapy has been shown to be effective (Rosenfeld ^et al. 2000, 2003). This study is described in more detail in Chapter 25, but the results are presented below (Figure 7.2).

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Figure 7.2 Outcomes of whiplash: ^MDT versus standard intervention date, although it suggests superiority of mechanical diagnosis and therapy over a control group, does not provide definitive evidence of treatment efficacy. Clearly more studies are needed in this area before firm conclusions can be drawn.

Mechanically determined directional preference Mechanically determined directional preference describes the situation when postures or movements in one direction centralise, abolish or decrease symptoms and lead to an improvement in mechanical presentation. Very often postures or movements in the opposite direction cause symptoms and signs to worsen, although in part this is a response to the length of exposure to the provocative loading.

The phenomenon of mechanically determined directional preference is characteristic of derangement syndrome and helps to identify the specific directional exercise that will lead to the best management strategy (Long ^et al. 2004). This study only involved patients with back pain, but it is a key study in demonstrating the importance of mechanically determined directional preference. It is proposed that mechanically determined directional preference will present in a similar way in patients with neck pain, although currently the evidence is limited. At randomisation patients were allocated to exercises that matched their mechanically determined directional preference (extension responder did extension exercises, for instance), were opposite to their mechanically determined directional preference (extension responder did flexion exercises), or general exercises

LITERATURE REVIEW

and evidence-based active care. At two weeks in nearly all outcome measures there were Significant differences favouring the matched group. Over 90% reported themselves to be resolved or better, compared to 24% in the opposite group and 42% in the evidence-based group (Long ^et al. 2004).

Donelson ^et al. ( 1997) examined the pain response to repeated end-range testing of sagittal plane movements in eighty-six patients with neck and referred pain. Patients were randomised to perform the movements in different orders, which did not affect responses.

In 45% of subjects, sagittal plane movements had consistent and opposite effects. Of these, 67% improved with retraction and extension and worsened with protrusion and flexion, and 33% improved with protrusion and flexion and worsened with retraction and extension.

In another ten subjects ( 12%), both flexion and protrusion caused peripheralisation of pain, but either decreased pain intensity, or centralisation only occurred with retraction or extension rather than both. Thus, in total 57% of this sample displayed mechanically determined directional preference - in a single mechanical evaluation limited to four sets of ten repetitions, which did not use overpressure, mobilisation or frontal plane forces. In 43% of subjects there was an increase in pain intensity or peripheralisation with lower cervical flexion (ilexion and protrusion) and a decrease in pain intensity or centralisation with extension and/or retraction.

Abdulwahab and Sabbahi (2000) investigated the effect of twenty minutes of sustained flexion and twenty repeated retraction move­

ments in thirteen patients with cervical radiculopathy and ten control subjects. Flexion was mid-range as participants were simply asked to read a magazine in their own relaxed style. Outcomes evaluated were radicular pain intensity and the H-reflex amplitude as a measure of compression of the nerve, with a decrease representing compression.

The H-reflex amplitude was Significantly decreased after flexion and significantly increased after the retraction exercises. There was a significant increase in symptoms following sustained flexion and a Significant decrease follOwing retraction exercises in the radiculopathy group (Figure 7.3). Even the asymptomatic control group felt some discomfort after the period of sustained flexion.

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Figure 7.3 Effects of sustained flexion and retraction exercises on cervical radiculopathy and controls (N ⁼ 23)

6

8 4

.., I

S 3

� c

o Before

- Patients

_ Controls

Source: Abdulwahab and Sabbahi 2000

Central isation

Aher reading Arler retractions

Centralisation refers to the phenomenon by which distal limb pain emanating [rom the spine is abolished in response to the deliberate application of loading strategies (Figure 7.4). The phenomenon is characteristic of derangement syndrome, and its high prevalence rate, reliability of assessment and value as a prognostic indicator has been established in a review (Aina ^et al. 2004). The review highlights the limited documented evidence about centralisation in the cervical spine.

Werneke ^et al. ( 1999) described the symptomatic responses o[ 289 patients, of whom 66 (23%) had neck pain. Centralisation was strictly defined as clear-cut abolition during mechanical evaluation that remained better and progressively improved at each session.

Another group, classified as 'partial reduction', displayed gradual improvement over time, but this was not necessarily progressive or directly related to the treatment session. Similar p�rcentages in the neck and back pain patients demonstrated centralisation (25% and 3 1 % respectively) and partial reduction (46% and 44% respectively).

There were no significant differences in outcome by pain site, so back and neck pain patients were analysed together. Centralisers averaged Significantly fewer visits (four) than the partial reduction and non-centralisation groups (eight). However, there was no significant difference in pain or functional outcome between centralisation and partial reduction groups, which were both Significantly better than the non-centralisation group.

LITERATURE �EVIEW

Figure 7.4 Centralisation of distal pain in response to repeated movements

Reliability

When an examination procedure is being used to determine manage­

ment strategies, it is important that it has good intertester reliability to ensure that the procedure is consistently interpreted between clinicians. If a procedure has poor reliability, it demonstrates that clinicians cannot agree on how to interpret a particular finding.

Unstable interpretations of physical examination findings are likely to lead to unsound and random clinical decisions about management.

Although reliability is widely considered an important aspect of any examination process, deciding 'how much' reliability is enough is unclear and controversial. Kappa values of 0.4 have been accepted (Seffinger ^et al. 2004), but values below 0.5 have been said to indicate poor levels of agreement (Altman 199 1), and 0.75 has been deemed a 'minimal requirement' (Streiner and Norman 2003).

Clare ^et al. (2004a) examined the reliability of fifty McKenzie­

credentialed therapists in classifying fifty patients, twenty-five each cervical and lumbar, from McKenzie assessment forms. Results were not separated for neck and back paper-based cases. Kappa value for syndromes was 0.56 and for sub-syndromes was 0.68.

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Clare ^et al. (2004c) examined reliability of assessment of fifty patients by pairs of therapists, fourteen in total; half of the patients had neck pain and half back pain. Prevalence of derangement was 88% / 84%, dysfunction 0% / 4%, posture 0% / 0% and 'Other' 12% / 12%

for the two therapists. Kappa values for lumbar syndromes and sub-syndromes were 1.0 and 0.89 and for cervical syndromes and sub-syndromes 0.63 and 0.84 respectively.

Dionne and Bybee (2003) videotaped twenty patients with neck pain during a mechanical evaluation and then had fifty-four therapists at varying levels of the mechanical diagnosis and therapy educational programme view the videos and classify the patients. Reliability on agreement for diagnosis was kappa 0.55, for sub-syndrome classifi­

cation was kappa 0.48 and for mechanically determined directional preference was 0.45.

Prevalence of mechanical syndromes in neck pain patients

Two surveys have been conducted of consecutive patients seen by McKenzie educational faculty (May 2004a, 2004b). In total, details of over one thousand patients were included in the two surveys from nearly eighty contributing faculty members, which included 256 patients with neck pain. The results were similar in the two studies, with most neck pain patients being classified as derangement (80%), fewer numbers in other mechanical syndromes (8%, mostly dysfunc­

tion) and some classified as non-mechanical syndrome (12 %). The minority of patients not receiving mechanical classification were mostly classified as mechanically inconclusive (4%), trauma (4%) and chronic pain state (3%).

Figure 7.5 Classification of 256 consecutive neck pain patients

-- Derangement - Dysfunction

Posture

I

Adherent nerve root --Other

Source: May 2004a, 2004b

LITERATURE REVIEW

Of those patients classified as derangement, the most common reductive force was extension (66%), but 25% used some element of the lateral treatment

p

rinciple and 6% used flexion as the treatment principle.

Conclusions

This chapter has outlined the available evidence that is directly relevant to the practice of mechanical diagnosis and therapy in the cervical spine. The main point is that the evidence is limited and so definitive conclusions about any aspect of the approach should be made with caution. In general, only one or two studies are available regarding any particular aspect; furthermore, a number of these studies are only available as abstracts or articles that have not been published in peer-reviewed journals. The evidence to date gives some support for efficacy, reliability, the existence of centralisation and mechani­

cally determined directional preference and a high prevalence rate of mechanical syndromes in neck pain patients. However, further research is needed to reach definitive conclusions about all these aspects of mechanical diagnosis and therapy in the cervical spine and nothing at all has been published relevant to the thoracic spine.

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In document This dissertation is submitted for the degree of Doctor of Philosophy (página 90-97)