Effectiveness of osteopathic interventions in patients with non-specific neck pain: A systematic review and meta-analysis

Methods

• Articles analyzed: 5
• Search string: use of the following keywords, as free terms or MeSH: “neck pain”, “non-specific neck pain”, “cervical pain”, “chronic neck pain”, “osteopathic manipulative treatment”, “osteopathy”, “osteopathic medicine” , “myofascial release”, “manipulation”, “manual therapy”, “craniosacral therapy”, “visceral manipulation”.
• Criteria of inclusion: randomized controlled trials applying OMT on adults (ages 18-70 years) with any type of non-specific neck pain; articles in English; interventions performed by professionals qualified in osteopathic manipulation; use of at least one clinical outcome related to non-specific neck pain (eg, pain intensity, functional status, quality of life, drug intake, and psychological attitude). published in the last 30 years

• Criteria of exclusion: neck pain secondary to specific pathologies; elderly people; studies with interventions applied by non-osteopathic professionals or not based on osteopathic principles; studies with purely psychological or economic outcomes; summaries, abstracts and conference proceedings.

Characteristics of the studies

• 4 studies with parallel design
• 1 study with cross-over design
• 4 studies with passive control (eg, no intervention)
• 1 study with active control (eg, exercise)
• 4 studies measured pain as the primary outcome
• 1 study measured pain and functional status as primary outcomes
• Drop-out rate between 0% and 22%
• Assessment of study quality through RoB (risk of bias in randomized trials)
  • studies of medium-good quality, however with high heterogeneity

Participants

• Number in the smallest study: 41 people (31 female and 10 male, mean age 43.15 years)
• Number in the biggest study: 87 people (80 female and 7 male, mean age 41.5 years)
• Total: 325 people (278 female and 47 male, mean age 46.75 years)

Interventions and evaluations

• Evaluation of pain and functional status after interventions or after a follow-up
  • pain assessment via Visual Analog Scale (VAS) or Numeric Rating Scale (NRS)
  • assessment of functional status through questionnaires
• Evaluation of the amount of medication taken, quality of life, adverse effects, any appropriate cost-effectiveness measure and psychological attitude (eg, fear of movement) using questionnaires
• 4 to 9 OMT sessions of 45 to 60 minutes, 1 session a week to 1 every 20 days, with a total study duration of 4 to 12 weeks
• OMT:
  • personalized treatment using different techniques (including myofascial, high velocity and low amplitude, visceral, muscle energy, balanced ligamentous tension) or craniosacral
  • In some cases on its own and in others associated with ultrasounds, sham or exercise
• Control: sham treatment, sham ultrasound, exercises, or no intervention

Results

• Primary outcomes: 
  • Pain: all studies have shown statistically significant results in favor of the OMT in reducing pain, both after treatment and at the follow-up (for the two studies that included one, at 3 months and at 20 weeks). The effect size (actual relevance of treatment) calculated from the studies was small in some studies and large in others.
  • Functional status: All studies showed a statistically significant improvement in functional status in the OMT group, both after treatments and at the follow-up. The four studies that used the Neck Disability Index (NDI) showed clinically meaningful results. The effect size calculated from the studies was from low to moderate.
• Secondary outcomes: with regard to the various secondary outcomes it was not possible to summarize them as, most of the time, they were analyzed with very different instruments by each individual study. It was not possible to make specific analyzes on the effectiveness of the single techniques or approaches.
• Adverse effects: the four out of five studies evaluating adverse effects found OMT to be a substantially safe treatment. Adverse effects emerged (headache, tiredness, increased pain, dizziness, tingling) which however resolved within a few days. Persistent rib pain was reported in only one case.

Discussion

OMT has been shown to improve both pain and functional status for non-specific neck pain, producing better results  than no treatment and  exercise programs. With regards to the follow-up, there has also been a positive trend in favor of OMT, although no more conclusions can be drawn due to the limited data available.

However, the osteopathic approaches used in the various studies analyzed were very heterogeneous (from single techniques to personalized treatments), which prevented specific sub-analyses from being carried out. Furthermore, given the few studies included in the meta-analysis and some bias found in their methodological evaluation, the overall quality of the results is quite low.

From this systematic review and from the analysis of the literature we can conclude that, in case of non-specific neck pain, treating other areas of the body can be particularly effective both for reducing pain and for improving functional status. One of the reasons may be the regulatory action of OMT on pathological processes such as central sensitization and tissue inflammation or on the redefinition of sensory body maps at the brain level. Given the few and transient adverse effects, OMT can be considered a safe therapy for non-specific neck pain.

Future studies will have to consider finding a good balance between the need for a standardized intervention protocol and the customization of OMT treatment, in order to define replicable and generalizable studies. In this regard, it is necessary that the techniques used, the approaches chosen and the evaluation processes leading to those choices are well described. One possibility is the use of the TIDier (Template for Intervention Description and Replication). It is also important to pay attention to the terminology used, as often different professionals use different words and terms to refer to the same manoeuvres, but this only generates confusion.

All of these measures are essential to bring OMT to a health system level and to evaluate its cost-effectiveness.

The limitations of this systematic review are that it only considered articles in English, that it did not define stricter inclusion criteria – although on one hand such approach is useful due to the personalized nature of OMT, on the other hand it prevented accurate study comparisons – and that it did not analyze potential bias of publication.