Manipulation of the Lumbar Spine

Original Editor - David Jones as part of the Nottingham University Spinal Rehabilitation Project
Top Contributors - Cindy John-Chu, Angeliki Chorti, David Jones, Kim Jackson, Jordan Finney, Brandon Springett, George Hunter and Jonathan Wong

Introduction

Spinal manipulation (SM) techniques are widely used by health professionals such as chiropractors, osteopathic physicians and physiotherapists. As widely used and acceptable as these techniques may be, it is important to analyse and review their effectiveness on commonly affected joints such as the lumbar spine and the sacroiliac joint that are prone to causing low back pain (LBP). The mechanisms underlying the effectiveness of the procedures, their efficacy, safety and contraindications are also important to be explored.

What is Manipulation?

Manipulation is a technique where a therapist applies a quick directed thrust to a joint at the end of physiological range of movement, often causing an audible sound by the joint. This differs from mobilisation where passive movement is carried out within available range of motion and then gradually increased to a larger range as the patient feels more comfortable.

The Use of Manipulations

Low back pain is the most common musculoskeletal problem globally with a prevalence of 7.5% across all age groups in the world and in the United States, life-time prevalence may reportedly be as high as 84%. Manipulation techniques as part of manual therapy to improve an individual’s movement potential are common within a physiotherapist's scope of practice. In fact, the lumbar spine is the second most common site of manipulation by UK physiotherapists. Manipulation techniques are often used for patients with chronic non-specific low back pain as they have been reported to be as equally effective as other interventions in its management.

How to Use Lumbar Manipulation

You can learn more about how lumbar manipulation can be used and its contraindications in Spinal Manipulation.

Example of a Lumbar Manipulation

An example of a lumbar manipulation technique is found in the video below:

Mechanisms of Action

The exact mechanism by which spinal manipulation works has not been fully established, but an array of biomechanical, muscular reflexogenic and neurophysiological responses have been reported in the literature to support effects such as pain relief and reduction of spinal stiffness.

Motor Neurone Excitability  

Hyper-excitability of the A motor neuron leads to increased muscle activity. Spinal manipulation has been thought to relax hyperactive muscles through modulating the A motor neuron activity. The influence on spinal stretch reflexes results in a brief muscle contraction possibly followed by a period of reduced muscle activity, bringing about pain relieving effects.

Muscle Activity

Individuals with LBP experience greater amount of spinal muscle hyperactivity in static postures than healthy participants.

The pain-spasm cycle suggests that pain causes muscular hyperactivity (spasm) and this spasm can cause further pain.  

Pain -> Hyperactivity (spasm) -> Pain  

The mechanical stimulation of spinal manipulation is thought to cause the sensory receptors to inhibit muscle activity - disrupting the pain-spasm-model.

Activation of Descending Pain Modulation  

Spinal manipulation is thought to activate the modulation circuit of pain descending pathways , specifically, the serotonin and noradrenaline pathways.

Segmental Inhibition

This theory proposes that nociceptive (small-diameter) A-δ and C sensory fibers carry pain stimuli to the dorsal horn and “open” the substantia gelatinosa layer, whereas non-nociceptive (large-diameter) A-β fibers inhibit transmission of pain signals by blocking the entry of A-δ and C fibers. Because mechanical stimulus applied during spinal manipulation may alter peripheral sensory input from paraspinal tissues, it has been presumed that manipulation may influence the gate closing mechanism by stimulating the A-β fibers from muscle spindles and facet joint mechanoreceptors.

Temporal Summation

Temporal summation is an increased perception of pain caused by repetitive nociceptive stimuli – it's related to aspects of central sensitization. Lumbar spine manipulation has been suggested to reduce temporal summation of pain.

Neuroendocrine Response  

Manipulations at the thoracolumbar segment of the spine may result in excitation of the preganglionic sympathetic cells and subsequent stimulation of mechanoreceptors. These inputs would then travel to several regions of the brain stem and lead to opioid-independent analgesia by influencing the hypothalamus and periaqueductal gray (PAG) in the midbrain. The hypothalamic release of corticotropin-releasing factor would then occur to modulate the SNS and HPA axis response. The neuroendocrine (SNS–HPA axis) system would then release its end products (catecholamines and glucocorticoids) to initiate anti-inflammatory and tissue-healing actions.

Non-Specific Responses  

The relevance of non-specific variables, such as individual expectations or psychosocial factors on pain or psychological outcome measures is not well understood since there is a greater focus on the effect of SM on pain and spine related disability. Nevertheless, there is some evidence supporting that spinal manipulation may have a small effect on psychological outcomes.

Efficacy of Lumbar Manipulations

Effectiveness as a sole treatment

Spinal manipulation can either be used alongside other forms of treatment or alone as an individual intervention. Its effectiveness as a sole treatment approach is discussed below.

A 2016 systematic review and meta-analysis compared SM with sham manipulation for non-specific LBP and showed that a greater reduction in pain scores was present in SM in comparison to those receiving a placebo.

A RCT compared the effectiveness of SM and a functional technique involving breathing on improving pain, disability, quality of life and fear of movement. Over a short-term period, SM only reduced disability in patients with chronic LBP and the other outcomes weren’t improved. The small sample size (n=62) may be a reason why improvements in disability weren’t clinically significant; it was concluded that SM didn’t result in clinically meaningful short-term benefits.

A RCT comparing the effectiveness of region-specific and non-region-specific spinal manipulation for improving pain intensity within chronic LBP patients found that both groups experienced immediate decrease in pain intensity.

The effect of spinal manipulation and spinal mobilization at reducing pain and disability compared with a placebo control group was studied in a cohort of young adults with chronic LBP. Participants received 6 treatment sessions over a 3-week period. However, neither spinal manipulation nor spinal mobilization were shown to be effective treatments for mild to moderate chronic LBP.

Required treatment Sessions  

A comparative study on spinal manipulation treatment sessions found that 12 sessions over a 6-week period yielded the greatest improvement in pain and functional disability, both in the short-term (12 weeks) and long term (52 weeks).

Effectiveness as an Adjunct to Exercise

Nice guidelines state that for patients with lower back pain manual therapies including manipulation should be considered as a package of treatment including exercise with/ without psychological therapy. Manipulations are commonly used alongside other therapies, and this has been shown to yield a statistically significantly better outcome in pain and function after 1 month of intervention.

In a randomised control trial, the use of manual therapies followed by exercises for patients with chronic nonspecific lower back pain was analysed. This study found that manual therapies (including manipulations) followed by exercises provided a statistically significant reduction in pain and disability compared with a sham therapy followed by exercises. This study was conducted on adults (20-65) with chronic nonspecific lower back pain without co-morbidities so may not be generalisable to all populations. Another randomised trial on adolescent (12-18) patients with non-specific lower back pain showed that spinal manipulations alongside exercise is more effective than exercise alone for lower back pain.

Manipulations as adjuncts to other treatments for lower back pain such as myofascial release and kinesio taping have been found to produce no significant benefit compared with manipulations alone .

Chronic vs Acute  

Due to the different mechanisms of pain between acute and chronic pain it is important to analyse the effectiveness of treatments between these two patient groups. The manipulations for chronic lower back pain have been found to be effective in multiple studies.  

A randomised control trial found that manipulations are significantly effective in reducing pain for chronic and sub-acute lower back pain with radiculopathy and improving range of motion. However, all participants to the study were given pain killers (paracetamol and gabapentin) which may have had an effect in reducing pain.  

For patients with acute lower back pain spinal manipulations may not be effective for many of these patients who will recover quickly with or without intervention. Furthermore, a randomised control trial found that patients with acute lower back pain do not recover more quickly with the addition of manipulation to first line care. A Cochrane review found low to very low-quality evidence suggesting that spinal manipulation was no more effective than other recommended therapies for acute lower back pain.

Safety of Spinal Manipulations

Safety

The research around safety and adverse events in lumbar manipulation is limited by the amount of good quality research. A review looked at spinal manipulation as a whole and show stroke (1 in 20,000–2,000,000 manipulations) or Vertebrobasilar accident (1 in 228,050–1,000,000 manipulations) as the most common serious adverse events. However, these events are caused by cervical manipulations and in the sole study looking at lumbar manipulation, the adverse event caused was lumbar disc hernia which the risk was assessed at 1 in 3.8m. The review was inconclusive about the overall safety of spinal manipulation as 46% conclude it was safe, 13% unsafe and 42% unclear. Further research needs to be done, especially into Lumbar manipulation safety as the anatomy would suggest it to be safer than cervical or thoracic, with most common adverse event being mild soreness, however there is a lack of research in to the area.

Swait and Finch also conducted a review in 2017 on the risks of manual techniques on the spine. 250 articles were included in the review, including observational studies, randomised studies and systematic reviews. Swait and Finch’s findings are in agreement with the findings of Neilson et al 2017. Benign adverse advents are commonplace in both adolescence and adults:

• Benign adverse events are common, affecting 23–83% of adult patients.

• These are mostly mild-moderate, transient (usually resolve within 24 h) and commonly include musculoskeletal pain, stiff-ness and headache.

• Dizziness, tiredness, feeling faint/lightheaded or tingling in the arms might also be experienced following neck treatment.

Serious adverse events appear to be rare and, as a result, estimates of the level of risk are problematic.

• However, cases of serious adverse events, including serious spinal or neurological problems as well as strokes affecting arteries in the neck, have been reported.

• Serious adverse events could result from pre-existing pathologies, therefore assessment for signs or symptoms of these is important.

• Where a serious adverse event is thought to have occurred following manual spinal intervention, use of a patient safety incident reporting system enables dissemination of accurate case details.

Safety of Lumbar Manipulation in Different populations

Age under 18

A review done between 1990 to 2019 looked at the safety of spinal manipulation in children under 10 years old.

Most adverse events found were mild (crying or soreness) but once case described a rib fracture to 3-week-old. The incidence of mild adverse events ranges from 0.3% (95% CI: 0.06, 1.82) to 22.22% (95% CI: 6.32, 54.74)

It was inconclusive as to whether spinal manipulative therapy was safe in under 10s. However, had poor study quality and quantity and may have had a conflicting interest as they were mandated by the College of Chiropractors of British Columbia to review the evidence which was the published in a chiropractic journal.

RCTs carried out looked at exercise and manual therapy in adolescents and both concluded there were no adverse reactions to the manipulations but also no benefit reported vs exercise alone.

Age 18-65

The review by Rubinstein et al (2019) of patients aged 35-60, found One study powered enough to examine risk (n=183) found no increased risk of an adverse event (relative risk 1.24, 95% confidence interval 0.85 to 1.81) or duration of the event (1.13, 0.59 to 2.18) compared with sham SMT.

Age over 65

In a systematic review which looked at effectiveness and safety of manipulations in the elderly, they found no conclusive result due the lack of studies investigating the area and the quality of those studies as well as a need for a standardised adverse event reporting system. They also found no difference in the number of adverse events in the ‘sham’ manipulation group vs the intervention group.