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Chronic low back pain (CLBP) and its best management pose a significant global health problem. Low back pain (LBP) is among the most common reasons to visit a primary care physician in the UK, with pain and disability being the main patient complaints (Cypress, 1991; Koes et al., 2006). Furthermore, with 5% of patients with LBP estimated to experience symptoms for longer than 12 weeks and develop CLBP and associated disability (Koes et al., 2006), this has significant cost implications, in particular for the NHS.
Clinical practice guidelines have been developed over the past 30 years in attempts to standardize clinical practice and improve healthcare (Miller and Petrie, 2000). The National Institute for Health and Clinical Excellence (NICE) provides national clinical guidelines for the National Health Service (NHS) to ensure high-quality, evidence-based and cost-effective care. NICE has published guidelines for LBP (NICE, 2009) but the recommendations exclude CLBP. There is a lack of guidance for CLBP management and this may in part be because of the difficulty in providing a diagnosis for the cause of LBP and the complexity of pain.
The lumbar spine contains numerous structures that have been found to give rise to pain, including joints, muscles, ligaments and nerves (Ackerman et al., 2004). However, up to 90% of all LBP may be best described as non-specific low back pain (NSLBP). This is when diagnostic tests fail to show specific pathology as the cause of pain (Koes et al., 2006). Furthermore, imaging is not always useful as changes do not always correlate with pain and symptoms (Carerra, 1980; van Tulder et al., 1997).
Lumbar zygapophyseal joints, more commonly known as facet joints, are paired synovial joints that articulate between vertebral levels (Dreyer and Dreyfuss, 1996). Controversy exists in the literature regarding lumbar facet joints being a common source of LBP (Manchikanti et al., 2000; Sehgal and Valentine, 2007; Wilde et al., 2007). Mooney and Robertson (1976) and McCall et al. (1979) found that pain can be induced by injecting facet joints with saline and then abolished by injecting local anaesthetic. However, referred pain from the anterior dura, annular ligament of the disc, and posterior and anterior ligaments has been found by Dreyfuss et al. (1994) and from the quadratus lumborum, multifidus and psoas by Ackerman et al. (2004) to produce pain indistinguishable from facet joint pain. The mechanism of pain arising from facet joints is not completely understood. Nociceptive pain is thought to arise from facet joints and the surrounding structures. The facet joint is innervated from a recurrent branch from the ipsilateral posterior primary rami at its own level and the level above. For example, the facet joint of L5 is innervated by L4 and L5 (Bogduk, 1983; Stilwell, 1956). This overlap of innervation may explain why the pattern of referred pain is not specific to a level (Carerra, 1980) or it may be in part because of multiple pain generators.
Weinstein (1991) and Procacci et al. (1999) have proposed the involvement of inflammatory neurotransmitters as a cause of pain. Substance P, calcitonin gene-related peptide and neurokinin A/B have been produced following stimulation of axon and spinal reflexes. Further research is required as the studies that have investigated the role of these substances have predominantly been conducted on animals, including rats, rabbits and guinea pigs. The data cannot be transferred directly to man as the quality and quantity of inflammatory substances are known to differ (Procacci et al., 1999). It has also been theorized that there is a conscious element to perceiving pain and that nerve receptors can signal without cause. Allodynia is a common feature in CLBP (Bowsher, 1991; Merskey and Bogduk, 1994). Abnormal pain perception may result from a problem with transmission somewhere along its course or pain transmission in the spinal cord either from source, the convergence of peripheral afferent information or at the conscious interpretation of the message in the brain (Weinstein, 1991). This may be attributed to hypersensitivity of sensitized nociceptors leading to an exaggerated pain response (Asbury and Fields, 1984). These factors may all have an effect on symptoms and therefore should be taken into consideration when assessing and managing CLBP.
There is currently no agreement on a reliable clinical method to diagnose facet joint pain (Jackson et al., 1989). Imaging is not useful as facet joints do not show noticeable radiographic changes with early degeneration and may not correlate with the symptom presentation (Lynch and Taylor, 1986). A clear history of symptoms is required and may help to indicate the facet joint as the primary source of symptoms. If pain radiates below the knee, it is thought to increase the likelihood of a radiculopathy rather than pain emanating from the facet joint, with further confirmation if there is associated true numbness or weakness (Deyo et al., 1992; Frehnhagen et al., 2006). Dermatome charts may help to identify a particular nerve root irritation but this may also be misleading because of the variability in symptom location between individuals (Butler, 1991) and the likelihood of multiple nerve fibre involvement affecting more than one nerve root (Tanaka et al., 2000). Furthermore, pain-inhibited weakness and non-dermatomal sensory loss can occur with facet joint pain and therefore is not conclusive (Bouhassiri et al., 2005). Clinical tests are used to help to prove or disprove the clinician's hypotheses. It has been postulated that lumbar spine extension with lateral flexion and rotation to the same side load the facet joint provocatively and has been used to aid diagnosis of facet joint pain (Laslett et al., 2004; Manchikanti et al., 2000; Schwarzer et al., 1995). In this position, maximal pressure is on the facet joints as they act to assist the disc in resisting compressive forces. Tenderness upon deep palpation helps to isolate the level at fault, with a palpable articular restriction being further confirmation (Dunlop et al., 1984).
Physiotherapy is used extensively to assess and manage patients with CLBP. Variation in physiotherapy practice exists, including the treatments that are offered. As previously discussed, this may in part be because of the difficulty in diagnosing the cause of LBP, the experience of the physiotherapist or the limited guidance from NICE. In spite of this, physiotherapy plays a major role in CLBP (Lewis et al., 2008).
Extensive research exists for many physiotherapy interventions, including exercise, manual therapy, aquatic therapy and acupuncture. The quality of the research is variable. However, the results of physiotherapy treatments are largely positive for reducing pain and improving function in CLBP (Aure et al., 2003; Chown et al., 2008; Hemmila et al., 2002; Koes et al., 2006; Kukkanen et al., 2007; Lewis et al., 2005; Liddle et al., 2005; Mannion et al., 2001; McIlveen and Robertson, 1998; Murphy and Longbottom, 2007; UK BEAM Trial Team, 2004). Much of the research available does not look specifically at one treatment intervention, which makes it difficult to determine the most effective physiotherapy treatment modalities (Lewis et al., 2008; Liddle et al., 2005; van Tulder et al., 2000). As a result, a combination of treatments are frequently used in physiotherapy practice.
The purpose of the current review was to focus the enormous subject of CLBP to the NHS, in particular to local practice. Many forms of treatments are available for CLBP, from a variety of health professionals. Within the NHS two forms of treatment frequently offered include physiotherapy and lumbar facet joint injections. The effectiveness and implications of these treatments on CLBP and the NHS are discussed below.
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The current review summarized the results of facet joint injection studies and physiotherapy treatment for CLBP (soft tissue massage, land-based lower back mobility exercise and spinal mobilizations). The use of a very structured approach ensured that only literature meeting the review's inclusion criteria was reviewed. A limitation of this was that the volume of literature reviewed was small.
The lumbar facet joint injection review found that facet joint injections appear to have a positive impact on patients’ pain for at least the first two weeks, and this may be longer in some patients. There is minimal recent research on lumbar facet joint injection available for review. Using the CASP screening tool enabled the methodological qualities of the studies to be assessed. Of the articles reviewed, all had methodological weaknesses. In part, this was because they did not include the information they were being assessed against – for example, not all of the studies accounted for all of the participants who started the trial or it was difficult to tell if the participants had been blinded to treatment. The author's main concerns about the studies reviewed were the lack of control groups or the method of allocation into groups; this prevented comparisons, introduced a risk of bias and reduced validity (Hicks, 2009; Juni et al., 2001). Furthermore, the lack of statistical power calculations and low sample sizes may have prevented the studies from producing statistically significant results (Moher et al., 1994). In spite of these limitations, there was a consistent pattern to the results. No study showed conclusively that benefits are maintained in the long term in the majority of study participants. Based on the review of the literature, further research is required during the first two weeks post-procedure, to consider how the benefits can be maintained.
The three physiotherapy treatments for CLBP that are most often used in local practice following lumbar facet joint injections were reviewed. The limited amount of research available for each of these treatments was disappointing. A variety of outcome measures were used within the studies and the results are consistently positive for the use of land-based lower back mobility exercise and soft tissue massage for improving CLBP. The positive benefits appear to last beyond the short term but it cannot be concluded that they are long term. The results came from studies with good methodology. All studies scored highly on the CASP screening but, with only four studies in each treatment category to review, generalizations cannot conclusively be made. The results show that further research should be carried out on land-based lower back mobility exercise and soft tissue massage with regard to their potential impact on the management of CLBP.
It was not possible to form any conclusions about the use of spinal mobilizations for CLBP because there was insufficient evidence available. As previously mentioned, Grade V spinal manipulation research was excluded from the current review because it is regarded as a being a different treatment technique to that of spinal mobilizations (Evans, 2002). It could be argued that, in order to form a conclusion on the use of spinal mobilizations, a compromise should be made by analysing the combination spinal treatment research that exists. A specific study looking at the effect of lumbar spinal mobilizations on CLBP would be beneficial to evaluating this treatment modality.
No studies have looked specifically at the cost-effectiveness of facet joint injection but, as this is an expensive procedure that has been shown to be short lasting, its use has been questioned (Zakaria and Skidmore, 2007). Based on local practice and the research that has been reviewed here, lumbar facet joint injections have a use in the treatment of CLBP. It is essential that the ‘window’ created is used to try to ensure longer-term outcomes. Further research is needed on how best to use this period most effectively.
The current review has provided enough evidence to show that there is a need to conduct further research in this field. One such study which could be of significance to the NHS would be to compare the outcomes of CLBP patients following lumbar facet joint injections with and without physiotherapy. It may be beneficial to include all physiotherapy treatments in an initial study because it is not known which physiotherapy treatments are optimal (UK BEAM Trial Team, 2004). The question that needs to be answered first is whether physiotherapy can improve long-term outcomes in CLBP. In the long term, it may be of use to expand the research to look more specifically at other variables that may play a part, including specific physiotherapy interventions. Many questions remain to be answered but the proposed benefit of combination treatment could lead to significant change in practice in the management of CLBP.