The clinical aspects of the acute facet syndrome: results from a structured discussion among European chiropractors
From: Chiropr Osteopat. 2009 Feb 5;17(1):2. [Epub ahead of print]
The term ‘facet joint’ became common in the 1970s, when surgeons developed an interest in the small joints of the lumbar spine as a source of low back pain. The formal name for these joints is the zygapophyseal joints, as endorsed by The International Anatomical Nomenclature Committee. They were suggested as a source of pain as early as 1911 and the term ‘facet syndrome’ was introduced by Ghormley in 1936. However, due to the discovery of the lumbar disc as a source of low back pain, the facet joints did not receive much further attention until the 1970s. In 1976, Mooney and Robertson demonstrated that the facet joints could be a source of pain and that certain patients could be relieved from pain by anesthetizing these joints. These findings were later reproduced and thus confirmed the basis for the concept of ‘facet syndrome’, ‘facet joint pain’ or ‘zygapophyseal joint pain’. The term ‘facet syndrome’ is really a contradiction in terms. A syndrome is characterized by a set of detectable characteristics, usually used when the pathophysiology has not yet been discovered. In the case of ‘facet syndrome’, the source of pain is identified but the clinical presentation is poorly defined. Nevertheless, the term is widely used.
During the past three decades, there have been numerous studies of the frequency of facet joint pain in chronic low back pain patients. In these studies, various types of facet joint injections were used to determine whether the facet joints were the source of pain. These included injection of local anaesthetic into the joint itself or the nerves that innervate them, resulting in relief from pain if the pain originated from these joints (diagnostic blocks). Prevalence rates of facet joint pain among those patients with chronic low back pain vary widely in the literature, ranging from 5% to 90% but there is a problem with a high false positive rate in many studies. Therefore, when confirmatory blocks are used, the prevalence rates are somewhat lower, ranging from 9% to 45%. As these studies investigated chronic low back pain, these prevalence rates indicate that the facet joints might be important contributors to the burden of chronic low back pain. However, there does not appear to be any studies describing the prevalence of facet joint pain in acute low back pain.
The etiology of pain from the facet joints has been investigated from several perspectives. Osteoarthrosis has been considered as a source of facet joint pain. Facet joint osteoarthrosis is very common in the general population; the frequency increases with age and the highest prevalence is at the L4-5 spinal level. However, the presence of osteoarthrosis in the facet joints, as seen on plain radiography, does not seem to be associated with low back pain. In contrast, facet joint oedema visualised by MRI correlated with back pain intensity in at least two studies. A common explanation in chiropractic textbooks is that small meniscoids formed of synovial folds and continuous with the periarticular tissues become entrapped or extrapped and through a cascade of events lead to acute locked low back. This is described as being amenable to manipulative therapy. Garges, White and Koestler offer an alternative or supplementary explanation of pain from the facet joints. They describe how inflammatory adhesions of the facet joints and their capsules may cause a painful reduction in motion.
The trapped meniscoid and inflammatory adhesion explanations have given rise to the theory that the ‘facet syndrome’ is a lesion which responds well to manipulative therapy. Cassidy and Kirkaldy-Willis write: “An adjustment (manipulation) that separates the articular surfaces may release entrapped synovial folds and stretch the segmental muscles initiating spindle mediated reflexes that relieve the state of hypertonicity [of paraspinal muscles splinting the posterior joints]”, and Murphy et al postulate that the facet joints are the target of all successful spinal manipulation. Likewise, Cox describes the facet syndrome as “probably the most common factor seen in chiropractic practices with low back pain patients….”.
It is therefore not surprising that the facet syndrome has a prominent place in chiropractic education and practice. Unfortunately, this is not reflected in research, which creates a gap between practice and scientific evidence. When practising evidence-based medicine, one has to draw on empirical evidence in the areas where scientific evidence is lacking. In the case of the acute facet syndrome, the amount of scientific evidence relating to diagnosis and treatment is almost non-existent. Despite this uncertainty, ‘acute facet syndrome’ appears to be a commonly used diagnosis in primary care among general practitioners, chiropractors and physiotherapists, at least in Denmark. Since the term ‘acute facet syndrome’ is widely used and accepted among chiropractors, research into the degree of consensus on the subject amongst a large group of practitioners was seen to be a useful contribution. Therefore, this study aims to describe chiropractors’ views of the clinical presentation of, and course of treatment for, acute facet syndrome in the lumbar spine.
Generally, the participating chiropractors’ views of the acute facet syndrome and the description of chronic facet joint pain found in the existing literature were surprisingly similar. The chiropractors attending the ECU workshop described the characteristics of an acute, uncomplicated facet syndrome as follows: local, ipsilateral pain, occasionally extending into the thigh with pain and decreased range of motion in extension and rotation both standing and sitting. They thought that the pain could be relieved by walking, lying with knees bent, using ice packs and taking NSAIDs, and aggravated by prolonged standing or resting. They also stated that there would be no signs of neurologic involvement and no sign of aggravation of pain from sitting, flexion or coughing/sneezing. Finally, they did not link the acute facet syndrome with an antalgic posture.
When interpreting results, it must be remembered that the groups were asked to agree on a maximum of three words. Thus, even if a term is only mentioned by one group, this does not necessarily mean that the other groups disagree. For example, to the question of relieving factors, one group chose to answer “avoid aggravating factors”. Although this was only mentioned by one group, it is likely that the other groups would agree. The authors decided they could only focus on obvious sources of disagreement in cases where the groups clearly contradicted each other and this did not happen in the study.
Since the early 1980s, several investigators have attempted to define clinical criteria to distinguish pain from the facet joints from other types of low back pain, but some results have been contradictory. Several authors agree that absence of positive signs of neurological compromise, such as positive straight leg raising, pain on coughing and dermatomal radicular pain, increases the likelihood of the pain originating in the facet joints. Likewise, there is some agreement that the frequency of facet joint involvement in chronic low back pain increases with age, but Manchikanti did not find an association with age in two earlier studies. Other studies failed to find any associations between response to facet joint blocks and patient history or physical examination, including straight leg raising and pain on movement. With the exception of Fairbank et al’s study from 1981, all of these studies included only patients with chronic low back pain. The essence is that so far only diagnostic blocks (including confirmatory blocks), not clinical signs and symptoms, can accurately diagnose back pain arising from the facet joints, regardless of whether it is acute or chronic.
Regarding the distribution of facet joint pain, some investigators have found it to be paraspinal, three studies have found pain extending into the groin or thigh and two found pain extending into the calf to be a negative indicator for facet joint pain. If the pain does extend into the leg it seems to be in the sclerodermal structures, referred from the nociceptors of the facet joint capsules.
The chiropractors in the current study agreed with the existing literature on chronic low back pain: local, paraspinal pain in the back, occasionally referring to groin and thigh, rarely below the knee. There was no information to be extracted from the workshop with regard to the intensity of pain, and interestingly, literature on this subject has not been found either. One finding that was a surprise was the chiropractors’ belief that the pain is located to the side of involvement. Mention of such laterality in the literature has not been found, nevertheless, all groups agreed on the pain only being present on the side of involvement.
As for aggravating and relieving types of movement, there is more disagreement in the existing literature. Fairbank reported pain on flexion, whereas absence of pain aggravation on forward flexion was reported in three other studies. Revel also reported absence of pain aggravation with extension and rotation while increased pain on extension was found in four other studies and increased pain on rotation in two. Furthermore, pain relief from lying supine/recumbent, from walking and from sitting has been reported. Finally, absence of pain when rising from sitting or flexion has been shown to distinguish facet joint pain from pain from other structures.
Also for aggravating and relieving types of movement, the participants in this study agreed to a large extent with the literature pertaining to chronic facet syndrome: primarily pain on extension and rotation and relief from walking and lying down. In addition, the chiropractors also considered sudden movements, prolonged standing and prolonged rest as aggravating factors. The authors have not found any evidence for or against this in the literature. The same was true for supported flexion, icepacks and NSAIDs as relieving factors. This might be because the retrieved literature related to the distinction between pain originating from the facet joints and pain from other structures. Supported flexion, icepacks and NSAIDs might be relevant for all types of acute low back pain. The only clear discrepancy between the responses in this study and the existing literature is that one of the study groups considered getting up from flexion an aggravating factor whereas both Revel and Laslett found that absence of aggravation of pain on rising from flexion was characteristic of pain originating from the facet joints.
The results of the open discussion with all participants on how to distinguish the acute pain of facet joints from that of discal structures was also in concordance with the existing literature relating to chronic pain. It was believed that pain on sitting, flexion and prolonged walking would indicate disc rather than facet joint involvement and the same symptoms would indicate a typical radicular pattern, especially if accompanied by coughing and sneezing. One thing raised in the discussion, which is not mentioned in the facet joint literature, was antalgic posture as a sign of discogenic pain but not a sign of facet joint pain. This might be because the literature primarily considered chronic pain, in which antalgia is less common.
The participants in this study generally considered the syndrome to have an uncomplicated course, typically requiring 2-4 treatments over a period of two weeks. There did not appear to be any existing literature with regard to chiropractic management of the acute facet syndrome.
The high agreement among chiropractors and between chiropractors and the literature may indicate that chiropractors have a common educational background, and that their beliefs about facet joint pain to a large degree reflect what they were taught. Since chiropractors have a profound belief that facet joint pain responds well to manipulation therapy, it is likely that this description is actually of the typical patient responding well to manipulation rather than a patient with acute pain originating in the facet joints. Nevertheless, it is possible that these results do indeed capture the clinical picture of a patient with facet joint pain.
Based on the opinion of the chiropractors in this study, two hypotheses can be generated: (1) acute facet joint pain can be clinically defined, and (2) acute facet joint pain responds well to spinal manipulative therapy. Both of these hypotheses can be tested by verifying diagnoses using diagnostic blocks. The results would have implications for clinical decisions with regard to diagnosis and treatment for patients with low back pain. Since the clinical presentation thought to represent this condition is rather common and, to date poorly investigated, it is hoped that the above hypotheses will be tested in the near future.
The chiropractors attending the workshop seemed to have a common understanding of pain originating from the facet joints. They described the characteristics of an acute, uncomplicated lumbar facet syndrome in much the same way as chronic pain from the facet joints has been described in the literature. Furthermore, the acute, uncomplicated facet syndrome was considered to have an uncomplicated clinical course, responding quickly to manipulative therapy – a concept that appears never to have been scientifically tested.
