What low back pain is and why we need to pay attention

Low back pain is a very common symptom. It occurs in high-income, middle-income, and low-income countries and all age groups from children to the elderly population. Globally, years lived with disability caused by low back pain increased by 54% between 1990 and 2015, mainly because of population increase and ageing, with the biggest increase seen in low-income and middle-income countries. Low back pain is now the leading cause of disability worldwide. For nearly all people with low back pain, it is not possible to identify a specific nociceptive cause. Only a small proportion of people have a well understood pathological cause-eg, a vertebral fracture, malignancy, or infection. People with physically demanding jobs, physical and mental comorbidities, smokers, and obese individuals are at greatest risk of reporting low back pain. Disabling low back pain is over-represented among people with low socioeconomic status. Most people with new episodes of low back pain recover quickly; however, recurrence is common and in a small proportion of people, low back pain becomes persistent and disabling. Initial high pain intensity, psychological distress, and accompanying pain at multiple body sites increases the risk of persistent disabling low back pain. Increasing evidence shows that central pain-modulating mechanisms and pain cognitions have important roles in the development of persistent disabling low back pain. Cost, health-care use, and disability from low back pain vary substantially between countries and are influenced by local culture and social systems, as well as by beliefs about cause and effect. Disability and costs attributed to low back pain are projected to increase in coming decades, in particular in low-income and middle-income countries, where health and other systems are often fragile and not equipped to cope with this growing burden. Intensified research efforts and global initiatives are clearly needed to address the burden of low back pain as a public health problem.

Low back pain in relation to lumbar disc degeneration

STUDY DESIGN

Cross-sectional magnetic resonance imaging (MRI) study.

OBJECTIVES

To study the relation of low back pain (LBP) to disc degeneration in the lumbar spine.

BACKGROUND DATA

Controversy still prevails about the relationship between disc degeneration and LBP. Classification of disc degeneration and symptoms varies, hampering comparison of study results.

METHODS

Subjects comprised 164 men aged 40-45 years-53 machine drivers, 51 construction carpenters, and 60 office workers. The data of different types of LBP, individual characteristics, and lifestyle factors were obtained from a questionnaire and a structured interview. Degeneration of discs L2/L3-L5/S1 (dark nucleus pulposus and posterior and anterior bulge) was assessed with MRI.

RESULTS

An increased risk of LBP (including all types) was found in relation to all signs of disc degeneration. An increased risk of sciatic pain was found in relation to posterior bulges, but local LBP was not related to disc degeneration. The risks of LBP and sciatic pain were strongly affected by occupation.

CONCLUSIONS

Low back pain is associated with signs of disc degeneration and sciatic pain with posterior disc bulges. Low back pain is strongly associated with occupation.

CT imaging of trunk muscles in chronic low back pain patients and healthy control subjects

Increasing documentation on the size and appearance of muscles in the lumbar spine of low back pain (LBP) patients is available in the literature. However, a comparative study between unoperated chronic low back pain (CLBP) patients and matched (age, gender, physical activity, height and weight) healthy controls with regard to muscle cross-sectional area (CSA) and the amount of fat deposits at different levels has never been undertaken. Moreover, since a recent focus in the physiotherapy management of patients with LBP has been the specific training of the stabilizing muscles, there is a need for quantifying and qualifying the multifidus. A comparative study between unoperated CLBP patients and matched control subjects was conducted. Twenty-three healthy volunteers and 32 patients were studied. The muscle and fat CSAs were derived from standard computed tomography (CT) images at three different levels, using computerized image analysis techniques. The muscles studied were: the total paraspinal muscle mass, the isolated multifidus and the psoas. The results showed that only the CSA of the multifidus and only at the lowest level (lower end-plate of L4) was found to be statistically smaller in LBP patients. As regards amount of fat, in none of the three studied muscles was a significant difference found between the two groups. An aetiological relationship between atrophy of the multifidus and the occurrence of LBP can not be ruled out as a possible explanation. Alternatively, atrophy may be the consequence of LBP: after the onset of pain and possible long-loop inhibition of the multifidus a combination of reflex inhibition and substitution patterns of the trunk muscles may work together and could cause a selective atrophy of the multifidus. Since this muscle is considered important for lumbar segmental stability, the phenomenon of atrophy may be a reason for the high recurrence rate of LBP.

A clinical prediction rule for classifying patients with low back pain who demonstrate short-term improvement with spinal manipulation

STUDY DESIGN

A prospective, cohort study of patients with nonradicular low back pain referred to physical therapy.

OBJECTIVE

Develop a clinical prediction rule for identifying patients with low back pain who improve with spinal manipulation.

SUMMARY OF BACKGROUND DATA

Development of clinical prediction rules for classifying patients with low back pain who are likely to respond to a particular intervention, such as manipulation, would improve clinical decision-making and research.

METHODS

Patients with nonradicular low back pain underwent a standardized examination and then underwent a standardized spinal manipulation treatment program. Success with treatment was determined using percent change in disability scores over three sessions and served as the reference standard for determining the accuracy of examination variables. Examination variables were first analyzed for univariate accuracy in predicting success and then combined into a multivariate clinical prediction rule.

RESULTS

Seventy-one patients participated. Thirty-two had success with the manipulation intervention. A clinical prediction rule with five variables (symptom duration, fear-avoidance beliefs, lumbar hypomobility, hip internal rotation range of motion, and no symptoms distal to the knee) was identified. The presence of four of five of these variables (positive likelihood ratio = 24.38) increased the probability of success with manipulation from 45% to 95%.

CONCLUSION

It appears that patients with low back pain likely to respond to manipulation can be accurately identified before treatment.

Prognostic factors for duration of sick leave in patients sick listed with acute low back pain: a systematic review of the literature

BACKGROUND

The percentages of patients with acute low back pain (LBP) that go on to a chronic state varies between studies from 2% to 34%. In some of these cases low back pain leads to great costs.

AIMS

To evaluate the evidence for prognostic factors for return to work among workers sick listed with acute LBP.

METHODS

Systematic literature search with a quality assessment of studies, assessment of levels of evidence for all factors, and pooling of effect sizes.

RESULTS

Inclusion of studies in the review was restricted to inception cohort studies of workers with LBP on sick leave for less than six weeks, with the outcome measured in absolute terms, relative terms, survival curve, or duration of sick leave. Of the studies, 18 publications (14 cohorts) fulfilled all inclusion criteria. One low quality study, four moderate quality studies, and nine high quality studies were identified; 79 prognostic factors were studied and grouped in eight categories for which the evidence was assessed.

CONCLUSIONS

Specific LBP, higher disability levels, older age, female gender, more social dysfunction and more social isolation, heavier work, and receiving higher compensation were identified as predictors for a longer duration of sick leave. A history of LBP, job satisfaction, educational level, marital status, number of dependants, smoking, working more than 8 hour shifts, occupation, and size of industry or company do not influence duration of sick leave due to LBP. Many different constructs were measured to identify psychosocial predictors of long term sick leave, which made it impossible to determine the role of these factors.

Are MRI-defined fat infiltrations in the multifidus muscles associated with low back pain?

BACKGROUND

Because training of the lumbar muscles is a commonly recommended intervention in low back pain (LBP), it is important to clarify whether lumbar muscle atrophy is related to LBP. Fat infiltration seems to be a late stage of muscular degeneration, and can be measured in a non-invasive manner using magnetic resonance imaging. The purpose of this study was to investigate if fat infiltration in the lumbar multifidus muscles (LMM) is associated with LBP in adults and adolescents.

METHODS

In total, 412 adults (40-year-olds) and 442 adolescents (13-year-olds) from the general Danish population participated in this cross-sectional cohort study. People with LBP were identified through questionnaires. Using MRI, fat infiltration of the LMM was visually graded as none, slight or severe. Odds ratios were calculated for both age groups, taking into account sex, body composition and leisure time physical activity for both groups, and physical workload (in adults only) or daily bicycling (in adolescents only).

RESULTS

Fat infiltration was noted in 81% of the adults but only 14% of the adolescents. In the adults, severe fat infiltration was strongly associated with ever having had LBP (OR 9.2; 95% CI 2.0-43.2), and with having LBP in the past year (OR 4.1; 1.5-11.2), but there was no such association in adolescents. None of the investigated moderating factors had an obvious effect on the OR in the adults.

CONCLUSION

Fat infiltration in the LMM is strongly associated with LBP in adults only. However, it will be necessary to quantify these measurements objectively and to investigate the direction of this link longitudinally in order to determine if the abnormal muscle is the cause of LBP or vice versa.

Long-term outcomes of standard discectomy for lumbar disc herniation: a follow-up study of more than 10 years

STUDY DESIGN

A retrospective analysis of the long-term outcomes of standard discectomy for lumbar disc herniation.

OBJECTIVES

To investigate the long-term outcomes of standard discectomy to address postoperative problems, including residual low back pain and recurrent herniation.

SUMMARY OF BACKGROUND DATA

Most previous investigators found that favorable outcomes of standard discectomy were maintained for the long-term postoperative period. Although they observed postoperative complications such as residual low back pain and recurrent herniation, detailed analyses of these results have not been conducted.

METHODS

The long-term follow-up results in patients who were observed for a minimum of 10 years after standard discectomy were evaluated by using the Japanese Orthopedic Association scoring system through direct examinations and questionnaires. Radiography also was used in patients who agreed to visit the hospital, and findings were compared with those on preoperative radiographs.

RESULTS

The average recovery rate calculated by using Japanese Orthopedic Association scores was 73.5 +/- 21.7%. Even though residual low back pain was found in 74.6% of the patients, only 12.7% had severe low back pain. The majority of the patients with severe low back pain were under 35 years of age at the time of operation, with preoperative advanced disc degeneration. The final Japanese Orthopedic Association scores in the patients with decreased disc height were significantly lower than those in patients with no decrease. However, the disc height of patients with a recurrent herniation was preserved.

CONCLUSION

The long-term outcome of standard discectomy in this series was favorable. Although patients with preserved disc height generally had favorable results, the risk of recurrent disc herniation was high in this population.

Changes in the cross-sectional area of multifidus and psoas in patients with unilateral back pain: the relationship to pain and disability

STUDY DESIGN

Prospective, cross-sectional observational study.

OBJECTIVES

The aim of this study was to determine if there was an association between wasting of psoas and multifidus as observed on MRI scans and the presenting symptoms, reported pathology, pain, or disability of a cohort of patients presenting with unilateral low back pain.

SUMMARY OF BACKGROUND DATA

Current physiotherapy practice is often based on localized spine stabilizing muscle exercises; most attention has been focused on transversus abdominus and multifidus with relatively little on psoas.

METHOD

Fifty consecutive patients presenting to a back pain triage clinic with unilateral low back pain lasting more than 12 weeks were recruited. The cross-sectional surface area (CSA) of the muscles was measured. Duration of symptoms, rating of pain, self-reported function, and the presence of neural compression were recorded.

RESULTS

Data analysis compared the CSA between the symptomatic and asymptomatic sides. There was a statistically significant difference in CSA between the sides (P < 0.001). There was a positive correlation between the percentage decrease in CSA of psoas on the affected side and with the rating of pain (rho = 0.608, P < 0.01), reported nerve root compression (rho = 0.812, P < 0.01), and the duration of symptoms (rho = 0.886, P < 0.01). There was an association between decrease in the CSA of multifidus and duration of symptoms.

CONCLUSIONS

Atrophy of multifidus has been used as one of the rationales for spine stabilization exercises. The evidence of coexisting atrophy of psoas and multifidus suggests that a future area for study should be selective exercise training of psoas, which is less commonly used in clinical practice.

Disc degeneration of the lumbar spine in relation to overweight

OBJECTIVE

To study the association between overweight and lumbar disc degeneration.

DESIGN

Population-based 4-y follow-up magnetic resonance imaging (MRI) study.

SUBJECTS

The subjects were 129 working middle-aged men selected to the baseline magnetic resonance imaging (MRI) study from a cohort of 1832 men representing three occupations: machine drivers, construction carpenters, and office workers. The selection was based on the paticipants' age (40-45 y) and place of residence. MR images of the lumbar spines were obtained at baseline and at 4-y follow-up.

MEASUREMENTS

Signal intensity of the nucleus pulposus of the discs L2/L3-L4/L5 was visually assessed by two readers using the adjacent cerebrospinal fluid as an intensity reference. The weight (at age 25 and 40-45 y) and height of the subjects, history of car driving, smoking, and back injuries were assessed by questionnaire.

RESULTS

Multiple regression analyses allowing for occupation, history of car driving, smoking, and back injuries showed that persistent overweight (body mass index (BMI) > or =25 kg/m(2) at both ages) associated strongly with an increased risk of the number of lumbar discs with decreased signal intensity of nucleus pulposus at follow-up, adjusted odds ratio (OR) being 4.3 (95% confidence intervals (95% CIs) 1.3-14.3). Overweight at young age (risk ratio (RR) 3.8; 95% CI 1.4-10.4) was a stronger predictor of an increase in the number of degenerated discs during follow-up than overweight in middle age (RR 1.3; 95% CI 0.7-2.7).

CONCLUSIONS

The study provides evidence that the BMI above 25 kg/m(2) increases the risk of lumbar disc degeneration. Overweight at young age seems to be particularly detrimental.

Pathobiology of Modic changes

PURPOSE

Low back pain (LBP) is the most disabling condition worldwide. Although LBP relates to different spinal pathologies, vertebral bone marrow lesions visualized as Modic changes on MRI have a high specificity for discogenic LBP. This review summarizes the pathobiology of Modic changes and suggests a disease model.

METHODS

Non-systematic literature review.

RESULTS

Chemical and mechanical stimulation of nociceptors adjacent to damaged endplates are likely a source of pain. Modic changes are adjacent to a degenerated intervertebral disc and have three generally interconvertible types suggesting that the different Modic change types represent different stages of the same pathological process, which is characterized by inflammation, high bone turnover, and fibrosis. A disease model is suggested where disc/endplate damage and the persistence of an inflammatory stimulus (i.e., occult discitis or autoimmune response against disc material) create predisposing conditions. The risk to develop Modic changes likely depends on the inflammatory potential of the disc and the capacity of the bone marrow to respond to it. Bone marrow lesions in osteoarthritic knee joints share many characteristics with Modic changes adjacent to degenerated discs and suggest that damage-associated molecular patterns and marrow fat metabolism are important pathogenetic factors. There is no consensus on the ideal therapy. Non-surgical treatment approaches including intradiscal steroid injections, anti-TNF-α antibody, antibiotics, and bisphosphonates have some demonstrated efficacy in mostly non-replicated clinical studies in reducing Modic changes in the short term, but with unknown long-term benefits. New diagnostic tools and animal models are required to improve painful Modic change identification and classification, and to clarify the pathogenesis.

CONCLUSION

Modic changes are likely to be more than just a coincidental imaging finding in LBP patients and rather represent an underlying pathology that should be a target for therapy.

A hypothesis of chronic back pain: ligament subfailure injuries lead to muscle control dysfunction

Clinical reports and research studies have documented the behavior of chronic low back and neck pain patients. A few hypotheses have attempted to explain these varied clinical and research findings. A new hypothesis, based upon the concept that subfailure injuries of ligaments (spinal ligaments, disc annulus and facet capsules) may cause chronic back pain due to muscle control dysfunction, is presented. The hypothesis has the following sequential steps. Single trauma or cumulative microtrauma causes subfailure injuries of the ligaments and embedded mechanoreceptors. The injured mechanoreceptors generate corrupted transducer signals, which lead to corrupted muscle response pattern produced by the neuromuscular control unit. Muscle coordination and individual muscle force characteristics, i.e. onset, magnitude, and shut-off, are disrupted. This results in abnormal stresses and strains in the ligaments, mechanoreceptors and muscles, and excessive loading of the facet joints. Due to inherently poor healing of spinal ligaments, accelerated degeneration of disc and facet joints may occur. The abnormal conditions may persist, and, over time, may lead to chronic back pain via inflammation of neural tissues. The hypothesis explains many of the clinical observations and research findings about the back pain patients. The hypothesis may help in a better understanding of chronic low back and neck pain patients, and in improved clinical management.

Changes in motor planning of feedforward postural responses of the trunk muscles in low back pain

Changes in trunk muscle recruitment have been identified in people with low-back pain (LBP). These differences may be due to changes in the planning of the motor response or due to delayed transmission of the descending motor command in the nervous system. These two possibilities were investigated by comparison of the effect of task complexity on the feedforward postural response of the trunk muscles associated with rapid arm movement in people with and without LBP. Task complexity was increased by variation of the expectation for a command to either abduct or flex the upper limb. The onsets of electromyographic activity (EMG) of the abdominal and deltoid muscles were measured. In control subjects, while the reaction time of deltoid and the superficial abdominal muscles increased with task complexity, the reaction time of transversus abdominis (TrA) was constant. However, in subjects with LBP, the reaction time of TrA increased along with the other muscles as task complexity was increased. While inhibition of the descending motor command cannot be excluded, it is more likely that the change in recruitment of TrA represents a more complex change in organisation of the postural response.

An MRI investigation into the function of the transversus abdominis muscle during "drawing-in" of the abdominal wall

STUDY DESIGN

An operator blinded dual modality trial of measurement of the abdominal muscles during "drawing-in" of the abdominal wall.

OBJECTIVES

1) To investigate, using magnetic resonance imaging (MRI), the function of the transversus abdominis muscle bilaterally during a drawing-in of the abdominal wall. 2) To validate the use of real-time ultrasound imaging as a measure of the deep abdominal muscle during a drawing-in of the abdominal wall.

SUMMARY OF BACKGROUND DATA

Previous research has implicated the deep abdominal muscle, transversus abdominis, in the support and protection of the spine and provided evidence that training this muscle is important in the rehabilitation of low back pain. One of the most important actions of the transversus abdominis is to "draw-in" the abdominal wall, and this action has been shown to stiffen the sacroiliac joints. It is hypothesized that in response to a draw in, the transversus abdominis muscle forms a deep musculofascial "corset" and that MRI could be used to view this corset and verify its mechanism of action on the lumbopelvic region.

METHODS

Thirteen healthy asymptomatic male elite cricket players aged 21.3 +/- 2.1 years were imaged using MRI and ultrasound imaging as they drew in their abdominal walls. Measurements of the thickness of the transversus abdominis and internal oblique muscles and the slide of the anterior abdominal fascia were measured using both MRI and ultrasound. Measurement of the whole abdominal cross-sectional area (CSA) was conducted using MRI.

RESULTS

Results of the MRI demonstrated that, as a result of draw-in, there was a significant increase in thickness of the transversus abdominis (P < 0.001) and the internal oblique muscles (P < 0.001). There was a significant decrease in the CSA of the trunk (P < 0.001). The mean slide (+/-SD) of the anterior abdominal fascia was 1.54 +/- 0.38 cm for the left side and 1.48 +/- 0.35 cm for the right side. Ultrasound measurements of muscle thickness of both transversus abdominis and the internal oblique, as well as fascial slide, correlated with measures obtained using MRI (interclass correlations from 0.78 to 0.95).

CONCLUSIONS

The MRI results demonstrated that during a drawing-in action, the transversus abdominis contracts bilaterally to form a musculofascial band that appears to tighten (like a corset) and most likely improves the stabilization of the lumbopelvic region. Real-time ultrasound imaging can also be used to measure changes in the transversus abdominis during the draw-in maneuver.

Clinical and imaging efficacy of infliximab in HLA-B27-Positive patients with magnetic resonance imaging-determined early sacroiliitis

OBJECTIVE

To evaluate the efficacy of infliximab in HLA-B27-positive patients with magnetic resonance imaging (MRI)-determined early sacroiliitis, using both clinical and MRI assessments.

METHODS

Forty patients with recent-onset inflammatory back pain, as assessed by the Calin criteria, HLA-B27 positivity, clinical disease activity as measured by the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), pain and morning stiffness, and magnetic resonance imaging (MRI)-determined sacroiliac joint bone edema were randomized in a double-blind manner to receive infliximab 5 mg/kg or placebo at 0, 2, 6, and 12 weeks. MRI scans were performed at baseline and 16 weeks and scored by 2 observers (blinded to both the order of the scans and to treatment group), using the Leeds scoring system. Clinical assessments included the BASDAI, the Bath Ankylosing Spondylitis Functional Index (BASFI), the Ankylosing Spondylitis Quality of Life (ASQoL) instrument, the ASsessment in Ankylosing Spondylitis International Working Group criteria (ASAS) for improvement, and markers of inflammation.

RESULTS

The mean reduction in the total MRI score from week 0 to week 16 was significantly greater in infliximab-treated patients compared with placebo-treated patients (P = 0.033). On average, significantly more lesions resolved in the infliximab group (P < 0.001), while significantly more new lesions developed in the placebo group (P = 0.004). Significantly greater improvement in the infliximab group versus the placebo group was also observed for changes from week 0 to week 16 in the BASDAI (P = 0.002), BASFI (P = 0.004), and ASQoL (P = 0.007) scores. Responses according to the ASAS criteria for 40% improvement, the ASAS criteria for 20% improvement in 5 of 6 domains, and ASAS partial remission were achieved by 61%, 44%, and 56% of infliximab-treated patients, respectively. Infliximab was well tolerated, and no serious adverse events were observed.

CONCLUSION

Infliximab was an effective therapy for early sacroiliitis, providing a reduction in disease activity by week 16. This study is the first to show that infliximab is effective for reducing clinical and imaging evidence of disease activity in patients with MRI-determined early axial spondylarthritis.

Correlation of radiographic and MRI parameters to morphological and biochemical assessment of intervertebral disc degeneration

Degenerative disc disease (DDD) is a common finding in MRI scans and X-rays. However, their correlation to morphological and biochemical changes is not well established. In this study, radiological and MRI parameters of DDD were assessed and compared with morphological and biochemical findings of disc degeneration. Thirty-nine human lumbar discs (L1-S1), age 19-86 years, were harvested from eight cadavers. Within 48 h postmortem, MRIs in various spin-echo sequences and biplanar radiographs of intact spines were obtained. Individual discs with endplates were then sectioned in the mid-sagittal plane and graded according to the morphological appearance. Samples from the nucleus of each disc were harvested for biochemical analysis including water and proteoglycan contents. On MRIs, T2-signal intensity, Modic changes, disc extension beyond the interspace (DEBIT), nucleus pulposus shape, annular tears, osteophytes and endplate integrity were graded. On radiographs, an independent observer classified the parameters disc height, endplate sclerosis, osteophytes, Schmorl's nodes, intradiscal calcifications and endplate shape. General linear-regression models were used for statistical analysis. Backward elimination with a 10% significance cut-off level was used to identify the most significant parameters, which then were summed to create composite scores for radiography, MRI and the combination of both methods. The grading was performed by three observers, and a reliability analysis using Cronbach's alpha model was used to control interobserver agreement. The three radiographic parameters height-loss, osteophytes and intradiscal calcifications correlated significantly with the morphological degree of degeneration (p<0.001, R2=642). Significant differences of even one morphological grade could also be differentiated in the composite radiological score (p<0.05), except at the extremes between grades 1 and 2 and grades 4 and 5. All MRI parameters correlated significantly with the morphological grade (p<0.05); however Modic changes, T2-intensity and osteophytes accounted for 83% of the variation in the data. T2-signal intensity correlated significantly with H2O and proteoglycan content (p<0.001), and was best for detecting highly degenerated discs. Regression showed that the combined score was better correlated with the morphological grade (p<0.001, R2=775) than either the composite radiographic (p<0.001, R2=642) or composite MRI (p<0.001, R2=696) alone. Based on the combined score, a backwards elimination of the regression was performed, in which the parameters Modic changes, and T2-intensity loss (MRI) as well as calcifications (X-ray) accounted for 87% of the variability. The interobserver validation showed a high correlation for all three scores (Cronbach's alpha values ranging from 0.95 to 0.97).

CONCLUSION

Selective imaging parameters and a newly created scoring scheme were found to correlate with disc degeneration as determined in a morphological manner. Surprisingly, radiographic parameters were able to distinguish different stages of degeneration, whereas MRI could only detect advanced stages of disc degeneration. We conclude that X-rays may remain a cost-effective, non-invasive in vivo-grading method to detect early disc degeneration, and, combined with MRI, correlate best with morphological and biochemical assessment of disc degeneration.

Facet joint osteoarthritis and low back pain in the community-based population

STUDY DESIGN

Cross-sectional study.

OBJECTIVE

To evaluate the association between lumbar spine facet joint osteoarthritis (FJ OA) identified by multidetector computed tomography (CT) and low back pain (LBP) in the community-based Framingham Heart Study.

SUMMARY OF BACKGROUND DATA

The association between lumbar FJ OA and LBP remains unclear.

METHODS

This study was an ancillary project to the Framingham Heart Study. A sample of 3529 participants of the Framingham Heart Study aged 40 to 80 underwent multidetector CT imaging to assess aortic calcification. One hundred eighty-eight individuals were consecutively enrolled in this ancillary study to assess radiographic features associated with LBP. LBP in the preceding 12 months was evaluated using a self-report questionnaire. FJ OA was evaluated on CT scans using a 4-grade scale. The association between FJ OA and LBP was examined used multiple logistic regression models, while adjusting for gender, age, and BMI.

RESULTS

CT imaging revealed a high prevalence of FJ OA (59.6% of males and 66.7% of females). Prevalence of FJ OA increases with age. By decade, FJ OA was present in 24.0% of <40-years-olds, 44.7% of 40- to 49-years-olds, 74.2% of 50- to 59-years-olds, 89.2% of 60- to 69-year-olds, and 69.2% of >70-years-olds. By spinal level the prevalence of FJ OA was: 15.1% at L2-L3, 30.6% at L3-L4, 45.1% at L4-L5, and 38.2% at L5-S1. In this community-based population, individuals with FJ OA at any spinal level showed no association with LBP.

CONCLUSION

There is a high prevalence of FJ OA in the community. Prevalence of FJ OA increases with age with the highest prevalence at the L4-L5 spinal level. At low spinal levels women have a higher prevalence of lumbar FJ OA than men. In the present study, we failed to find an association between FJ OA, identified by multidetector CT, at any spinal level and LBP in a community-based study population.

Systematic review of tests to identify the disc, SIJ or facet joint as the source of low back pain

Clinical practice guidelines state that the tissue source of low back pain cannot be specified in the majority of patients. However, there has been no systematic review of the accuracy of diagnostic tests used to identify the source of low back pain. The aim of this systematic review was therefore to determine the diagnostic accuracy of tests available to clinicians to identify the disc, facet joint or sacroiliac joint (SIJ) as the source of low back pain. MEDLINE, EMBASE and CINAHL were searched up to February 2006 with citation tracking of eligible studies. Eligible studies compared index tests with an appropriate reference test (discography, facet joint or SIJ blocks or medial branch blocks) in patients with low back pain. Positive likelihood ratios (+LR) > 2 or negative likelihood ratios (-LR) < 0.5 were considered informative. Forty-one studies of moderate quality were included; 28 investigated the disc, 8 the facet joint and 7 the SIJ. Various features observed on MRI (high intensity zone, endplate changes and disc degeneration) produced informative +LR (> 2) in the majority of studies increasing the probability of the disc being the low back pain source. However, heterogeneity of the data prevented pooling. +LR ranged from 1.5 to 5.9, 1.6 to 4.0, and 0.6 to 5.9 for high intensity zone, disc degeneration and endplate changes, respectively. Centralisation was the only clinical feature found to increase the likelihood of the disc as the source of pain: +LR = 2.8 (95%CI 1.4-5.3). Absence of degeneration on MRI was the only test found to reduce the likelihood of the disc as the source of pain: -LR = 0.21 (95%CI 0.12-0.35). While single manual tests of the SIJ were uninformative, their use in combination was informative with +LR of 3.2 (95%CI 2.3-4.4) and -LR of 0.29 (95%CI 0.12-0.35). None of the tests for facet joint pain were found to be informative. The results of this review demonstrate that tests do exist that change the probability of the disc or SIJ (but not the facet joint) as the source of low back pain. However, the changes in probability are usually small and at best moderate. The usefulness of these tests in clinical practice, particularly for guiding treatment selection, remains unclear.

Fat content of lumbar paraspinal muscles in patients with chronic low back pain and in asymptomatic volunteers: quantification with MR spectroscopy

PURPOSE

To prospectively evaluate the fat content of paraspinal muscles by using proton magnetic resonance (MR) spectroscopy in patients with chronic low back pain (LBP) and in asymptomatic volunteers matched with regard to age, sex, and body mass index.

MATERIALS AND METHODS

The study was approved by the responsible institutional review board. Informed consent was obtained from each patient and each volunteer. Single-voxel proton MR spectroscopy was used to measure the fat content of the lumbar multifidus and longissimus muscles in 25 patients (13 women, 12 men; mean age, 40.5 years) with chronic LBP and in 25 matched asymptomatic volunteers (13 women, 12 men; mean age, 39.8 years). The fat content was also graded semiquantitatively (grades 0-4). The relationship between fat content and LBP duration, LBP intensity, and self-rated disability was assessed (Pearson correlation).

RESULTS

The mean percentage fat content of the multifidus muscle was 23.6% (95% confidence interval [CI]: 17.5%, 29.7%) in patients with chronic LBP and 14.5% (95% CI: 10.8%, 18.3%) in the volunteers (P = .014). The corresponding values for the longissimus muscle were 29.3% (95% CI: 23.4%, 35.3%) in patients with LBP and 26.0% (95% CI: 21.9%, 30.0%) in the volunteers (P = .66). The semiquantitative grading of the fat content of the multifidus muscle was 0 in 12 (48%) of 25 patients and in 14 (56%) of 25 volunteers, 1 in 11 (44%) patients and in eight (32%) volunteers, and 2 in two (8%) patients and three (12%) volunteers. The semiquantitative grading of the fat content of the longissimus muscle was 0 in nine (36%) of 25 patients and 15 (60%) of 25 volunteers, 1 in 13 (52%) patients and nine (36%) volunteers, and 2 in three (12%) patients and one (4%) volunteer. Neither grade 3 nor grade 4 was assigned to any muscle. The grading differences were not significant between patients and volunteers. No significant correlation was found between fat content and pain intensity, pain duration, or self-rated disability.

CONCLUSION

Proton MR spectroscopy demonstrates a significantly higher fat content in the multifidus muscle in patients with chronic LBP than in asymptomatic volunteers. No difference was detected with a semiquantitative grading system.

Trunk muscle stabilization training plus general exercise versus general exercise only: randomized controlled trial of patients with recurrent low back pain

BACKGROUND AND PURPOSE

The purpose of this randomized controlled trial was to examine the usefulness of the addition of specific stabilization exercises to a general back and abdominal muscle exercise approach for patients with subacute or chronic nonspecific back pain by comparing a specific muscle stabilization-enhanced general exercise approach with a general exercise-only approach.

SUBJECTS

Fifty-five patients with recurrent, nonspecific back pain (stabilization-enhanced exercise group: n=29, general exercise-only group: n=26) and no clinical signs suggesting spinal instability were recruited.

METHODS

Both groups received an 8-week exercise intervention and written advice (The Back Book). Outcome was based on self-reported pain (Short-Form McGill Pain Questionnaire), disability (Roland-Morris Disability Questionnaire), and cognitive status (Pain Self-Efficacy Questionnaire, Tampa Scale of Kinesiophobia, Pain Locus of Control Scale) measured immediately before and after intervention and 3 months after the end of the intervention period.

RESULTS

Outcome measures for both groups improved. Furthermore, self-reported disability improved more in the general exercise-only group immediately after intervention but not at the 3-month follow-up. There were generally no differences between the 2 exercise approaches for any of the other outcomes.

DISCUSSION AND CONCLUSION

A general exercise program reduced disability in the short term to a greater extent than a stabilization-enhanced exercise approach in patients with recurrent nonspecific low back pain. Stabilization exercises do not appear to provide additional benefit to patients with subacute or chronic low back pain who have no clinical signs suggesting the presence of spinal instability.

Possible pathogenesis of painful intervertebral disc degeneration

STUDY DESIGN

We collected the specimens of lumbar intervertebral disc (i.e., the symptomatic degenerative disc) from patients with discogenic low back pain to study the histopathologic features and growth factor expressions.

OBJECTIVES

To study the pathogenesis of disc degeneration, meanwhile discriminating between common disc degeneration (aging disc) (i.e., black asymptomatic disc, not clinically relevant) and painful disc degeneration (i.e., symptomatic disc, clinically relevant).

SUMMARY OF BACKGROUND DATA

The pathogenesis of intervertebral disc degeneration is poorly understood, mainly because of the difficulty to establish the experimental model with good reproducibility. Recently, the popularity of spinal fusion leads to more opportunities to obtain disc specimens, which could be applied to explore the pathogenesis of disc degeneration with modern biologic techniques.

METHODS

There were 21 specimens of lumbar intervertebral discs from 15 patients with discogenic low back pain during posterior lumbar interbody fusion, 16 aging discs from patients without low back pain, and 10 normal discs as control collected for the study of their histopathologic features, as well as the expressions of basic fibroblast growth factor (bFGF) and its receptor (Flg), transforming growth factor-beta1 (TGF-beta1) and its receptor (TGF-betaRI) by immunohistochemistry. The distribution of macrophages and mast cells was also noted. Proliferating cell nuclear antigen was assessed to evaluate proliferating activities of disc cells.

RESULTS

The distinct histologic characteristic of the disc from the patient with discogenic low back pain was the ingrowth of vascularized granulation tissue along torn fissures, extending from the external layer of the anulus fibrosus into the nucleus pulposus. The immunohistochemical staining showed that there were strong expressions of bFGF and TGF-beta1 and their receptors, as well as a strong expression of proliferating cell nuclear antigen in the zones of granulation tissue in the painful discs. However, there were only weak expressions in the nongranulation tissue zones in the painful discs and aging discs, and no expression in the control discs. In addition, abundant macrophages and mast cells were found in the granulation tissue zones of painful discs but absent in the nongranulation tissue zones of painful discs or aging discs and the normal control discs.

CONCLUSIONS

The findings indicated that degeneration of the painful disc might originate from the injury and subsequent repair of anulus fibrosus. Growth factors, such as bFGF and TGF-beta1, macrophages and mast cells might play a key role in the repair of the injured anulus fibrosus and subsequent disc degeneration.

Structural, psychological, and genetic influences on low back and neck pain: a study of adult female twins

OBJECTIVE

To assess genetic and environmental influences on low back and neck pain in a classic twin design and to examine the extent to which these are explained by structural changes seen on magnetic resonance imaging (MRI) and psychological and lifestyle variables.

METHODS

The subjects comprised 1,064 unselected women (181 monozygotic [MZ] and 351 dizygotic [DZ] twin pairs) recruited from a national registry of twin volunteers. Outcome measures included lifetime history of low back and neck pain (using a range of increasingly stringent definitions), MRI scores of disc degeneration in the lumbar and cervical spine, psychological distress as assessed by the General Health Questionnaire (GHQ), and lifestyle variables assessed by questionnaire.

RESULTS

For all definitions of pain, there was a consistent excess concordance in MZ when compared with DZ twins, equating to a heritability for low back pain in the range of 52-68% and for neck pain in the range of 35-58%. The strongest associations were between low back pain and MRI change (odds ratio [OR] 3.6, 95% confidence interval [95% CI] 1.8-7.3]) and between neck pain and response on the GHQ (OR 3.3, 95% CI 2.1-5.0). These associations were mediated genetically.

CONCLUSIONS

Genetic factors have an important influence on back and neck pain reporting in women. These factors include the genetic determinants of structural disc degeneration and an individual's inherited tendency toward psychological distress. MRI changes are the strongest predictor of low back pain.

Modic changes in endplates of lumbar vertebral bodies: prevalence and association with low back and sciatic pain among middle-aged male workers

STUDY DESIGN

Cross-sectional comparison of self-reported low back pain (LBP) symptoms and Modic findings on magnetic resonance imaging (MRI).

OBJECTIVES

To investigate associations of frequency and intensity of LBP and sciatic pain with Modic changes in a sample of middle-aged male workers with or without whole-body vibration exposure.

SUMMARY OF BACKGROUND DATA

Vertebral endplate changes are bone marrow lesions visible on MRI and are assumed to be associated with degenerative intervertebral disc disease. Associations of these so-called Modic changes with clinical symptoms are controversial. Furthermore, most of these studies have been performed in selected series of patients.

METHODS

A total of 228 middle-aged male workers (159 train engineers and 69 sedentary controls) from northern Finland underwent sagittal T1 and T2-weighted MRI. Both endplates of 1140 lumbar interspaces were graded for type and extent of Modic changes. Logistic regression was used to analyze associations of pain variables with Modic changes.

RESULTS

Train engineers had on the average higher sciatic pain scores than the sedentary controls, but the prevalence of Modic changes was similar in both occupational groups. Altogether, 178 Modic changes in 128 subjects were recorded: 30% were type I, 66% type II, and 4% both types I and II. Eighty percent of changes occurred at L4-L5 or L5-S1. Modic changes at L5-S1 showed significant association with pain symptoms with increased frequency of LBP (odds ratio [OR] 2.28; 95% confidence interval [CI] 1.44-3.15) and sciatica episodes (OR 1.44; 95% CI 1.01-1.89), and with higher LBP visual analog scores during the past week (OR 1.36; 95% CI 1.06-1.70). Type I lesions and extensive lesions in particular were closely associated with pain.

CONCLUSIONS

Modic changes at L5-S1 and Modic type I lesions are more likely to be associated with pain symptoms than other types of Modic changes or changes located at other lumbar levels.

Tumor necrosis factor-immunoreactive cells and PGP 9.5-immunoreactive nerve fibers in vertebral endplates of patients with discogenic low back Pain and Modic Type 1 or Type 2 changes on MRI

STUDY DESIGN

Immunohistochemistry for tumor necrosis factor (TNF) and protein gene product (PGP) 9.5 in vertebral endplates of patients with discogenic low back pain and Modic Type 1 or Type 2 endplate changes on MRI.

OBJECTIVES

To examine whether inflammatory cytokines and nerve in-growth into the vertebral endplate are associated with discogenic low back pain.

SUMMARY AND BACKGROUND DATA

Degenerated discs and endplate abnormalities can be a cause of discogenic low back pain. However, the presence of TNF-immunoreactive cells and PGP 9.5-immunoreactive nerve fibers has not been studied in patients with discogenic low back pain and endplate changes on MRI.

METHODS

Eighteen endplates showing either normal intensity signals on MRI (endplate change -), Modic Type 1 signals (low intensity on T1-weighted spin-echo images), or Modic Type 2 signals (high intensity) from patients with discogenic low back pain (n = 14) or controls requiring surgery for other back problems (n = 4; scoliosis and traumatic injury of vertebra) were harvested during surgery. Endplates were immunostained using antibodies to TNF and PGP 9.5 and immunostained cells and nerve fibers in the endplates were counted.

RESULTS

Vertebral endplates from patients with Modic Type 1 or Type 2 endplate changes on MRI had significantly more PGP 9.5-immunoreactive nerve fibers and TNF-immunoreactive cells in comparison with patients with normal endplates on MRI (P < 0.01). The number of TNF-immunoreactive cells in endplates exhibiting Modic Type 1 changes was significantly higher than in endplates exhibiting Modic Type 2 changes (P < 0.05).

CONCLUSIONS

The results suggest that endplate abnormalities are related to inflammation and axon growth induced by TNF. TNF expression and PGP 9.5-positive nerve in-growth in abnormal endplates may be a cause of low back pain.

Three-year incidence of low back pain in an initially asymptomatic cohort: clinical and imaging risk factors

STUDY DESIGN

Prospective cohort study of randomly selected Veterans Affairs out-patients without baseline low back pain (LBP).

OBJECTIVE

To determine predictors of new LBP as well as the 3-year incidence of magnetic resonance imaging (MRI) findings.

SUMMARY OF BACKGROUND DATA

Few prospective studies have examined clinical and anatomic risk factors for the development of LBP, or the incidence of new imaging findings and their relationship to back pain onset.

METHODS

We randomly selected 148 Veterans Affairs out-patients (aged 35 to 70) without LBP in the past 4 months. We compared baseline and 3-year lumbar spine MRI. Using data collected every 4 months, we developed a prediction model of back pain-free survival.

RESULTS

After 3 years, 131 subjects were contacted, and 123 had repeat MRI. The 3-year incidence of pain was 67% (88 of 131). Depression had the largest hazard ratio (2.3, 95% CI = 1.2-4.4) of any baseline predictor of inci-dent back pain. Among baseline imaging findings, central spinal stenosis and nerve root contact had the highest, though nonsignificant, hazard ratios. We did not find an association between new LBP and type 1 endplate changes, disc degeneration, annular tears, or facet degeneration. The incidence of new MRI findings was low, with the most common new finding being disc signal loss in 11 (9%) subjects. All five subjects with new disc extrusions and all four subjects with new nerve root impingement had new pain.

CONCLUSION

Depression is an important predictor of new LBP, with MRI findings likely less important. New imaging findings have a low incidence; disc extrusions and nerve root contact may be the most important of these findings.