Tapio Videman

Determinants of Lumbar Disc Degeneration: A Study Relating Lifetime Exposures and Magnetic Resonance Imaging Findings in Identical Twins

Study Design Retrospective cohort. Objectives To investigate the effects of lifetime exposure to commonly suspected risk factors on disc degeneration using magnetic resonance imaging, and to estimate the effects of these suspected risk factors relative to age and familial aggregation, reflecting genetic and shared environmental influences. Summary of Background Data Structural and biochemical changes associated with disc degeneration are suspected as the underlying conditions of many back-related symptoms. Little is known about the determinants of disc degeneration. Methods Based on lifetime discordance in suspected environmental risk factors for disc degeneration, 115 male identical twin pairs were selected. An indepth interview was conducted of occupational and leisure time physical loading, driving, and smoking. Disc degeneration was evaluated using observational and digital magnetic resonance imaging assessment methods. Results Heavier lifetime occupational and leisure physical loading was associated with greater disc degeneration in the upper lumbar levels (P = 0.055− 0.001), whereas sedentary work was associated with lesser degeneration (P = 0.006). These univariate associations did not reasch statistical significance in the lower lumbar region. In multivariate analyses of the upper lumbar levels, the mean job code explained 7% of the variability in observational disc degeneration scores; the addition of age explained 16%, and familial aggregation improved the model such that 77% of the variability was explained. In the lower lumbar levels, leisure time physical loading entered the multivariate model, explaining 2% of the variability. Adding age explained 9%, and familial aggregation raised the variability in disc degeneration scores explained to 43%. Conclusion The present study findings suggest that disc degeneration may be explained primarily by genetic influences and by unidentified factors, which may include complex, unpredictable interactions. The particular environmental factors studied, which have been among those most widely suspected of accelerating disc degeneration, had very modest effects.

Lumbar disc degeneration: epidemiology and genetic influences.

Study Design. A literature review. Objective. To synthesize the scientific literature on the prevalence of lumbar disc degeneration and factors associated with its occurrence, including genetic influences. Methods. A literature review was conducted of the prevalence of disc degeneration. Studies of the etiology of disc degeneration were summarized, with particular attention given to studies of genetic influences. Results and Conclusions. There are extreme variations in the reported prevalence of specific degenerative findings of the lumbar spine among studies, which cannot be explained entirely by age or other identifiable risk factors (e.g., prevalence figures for disc narrowing varied from 3% to 56%). It is likely that these variations are due, in great part, to inconsistencies in case definitions and measurements, which are impeding epidemiologic research on disc degeneration. Research conducted over the past decade has led to a dramatic shift in the understanding of disc degeneration and its etiology. Previously, heavy physical loading was the main suspected risk factor for disc degeneration. However, results of exposure-discordant monozygotic and classic twin studies suggest that physical loading specific to occupation and sport has a relatively minor role in disc degeneration, beyond that of upright postures and routine activities of daily living. Recent research indicates that heredity has a dominant role in disc degeneration, explaining 74% of the variance in adult populations studied to date. Since 1998, genetic influences have been confirmed by the identification of several gene forms associated with disc degeneration.

1991 volvo award in clinical sciences : smoking and lumbar intervertebral disc degeneration : an MRI study of identical twins

The primary objective of this study was to determine whether disc degeneration, as assessed through magnetic resonance imaging, is greater in smokers than in nonsmokers. To control for the maximum number of potentially confounding variables, pairs of identical twins highly discordant for cigarette smoking were selected as study subjects. Data analyses revealed 18% greater mean disc degeneration scores in the lumbar spines of smokers as compared with nonsmokers. The effect was present across the entire lumbar spine, implicating a mechanism acting systemically. This investigation demonstrates the efficiency of using carefully selected controls in studying conditions of multifactorial etiology, such as disc degeneration.

Intragenic polymorphisms of the vitamin D receptor gene associated with intervertebral disc degeneration.

Study Design. A study in genetic epidemiology of disc degeneration, based on lifetime exposure data, findings on magnetic resonance imaging, and genotyping of intragenic markers. Objectives. To pursue the potential correlation between common allelic variations in the vitamin D receptor locus and degeneration of the intervertebral disc. Summary of Background Data. Familial aggregation has been observed in intervertebral disc degeneration, but the relative significance of the genetic component and shared environmental influences is unknown. The identification of relevant candidate genes associated with disc degeneration would specify a genetic component and increase our understanding of the etiopathogenesis of disc degeneration. Methods. From the population‐based Finnish Twin cohort, 85 pairs of male monozygotic twins were selected based on exposure to suspected risk factors for disc degeneration. Interview data were gathered on relevant lifetime exposures, and thoracic and lumbar disc degeneration was determined through quantitative and qualitative assessments of signal intensity on magnetic resonance imaging, and qualitative assessments of disc bulging and disc height narrowing. Possible associations were examined between disc degeneration measures and two polymorphisms of the coding region of the vitamin D receptor locus. Results. Two intragenic polymorphisms of the vitamin D receptor gene revealed an association with disc degeneration. Quantitatively assessed signal intensities of thoracic and lumbar (T6‐S1) discs were 12.9% worse in men with the TaqI tt genotype and 4.5% worse in men with the Tt genotype, compared with signal intensity in men with the TT genotype (age‐adjusted P = 0.003). A similar pattern was found between disc signal intensity and FokI genotypes; men with the ff and Ff genotypes had mean signal intensities that were 9.3% and 4.3% lower, respectively, than those in men with FF genotypes (age‐adjusted P = 0.006). The summary scores of qualitatively assessed signal intensity, bulging, and disc height were 4.0% and 6.9% worse in men with Ff and ff genotypes, respectively, when compared with those in men with the FF genotype (age‐adjusted P = 0.029). Conclusion. Specific vitamin D receptor alleles were associated with intervertebral disc degeneration as measured by T2‐weighted signal intensity, demonstrating for the first time the existence of genetic susceptibility to this progressive, age‐related degenerative process.

Dallas discogram description. A new classification of CT/discography in low-back disorders.

A new classification method for CT/discography was developed. The Dallas discogram description (DDD) related five separate categories of information. Degeneration and annular disruption were regarded as separate phenomena. Additionally, provoked pain response, contrast volume, and miscellaneous information were recorded. Discogram findings of 59 patients with low-back and/or leg pain were graded according to the new method and compared with standard methods using routine anteroposterior and lateral discographic images. Findings from routine discogra-phy and CT/discography were graded and correlated with myelographic and plain computerized axial tomography (CAT) scans. This study demonstrated that the contrast-enhanced axial view provided by CT/discography served as a useful projection for demonstrating disc pathology. CT/discography analyzed according to DDD offered a more sensitive discriminator of disc degeneration from annular disruption (disc protrusion/leaking). This evaluation can be recommended as the procedure of choice when revision of spine surgery is considered or when there is an equivocal or negative correlation between clinical information and myelography or CAT scan.

The Long-term Effects of Physical Loading and Exercise Lifestyles on Back-related Symptoms, Disability, and Spinal Pathology Among Men

Study Design Historical cohort, including selected subgroups. Objectives To understand the long-term effects of exercise on back-related outcomes, back pain, sciatica, back-related hospitalizations, pensions, and magnetic resonance imaging findings were studied among former elite athletes. Summary of Background Data Exercise and sports participation have become increasingly popular, as have recommendations of exercises for back problems, but little is known about their long-term effects. Methods Questionnaires were returned by 937 former elite athletes and 620 control subjects (83% response rate). Identification codes allowed record linkage to hospital discharge and pension registers. Magnetic resonance images were obtained of selected subgroups with contrasting physical loading patterns. Results Odds ratios for back pain were lower among athletes than among control subjects, with significant differences in endurance, sprinting and game sports, and wrestling and boxing. No differences in the occurrence of sciatica or in back-related pensions and hospitalizations were seen. When comparing lumbar magnetic resonance images of 24 runners, 26 soccer players, 19 weight lifters, and 25 shooters, disc degeneration and bulging were most common among weight lifters; soccer players had similar changes in the L4-S1 discs. No significant differences were seen in the magnetic resonance images of runners and shooters. Conclusions Maximal weight lifting was associated with greater degeneration throughout the entire lumbar spine, and soccer with degeneration in the lower lumbar region. No signs of accelerated disc degeneration were found in competitive runners. However, back pain was less common among athletes than control subjects and there were no significant differences in hospitalizations or pensions. No benefits were shown for vigorous exercise compared with lighter exercise with respect to back findings.

Reported pain during lumbar discography as a function of anular ruptures and disc degeneration : a re-analysis of 833 discograms

Study Design This re-analysis was based on 833 computed tomography/discograms collected from 306 candidates for back surgery. Objectives The goal was to test the hypothesis that outer anular ruptures are the main determinant of the pain of discography. Summary of Background Data Previous analyses indicated univeriate associations of pain with disc degeneration and anular ruptures. Methods If present, pain was classified as “exact”, “similar”, or “dissimilar” reporduction of the previously experienced pain. For each disc, ruptures and degeneration were separately evaluated by a four-point scale. Multiple logistic regression with random effects was used in the analysis. Results Outer anular ruptures were the only predictor of the responses “similar” and “exact”. General disc degeneration was the only predictor of the response “dissimilar”. There was no effect modification due to gender, age, and spinal level. Conclusions During discography, the outer anulus appears to be the origin of pain reproduction.

Lumbar disc degeneration: epidemiology and genetics.

Research conducted over the past decade has led to a dramatic shift in the understanding of disc degeneration and its etiology. Previously, heavy physical loading-often associated with occupation-was the main suspected risk factor for disc degeneration, which was commonly viewed as a wear-and-tear phenomenon exacerbated by the precarious nutritional status of the disc. However, results of studies on twins suggest that physical loading specific to occupation and sport plays a relatively minor role in disc degeneration. Recent research indicates that heredity has a dominant role in disc degeneration, which would explain the variance of up to 74% seen in adult populations that have been studied to date. Since 1998, genetic influences have been confirmed by the identification of several gene forms associated with disc degeneration. This research is paving the way for a better understanding of the biologic mechanisms through which disc degeneration occurs, including specific interactions between genes and environment. Research into disc degeneration and genetics has become more limited by phenotypes or definitions and measures of disc degeneration than by DNA analysis. Standardized, universally accepted definitions of disc degeneration are lacking, in part due to limited knowledge of the process. The measurements that are selected depend on the method used to evaluate the disc and are often qualitative ordinal rating scales, lacking in precision. Although it is generally agreed that disc degeneration is common, the prevalence of specific findings is unclear. A review of the epidemiology of disc degeneration reveals wide-ranging prevalence estimates for various signs of disc degeneration in samples of the general population and in patients with back symptoms. The extreme variations in prevalence rates are likely largely due to inconsistencies in the definitions and measurements of disc degeneration. Such inconsistencies and inaccuracies impede epidemiologic research on disc degeneration.

Low-Back Pain in Nurses and Some Loading Factors of Work

Questionnaires were sent to qualified nurses (QNs) and nursing aides (NAs) to study the prevalence of low-back pain (LBP) and sciatica In relation to age, work-load, free time activities, menstruation, pregnancies and number of children. LBP and sciatica severe enough to make them unfit for daily tasks were significantly more common in NAs. Back Injury and disability pension due to sciatic symptoms were also more common in NAs. Occupationally, NAs had twice the amount of lifting, bending, and rotation, while QNs reported more sitting and standing at work. Under the age of 30, the heaviness of the work was related to LBP in both NAs and QNs. It was concluded that prevention should be directed to improvements in the occupational work load, particularly for younger nurses.

1990 Volvo Award in clinical sciences. Lumbar spinal pathology in cadaveric material in relation to history of back pain, occupation, and physical loading.

The occurrence of symmetric disc degeneration, anular ruptures, end-plate defects, vertebral body osteophytosis, and facet joint osteoarthrosis was examined radiographically and osteologically in 86 male cadavers for whom occupational, physical loading, and back pain histories were obtained from the mens families. History of back pain and the parameters of spinal pathology were related to the highest and lowest degrees of physical loading. In multivariate analyses, history of back injury was related to the occurrence of symmetric disc degeneration, anular ruptures, and vertebral osteophytosis. Symmetric disc degeneration was associated with sedentary work, and vertebral osteophytosis was related to heavy work. History of back pain was related to occupational physical loading after control for the effects of the other covariates. The results indicate that the least pathology stemmed from moderate or mixed physical loading, but the least back pain was associated with sedentary work.