Low back pain (LBP) is a prevalent musculoskeletal condition and represents a substantial socioeconomic burden. Plain film radiography is a commonly used imaging technique. Radiographic features (RFs) such as disc space narrowing, osteophytes, spondylosis, endplate sclerosis, spondylolisthesis, and facet joint osteoarthritis have all been debated as potential pain generators in the lumbar spine. The aim of this study is to (1) determine the association between LBP and lumbar spine RFs in both community- and occupation-based groups and (2) to determine if there are differences in these associations between these two groups.
A systematic electronic search of PubMed, EMBASE, CINAHL, and Cochrane was conducted with keywords related to LBP and lumbar spine RFs. The search was restricted from inception of each respective database to April 2014. Inclusion criteria consisted of observational studies of adults (≥18 years) with and without nonspecific LBP. Studies were excluded if they investigated LBP related to infection, malignancy, or rheumatologic nature or were conducted in cadavers. Quality assessment was conducted with the Item Bank for Assessment of Risk of Bias and Precision for Observational Studies of Interventions or Exposures. Random effect models were used for all pooled analyses with associations represented by odds ratios (OR) and 95% confidence intervals (95% CIs). Statistical heterogeneity was assessed with I(2), with significant heterogeneity represented as >50%.
Overall, 28 (22 community-based and six occupation-based) studies met the eligibility criteria consisting of 26,107 subjects. A significant, positive association was found between disc space narrowing and LBP, which did not differ (p = 0.22) in both community- and occupation-based studies [OR = 1.47 (95% CI: 1.36-1.58)] and [OR = 1.76 (95% CI: 1.34-2.33)], respectively. No significant statistical heterogeneity was present in either estimate (I(2) = 0.0%). A significant association was found between spondylolisthesis and LBP in occupation-based studies [OR = 2.21 (95% CI: 1.44-3.39)] that differed significantly (p < 0.01) from community-based studies [OR = 1.12 (95% CI: 1.03-1.23)]. These individual estimates were also homogeneous (I(2) = 0.0%). The association between other radiographic features was modest (i.e., spondylosis and osteophytes) or non-significant (i.e., endplate sclerosis and facet joint). Quality of included studies varied, with the majority demonstrating good quality.
A significant association was found between disc space narrowing in both community- and occupational-based populations without significant differences between the associations. A significant strong association was found between spondylolisthesis and LBP among the occupational group but was weakly associated in the community-based group, which supports that spondylolisthesis may contribute a specific cause for LBP.