Background context: Compared with the cervical spine, little attention has been paid to rheumatoid arthritis (RA)-related lumbar disorders. Only a few articles have described the status of the lumbar spine affected by RA based on plain X-ray films and magnetic resonance imaging (MRI).
Purpose: To describe the features and prevalence of radiological changes of the lumbar spine of patients with RA and to clarify the correlations of such features with disease activity.
Study design: Transverse radiological study.
Patient sample: We radiographically examined 104 patients with RA whose age ranged from 21 to 78 years (mean, 51.0). In each, the duration of RA exceeded 10 years (mean, 17.7 years).
Outcome measures: Clinical outcomes included Ochi's classification, Lansbury index, C-reactive protein (CRP) (mg/dL), rheumatoid factor (RF) (U/mL), and platelet (count/mm). Radiological outcomes included radiography and MRI.
Methods: One hundred four RA patients were included in this study regardless of the presence/absence of low back pain. We examined discs from L1-2 to L5-S, including endplates, in each patient on plain X-ray films and magnetic resonance images and used a comprehensive grading system to evaluate each feature of the lumbar spine affected by RA based on the present findings and published reports. The correlations of these radiological features with RA activity and Ochi's classification were examined. To quantify disease activity, we determined the Lansbury index, serum CRP (mg/dL), RF (U/mL), and platelet count (count/mm) at the time of radiological examinations.
Results: Of the 104 patients, 47 (45.2%) exhibited a lumbar lesion. There were two types of lumbar disc lesions related to RA: disc narrowing and disc ballooning. The Lansbury index of patients with the most severe lesions was significantly higher than that of patients with less severe lesions (p<.01). The frequency of lumbar involvement also increased as the number of affected peripheral joints increased, and Ochi's classification appeared to be useful in predicting the occurrence of lumbar lesions.
Conclusion: Of 104 patients, 47 (45.2%) exhibited abnormalities on X-ray films and MRI. There were two types of disorders, disc narrowing and disc ballooning. Both the Lansbury index and Ochi's classification reflected the severity of lumbar lesions in RA patients.