To explore the associations between spinal morning stiffness and lumbar disc degeneration (LDD).
Data from a cross-sectional general population-based study (Rotterdam Study-I) were used. Intervertebral disc spaces and osteophytes of people aged ≥55 years were scored on lumbar lateral radiographs (L1-2 through L5-S1 was scored). Logistic regression analysis was used to explore associations between spinal morning stiffness and two definitions of LDD (i.e., 'narrowing' and 'osteophytes'). Spinal morning stiffness combined with low back pain and its association with LDD was also analyzed. Similar analyses were performed for knee and hip pain, morning stiffness in the legs, and radiographic knee and hip osteoarthritis (OA) in order to compare these associations with those of LDD. All analyses were adjusted for age, gender, and body mass index (BMI).
Lumbar lateral radiographs were scored for 2,819 participants. Both definitions of LDD were associated with spinal morning stiffness: adjusted odds ratio (aOR) 1.3; 95% confidence interval (CI): 1.1-1.6 for 'osteophytes' and aOR 1.8; 95% CI: 1.4-2.2 for 'narrowing'. Both the odds ratios increased when spinal morning stiffness was combined with low back pain: aOR 1.5; 95% CI: 1.1-2.0 for 'osteophytes' and aOR 2.5; 95% CI: 1.9-3.4 for 'narrowing'. When morning stiffness in the legs was combined with knee or hip pain, the associations with radiographic knee or hip OA were: aOR 3.0; 95% CI: 2.1-4.1 for knee OA and aOR 3.1; 95% CI: 1.9-5.0 for hip OA.
Reported spinal morning stiffness is associated with LDD. The associations increased when we combined spinal morning stiffness with low back pain. The magnitude of the association for the definition 'narrowing' is similar to the association between morning stiffness in the legs and knee or hip OA.