Diffuse central sensitization in low back patients: A secondary analysis of cross-sectional data including tender point examination and magnetic resonance imaging of the lumbar spine

Consistency between back pain intensity and degenerative changes on magnetic resonance imaging (MRI) of the lumbar spine is poor. This study aimed to show whether tender point (TP) examination, used as a test for diffuse central sensitization, may add valuable information to clinical assessment of patients with low back pain (LBP). This was a cross-sectional study including 141 patients with LBP on sick leave. Baseline measures comprised back pain, leg pain intensity, and LBP examination including TP examination. Degenerative MRI findings were assessed in a standardized manner and blinded for clinical data. The number of TPs was analyzed in relation to sex, widespread pain, radiculopathy, pain duration, and degenerative changes on MRI. The number of TPs was positively associated with the female sex, widespread pain, and pain duration. It was negatively associated with degenerative manifestations and radiculopathy, the latter displaying a low level similar to that of the general population. A positive association between back pain intensity and TPs was present in patients with and without radiculopathy and in patients with substantial degenerative changes. Men with >7–8 TPs and women with >10–11 TPs had more back pain and similar or fewer degenerative changes than patients with few TPs (<3 and <6 TPs, respectively), thereby identifying 34% to 44% of patients with nonspecific LBP and 5% to 8% of patients with radiculopathy, respectively, with disproportionate back pain in relation to degenerative changes. Supplemental TP examination improved clinical and MRI evaluation of patients with LBP. By using gender-specific cut points, patients with disproportionate back pain were identified, presumably indicating diffuse central sensitization.