To prospectively compare the prevalence and frequency of subchondral bone marrow edema (BME) in the lumbar facet joints of low back pain patients and healthy subjects.
Lumbar magnetic resonance imaging (MRI) examinations were performed on 55 asymptomatic participants (18 men; age range 21-63; mean 36 ± 12 years; body mass index (BMI) range 16-31; mean 22.6 ± 3.2 kg/m) and 79 low back pain patients (36 men; age range 18-77; mean 47 ± 14 years; BMI range 18-40; mean 27.8 ± 4.4 kg/m). In both groups, facet joint subchondral BME signal was evaluated using T2-weighted STIR imaging, and facet joint osteoarthritis was characterized as mild, moderate, and severe.
The BME signal was found in seven asymptomatic participants (12.7%) and 28 low back pain patients (35.4%) (P = 0.003). A significant portion of the patients (15.2%) presented more than one BME signal (P = 0.011). By pooling the ten facet joints of all subjects in each group, a significant difference in osteoarthritis grade distribution was observed between the two groups (P < 0.001). When adjusted for low back pain status, age, BMI, Modic type 1, disk herniation, and facet joint osteoarthritis maximal grade, only the latter was significantly associated with the facet joint BME signal (P < 0.001).
Despite the higher prevalence and frequency of the BME signal in facet joints of low back pain patients compared to that in healthy subjects, the signal was found to be associated with the severity of the patients’ osteoarthritis and not with their low back pain status.