OBJECTIVETo investigate the possible relationship between Runx2 and the low bone mass of adolescent idiopathic scoliosis(AIS) patients at the osteoblast level.

METHODSTwenty eight AIS patients (mean age 14.9 years, mean Cobb angle 57.3 degrees ) in experimental group, including 2 male and 26 female, underwent posterior instrumentation between March and December 2008. They were divided into two groups. Patients in group A maintained normal bone mineral density (BMD). Patients in group B sustained osteopenia. Normal group, including 8 patients (2 males and 6 females) with a mean age of 15.3 years, were age-matched non-scoliosis adolescents who underwent spinal surgery. BMD of the lumbar spine and proximal femur was measured by using dual energy X-ray absorptiometry in three groups. Small cancellous bone samples were harvested from the iliac crest during the operation. The chipped explants were cultured to obtained the osteoblasts. P2 generation osteoblasts were analyzed to confirm the cell phenotype. Expression of mRNA and protein of Runx2 were detected by using RT-PCR and Western blot in P2 generation osteoblasts from three groups.

RESULTSThe expression of Runx2 of osteoblasts had decreased obviously in group B compared with group A and group C (P < 0.05). However, there was no significant difference between group A and group C (P > 0.05).

CONCLUSIONSThe abnormal expression of Runx2 of osteoblasts may be responsible for the low bone mass in adolescent idiopathic scoliosis patients.