Changes of bone mineral density in association with serum interleukin-6 in adolescent idiopathic scoliosis

Jie WU; Yong QIU; Le ZHANG; Yanfang SUN; Xin CHEN

ABSTRACT

BACKGROUND:

There has been increasing attention in the study of adolescent idiopathic scoliosis (ALS)and bone metabolism, which is accompanied by osteopenia and osteoporosis. Interleukin(IL) -6, a cytokine that strongly promotes bone resorption, participates in the regulation of bone metablism.

OBJECTIVE:

To explore the relationship between changes of bone mineral density(BMD) and serum IL-6 content in AIS.

DESIGN:

A controlled non-randomized concurrent study involving patients with AIS and and healthy volunteers.

SETTING:

The clinic and wards of the department of spinal surgery of a university-affiliated hospital.

PARTICIPANTS:

Thirty-six patients with AIS(6 males and 30 females aged 12 to 18 years) were treated in the Department of Spinal Surgery, Drum Tower Hospital, Medical College of Nanjing University from July to October 2003, who had a Cobb angle ranging from 34° - 109° and curvature of the thoracic spine. Thirty-six healthy adolescent volunteers(7 males and 29 females within the range of 13 - 18 years old) served as the control group.

METHODS:

The BMD was measured at L2- L4 and the proximal femur;(including the femoral neck, greater trochanter and Ward' s triangle) by dual-energy X-ray absorptiometry and serum IL-6 determined by enzyme-linked immunosorbent assay(ELISA).MAIN OUTCOME

MEASURES:

① BMD of the lumbar spine and femur ② Comparison of serum IL-6 content of all the subjects.

RESULTS:

The BMD of AIS patients at L2- L4, femoral neck, greater trochanter and Ward' s triangle was 0.79±0. 12, 0.78±0. 12, 0.65± 0. 10, and 0. 69 ± 0. 13 g/cm2, respectively, all significantly lower than the corresponding measurements of the control group(1.09 ± 0. 11, 0.95 ± 0. 11,0. 78 ± 0. 10, and 0. 88 ± 0. 11 g/cm2, respectively, P ＜ 0. 001), whereas the serum IL-6 content in the patients was significantly higher than that in the control subjects ( P ＜ 0. 005). The changes of BMD at the lumbar spine and the three sites of femur were negatively correlated with serum IL-6 in AIS patients( P ＜ 0. 001 ), but not so in the control group( P ＞ 0.05).

CONCLUSION:

The BMD is decreased and serum IL-6 elevated in patients with AIS, and excessive secretion of IL-6 might be one of the important factors of osteopenia in AIS.