Serum vitamin D level can affect the treatment outcome of whole-body vibration for low bone mass in girls with adolescent idiopathic scoliosis

Tsz Ping Lam; Franco Tsz Fung Cheung; Queenie Wah Yan Mak; Fiona Wai Ping Yu; Kwong Man Lee; Bobby Kin Wah Ng; Jack Chun Yiu Cheng

doi:10.1530/boneabs.2.OC27

Objectives: Adolescent idiopathic scoliosis (AIS) was associated with low bone mass which, apart from being an important health issue that could persist into adulthood, was also a significant prognostic factor for curve progression in AIS. We have performed a randomized controlled trial on whole-body vibration (WBV) and reported its effect on increasing femoral neck areal bone mineral density (aBMD) mainly at the dominant leg. The objective of this study was to evaluate the role of Vit-D in moderating the anabolic bone effect of WBV.

Methods: This was a study nested within a randomized controlled trial, with enrolment of 122 AIS girls (15–25 years old) with BMD Z-scores <−1. They were randomly allocated to the treatment or control group. The treatment group received WBV by standing on a low-magnitude high-frequency WBV platform 20 mins/day, 5 days/week (acceleration 0.3 g, frequency 35 Hz). The control group received observation alone. The study period was one year. aBMD at bilateral femoral necks was measured with Dual-Energy X-ray Absorptiometry at baseline and at 12-month. Serum 25(OH)Vit-D level by liquid chromatography–tandem mass spectrometry was measured at 6-month within the treatment period.

Results: The mean age was 17.8(S.D.=1.5) years old and mean Cobb angle was 29.4(S.D.=8.8) degrees. Subgroup analysis for those with serum 25(OH)Vit-D >40 nmol/l revealed not only the positive effects of WBV were greater at both sides, treatment effects were explicitly also noted at the non-dominant leg(Table 1). In addition, the positive correlation between serum 25(OH)Vit-D and percentage increase in femoral neck aBMD that was not present in the Control group was explicitly detectable in the Treatment group at the non-dominant leg (P=0.004).

Table 1 Percentage change in femoral neck a BMD from baseline to 12-month follow-up for the treatment and control group (S.D.: P from independent samples t-test, *:P<0.05).
	Percentage change
	Treatment group		Control group
	Mean	S.D.	Mean	S.D.	P
All cases n=61 (Treatment group) and (n=61 Control group)
Dominant femoral neck aBMD (g/cm²)	2.15	4.32	0.14	3.67	0.007*
Non-dominant femoral neck aBMD (g/cm²)	2.11	3.95	1.97	3.29	0.835
For those with serum 25(OH)Vit-D level <=40 (n=46 (Treatment group), n=42 Control group)
Dominant femoral neck aBMD (g/cm²)	1.50	4.11	−0.17	3.37	0.039*
Non-dominant femoral neck aBMD (g/cm²)	1.40	3.36	2.26	3.39	0.238
For those with serum 25(OH)Vit-D level > 40 (n=15 (Treatment group), n=19 Control group)
Dominant femoral neck aBMD (g/cm²)	4.14	4.48	0.83	4.28	0.035*
Non-dominant femoral neck aBMD (g/cm²)	4.27	4.91	1.33	3.040	0.040*

Conclusion: The results strongly suggested the treatment effect of WBV could be enhanced through its synergistic factor interaction with Vit-D. The study carried significant clinical implication in that Vit-D insufficiency could affect negatively the treatment outcome of WBV for low bone mass in girls with AIS.

Funding source: General Research Fund, Research Grants Council of Hong Kong (project nos: 467808 and 468809).

Bone Abstracts

OC27