Postural stabilizing effect of alfacalcidol and active absorbable algal calcium (AAA Ca) compared with calcium carbonate assessed by computerized posturography

Abstract

Sway and postural instability have drawn attention as a risk factor for osteoporotic fracture, in addition to low bone mineral density (BMD) and poor bone quality. In view of the fracture-reducing effect of alfacalcidol and active absorbable algal calcium (AAA Ca) not readily explained by rather mild increases of BMD, attempts were made to evaluate postural stabilizing effect of alfacalcidol, AAA Ca, and calcium carbonate (CaCO(3)) by computerized posturography. Track of the gravity center was analyzed to calculate parameters related to tract length, track range, and track density to express the degree of sway before and after supplementation in 126 subjects ranging in age between 20 and 81 years randomly divided into four groups. Supplementation with AAA Ca containing 900 mg elemental Ca (group A), no calcium (group B), CaCO(3) also containing 900 mg elemental Ca (group C), or alfacalcidol (group D) continued daily for 12 months. For each parameter, the ratio closed eye value/open eye value (Romberg ratio) was calculated to detect aggravation of sway by eye closure. Age, parameters of Ca and P, and proportions of subjects with fracture and those with low BMD showed no marked deviation among the groups. With eyes open, significant decreases of a track range parameter (REC) from group B was noted in groups A (P = 0.0397) and D (P = 0.0296), but not in group C according to multiple comparison by Scheffe, indicating superior postural stabilizing effect of A and D over C. In the first 2 months, a significant fall was already evident in REC from group B in group D (P = 0.0120) with eyes open. Paired comparison of sway parameters before and after supplementation revealed a significant increase of track density parameter (LNGA), indicating sway control efficiency and a significant decrease of REC in groups A and D compared to group B with eyes open. With eyes closed, only group A showed a significant improvement from group B (P = 0.0456; Fig. 1), with a significant shortening on paired After/Before comparison (P = 0.0142; Fig. 2). Computerized posturography appears to be useful in analyzing sway phenomena especially as to the effects of vitamin D and various Ca preparations.