Bone Abstracts

Bisphosphonates (BPs) including alendronate (ALN) are the most widely prescribed therapy for post-menopausal osteoporosis. Despite their overall excellent safety record and efficacy in reducing fractures, concerns have been expressed lately regarding potential detrimental effects due to prolonged bone turnover reduction, although no definite cause–effect relationship has been established to date. The purpose of the present study was to determine bone material quality by Raman microspectroscopic analysis of iliac crest biopsies from postmenopausal osteoporosis patients that were either on 5-year ALN therapy followed by another 5 years of placebo (PLC) (n=14), or on 5 mg/day ALN for 10 years (n=10), or 10 : mg/day ALN for 10 years (n=6). The parameters monitored and expressed as a function of tissue age defined on basis of double tetracycline labels and geometrical centra of trabeculae were: i) the mineral : matrix ratio (MM), ii) the relative proteoglycan content (PG), iii) the relative lipids content (LPD), iv) the mineral maturity/crystallinity (MMC), and vi) the relative pyridinoline content (PYD). The results indicate that 10-year ALN use (both 5 and 10 mg/day) does not result in any detrimental changes compared to use for 5 years. The only differences were transient ones at bone forming surfaces, implying potential differences in bone matrix maturation that nevertheless did not result in differences of these values in mature tissue. These results indicate that as far as the parameters monitored are concerned, 10 years ALN use does not change the bone material quality at the examined tissue ages compared to 5-year use. Additionally, it is suggested that prolonged bisphosphonate use when accompanied with residual bone turnover may not be responsible by itself for an impairment in bone material quality contributing to adverse conditions such as atypical femoral fractures.