EFFECTS OF ZOLEDRONIC ACID ON OOFORECTOMIZED RATS' TIBIAE: A PROSPECTIVE AND RANDOMIZED STUDY

To investigate clinical, biomechanic and histomorphometric effects of zoledronic acid on osteoporotic rats' tibiae after bilateral ooforectomy.

40 female Wistar (Rattus novergicus albinus) rats were prospectively studied. On the 60th day of life, the animals were randomized into two groups according to the surgical procedure: bilateral ooforectomy (O) (n=20) and sham surgery ("sham") (P) (n=20). After 30 days, the animals were divided into four groups, according to the administration of zoledronic acid (ZA) 0.1mg/kg or distilled water (DW): OZA (n=10), ODW (n=10), PZA (n=10) and PDW (n=10). After 12 months, the animals were sacrificed, and had their tibiae assessed. In the clinical study, animals' weight was considered; in the biomechanical study, compressive assays were applied and, in the histomorphometric analysis, the bone trabecular area was determined.

"O" groups showed a significantly greater weight gain than "P" groups (p=0.005). Groups OZA and PZA showed an insignificant weight gain when compared to ODW (p=0.47) and PDW (p=0.68). The groups receiving zoledronic acid and distilled water were able to bear maximum load, similar (p=0.2), at the moment of fracture. In the groups receiving zoledronic acid, an insignificant increase of the bone trabecular area was found when compared to the groups receiving distilled water (p=0.21). There was a positive correlation between trabecular area and maximum load (p=0.04; r=0.95).

Zoledronic acid did not significantly influence animals' weight. The results showed an insignificant increase both of the tibial shaft bone resistance and the bone trabecular area.