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Effect and mechanism of zoledronate on prevention of collapse in osteonecrosis of the femoral head.

OBJECTIVE
To observe the effect and mechanism of zoledronate on prevention of collapse in an animal model of osteonecrosis.


METHODS
Ischemic osteonecrosis was surgically induced in 16 SD rats (which were further divided into zoledronate group and placebo group); another 8 rats were used as sham surgery group (n=8). The animals were killed 5 weeks after surgery. Radiographic, Micro-CT, histological, and immunohistochemical assessments were performed.


RESULTS
Radiographic assessment showed better preservation of the femoral head shape in the zoledronate group than in the placebo group but not significantly different from the sham surgery group. Micro-CT assessment showed higher total volume, bone volume, and total mineralized content in the zoledronate group(all P0.05). Compared with the placebo group, the zoledronate group had reduced osteoclast and osteoblast activity, as confirmed by histological examinations.


CONCLUSION
Zoledronate can decrease the femoral head deformity by reducing the osteoclast activity while suppressing new bone and vessels formation in a rat model of traumatic osteonecrosis, and therefore may delay the collapse of femoral head.