Zoledronate

Short-term effects of zoledronate on the histomorphology of osteoclast in young albino rats.

"Zoledronate, a third generation bisphosphonate, [was appliead] on the metaphysis of the proximal end of tibia in twenty day old male albino rats. Zoledronate (2.8 μg/kg body weight), was daily given subcutaneously for eleven days. The animals were sacrificed; tibiae were dissected out and decalcified in EDTA. Seven micron thick, serial longitudinal paraffin sections were stained with haematoxylin and eosin and examined under a Zeiss light microscope and Image Pro-Express Analyzer. In zoledronate treated rats, a significant increase in the number of osteoclasts was observed both in the regions of primary spongiosa (zoledronate treated: 6.41 ± 0.30/mm(2), control: 2.90 ± 0.28/mm(2)) and secondary spongiosa (zoledronate treated: 49.58 ± 0.84/mm(2), control: 31.81 ± 2.02/mm(2)) along with a significant increase in the length of the metaphyseal region as compared to the control group. The number of nuclei per osteoclast and area of the osteoclast also showed a significant increase following the uptake of zoledronate."

Length of Tibia of Saline treated rats in mm: 25.37 ± 0.56
Length of Tibia of Zoledronate treated rats in mm: 25.35 ± 1.03

The higher standard deviation means that it's possible that zoledronate could possibly increase bone length but not above measurement.

"Photomicrograph of a longitudinal section of proximal tibia showing the extent of metaphysis in control and zoledronate treated group. In the experimental rat, trabeculae are seen to extend deeper into the medullary cavity of the diaphyseal region as compared to the control. "  The growth plate looks to be of higher quality in the control group.

"Abbreviations: GP: growth plate; GCMJ: growth cartilage metaphyseal junction; PS: primary spongiosa; SS: secondary spongiosa; trab: trabeculae; mc: medullary cavity."

" in rats, long-term administration of bisphosphonates APD[also known as pamidronic acid] caused a significant shortening of radius"

It's likely that zoledronate has some effect on height but we don't know whether that effect is positive or negative.