to tag on - while there are some very old preliminary studies of boron,
the only one specific to osteo, that i know of is:

Travers RL, Rennie GC, Newnham RE. Boron and arthritis: the results of a
double-blind pilot study. J Nutr Med. 1990;1:127–132. this study has
been widely touted in the the 'townsend letter'...hardly a bastion of
peer review...

most of the other studies have been general [having to do with it's
helper status with vit D3] these were animal/agricultural studies and
not human. "Plants need boron for proper health, but it's not known
whether humans do."

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dopt=Abstra
ctPlus&list_uids=7889878&itool=iconabstr&query_hl=1&itool=pubmed_docsum

the crux of the 1994 finding was "The influence of vitamin D3 on
cartilage and bone mineralization is mediated in part through its role
as a regulator of energy substrate utilization; calcification is an
energy-intensive process. There is considerable evidence that dietary
boron alleviates perturbations in mineral metabolism that are
characteristic of vitamin D3 deficiency."

'deficiency' being the key issue/point...as to boron itself, it is
extremely rare to have a deficiency of boron.

there is a section related to the amount of boron in diet, and some
information thereof:
http://www.nlm.nih.gov/medlineplus/druginfo/natural/patient-boron.html