Well ;
As for HO , i think it is easy for you to collect reliable knowledge regarding from Internet just search for up to date articles in PDF you will find much .
Just i searched quickly to find out the following :
http://www.jaaos.org/cgi/content/abstract/12/2/116
http://www.emedicine.com/radio/topic336.htm
from 2006 http://www.emedicine.com/pmr/topic112.htm
and a good PDF article attached above .
Of course , you are OT knows that we are just searching for knowledge basing the search on the reilable diagnosis of the MD .I will try to read as possible from the links above then give my view .I think if the case is Myositis ossificans it is better to let that resolve by itself , i saw before around 3 patients with Myositis ossificans just anterior to the elbow aspect ,with rehabilitaion the extension gained very well , the flexion was blocked by the Myositis ossificans ,i refused to apply any aggressive procedures at that time ,i saw one child from them after 6 months .The bony ossification resolved alone .and the flexion ROM was fully function .
Hope my views are not causing problem for you ,just collect knowledge then decide !!
Cheers
Emad