As far as I know, yes it can be ossified. Please note that ossification of aponeurotic opening is a rare, and if you have encountered anything like this with credible evidence then its worth publishing. Ossification could be related clinically, and if you have any information on where the dry femur was obtained ( e.g from which cadaver) then its worth checking.
The adductor longus strains in horseback rides may produce pain. Ossification of the tendons sometimes occurs because actively adduct their thighs to keep from falling. Ossified tendons are called “riders bones”
Thank you for the message, please note dr nelson answer, and just to add overuse of certain type of drugs may also add to the ossification process in human body as a whole, hence its important to know the details on where the bone (and the cadaver) was obtained from. I think you have an interesting paper in hand already just for the fact that the osseoaponeurotic opening of adductor magnus was ossified, you just need to do some literature review (you may get only few paper, but you have to associate your findings with paper concentrating on why ossification occurs prematurely or abnormally, and correlate with the case on adductor magnus that you have got).