It is very unlikely that the diaphragm ruptured spontaneously during cough. Rib fractures are known with cough in patients with osteopenia. Most likely the patient had a thinned out diaphragm e.g. with eventration and was unaware of this. The thinned out part may have ruptured spontaneously. Weight reduction is of paramount importance in such patients to be able to lead a good quality life. It is also necessary to rule out obstructive sleep apnoea in someone like this.