Don't try to make Joomla into a medical records app. That way lies heartbreak and a pile of code that does something but that you can never quite trust.

Build from the database out. And please use encryption appropriately.

In the US at least you are dealing with HIPAA which has a deep set of requirements your system will have to meet.

And you are dealing with crucial information, if you screw up medical records such that crucial information is left out or garbled or lost you could potentially kill people.

So use tools that give you a clear view into the development process and let you track, record and correct the system as you are building it.

Use whatever language the team is most familiar with and don't think that any framework will make your work easier unless you already know that framework well.

Medical records? Ethically your number 1 issue is security now, and it may be legally also depending upon where you're building this.

While a web framework is a great place to start for things like this, I do implore you to keep the medical records that it stores as far away from the Internet as possible, if you can. At least consult really good security guy if you must have them on the net.

Opinions:

Both are notionally MVC web packages.

* Joomla: Joomla is actually a CMS - and most medical records are text, so - maybe it'd work - but I'd be worried about the burden of the cruft, as well as laying your own security over something that's designed for publishing stuff. It'll be quick to get something up, though.

* Django: You can build any kind of database, CMS or virtually anything you can see on the web in Django - so I'd start there. Django has usable security out of the box, too.

Joomla is PHP and Django is Python, so in the interests of code reuse I'd personally go Django every time. Some quite big desktop apps are built in Python, so you'd be in good company.

I like SQLAlchemy as my DB abstraction. Then you aren't tied to a web app. However, for starting I use pylons, and have been playing with FormAlchemy. It gives you a simple admin interface, but you can customize all you want.

You should use a platform that you already know well. Starting from scratch with a new framework/language is certainly fun but I don't recommend it for paid projects unless you have a solid experience and expertise and very confident about your abilities.