My caregiver put out her back by carrying my son!

Your licensed nanny just put out her lower by waking your baby from his nap. Fortunately, her husband was there and was able to look after your baby. This situation is one of the possible hazards of regular care with a home
caregiver.

Of course, you are very upset to see her in this state and want her to get better quickly. But of course, once past the stress, you wonder what will be your role, from an administrative point of view.

Worker's Compensation

Registered home caregiver's should be paying into their WCB (Worker's Compensation Board) and therefore should be covered in the case of a work-related accident. 

In this case you may be required to find a temporary replacement for your childcare assistant while she is unable to work. In this case, you should not be obligated to pay her for the time when she is off work.

Adding a clause in the contract

It may be worth adding a clause in your contract with the childcare professional stating that she is responsible for any work related accidents as she is an independent contractor and not your employee. You can also ask for proof that she is covered by insurance for such accidents or is registered with WorkSafe in your province.