Even though the reimbursement came in 2017, it's not included on your 2017 return.
CRA's rule for medical expenses is that you should only claim amounts for which you haven't been or will not be reimbursed. In your case, since you were reimbursed for these 2016 amounts, you'll need to file an adjustment to your 2016 return to remove the expenses for which you have been reimbursed.
https://turbotax.community.intuit.ca/replies/2647992