How long Ontarians wait for surgery. Average wait times for the typical patient (classed as Priority 4). Hip replacement 80 days from referral until 1st appointment, 159 days from decision to operate until surgery. Knee replacement 90 days from referral until 1st appointment, 168 days from decision to operate until surgery. Cataract surgery 91 days from referral until 1st appointment, 124 days from decision to operate until surgery.