This is a pilot study that will look at how pain management will be effected when pharmacogenomic testing is utilized to select and dose narcotic pain medications prescribed for breakthrough pain in post-operative total knee arthroplasty (TKA) patients. Patients will receive individualized analgesics and doses for pain mitigation based on genetic testing results. Post op pain scores, narcotic consumption, adverse reactions, length of stay and patient satisfaction with pain management will be collected and analyzed to determine the significance of the pharmacogenomic analgesic testing.