You may be prescribed narcotic analgesics for pain relief after your unicompartmental knee arthroplasty. These come in many forms, one of which is oxycodone. Oxycodone is a very effective pain reliever, but also has numerous possible side effects including drowsiness, nausea and constipation. As such, it is preferable to only take the oxycodone when you feel that you need to. Usually, the pain after unicompartmental knee arthroplasty becomes manageable within 3 to 4 days following the surgery.
Beyond this point, it is usually adequate for you to wean off the oxycodone medication and use medication that is designed to take care of low levels of pain including acetaminophen and ibuprofen. However, if you continue to require oxycodone for slightly longer period then this does not mean there was anything wrong with the knee replacement or your recovery, it may simply mean that your experience of the pain is slightly worse in the majority of patients who undergo this surgery. This is normal and not something to worry about.