Postoperative Pain and Analgesic Requirements After Preoperative Methadone for Primary TKA

The goal of this prospective, randomized study is to compare the outcomes of two cohorts of patients undergoing primary Total Knee Arthroplasty (TKA) and to determine whether a single dose of methadone administered preoperatively is effective at reducing postoperative opioid usage and postoperative pain versus a control group of patients receiving standard intraoperative opioids only for primary TKA. The main questions it aims to answer are: * What is the efficacy of a single preoperative dose of methadone in reducing opioid consumption and postoperative pain in primary total knee arthroplasty? * Will the study results demonstrate the effectiveness and safety of a single preoperative dose of methadone (10 mg) in primary total knee arthroplasty in reducing postoperative opioid usage while maintaining a similar or better level of pain control when compared to a standard pain control regimen? Researchers will compare Methadone to a standard pain control regimen (Oxycodone) to see if Methadone is equivalent or more effective at reducing opioid consumption and postoperative pain in primary total knee arthroplasty Participants will: * be randomized into one of two groups * undergo a primary TKA * complete a tracking sheet documenting daily pain medicine usage and VAS pain level for the first 14 days following the TKA * return to office at 2 weeks and 6 weeks postop for follow-up * complete additional questionnaires at 2 weeks and 6 weeks postop