Effects of Sustained-release Oral Sodium Nitrite on Postoperative Pain and Recovery Following Total Knee Arthroplasty

Inclusion Criteria: * Male and female individuals aged 18-70 * Ambulatory with knee pain for greater than 6 months prior to surgery, and willing and able to comply with all study requirements will be considered eligible. Exclusion Criteria: * Severe hypertension (systolic blood pressure greater than or equal to 200 mmHg or diastolic blood pressure greater than or equal to 120 mmHg); * BMI greater than 45 kg/m2; * Active smoker or stopped smoking within 6 months of enrollment; * Active local or systemic malignancy, such as lung cancer or leukemia; * Cardiovascular disease resulting in dyspnea at rest; * Peripheral neurovascular disease; * Anemia; * Hematological disease (eg, coagulopathy, sickle cell disease/anemia); * Hemoglobin variant; * Glucose-6-phosphate dehydrogenase deficiency; * Methemoglobin reductase deficiency; * Known sensitivity to nitrites; * Liver disease; * Use of phosphodiesterase type 5 inhibitors; * Use of sildenafil (Viagra); * Systemic treatment with antibiotics, immunosuppressants including corticosteroids, medications for migraine, allopurinol, tricyclic antidepressants, antihistamines, and/or nitrates currently or in the last month; * Use of nitrovasodilators (e.g. GTN) within the last month; * Use of protein pump inhibitors within the last month; * History of substance abuse; * Recent surgery or hospitalization (within last 6 months); * Inability to swallow a pill; * Failure to provide full consent; * Involvement with a worker's compensation, perso…