Efficacy and Safety of Tapentadol Extended Release Tablets in the Treatment of Moderate to Severe Pain in Subjects With Knee Osteoarthritis

Inclusion Criteria: * Subjects with a clinical diagnosis of osteoarthritis of the knee based symptoms and/or radiographic criteria present for at least 3 months * Moderate to severe chronic pain due to knee osteoarithritis Exclusion Criteria: * Previously opioid treated subject who had a history of withdrawal after cessation of the opioid * History of seizure disorder, psychiatric disease and history of head trauma requiring evaluation by hospital based staff, or unconsciousness of unknown origin. Subjects who, in the investigator's judgment, have well-controlled depression or anxiety disorder may participate * Subjects with history of uncontrolled hypertension (systolic blood pressure \> 160 mmHg or diastolic blood pressure \> 95 mmHg) * Intake of tricyclic antidepressants, serotonin norepinephrine reuptake inhibitors, barbiturates, neuroleptics, monoamine oxidase inhibitors, and antiparkinsonian drugs within the 30 days prior to the screening visit