Rofecoxib Efficacy and Safety Evaluation Trial in Hemophilic Arthropathy

Inclusion Criteria: * Diagnosis of hemophilia A or B * Either on a stable prophylaxis regimen for their bleeding disorder (factor, bypassing agent, or nonfactor product therapy) OR currently taking or agree to initiate a gastroprotective agent (esomeprazole) for the duration of the trial * Diagnosis of Hemophilic Arthopathy for at least 6 months prior to screening * Chronic symptomatic pain in one or more joint(s) on 20 of the 30 days prior to screening. * Able and willing to wash out of non-study analgesic medications/agents for at least 7 days prior to Randomization including: acetaminophen (paracetamol), NSAIDs, opioids, cannabinoids, topical analgesics, benzodiazepines, gabapentin/pregabalin-containing products and other antiepileptic drugs used for pain * Primary source of pain is due to Hemophilic Arthropathy Exclusion Criteria: * Taking opioids for greater than 4 days per week prior to screening * Has a history of advanced renal disease or severe liver disease (within the last 6 months) * Receiving emicizumab while also receiving activated prothrombin complex concentrate (FEIBA) * Uncontrolled or poorly controlled hypertension * History of major cardiac or cerebrovascular disease * History of an upper GI perforation, obstruction, or major GI bleed or current evidence of GI bleeding * Has active hepatitis C or hepatitis B infection or uncontrolled HIV. Note: Patients who are HIV positive are allowed to participate if considered to be controlled. * Has a positive drug screen for all prohibited drugs of potential abuse at screening * Has had an intra-articular injection (within 3 months), initiated physical therapy (within 30 days) or has had orthopedic surgery (within 4 months) prior to screening