The search for new safe and effective methods of pain relief after surgery on large joints is still an urgent problem. The most optimal approach in the treatment of postoperative pain is the use of multimodal analgesia with a different mechanism of action that act on various mechanisms of pain and can include opioids, nonsteroidal anti-inflammatory drugs (NSAIDs), acetaminophen, anticonvulsants, NMDA antagonists, alpha-2-agonists, and sodium and calcium channel blocking agents, as well as local anesthetics. NSAIDs are the most popular and safe means for pain relief. Therefore, a lot of efforts are aimed at increasing the effectiveness of NSAIDs use. The aim of this study was to evaluate the effectiveness of simultaneously administering two or three NSAIDs, compared to using only one NSAID, for pain relief after surgery on large joints such as hip or knee arthroplasty.

This is 6 days, randomized, double blind, parallel group, single-center study in 105 subjects. The distribution into groups was carried out by sequentially alternating the set into 4 groups celecoxib 400 mg orally daily, aspirin 100 mg and ketorolac 90 mg orally daily, ketorolac 90 mg and celecoxib 400 mg orally daily; aspirin 200 mg, ketorolac 90 mg and celecoxib 400 mg orally daily.

Inclusion Criteria:

• The patients with diagnosis of osteoarthritis of the knee or hip joint (M15.0, M16, M17) after primary knee or hip arthroplasty.
• Informed consent.

Exclusion Criteria:

• Patients who cannot cooperate with the trial.
• Pregnant or breast feeding women,
• Оpioid addiction,
• Contraindication to NSAIDs (allergy to NSAID, history of ulcer and gastrointestinal bleeding, liver failure, renal failure (eGRF < 60 ml/kg/1,73m2) and chronic kidney disease 2-5, known thrombocytopenia (<100 mia/L)