Complex Molecular Etiology and Cellular Landscape of Hip Osteoarthritis

This study collects tissue samples from patients undergoing hip replacement surgery to better understand the biological causes of hip osteoarthritis (joint wear and tear). Researchers want to find the molecular and cellular differences between arthritic hips and healthy hips damaged by injury. There is also a smaller sub-study for patients with rheumatoid arthritis. **You may be eligible if...** - You are an adult (aged 18–74) having an elective hip replacement for osteoarthritis - OR you are an adult having an emergency hip replacement due to a traumatic injury (as a control participant) - For the sub-study: you have rheumatoid arthritis and are having an elective hip replacement **You may NOT be eligible if...** - Your BMI is 35 or higher - You are younger than 18 or older than 74 - You have diabetes, rheumatoid arthritis, or metabolic syndrome (for the main osteoarthritis group) Talk to your doctor to see if this trial is right for you.