What red flag symptom in an elderly patient may indicate the need for additional workup other than X-rays for suspected OA?

The presence of constitutional symptoms in an elderly patient can indicate a more serious underlying condition beyond osteoarthritis (OA). Constitutional symptoms may include fever, weight loss, fatigue, or malaise, and their presence can suggest systemic issues such as infections, malignancies, or inflammatory disorders like rheumatoid arthritis instead of typical osteoarthritis. An elderly patient exhibiting these symptoms necessitates further evaluation, potentially including laboratory tests or imaging beyond X-rays, to rule out serious conditions that may require different management.

Other options such as obesity, prior knee surgery, and age-related stiffness may indeed impact the management or progression of osteoarthritis but do not inherently signal the need for additional work-up beyond standard imaging. While these factors are important in assessing overall joint health and function, they are not considered "red flags" that would prompt an investigation for potentially life-threatening or significant systemic illness. Therefore, constitutional symptoms stand out as a critical indicator for a need for further diagnostic consideration.