Which of the following is considered a red flag for lower extremity complaints?

In this context, the inability to bear weight is recognized as a significant red flag for lower extremity complaints because it can indicate a serious underlying condition. This symptom suggests more than just simple discomfort or minor issues; it could be associated with severe injuries such as fractures, ligament tears, or other structural problems in the muscles and joints. When a patient cannot bear weight, it often requires immediate evaluation to rule out serious complications that could necessitate more aggressive treatment or intervention.

In contrast, minor discomfort while walking is relatively common and does not typically raise concern for severe underlying issues. Localized swelling without pain may indicate a less serious condition or an inflammatory response that doesn't require urgent attention. A history of previous injury can provide context for current complaints but does not inherently signal a red flag unless accompanied by more concerning symptoms. Therefore, the inability to bear weight stands out as a critical sign that demands thorough assessment and action.