- Traumatic (history usually revealing)
- Bleeding diathesis (e.g. hemophilia)
- Use of anti-coagulants or anti-platelet agents (often coupled w/low grade trauma)
- Use of anti-coagulants
- Any process that leads to falls (e.g. neurological disorders, substance abuse, weakness, other)
- Underlying bleeding disorder
- Acute pain and swelling of affected joint
- Evidence of effusion in affected joint
- Can be painful (in particular if trauma related), decreased range of motion
- Aspiration of fluid can be diagnostic (if not clear on basis of history)
- Imaging can be helpful if history unclear: x-ray suggestive; MRI better anatomic definition