| Condition | Mechanism & historical features | Common symptoms | Key examination findings | Additional comments |
| Activity related |
- Chronic osteochondral defect
| - Mild repetitive trauma (running/jumping)
| - Diffuse knee pain worse with and after activity
| - Activity related effusion
| - Radiographs or advanced imaging (MRI) needed for diagnosis
|
| | - Usually adults 50 years or older
- Activity-related pain; brief stiffness after inactivity
| - Diffuse knee pain
- Delayed swelling (12 to 24 hours post activity)
| - Effusion present
- Ligaments stable; meniscus testing equivocal
- Inability to fully flex or extend knee common
| - Weight bearing radiographs show sclerosis, osteophytes, and joint space narrowing
|
| Not activity related |
| | - Acute knee pain and effusion
- No trauma or recent activity
| - Diffuse knee pain and swelling
- Weight bearing can be difficult
| - Erythema, warmth, tenderness, and swelling of knee
- Knee flexion limited by effusion and pain
| - Joint aspiration required for diagnosis
- Serum uric acid level should not be used for diagnosis
|
| | - Acute knee pain and effusion
- No trauma or recent activity
| - Diffuse knee pain and swelling
- Weight bearing can be difficult
| - Erythema, warmth, tenderness, and swelling of knee
- Knee flexion limited by effusion and pain
| - Medical emergency
- Joint aspiration critical for diagnosis
|
- Systemic rheumatic disease
| - Include RA, SLE, Sjögren's syndrome, systemic sclerosis, spondyloarthropathy, polymyositis, and dermatomyositis
- RA is most prevalent
| - Systemic symptoms (fever, night sweats, fatigue, weight loss) and polyarthralgia common
| - Examination findings highly variable
| - Consider in oligoarticular or polyarticular joint disease, pain with swelling, systemic symptoms, or a positive family history
|
