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Ballottable Patella Sign
Aka: Ballottable Patella Sign, Ballottement Test, Patellar Tap
- Indication
- Evaluation for large Knee Joint effusion
- Technique
- Patient lies supine on table
- Examiner forces fluid from suprapatellar pouch
- Firmly grasp just above Patella with one hand
- Forces Joint Fluid between Patella and femur
- Examiner pushes Patella downward into femur with 2-3 fingers
- Use a quick sharp motion in pushing the Patella down
- Assess for palpable click on Patella striking femur
- Interpretation: Positive test suggests large effusion
- Large Knee Joint effusion: Palpable click present as Patella strikes the trochlea
- No joint effusion (normal): no click palpated
- References
- Bates (1991) Physical Exam, Lippincott
- Kastelein (2009) Arch Phys Med Rehabil 90(1): 82-86 [PubMed]