Which test is used to assess knee effusion by milking the suprapatellar pouch and performing a ballot or tap?

Which test is used to assess knee effusion by milking the suprapatellar pouch and performing a ballot or tap?

• A. Fluctuation Ballottement
• B. Patellar Apprehension Test
• C. J Sign
• D. Patellar Grind Test

Answer: (A)

The test is all about detecting an intra-articular knee effusion by mobilizing the fluid in the suprapatellar pouch and then tapping the patella to feel a fluid wave. When there is fluid in the joint, milking the suprapatellar pouch gathers that fluid toward the patella, and a quick tap or pressure on the patella causes the fluid to move and the patella to “ballotte” or bounce back. This combination—fluids moving during the maneuver and the palpable or visible wave—is the fluctuation ballottement sign that confirms effusion. Why this is the best choice: it directly assesses for excess joint fluid rather than evaluating patellar stability or cartilage surfaces. The name itself reflects the mechanism: fluctuation of the joint fluid and ballottement of the patella. For context, the other tests assess different knee issues. The patellar apprehension test checks whether the patella is prone to dislocation, not effusion. The J sign looks at lateral patellar tracking during knee extension. The patellar grind test evaluates patellofemoral joint pain and cartilage wear by pressing the patella into the femur and asking the patient to contract the quadriceps.

The test is all about detecting an intra-articular knee effusion by mobilizing the fluid in the suprapatellar pouch and then tapping the patella to feel a fluid wave. When there is fluid in the joint, milking the suprapatellar pouch gathers that fluid toward the patella, and a quick tap or pressure on the patella causes the fluid to move and the patella to “ballotte” or bounce back. This combination—fluids moving during the maneuver and the palpable or visible wave—is the fluctuation ballottement sign that confirms effusion.

Why this is the best choice: it directly assesses for excess joint fluid rather than evaluating patellar stability or cartilage surfaces. The name itself reflects the mechanism: fluctuation of the joint fluid and ballottement of the patella.

For context, the other tests assess different knee issues. The patellar apprehension test checks whether the patella is prone to dislocation, not effusion. The J sign looks at lateral patellar tracking during knee extension. The patellar grind test evaluates patellofemoral joint pain and cartilage wear by pressing the patella into the femur and asking the patient to contract the quadriceps.