The patellar tap test is used to detect large knee effusions.

Performing the Test

  1. With the patient supine, compress the suprapatellar pouch against femur by placing left hand 15 cm proximal to patella (thumb and index finger on either side of patella)
  2. The examiner applies pressure and slides their hand towards the patella, maintaining the pressure
  3. The examiner then pushes down quickly on the patella with the right hand
  4. The test is positive if there is a palpable tap or click felt by the thumb and index finger of left hand
  5. A small effusion will produce negative test


  1. Pawa J, Lesniak, D., & Lott, A. Approach to the OSCE: The Edmonton Manual of Common Clinical Scenarios. Edmonton Manual; 2011.
  2. Magee D. Orthopedic Physical Assessment. 1st ed. Philadelphia:Saunders; 1986.