Patellar Grind Test
Original Editor - Beth Barrett
This test is also known as Clarke's Test.
Patient is positioned in supine or long sitting with the involved knee extended. The examiner places the web space of his hand just superior to the patella while applying pressure. The patient is instructed to gently and gradually contract the quadriceps muscle. A positive sign on this test is pain in the patellofemoral joint .
Alternative Method 
Rieder recommends pushing down on the patella directly. The patient is then asked to contract the Quadriceps muscles while the examiner pushes down.
- If the patient can complete and maintain the contraction without pain, the test is considered negative.
- If the test causes Retropatellar Pain and the patient cannot maintain the contraction wihout pain, the test is considered positive. '
The amount of pressure applied must be carefully controlled as more pressure can elicit positive response even in normal individuals.
- The best way to do is to repeat the procedure several times, increasing the pressure each time and comparing the results with those of the unaffected side.
- To test different parts of the patella , the knee should be tested in 300 , 600, 900 and in full extension.
This technique is based on the mechanics of the patellofemoral joint and has not been specifically tested. Many patients will have pain with this test regardless of whether they exhibit signs and symptoms of patellofemoral pain . Most of the clinical test for patellofemoral pain have low reliability or are untested, and there is no gold standard test for diagnosis of this disorder. Since there is very limited specificity with this test, it should not be used alone to determine the presence of patellofemoral pain.
Odds Ratio 
Positive Likelihood ratio 1.94
Negative Likelihood ratio 0.69
Recent Related Research (from Pubmed)
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- Baxter R. Pocket Guide to Musculoskeletal Assessment, 2nd edition. Copyright 2003, Elsevier Science (USA).
- Magee DJ: Orthopedic Physical Assessment, 5th ed. Philadelphia, WB Saunders, 2008.
- Magee DJ: Orthopedic Physical Assessment, 4th ed. Philadelphia, WB Saunders, 2002.
- Fredericson M, Yoon K. Physical Examination and Patellofemoral Pain Syndrome. Am J Phys Med Rehabil. 2006 Mar;85(3):234-43.