Clarke’s Sign | Patellar Grind Test | Patellofemoral Pain Assessment

Clarke’s Sign aka the patella grind test aims to identify pathological changes in retropatellar cartilage by exerting a compressive force on the patella.

Cook et al. (2012)  reviewed the literature on evidence regarding the test’s diagnostic ability to detect patellofemoral disorders in patients with pain identified near the anterior aspect of the knee and found positive likelihood ratios between 0.9 to 7.4 and negative likelihood ratios between .7 to 1.1. None of the studies demonstrated high methodological quality, which is why only a weak clinical value can be attributed to the test.

To conduct the test, the patient is lying supine with the knees extended. Position yourself next to the patient on the involved side and place the web space of the thumb on the superior border of the patella. Then ask your patient to contract the quadriceps as if they were to extend the knee while you apply downward and inferior pressure on the patella.

Pain with movement of the patella or the inability to complete the test is indicative of patellofemoral dysfunction and is considered a positive test.

Other common orthopedic tests to assess for patellofemoral pain syndrome are:

• Patellar Apprehension Test
• Moving Patellar Apprehension Test
• Decline Step-Down Test

Cook C, Mabry L, Reiman MP, Hegedus EJ. Best tests/clinical findings for screening and diagnosis of patellofemoral pain syndrome: a systematic review. Physiotherapy. 2012 Jun 1;98(2):93-100.

Nijs J, Van Geel C, Van de Velde B. Diagnostic value of five clinical tests in patellofemoral pain syndrome. Manual therapy. 2006 Feb 1;11(1):69-77.