Chondromalacia patella (CMP) is a disease in which the cartilage of patella is genetically soften and easily wears away. CMP is commonly presented as mechanical anterior knee pain during the second and third decades of life. It more commonly occurs in women than men. When the patients cover the entire front of the knee with their hand after asked to identify the location of discomfort, called the “grab sign”. Chondromalacia patella may produce noisy knee, giving way or catching sensation under the patella. In physical examination of the patients with CMP, there are three major findings including: Positive patellar facet tenderness test, Positive patellofemoral compression test or "Shrug test" and Patellar crepitation or “Rabot test". There is not any biochemical, serologic or acute phase reactant abnormality in CMP. Plain films of the knee including weight bearing posteroanterior, lateral and sunrise (axial) views are useful to be normal for CMP and to rule out other sources of anterior knee pain including bipartite patella, osteoarthritis, loose bodies and occult fractures. This technique is not expensive or invasive, so it practically can be done but it is not capable to show the cartilage. Magnetic resonance imaging (MRI) shows softening, wear and tear of patellar cartilage along with normal meniscuses and other cartilages of knee, it confirms the diagnosis of CMP. This imaging is semi-expensive, noninvasive and radiationless. The arthroscopy of knee is capable to provide the specialist with a directed visualizing of the patellar cartilage, so it is an accurate way to detection of CMP, but it is invasive and expensive procedure and not routinely accessible for the patient with CMP. We think that the MRI is a practical gold standard way but the arthroscopy of knee is a non-practical gold standard to detecting CMP. Many years of practice in the field of Rheumatology, gave the corresponding author (ISA) an opportunity to encounter hundreds of patients with CMP. Right now by this letter corresponding author wants to deliver a diagnostic criteria for CMP showing in table A and the ACR, EULAR, APLAR,… are requested to evaluate this new diagnostic criteria for CMP. If this criteria is really detected to be cost-benefit/cost-effective, it will be a simple instrument for diagnosis of CMP.

Chondromalacia Patella, Grab Sign, Shrug Test, Rabot Test, Knee MRI, Knee Arthroscopy, Diagnostic Criteria