Title: Patello-femoral cartilage damage: patients with grade 4 chondral defects of the patella have increased disability
Abstract: Purpose: Patello-femoral (PF) cartilage damage can cause severe knee pain and result in increasing disability. The purpose of this study was to identify factors associated with grade 4 defects of the patello-femoral joint. Methods: A cohort of 2601 patients (average age=45, range, 18 to 83) who underwent knee arthroscopy for knee pathology were studied prospectively. All patients had complete demographic data, surgical data, WOMAC scores, and health status (SF12) collected at initial exam and stored in a data registry. Patients with chondral defects of the knee were included. Patients less than 18 years of age were excluded. Results: Grade 4 PF chondral defects were seen in 23% (586) of knees, with 6% (150) patellar (PAT) defects, 10% (267) trochlear groove (TG) defects and 6% (169) combined PAT and TG defects. 29% of patients with grade 4 PF chondral defects had medial compartment chondral defects, while 14% of patients with no PF chondral defect had medial compartment chondral defects (p<0.001). 20% of patients with PF chondral defects had lateral compartment chondral defects, while 12% of knees with no PF chondral defect had lateral compartment chondral defects. PF chondral defects were 3.0 [95%CI: 2.1 to 4.3] times more likely to be chronic injuries. Knees without PF defects were 20 [95%CI: 15.7 to 26.2] times more likely to have ligament injuries than knees with PF defects. Patients with grade 4 TG defects were older (51 vs 45) and had increased stiffness (how was stiffness determined?) compared to other patients (p<0.001). Patients with grade 4 PAT defects were older (52 vs 45; p<0.001) and had increased pain compared to other patients. Patients with diffuse grade 4 PAT defects had increased age, increased WOMAC (increased disability) and decreased Lysholm scores. Conclusions: This study confirms that grade 4 defects of the PF compartment are common. They often occur with chondral defects in other compartments; however, they are not associated with ligament or meniscus injuries. Patients with PF defects are older than patients with other cartilage damage, and patients with grade 4 diffuse defects of the patella suffer the most disability and loss of function. These data confirm the importance of new treatment strategies for chondral defects of the patellofemoral compartment, especially since patellar resurfacing remains controversial.