Magnetic resonance imaging of articular cartilage abnormalities of the far posterior femoral condyle of the knee.

Background: Incidental articular cartilage lesions of the far posterior femoral condyle (FPFC) are commonly detected. Whether or not these cartilage lesions are symptomatic or clinically significant is unknown.

Purpose: To characterize and assess prevalence of articular cartilage abnormalities of the FPFC and associated bone marrow edema (BME) and/or internal derangements through magnetic resonance (MR) images.

Material And Methods: 654 knee MR examinations were reviewed retrospectively. Sagittal fast spin-echo proton density-weighted images with and without fat suppression were acquired with a 1.5T scanner, and were evaluated by two readers by consensus. The following factors were assessed: 1) the prevalence of cartilage abnormalities, 2) laterality, 3) the type of cartilage abnormalities, 4) cartilage abnormality grading, 5) associated BME, 6) complications such as meniscal injury and cruciate ligament injury, and 7) knee alignment (femorotibial angle [FTA]).

Results: Articular cartilage abnormalities of the FPFC were demonstrated in 157 of the 654 patients (24%). Of these, 40 patients demonstrated medial and lateral FPFC cartilage abnormalities and were thus counted as 80 cases. Focal lateral FPFC abnormalities were demonstrated in 117 of 197 cases (59.4%), while diffuse lateral FPFC abnormalities were demonstrated in 24 of 197 cases (12.2%). Focal medial FPFC abnormalities were demonstrated in 23 of 197 cases (11.6%), while diffuse medial FPFC abnormalities were demonstrated in 33 of 197 cases (16.8%). No statistically significant pattern of associated BME, FTA, or internal derangements including meniscal and cruciate ligament injury was demonstrated.

Conclusion: Articular cartilage abnormalities of the FPFC are common and were demonstrated in 24% of patients or 30% of cases. Lateral FPFC abnormalities occur 2.5 times more frequently than medial FPFC abnormalities and were more frequently focal compared with medial cohorts. BME is associated in 36.5% of cases.