MORPHOLOGICAL ANALYSIS OF 3D MR IMAGES OF PF JOINTS IN ASYMPTOMATIC SUBJECTS

Abstract

Understanding the pathogenesis of patellofemoral osteoarthritis (PFOA) will be enhanced by elucidating the onset and progression in asymptomatic PFOA. Demonstrating of the cartilage defect of 3D MR images, obtained from a cohort population, in order from the smallest to the largest, can mimic the morphological progression process of PFOA. The purpose of this study was to clarify the frequency, classification, and morphological progression process of PFOA by observing MRI 3D images in a cohort population of subjects without a history of visiting hospitals for knee disease. The subjects were 561 at 30–79 years old who were registered in the Kanagawa Knee Study. The main exclusion criteria were those who have a past history of consecutive visits to the hospital for more than 3 months for knee symptoms. We obtained 3D MR images of the PF joints using 3D image analysis system volume analyzer (SYNAPSE 3D, Fujifilm Corporation, Tokyo). The cartilage defects were classified as medial and lateral type. MR images of the PF joints were displayed with cartilage area ratios of the patella and presented in order of highest to lowest, separated into the medial and lateral type. Of the 561 subjects, cartilage defects were detected on 3D images of the patella in 37 subjects (6.6%). Medial lesion was detected in 26 subjects (4.6%) and lateral lesion in 11 subjects (2.0%), showing that medial lesion was significantly more frequent (p=0.01). For the medial type, the patellar cartilage defect was located in the center of the medial facet, expanded to the surrounding area, and further distally and medially. 3D MR images of the patellofemoral joint showed the cartilage defect of the patella expanded along with the medial ridge of the femoral trochlea. For the lateral type, the patellar cartilage defect was located in the center of the lateral facet, expanded to the surrounding area, and further distally and laterally. 3D MR images of the patellofemoral joint showed the cartilage defect of the patella expanded along with the lateral ridge of the femoral trochlea (Fig. 1). According to 3D MR images, the frequency of the patella cartilage defect was 6.6% in 561 asymptomatic subjects. Patellar cartilage defects occurred more frequently on the medial facet than on the lateral facet. The patellar cartilage defect occurred at the center of each facet and expanded along with each side of the ridge of the femoral trochlea. Fujifilm Corporation and Japan Society for the Promotion of Science Grant JP22K09349 I Sekiya received a research grant from Fujifilm Corporation including lending of the analysis software used in this study. Kimiko Takanashi is to be thanked for technical assistance. CORRESPONDENCE ADDRESS: sekiya.arm@tmd.ac.jp