Analysis of MRI-detected cartilage damage in KL grade 0 and 1 knees

Purpose: It is difficult to evaluate early osteoarthritis (OA) by plain X-ray, and MRI is thought to be useful for early detection of OA. We investigated incidence of MRI-detected cartilage damage in plain X-ray KL grade 0 and 1 knees, and analyzed the radiographic factors associated with the cartilage damage. Methods: Fifty knees of volunteer women with KL grade 0 and 1 (39 and 11 knees) without current knee pain were investigated (Age; mean 54, median 59, min-max 22-83, 25-75% 41-67 y.o.). Fat-Sat spoiled gradient recalled acquisition in the steady state (SPGR) sagittal images were obtained using 3T MRI (Signa HDx 3.0-T system, GE Healthcare) and 8-channel knee coil (8-channel HD T/R knee array, GE Healthcare). In addition, plain X-ray was performed with a full-length legs frontal view in a standing position (RAD Speed Safire, Shimadzu Corporation, Japan). The presence and localization of cartilage defects were investigated in SPGR images by two orthopedic surgeons. Radiographic parameters (femorotibial angle, mechanical axis, femoral length, femoral condyle width, tibial length, and tibial condyle width etc.) were measured in plain X-ray. Age, BMI, and radiographic parameters were compared between cartilage damaged and intact groups using Mann-Whitney test. Results: Eight knees (16%) (KL grade 0 and 1: 6 and 2 knees) (mean 65, min-max 55-73 y.o.) had small cartilage defects in SPGR images. All of them occurred at medial femoral condyle. Age and TW/TL (tibial condyle width/tibial length) were significantly higher in cartilage damaged group (P<0.05). Conclusions: 16% of KL grade 0 and 1 knees had small cartilage defects at medial femoral condyle, and age and TW/TL were higher in this group. Higher TW/TL might be caused by decreased TL due to aging. View Large Image Figure ViewerDownload Hi-res image Download (PPT)