Mucoid Degeneration of Anterior Cruciate Ligament: Correlation between MR Imaging and Pathologic Findings in Patients with Osteoarthritis of the Knee

ABSTRACT

PURPOSE: To evaluate the mucoid degeneration (MD) of the anterior cruciate ligament (ACL) of the knee by correlation of MRI findings with pathology, in the patients with osteoarthritis (OA). MATERIALS AND METHODS: This study included 17 patients (mean 68.8 years old) who underwent preoperative MRI. In proton density-weighted sagittal and coronal images ACLs were evaluated for the thickness and signal intensity (SI). Total knee replacement arthroplasty was performed and the pathologic findings of ACL were evaluated. MD was classified as 3 grades according to the degenerated amount in microscopy. Thickness and SI was evaluated as normal or increased on MRI. RESULTS: All of the 4 patients who showed thickened ACL showed increased SI on MRI. All of the 8 patients with increased SI of the ACL on MRI had MD in the ACL. However, remained 9 patients also had MD, in spite of their normal thickness and SI on MRI. Calcification was seen in 5 patients. CONCLUSION: Eight cases who showed ACL thickening or increased SI on MRI were well correlated with MD, however, because the other nine cases who showed normal thickness and normal SI of ACL on MRI also showed MD in pathology, normal MRI finding should not exclude the possibility of MD of ACL.