Magnetic Resonance Imaging (MRI) Anatomy of the Ovine Stifle

Objective To describe magnetic resonance imaging (MRI) anatomy of the ovine stifle and investigate meniscotibial and cruciate ligaments anatomy. Study Design Descriptive ex vivo study. Animals Pelvic limbs (n = 44) from 22 adult Texel ewes. Methods Forty limbs (n = 40) were scanned using 3 Tesla MRI before gross anatomic dissection. Two other limb pairs were frozen and transected to obtain sections that were compared with MRI images for identification of anatomic structures. Results In all stifles, the craniomedial bundle of the cranial cruciate ligament inserted caudally to the cranial attachment of the medial meniscus. No transverse intermeniscal ligament was identified in 80% of stifles, whereas a few small ligamentous fibers were seen crossing from 1 cranial horn to the other in 20% of stifles. There was good differentiation of menisci, ligaments, and synovial cavities on MRI images. Two bundles were identified in all cranial cruciate ligaments on MRI. Sensitivity and specificity of 3T MRI for detection of transverse intermeniscal ligament were 42% and 84%, respectively. Conclusion 3T MRI provided well defined reference images for menisci, synovial cavities, and most ligaments.