Some aspects of rat femorotibial joint microanatomy as demonstrated by high-resolution magnetic resonance imaging.

High-resolution magnetic resonance images (MRI) of the right femorotibial joint of normal Han:Wistar rats were acquired using a 4.7 Tesla magnet and a single-turn solenoid radio frequency coil (built in-house). Some anatomical findings of the rat femorotibial joint, which have not been reported previously using MRI, are described. The separation of patellar ligament and crural fascia was feasible on MRI. This separation would not be seen on images of lower resolution and its presence on high-resolution images could be mistaken for artefact due to the magic angle effect. Band-like fibrous structures exist in the infra-patellar fat pad, which might be mistaken as ligaments within the femorotibial joint. On sagittal MRI a vessel was seen inserted on the central part of the caudal surface of the patellar ligament. Subcutaneous fascia/cutaneous muscles (panniculus carnosus) could also be demonstrated with MRI in the femorotibial joint area.