The cruciate ligaments of the canine stifle: an anatomical and functional analysis

Fifty canine stifles were used to study the anatomy and function of the cruciate ligaments. The morphology of the ligaments and the shape of their bony attachments were determined by dissection. The relative tension of the ligaments in flexion and extension was determined by identifying the points of attachment of ligament fibers with small pins and making multiple radiographs as the stifle was taken through a range of motion. The distance between these points was then measured and the linear changes in the ligaments were defined. Measurements of rotation, craniocaudal displacement, extension, and flexion were made before and after cutting of one or both ligaments. It was found that both cruciate ligaments were composed of 2 component parts and that the geometry of their femoral attachments was responsible for a reciprocal loosening and tightening of these components through a range of motion. It was also found that transection of one or both cruciate ligaments resulted in marked joint instability.