Iliac axis

The iliac axis is a landmark used to assess the anatomy of the hip joint in dogs. It is used to define the center-edge angle and acetabular index (slope) angle. It is determined from a ventrodorsal radiograph of the hips. The the dog is placed dorsal recumbency and the pelvic limbs are extended caudally, the femurs are parallel to each other. Positioning is considered satisfactory if :

• the pelvis is symmetrical (iliums and obturator foramina are symmetrical)

• the femur cortex pass through the middle of the sesamoid bones of the gastrocnemius muscle

• the patellas are centered on the trochlea of femur.

The iliac axis is the longitudinal axis of the body of ilium. It is defined as the line extending at the level of the caudal extent of the caudal dorsal iliac spine and bisecting the body of the corresponding ilium.