The Surgical Anatomy of the Canine Sacrum for Lag Screw Fixation of the Sacroiliac Joint

One hundred canine sacral bone specimens were examined to identify surgical landmarks that may improve screw placement in sacroiliac repair. A lateral view of the sacral wing was studied, as this structure is most easily identified in the dorsal approach used for sacroiliac repair. The height and length of each sacral wing were measured. Four other features of the canine sacrum were identified and measured in comparison with the sacral wing height and length. The cranial overlap of the sacral wing over the intervertebral space of L7‐S1 was found to have a mean of 14% of the length of the sacral wing. The ventral overlap of the sacral wing over the pelvic canal was found to be 21% of the height of the sacral wing. The ventral limit of the spinal canal (dorsal limit of the sacral body) was 45% of the sacral wing height. The first pelvic foramen was located at a mean distance of 64% of the sacral wing length and 20% of the sacral wing height. Using these four features, a composite view of the sacral wing is described to illustrate the area of the sacral body where screw placement is optimal.