Implanting Fusion Cages in Pig's Vertebrae.

Meet Henry (if presumed male) or Mary, the lab guys did not know the sex, or they kept it as confidential to protect him/her.

Pig has 5 to 7 lumbar vertebrae.  Interestingly, implanting lumbar fusion cage (much smaller ones than in human lumbar interspace, the size is similar to cervical cage for human) is not as difficult as I once thought.  The approach is my preferred one: lateral access. Using this approach, there was not much bleeding, but the psoas muscle had to be transected in order to expose 3 to 4 levels of lumbar discs. The caudal disc (above sacrum) could not be accessed due to obstruction by the pelvis.  But in human, the last lumbar disc can be accessed laterally after mobilizing the great veins, plus other tricks.
  To my surprise, those pigs who had the psoas muscle transected did not have lumbar nerve injury occurred. Unlike human, the opposite is true. All those pigs survived well after cage implantation, without limp, life was as usual: eat, hanging around, and sleep, but no sex, all were castrated. But they seemed to have a short period time of melancholy, possibly due to surgical pain.
  Pig's lumbar disc heights are pretty narrow, may be less than 5 mm. Also the axial surface is more elongated, unlike the oval shape of human disc. The AP diameter may be only 1/2 of transverse diameter.

Axial view of pig's lumbar disc

Implanting the cage in is a difficult task, because of the narrow disc height. Wedge osteotomy has to be done in order to get the curet inside the disc space and clean out disc material. Complete discectomy is difficult not to mention decortication. It seems that only lateral 1/2 or 1/3 of discectomy can be done. Cage insertion is another challenge that you have to use force to punch the cage in. Metal cage is fine but PEEK cage has to be careful not to break it during hammering.

3 months follow-up X-ray. No idea if fused or not.

    Sacrificing the pig and take the lumbar column out is a new experience.  This only happens in autopsy which surgeons rarely do. Fortunately, it is not my routine work. The lab did not provide the necessary tools (chisel, osteotome), the column had to be transected using hand saw.