Iatrogenic Flatback

Pedicle Subtraction Osteotomy
The goal of a pedicle subtraction osteotomy procedure is to create a normal amount of lumbar lordosis (approximately 50 degrees). In this type of osteotomy, the “pedicle” (a bony tube going from the back and front of the vertebra) is “subtracted” (removed). A wedge is taken from the bone, and the whole vertebra is bent backwards. This allows 20-40 degrees of lordosis to be restored at a single level. It is not dependent on the flexibility of the discs like the Smith-Peterson osteotomy does.

Two side views:
on the left, the amount of bony resection; on the right, the osteotomy after closure. If done properly, the front of the vertebra is roughly twice as high as the back.

A 52 year old gentleman had several surgeries to treat an L4-5 degenerative spondylolisthesis - a common form of arthritis that causes low back and leg pain. After multiple failed surgeries, he presented to Dr. Rinella with extreme back and leg pain, and was unable to stand up straight. A lumbar spine myelogram (an xray with special contrast so we can see the nerves) demonstrated the level above the fusion collapsed, and there was significant pressure on the nerves. Dr. Rinella performed a pedicle subtraction osteotomy . Dr. Rinella was able to take the pressure off the nerves, and restore the normal curvature to his lumbar spine so he could stand up straight.