Osteotomies are bone-cutting procedures. In the spine, their goal is to produce lordosis. They can also correct rigid or angular scoliosis that occurs over a short segment.
TH required multiple posterior osteotomies (called “Smith-Peterson” or “Ponte Osteotomies”) to straighten her spine to normal degrees of kyphosis. Normally the vertebra contact each other through 3 joints at each level: one disc in the front, and two sliding facets in the back. In the thoracic spine, the facets look like shingles on a roof, and will only allow you to bend backward so far. In this osteotomy, we remove the facets and bend the spine backward further than normal. Over one level, only a little bit of correction will occur (5-15 degrees). However, over many levels, large amounts of correction can be achieved.
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.
The vertebral column resection the most powerful and dangerous procedure that can be performed on the spine. An entire vertebra or more are removed from the back of the spine. This dislocates the spine so it can be repositioned properly. In this procedure, we must stabilize the spine above and below the osteotomy with pedicle screws and rods. The nerves are completely decompressed before the spine is repositioned.
The anterior-posterior osteotomy is very similar to a vertebral column resection. In a vertebral column resection, an entire vertebra or more are removed from the back of the spine. This dislocates the spine so it can be repositioned properly. The anterior-posterior osteotomy has the same effect, but the back portion of the bone is removed from the back of the spine, and the front portion is removed from a separate anterior incision. This avoids reaching around the nerves to remove all of the vertebra.