Since first being described by Thomasen in 1985, pedicle subtraction osteotomy (PSO) has been used increasingly for the surgical correction of fixed coronal and sagittal plane deformities [7]. A PSO refers to doing a V-shaped resection through the posterior elements, pedicles, and vertebral body. A PSO is applied to patients with significant sagittal imbalance, those with sharp, angular, rigid scoliosis, kyphosis, and kyphoscoliosis, and those who have circumferential fusion spanning multiple segments [8].

For most of the cases, the levels of PSO should be the apex of scoliosis or kyphosis. If levels of the apex of scoliosis and kyphosis are different in patients with kyphoscoliosis, PSO should be performed at the levels of kyphosis for reconstruction of the sagittal alignment. Theoretically, osteotomy at the apical vertebrae results in good correction. And most of the patients with ankylosing spondylitis have apex on the thoracolumbar junction. Even though the correction angle is the same, osteotomy at the lower level can achieve better sagittal alignment because of the long lever arm. For patients with rigid kyphosis due to ankylosing spondylitis, PSO should be performed at the lumbar spine for better correction of the sagittal alignment. In most circumstances, surgeons feel that one PSO is enough for the treatment of kyphosis. However, sometimes a single PSO will not afford enough correction for severe or a round kyphosis; therein, one might consider another PSO or combing this with 2 or 3 SPOs or Ponte osteotomies [9].

In 1984, Ponte et al described shortening of the posterior column by employing multiple osteotomies and posterior compression instrumentation and fusion [10]. The Ponte osteotomy is similar to the Smith-Peterson osteotomy except that it is performed at multiple levels in the thoracic spine. And Smith-Peterson’s original osteotomy was in the lumbar spine, at one level, in patients with rheumatoid arthritis.

Ponte osteotomy and Smith-Peterson osteotomy could be performed at multiple levels in the deformities which have mobility in the anterior column. They could be chosen for patients with relatively round deformities. And sometimes they could be performed in adjacent levels as a supplemental technique for VCR or PSO for better correction.