Application and progress of pedicle subtraction osteotomy and its modification for rigid spinal kyphosis deformity / 中华骨科杂志

ABSTRACT

Rigid spinal kyphosis deformity is typically characterized by a large kyphotic Cobb angle (≥70°) and a significant decrease of intervertebral flexibility (bending flexibility<30°), due to primary spinal disease, spinal trauma or other diseases. Severe kyphotic deformity leads to a poor posture and spinal cord or neurological impairment. Three-column osteotomy, including pedicle subtraction osteotomy (PSO) and its modified methods, is the only effective treatment for such patients. For example, asymmetrical PSO (APSO) could not only achieve successful realignment of spinal biplanar balance, but also realize complete closure of osteotomy gap, which is conducive to realize solid bony fusion and provide better stability. In partial pedicle subtraction osteotomy (PPSO), the remaining cortical shell of pedicle could decrease the risk of neural injury without significant loss of correction amount, so PPSO could be a viable surgical option for spinal deformity. Besides, modified partial pedicle subtraction osteotomy (MPPSO) is commonly used for post-traumatic thoracolumbar kyphosis with an injured disc. The potential superiorities of MPPSO are that it not only increases regional stability by reserving the integrity of the lower facet joint, but also promotes direct interbody fusion in the upper disc space. For closing-opening wedge osteotomy (COWO), it could obtain more kyphotic corrections by closing posterior column and opening anterior column simultaneously. Modified closing-opening wedge osteotomy (MCOWO) is an ideal option in treating cases of thoracolumbar posttraumatic kyphosis with flat discs or wedge-shape vertebra, because great correction results were observed at follow-up with postero-superior triangular corner primarily resected. Although technically difficult and demanding, bone-disc-bone osteotomy (BDBO) is still a good option for achieving "bone-to-bone" closure of the osteotomy site to yield higher fusion rates and decrease the risk of pseudoarthrosis. A full understanding of the osteotomy range, correction effects and advantages for each type of modified PSO is essential for preoperative plans, optimal spinal sagittal reconstructions and excellent prognosis.