The Mini-Open Pedicle Subtraction Osteotomy for Flat-Back Syndrome and Kyphosis Correction: Operative Technique

The pedicle subtraction osteotomy (PSO) has been a mainstay treatment for flat-back syndrome. The morbidity of open deformity correction can be high, and minimally invasive applications may reduce such morbidity.

To describe an operative technique of the mini-open PSO.

Two patients underwent percutaneous fixation above and below the PSO, and the PSO was performed in a mini-open fashion. The correction was obtained by cantilever.

The patient who underwent the L3 PSO had a prior fusion from T11 to L4 for scoliosis 35 years ago. On presentation at 62 years of age, he had a pelvic incidence of 54°, lumbar lordosis of 23°, sagittal vertical axis of +14 cm, and pelvic tilt of 25°. He underwent an anterior lumbar interbody fusion at L5-S1 followed by a min-open L3 PSO. He had a postoperative lumbar lordosis of 64° (correction of 41°), and his sagittal vertical axis went to +3 cm. His Oswestry Disability Index and visual analog scale scores decreased after surgery. The second patient was 64 years of age and underwent an L1 PSO. He had 43° of kyphosis from T10 to L2. He had a preoperative pelvic incidence of 63°, lumbar lordosis of 35°, pelvic tilt of 24°, and sagittal vertical axis of 3 cm. His postoperative kyphosis improved from 43° to 32°.

The mini-open PSO can achieve significant lordosis, although it is heavily reliant on anterior arthrodesis. Larger studies are needed to compare this approach with an open PSO.