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

BACKGROUND: 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. OBJECTIVE: To describe an operative technique of the mini-open PSO. METHODS: 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. RESULTS: 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 degrees, lumbar lordosis of 23 degrees, sagittal vertical axis of +14 cm, and pelvic tilt of 25 degrees. 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 degrees (correction of 41 degrees), 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 degrees of kyphosis from T10 to L2. He had a preoperative pelvic incidence of 63 degrees, lumbar lordosis of 35 degrees, pelvic tilt of 24 degrees, and sagittal vertical axis of 3 cm. His postoperative kyphosis improved from 43 degrees to 32 degrees. CONCLUSION: 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.