Results of Lumbar Pedicle Subtraction Osteotomies for Fixed Sagittal Imbalance

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Abstract
Retrospective study. To report results at a minimum 5 years after pedicle subtraction osteotomy for fixed sagittal imbalance. No one has reported results of pedicle subtraction osteotomies with a 5- to 8-year follow-up. Thirty-five consecutive patients with sagittal imbalance (29 females/6 males, average age at surgery, 53.1 years) treated with lumbar pedicle subtraction osteotomies (1 at L1, 13 at L2, 20 at L3, and 1 at L4) at 1 institution were analyzed (average follow-up, 5.8 years; range, 5–7.6 years). Radiographic and clinical outcomes analysis was performed. There were no significant regional radiographic changes between 2 years postoperative and the ultimate follow-up (proximal junctional change, P = 0.30; thoracic kyphosis, P = 0.38; and lumbar lordosis, P = 0.84), although many patients did demonstrate an increasingly anterior C7 sagittal plumb with time. Ten pseudarthroses (29%) occurred in 8 patients and were revised between 2 and 5 years postoperative. There were no pseudarthroses at the osteotomy level (9 at the thoracolumbar junction, 1 at the LS junction), but at the levels added to the previous fusions. There was no degradation in Oswestry and Scoliosis Research Society (SRS) outcome scores between 2 years postoperative and ultimate follow-up (P = 0.23 and 0.90, respectively). Patients reported very good satisfaction (87%), good self-image (76%), good function (69%), and fair pain subscales (66%) at ultimate follow-up. Sagittal vertical axis <8 cm at ultimate follow-up was significant for better SRS outcomes scores (P = 0.038). Eight patients with revised pseudarthroses did not demonstrate poorer SRS outcomes scores (P = 0.52). Those 8 patients were queried after their pseudarthrosis revision surgery. Pedicle subtraction osteotomy can provide satisfactory clinical and radiographic outcomes for patients with a minimum 5-year follow-up despite needing pseudarthrosis revision and some component of increasingly positive sagittal vertical axis between 2 years and 5 to 8 years of follow-up. The level of patient satisfaction and self-image subscales were high after more than 5 years of follow-up. Restoration and maintenance of sagittal vertical axis <8 cm were important to the ultimate sagittal reconstruction.