Outcome of Pedicle Subtraction Osteotomies for Fixed Sagittal Imbalance of Multiple Etiologies A Retrospective Review of 140 Patients

SPINE Volume 37, Number 19, pp 1667–1675
©2012, Lippincott Williams & Wilkins


CLINICAL CASE SERIES
Outcome of Pedicle Subtraction Osteotomies for
Fixed Sagittal Imbalance of Multiple Etiologies
A Retrospective Review of 140 Patients
Ki-Tack Kim , MD, Sang-Hun Lee , MD, Kyung-Soo Suk , MD, Jung-Hee Lee , MD, and Bi-O Jeong , MD


Study Design. A retrospective study.
Objective. To evaluate the efficacy and safety of the pedicle subtraction osteotomy (PSO) as a technique for correction of fixed sagittal imbalance with multiple etiologies.
Summary of Background Data. This report represents the largest and longest series of patients with fixed sagittal imbalance other than ankylosing spondylitis who were managed with PSO.
Methods. A total of 140 consecutive patients who had undergone PSO for the management of sagittal imbalance with any etiology were reviewed. Etiologic diagnoses were ankylosing spondylitis in 86 patients, flatback syndrome in 20, post-traumatic kyphosis in 17, congenital kyphoscoliosis in 9, and post-tuberculotic kyphosis in 8 patients. The average duration of the follow-up period was 8 years (range, 5–12.5 yr). Radiological and clinical outcome analyses were performed.
Results. All patients showed a solid union upon follow-up radiographs and no pseudarthrosis was noted. Correction with PSO averaged 36.2 °. Blood loss averaged 1515.6 mL. The Oswestry
Disability Index improved from 40.5 to 18.8 at the last follow-up, and 90.7% of the patients were very or somewhat satisfi ed. There were 15 cases (10.7%) of reversible complications including transient radiculopathy and 3 cases (2.1%) of irreversible complications.
Conclusion. Based on the results of this study, PSO is considered a reliable and relatively safe procedure for the correction of fixed sagittal imbalance with multiple etiologies.
Key words: fixed sagittal imbalance , pedicle subtraction
osteotomy. Spine 2012 ; 37 : 1667 – 1675


Sagittal imbalance of the spine that results in abnormal weight bearing on the physiological sagittal vertical axis might occur after fi xation of thoracolumbar fracture, distal lumbar arthrodesis, multiple laminectomy, infectious spondylitis, and severe lumbar disc degeneration, or in patients with ankylosing spondylitis. The imbalance causes changes in the mechanical axis of spinal extensor muscles that lead to degenerative changes of the spine, weakness of muscle power, chronic back pain, and functional disability. 1 , 2
In severe cases, maintenance of body balance becomes difficult, and kyphosis makes abdominal organs sensitive to pressure and forward gaze diffi cult, all of which contributing to many disabilities including limitation of social activities. 1 , 2
Therefore, a reconstructive procedure that restores functional sagittal spinal alignment is necessary.


Surgical management of sagittal imbalance has been developed using various operation techniques by several surgeons.
Two common methods used to correct the sagittal imbalance include the Smith-Peterson osteotomy 3 – 6 and the pedicle subtraction osteotomy (PSO). 7 – 16 In particular, PSO has been recognized as a well-established procedure for the management of fi xed sagittal deformity with multiple etiologies. 17 – 22
However, mid- to long-term studies after the results of PSO for sagittal imbalance during 5 years are rarely found in the literature.


The purpose of this study was to review outcomes and complications obtained in our 140 patients who underwent PSO and followed up for 5 to 12.5 years and to evaluate the efficacy and safety of PSO as a technique for the correction ofsagittal imbalance with multiple etiologies.