Fixed sagittal imbalance (a syndrome in which the patient is only able to
stand with the weight-bearing line in front of the sacrum) has many
etiologies. The most commonly reported technique for correction is the
Smith-Petersen osteotomy. Few reports on pedicle subtraction procedures
(resection of the posterior elements, pedicles, and vertebral body through a
posterior approach) are available in the peer-reviewed literature. We are
aware of no report involving a substantial number of patients with coexistent
scoliosis who underwent pedicle/vertebral body subtraction for the treatment
of fixed sagittal imbalance.
Twenty-seven consecutive patients in whom sagittal imbalance was treated
with lumbar pedicle subtraction osteotomy at one institution were analyzed.
Radiographic analysis included assessment ofthoracic kyphosis, lumbar
lordosis, lordosis through the pedicle subtraction osteotomy site, and the C7
sagittal plumb line. Outcomes analysis was performed with use of a
before-and-after pain scale, items from the Oswestry questionnaire, and the
Scoliosis Research Society (SRS) questionnaire after a minimum duration of
follow-up of two years. Complications and radiographic findings were also
analyzed for the entire group.
Overall, the average increase in lordosis was 34.1° and the average
improvement in the sagittal plumb line was 13.5 cm. One patient had
development of a lumbar pseudarthrosis through the area of pedicle subtraction
osteotomy, and six patients had development of a thoracic pseudarthrosis. Two
patients had development of increased kyphosis at L5/S1, caudad to the fusion,
resulting in some loss of sagittal correction. There were significant
improvements in the overall Oswestry score (p < 0.0001) and the pain-scale
score (p = 0.0002). Most patients reported improvement in terms of pain and
self-image as well as overall satisfaction with the procedure.
Pedicle subtraction osteotomy is a useful procedure for patients with fixed
sagittal imbalance. A worse clinical result is associated with increasing
patient comorbidities, pseudarthrosis in the thoracic spine, and subsequent
breakdown caudad to the fusion.