title: Anterior elongation as a minimally invasive alternative for sagittal imbalance-a case series.
abstract: BACKGROUND
  Degenerative and iatrogenic conditions may lead to flat back or even to kyphotic deformity, and sagittal imbalance can cause significant clinical impairment. Minor imbalance cases are usually treated with conservative care. Among currently popular surgical techniques for the correction of sagittal imbalance are posterior-based procedures, which are associated with access-related risks (mostly neurological) and postoperative morbidity risks.
  
  
  OBJECTIVE
  This study aims to report a minimally invasive lateral approach using hyperlordotic cages in the treatment of mild sagittal imbalance. Radiological correction, clinical improvement, and safety will be analyzed.
  
  
  METHODS
  Eight patients (mean age 71.8 years, SD 7.8; mean BMI 27.5, SD 2.3) with symptomatic sagittal imbalance were retrospectively reviewed. Eight cases were treated by anterior interbody fusion with lordotic cages. A minimally invasive lateral retroperitoneal approach was used in the surgical procedures, with or without percutaneous pedicle screw supplementation.
  
  
  RESULTS
  No major complications occurred and just one case needed revision for direct decompression. Clinical outcomes Visual Analog Scale score changed from 88 at preoperative visit to 51 at 1-week visit, and Oswestry Disability Index score decreased from 82 at preoperative visit to 44 at 6-week visit. The 6-month radiological assessment revealed improvement in spinopelvic parameters: Focal lordosis improved from 2.3° ± 7.7 to 27.1° ± 6.7. Sagittal vertical alignment improved from 11.7 ± 5.3 to 6.2 ± 4.0 cm. Preoperative sacral slope improved from 20.1° ± 5.8 to 29.4° ± 10.3 and preoperative pelvic tilt improved from 35.2° ± 5.2 to 23.8° ± 4.3. Short-term results indicate that the minimally invasive lateral approach can be applied to the treatment of mild sagittal imbalance, with special advantage in elderly patients or those in which posterior approaches are relatively contraindicated.
authors.affiliation: Department of Minimally Invasive Surgery, Instituto de Patologia da Coluna, Vergueiro Street 1421, Room 305, 04101-000 São Paulo, SP Brazil ; Department of Imaging Diagnosis, Universidade Federal de São Paulo, São Paulo, Brazil.
authors.forename: Luis
authors.initials: L
authors.lastname: Marchi
authors.forename: Leonardo
authors.initials: L
authors.lastname: Oliveira
authors.forename: Rodrigo
authors.initials: R
authors.lastname: Amaral
authors.forename: Carlos
authors.initials: C
authors.lastname: Castro
authors.forename: Thiago
authors.initials: T
authors.lastname: Coutinho
authors.forename: Etevaldo
authors.initials: E
authors.lastname: Coutinho
authors.forename: Luiz
authors.initials: L
authors.lastname: Pimenta
keywords: interbody fusion; lumbar spine; minimally invasive surgery; sagittal balance; spine; spine fusion