title: Insufficient restoration of lumbar lordosis and FBI index following pedicle subtraction osteotomy is an indicator of likely mechanical complication.
abstract: OBJECTIVE
  Pedicle subtraction osteotomies (PSO) enable correction of spinal deformities but remain difficult and are associated with high complication rates. This study aimed to prospectively review different post-operative complications and mechanical problems in patients who underwent PSO as treatment for sagittal imbalance as sequelae of degenerative disc disease or previous spinal fusion.
  
  
  METHODS
  This was a descriptive prospective single center study of 63 patients who underwent sagittal imbalance correction by PSO. Radiographic analysis of pre- and post-operative pelvic and spinal parameters was completed based on EOS images following 3D modeling. Global and sub-group analyses were completed based on the Roussouly classification. A systematic analysis of post-operative complications was conducted during hospital stay and at follow-up visits.
  
  
  RESULTS
  Complications included 15 cases (20.2%) of bilateral leg pain, with transient neurological deficit in 6 cases (9.5%), and 9 cases (12.5%) of early surgical site infections. Intra-operative complications included five tears of the dura mater and two cases of excessive blood loss (>5,000 mL). Two mortalities occurred from major intracerebral bleeds in the early post-operative period. Mechanical complications were principally non-union (9 cases) and junctional kyphosis (3 cases). All 19 post-operative complications (28.1%) were revised at an average of 2 years following surgery. All mechanical complications were found in the patients who had insufficient imbalance correction and this was mainly associated with high PI (>60°) or a moderate PI (45-60º) combined with excess FBI pre-operatively that remained >10° post-operatively.
  
  
  CONCLUSIONS
  Infection and neurologic complications following PSO are relatively common, and frequently reported in the literature. The principal cause of mechanical complications, such as non-union or junctional kyphosis, was insufficient sagittal correction, characterized by post-operative FBI >10°. The risks of insufficient correction are greater in patients with higher pelvic incidence and those patients who required very high correction.
authors.affiliation: Spine Unit 2, Surgical Research Lab Deterca, Bordeaux University Hospital, CHU Pellegrin, 33076, Bordeaux, France, j-c.lehuec@u-bordeaux.fr.
authors.forename: J C
authors.initials: JC
authors.lastname: Le Huec
authors.forename: A
authors.initials: A
authors.lastname: Cogniet
authors.forename: H
authors.initials: H
authors.lastname: Demezon
authors.forename: J
authors.initials: J
authors.lastname: Rigal
authors.forename: R
authors.initials: R
authors.lastname: Saddiki
authors.forename: S
authors.initials: S
authors.lastname: Aunoble
mesh_terms: D000293:Adolescent; D000328:Adult; D016063:Blood Loss, Surgical; D002543:Cerebral Hemorrhage / Q000401:mortality; D002648:Child; D002675:Child, Preschool; D004388:Dura Mater / Q000293:injuries; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007431:Intraoperative Complications; D007738:Kyphosis / Q000601:surgery*; D008141:Lordosis / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D010027:Osteotomy / Q000379:methods*; D010149:Postoperative Pain; D011183:Postoperative Complications; D011446:Prospective Studies; D012086:Reoperation; D013530:Surgical Wound Infection; D055815:Young Adult