title: A technique of anterior screw removal through a posterior costotransversectomy approach for posterior-based osteotomies.
abstract: METHODS
  Case report.
  
  
  OBJECTIVE
  To describe a novel technique to remove anterior instrumentation from a posterior approach while performing posterior-based osteotomies for spinal deformities.
  
  
  BACKGROUND
  Posterior-based osteotomies such as pedicle subtraction osteotomies (PSOs) and vertebral column resections are performed to restore sagittal alignment. The removal of previously placed anterior implants at the desired osteotomy level can often be challenging. We propose a technique for the removal of anterior instrumentation through a posterior approach to facilitate osteotomy closure and deformity correction, while avoiding the need for an anterior incision.
  
  
  METHODS
  A 34-year-old woman presented with a residual deformity after several anterior and posterior procedures. The residual coronal Cobb angle measured 60 degrees between T7 and L2, with a 46 degrees thoracolumbar kyphosis between T10 and L2. The screw head at the desired osteotomy level was in close proximity to the liver after the previous right-sided thoracoabdominal approach. Therefore, the T11 anterior screw was accessed through a posterior costotransversectomy approach and disconnected from the rod proximally and distally with a high-speed side-cutting burr. A portion of the right lateral vertebral body of T11 was removed to expose the neck of the screw, which was separated from the shaft with the same burr. A PSO was performed at T11 and the remaining screw shank was removed with the posterior-based osteotomy.
  
  
  RESULTS
  No major complications were encountered during the procedure. The anterior screw at T11 was removed from posteriorly, and the PSO was completed successfully. Postoperative recovery was without incident, and the patient was very satisfied with her results.
  
  
  CONCLUSIONS
  This technique describes a novel, safe, and effective method to deal with anterior instrumentation from the posterior approach while performing posterior-based osteotomies for rigid spinal deformities.
authors.affiliation: Division of Orthopaedics, Toronto Western Hospital, 399 Bathurst Street, Toronto, Ontario, Canada. stephen.lewis@uhn.on.ca
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Lewis
authors.forename: Kenny
authors.initials: K
authors.lastname: David
authors.forename: Syndie
authors.initials: S
authors.lastname: Singer
authors.forename: Sarah A
authors.initials: SA
authors.lastname: Bacon
authors.forename: Michaela
authors.initials: M
authors.lastname: Kopka
authors.forename: Randolph
authors.initials: R
authors.lastname: Gray
authors.forename: Sofia
authors.initials: S
authors.lastname: Magana
mesh_terms: D000328:Adult; D001863:Bone Screws; D005260:Female; D006801:Humans; D007738:Kyphosis / Q000601:surgery*; D008159:Lumbar Vertebrae / Q000601:surgery*; D010027:Osteotomy / Q000379:methods*; D013123:Spinal Fusion / Q000295:instrumentation / Q000379:methods*; D013904:Thoracic Vertebrae / Q000601:surgery*; D016896:Treatment Outcome