title: Are We Underestimating the Significance of Pedicle Screw Misplacement?
abstract: METHODS
  A retrospective review of charts, x-rays (XRs) and computed tomography (CT) scans was performed.
  
  
  OBJECTIVE
  To evaluate the accuracy of pedicle screw placement using a novel classification system to determine potentially significant screw misplacement.
  
  
  BACKGROUND
  The accuracy rate of pedicle screw (PS) placement varies from 85% to 95% in the literature. This demonstrates technical ability but does not represent the impact of screw misplacement on individual patients. This study quantifies the rate of screw misplacement on a per-patient basis to highlight its effect on potential morbidity.
  
  
  METHODS
  A retrospective review of charts, XRs and low-dose CT scans of 127 patients who underwent spinal fusion with pedicle screws for spinal deformity was performed. Screws were divided into four categories: screws at risk (SAR), indeterminate misplacements (IMP), benign misplacements (BMP), accurately placed (AP).
  
  
  RESULTS
  A total of 2724 screws were placed in 127 patients. A total of 2396 screws were placed accurately (87.96%). A total of 247 screws (9.07%) were BMP, 52 (1.91%) were IMP, and 29 (1.06%) were considered SAR. Per-patient analysis showed 23 (18.11%) of patients had all screws AP. Thirty-five (27.56%) had IMP and 18 (14.17%) had SAR. Risk factor analysis showed smaller Cobb angles increased likelihood of all screws being AP. Sub-analysis of adolescent idiopathic scoliotic patients showed no curve or patient characteristic that correlated with IMP or SAR. Over 40% of patients had screws with either some/major concern.
  
  
  CONCLUSIONS
  Overall reported screw misplacement is low, but it does not reflect the potential impact on patient morbidity. Per-patient analysis reveals more concerning numbers toward screw misplacement. With increasing pedicle screw usage, the number of patients with misplaced screws will likely increase proportionally. Better strategies need to be devised for evaluation of screw placement, including establishment of a national database of deformity surgery, use of intra-operative image guidance, and reevaluation of postoperative low-dose CT imaging.
  
  
  METHODS
  3.
authors.affiliation: *Department of Pediatric Orthopedics, Cohen's Children Medical Center, New Hyde Park†Department of Epidemiology & Population Health‡Department of Orthopaedic Surgery, Albert Einstein College of Medicine§Department of Radiology, Montefiore Medical Center/Albert Einstein College of Medicine, Bronx, NY.
authors.forename: Vishal
authors.initials: V
authors.lastname: Sarwahi
authors.forename: Stephen F
authors.initials: SF
authors.lastname: Wendolowski
authors.forename: Rachel C
authors.initials: RC
authors.lastname: Gecelter
authors.forename: Terry
authors.initials: T
authors.lastname: Amaral
authors.forename: Yungtai
authors.initials: Y
authors.lastname: Lo
authors.forename: Adam L
authors.initials: AL
authors.lastname: Wollowick
authors.forename: Beverly
authors.initials: B
authors.lastname: Thornhill
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D005260:Female; D006801:Humans; D007431:Intraoperative Complications / Q000000981:diagnostic imaging* / Q000453:epidemiology; D008297:Male; D065289:Pedicle Screws / Q000009:adverse effects; D012189:Retrospective Studies; D013122:Spinal Diseases / Q000000981:diagnostic imaging* / Q000601:surgery*; D013123:Spinal Fusion / Q000009:adverse effects / Q000295:instrumentation*; D014057:Tomography, X-Ray Computed; D055815:Young Adult