title: Posterior-only correction of Scheuermann kyphosis using pedicle screws: economical optimization through screw density reduction.
abstract: BACKGROUND
  Posterior-only approach using pedicle screws' fixation has emerged as the preferred surgical technique for Scheuermann kyphosis (SK) correction. Insertion of multiple pedicle screws while increasing stability increases also the risk of complications related to screw malpositioning and surgical cost. The optimal screw density required in surgical correction of SK remains unclear. This study compares the safety and efficacy of low screw density (LSD) versus high screw density (HSD) technique used in posterior-only correction of SK.
  
  
  METHODS
  Twenty-one patients underwent surgical correction of SK between 2007 and 2011 and were reviewed after a mean of 29 months. HSD technique (i.e., 100 % of available pedicles, averaged 25.2 ± 4 screws) was used in 10 cases and LSD technique (i.e., 54-69 % of available pedicles in a pre-determined pattern, averaged 16.8 ± 1.3 screws; p < 0.001) was used in 11 cases. Kyphosis correction was assessed by comparing thoracic kyphosis, lumbar lordosis and sagittal balance on preoperative and postoperative radiographs. Cost saving analysis was performed for each group.
  
  
  RESULTS
  Preoperative thoracic kyphosis, lumbar lordosis and sagittal balance were similar for both groups. The average postoperative kyphosis correction was similar in both HSD and LSD groups (29° ± 9° vs. 34° ± 6°, respectively; p = 0.14). Complication occurred in four patients (19 %) in the HSD group and in two patients (9 %) in the LSD group (p = 0.56). Three patients required re-operation. Compared to HSD using LSD saves 4,200 pounds sterling per patient in hardware and 88,200 pounds sterling for the entire cohort.
  
  
  CONCLUSIONS
  LSD technique is as safe and effective as HSD technique in posterior-only correction of SK. Implant-related cost could be reduced by 32 %.
authors.affiliation: The Centre for Spinal Studies and Surgery, Queen's Medical Centre, Nottingham, UK, eyalbehrbalk@yahoo.com.
authors.forename: Eyal
authors.initials: E
authors.lastname: Behrbalk
authors.forename: Ofir
authors.initials: O
authors.lastname: Uri
authors.forename: Ruth M
authors.initials: RM
authors.lastname: Parks
authors.forename: Michael Paul
authors.initials: MP
authors.lastname: Grevitt
authors.forename: Marcus
authors.initials: M
authors.lastname: Rickert
authors.forename: Bronek Maximilian
authors.initials: BM
authors.lastname: Boszczyk
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D017046:Cost Savings; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000601:surgery; D008297:Male; D017063:Outcome Assessment, Health Care; D065289:Pedicle Screws / Q000009:adverse effects* / Q000191:economics; D011183:Postoperative Complications / Q000191:economics / Q000209:etiology* / Q000601:surgery; D011859:Radiography; D012086:Reoperation; D012189:Retrospective Studies; D012544:Scheuermann Disease / Q000191:economics / Q000601:surgery*; D013123:Spinal Fusion / Q000009:adverse effects* / Q000191:economics / Q000295:instrumentation*; D013904:Thoracic Vertebrae / Q000000981:diagnostic imaging / Q000601:surgery; D016896:Treatment Outcome; D055815:Young Adult
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