title: Surgical correction in patients with lumbar degenerative kyphosis who had low bone mineral density: an analysis of 40 patients with a minimum follow-up of two years.
abstract: METHODS
  Retrospective study.
  
  
  OBJECTIVE
  To investigate influence of bone mineral density (BMD) on the surgical correction of lumbar degenerative kyphosis (LDK).
  
  
  BACKGROUND
  No studies so far have reported the influence of BMD on the surgical correction of LDK.
  
  
  METHODS
  Forty LDK patients with more than 2 years follow-up were studied. Pelvic incidence (PI), pelvic tilt, sacral slope, sagittal vertical axis (SVA), lumbar lordosis (LL), and thoracic kyphosis were measured preoperatively, immediate postoperatively and at final follow-up. Adverse outcomes: proximal adjacent fractures, sagittal decompensation, pseudoarthrosis, and cage subsidence were documented.
  
  
  RESULTS
  There were 37 females and 3 males. Average age was 65.1±4.5 years and mean follow-up was 34.2±16.7 months. 42.5% were Takemitsu type 3 curves, 27.5% type 2, 20.0% type 4 and 10.0% type 1. 37.5% had osteopenia, 40.0% osteoporosis and 22.5% had severe osteoporosis. SVA improved from 237.0±96.7 mm preoperatively to 45.3±41.8 mm postoperatively (p=0.000). LL improved from 10.5°±14.7° to -40.6°±10.9° postoperatively (p=0.000). At final follow-up SVA deteriorated to 89.8±72.2 mm and LL to 34.7°±15.8° (p=0.000). The association between late sagittal decompensation, pseudoarthrosis, or proximal adjacent fractures and osteoporosis was insignificant. The difference between immediate postoperative LL and PI (PIDiff) had a significant association with sagittal decompensation and pseudoarthrosis.
  
  
  CONCLUSIONS
  Osteoporosis did not influence the degree of correction, late sagittal decompensation, proximal adjacent fractures, and pseudoarthrosis in LDK. PIDiff had a significant association with sagittal decompensation and pseudoarthrosis.
authors.affiliation: Department of Orthopaedic Surgery, Spine Center, Kyung Hee University Hospital at Gangdong, Seoul, Korea.
authors.forename: Ki Tack
authors.initials: KT
authors.lastname: Kim
authors.affiliation: Department of Orthopaedic Surgery, Faculty of Medicine, University Malaya, Kuala Lumpur, Malaysia.
authors.forename: Chris Yin Wei
authors.initials: CY
authors.lastname: Chan
authors.affiliation: Department of Orthopaedic Surgery, Spine Center, Kyung Hee University Hospital at Gangdong, Seoul, Korea.
authors.forename: Sang Hun
authors.initials: SH
authors.lastname: Lee
authors.affiliation: Department of Orthopaedic Surgery, CMHospital, Seoul, Korea.
authors.forename: Dae Seok
authors.initials: DS
authors.lastname: Huh
authors.affiliation: Department of Orthopaedic Surgery, Dongsan Medical Center, Keimyung University College of Medicine, Daegu, Korea.
authors.forename: Eun Seok
authors.initials: ES
authors.lastname: Son
keywords: Bone mineral density; Lumbar degenerative kyphosis; Osteoporosis; Outcome; Surgery