title: Factors that Influence Reduction Loss in Proximal Humerus Fracture Surgery.
abstract: OBJECTIVE
  This study was performed to identify the risk factors for reduction loss after locking plate fixation of proximal humerus fractures.
  
  
  METHODS
  Retrospective study.
  
  
  METHODS
  University trauma center.
  
  
  METHODS
  We retrospectively evaluated 252 patients who had been surgically treated for proximal humeral fractures with locking plates between January 2004 and December 2011.
  
  
  METHODS
  Charts and standardized x-rays (true anteroposterior and axillary lateral views) were used to evaluate the Neer and AO OTA fracture types, initial neck-shaft angle (NSA, varus displacement), medial comminution, postoperative NSA (reduction adequacy), medial support restoration, healing progress, reduction loss, and implant-related problems immediately after surgery and at 2 weeks, 1 month, 3 months, 6 months, 9 months, and at least 1 year after surgery. Reduction loss was defined as (1) ≥10 of angulation in any direction, (2) ≥5 mm of height loss of the humeral head from the plate, and (3) fixation failure.
  
  
  RESULTS
  Reduction loss occurred in 6.7% (17 of 252) of cases; revision surgeries were performed in all cases. Univariable logistic regression analysis revealed that older age (P = 0.023), osteoporosis (P = 0.001), varus displacement (P = 0.001), medial comminution (P = 0.001), reduction adequacy (P = 0.036), and insufficient medial support (P = 0.001) had significant correlations with reduction loss.
  
  
  CONCLUSIONS
  Multivariable regression analysis revealed that osteoporosis (less than -2.5 bone mineral density, P = 0.015), displaced varus fracture (less than 110° of NSA, P = 0.025), medial comminution (more than 1 fragment, P = 0.018), and insufficient medial support (no cortical or screw support, P = 0.001) were independent risk factors for reduction loss in the proximal humerus fractures surgery.
  
  
  METHODS
  Prognostic Level II. See Instructions for Authors for a complete description of levels of evidence.
authors.affiliation: Department of Orthopedic Surgery, Samsung Changwon Hospital, Sungkyunkwan University School of Medicine, Changwon, Korea.
authors.forename: Sung-Weon
authors.initials: SW
authors.lastname: Jung
authors.forename: Seung-Bo
authors.initials: SB
authors.lastname: Shim
authors.forename: Hyoung-Min
authors.initials: HM
authors.lastname: Kim
authors.forename: Ji-Heon
authors.initials: JH
authors.lastname: Lee
authors.forename: Hae-Seong
authors.initials: HS
authors.lastname: Lim
mesh_terms: D000328:Adult; D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D001860:Bone Plates; D001863:Bone Screws; D015897:Comorbidity; D005260:Female; D005593:Fracture Fixation, Internal / Q000295:instrumentation / Q000706:statistics & numerical data*; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D010014:Osteolysis / Q000175:diagnosis / Q000453:epidemiology* / Q000517:prevention & control; D011183:Postoperative Complications / Q000175:diagnosis / Q000453:epidemiology* / Q000517:prevention & control; D012086:Reoperation / Q000706:statistics & numerical data; D056910:Republic of Korea / Q000453:epidemiology; D012189:Retrospective Studies; D012307:Risk Factors; D017678:Sex Distribution; D012784:Shoulder Fractures / Q000175:diagnosis / Q000453:epidemiology* / Q000601:surgery*; D016896:Treatment Outcome