title: Predicting failure after surgical fixation of proximal humerus fractures.
abstract: BACKGROUND
  Several studies reported high failures rates after internal fixation of proximal humerus fractures. Loss of reduction and screw cut-out are the most common reasons for revision surgery. Several risk factors for failure have been described in the literature. The aim of the present study was to assess risk factors for failure after surgical fixation of unstable proximal humerus fractures in a multivariate setup.
  
  
  METHODS
  Two different surgical techniques (PHILOS locking plate and Humerusblock) were used. In the PHILOS group, every kind of postoperative relative movement between the implant and the humeral head or shaft was defined as failure. In the Humerusblock group, postoperative movement between the humeral head and the shaft in terms of angulation or translational displacement was defined as failure. The following parameters were assessed: age, gender, cancellous bone mineral density (BMD) of the humeral head, fracture type, medial metaphyseal comminution, medial metaphyseal head extension, initial angulation of the humeral head in the frontal plane, initial anteversion of the humeral head, medial hinge displacement, maximum displacement of the tuberosities with respect to the head, surgical technique, anatomic reconstruction and restoration of the medial cortical support.
  
  
  RESULTS
  The following parameters were found to have a significant influence on the failure rate: age, local BMD, anatomic reduction, and restoration of the medial cortical support. The failure rate significantly increased with the number of risk factors.
  
  
  CONCLUSIONS
  Preoperative assessment of the local BMD and the patients' biological age as well as intraoperative anatomic reduction and restoration of the medial cortical support are the essentials for successful surgical fixation of proximal humerus fractures. Multifragmentary fracture patterns in old patients with low local BMD are prone for fixation failure. If the surgeon is not able to achieve anatomic reduction and restoration of the medial cortical support intraoperatively in this situation, adjustments such as augmentation or primary arthroplasty should be considered.
authors.affiliation: Department of Trauma Surgery and Sports Medicine, Innsbruck Medical University, Anichstraße 35, A-6020 Innsbruck, Austria. Dietmar@Krappinger.eu
authors.forename: Dietmar
authors.initials: D
authors.lastname: Krappinger
authors.forename: Nicola
authors.initials: N
authors.lastname: Bizzotto
authors.forename: Stephan
authors.initials: S
authors.lastname: Riedmann
authors.forename: Christian
authors.initials: C
authors.lastname: Kammerlander
authors.forename: Clemens
authors.initials: C
authors.lastname: Hengg
authors.forename: Franz Sebastian
authors.initials: FS
authors.lastname: Kralinger
mesh_terms: D000367:Age Factors; D000368:Aged; D015519:Bone Density; D001860:Bone Plates; D001863:Bone Screws; D019544:Equipment Failure Analysis / Q000379:methods*; D005260:Female; D005593:Fracture Fixation, Internal / Q000379:methods* / Q000706:statistics & numerical data; D006801:Humans; D058430:Humeral Head / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D011475:Prosthesis Failure / Q000209:etiology*; D012086:Reoperation; D012307:Risk Factors; D012784:Shoulder Fractures / Q000453:epidemiology / Q000534:rehabilitation / Q000601:surgery*; D017211:Treatment Failure