title: Analysis of efficacy and failure in proximal humerus fractures treated with locking plates.
abstract: OBJECTIVE
  The purpose of this study was to determine the efficacy of proximal humerus locking plates (PHLP) and to clarify predictors of loss of fixation.
  
  
  METHODS
  Retrospective review of patients with proximal humerus fractures fixed with a PHLP.
  
  
  METHODS
  Five Level 1 trauma centers.
  
  
  METHODS
  One hundred fifty-three patients (111 female, 42 male) 18 years or older with a displaced fracture or fracture-dislocation of the proximal humerus treated with a PHLP between January 1, 2001 and July 31, 2005.
  
  
  METHODS
  Demographic data, trauma mechanism, surgical approach, and perioperative complications were collected from the medical records. Fracture classification according to the AO/OTA, radiographic head-shaft angle, and screw tip-articular surface distance in true anteroposterior (AP) and axillary lateral radiographs of the shoulder were measured postoperatively. Varus malreduction was defined as a head-shaft angle of <120 degrees.
  
  
  METHODS
  Statistical analysis was done to establish correlations between loss of fixation and postoperative head-shaft angle in the true AP radiograph, patient age, fracture type, trauma mechanism, number of locking head screws, and type of plate.
  
  
  RESULTS
  The mean age was 62.3 +/- 15.4 years (22-92) and the mean injury severity score (ISS) was 9.5 +/- 10.16 (4-57; n = 73). The surgical approach was deltopectoral (90.2%) or transdeltoid (9.8%). No intraoperative complications were reported. The mean postoperative head-shaft angle was 130 degrees (95 degrees to 160 degrees; SD = 13). The overall incidence of loss of fixation was 13.7%. There was a statistically significant association between varus reduction (<120 degrees) and loss of fixation (30.4% when the head-shaft angle was <120 degrees versus 11% when the head-shaft angle was > or =120 degrees; P = 0.02).
  
  
  CONCLUSIONS
  This series presents the experience using PHLP in 5 Level 1 trauma centers. There were no intraoperative complications related to the locking plate systems. Despite the use of fixed-angle devices, loss of fixation occurred, primarily in the presence of varus malreduction. Our findings suggest that avoiding varus should substantially decrease the risk of postoperative failures.
authors.affiliation: Department of Orthopaedic Surgery, Denver Health Medical Center, University of Colorado School of Medicine, Denver, CO 80204, USA. juan.agudelorivera@uchsc.edu
authors.forename: Juan
authors.initials: J
authors.lastname: Agudelo
authors.forename: Matthias
authors.initials: M
authors.lastname: Schürmann
authors.forename: Philip
authors.initials: P
authors.lastname: Stahel
authors.forename: Peter
authors.initials: P
authors.lastname: Helwig
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Morgan
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Zechel
authors.forename: Christian
authors.initials: C
authors.lastname: Bahrs
authors.forename: Anand
authors.initials: A
authors.lastname: Parekh
authors.forename: Bruce
authors.initials: B
authors.lastname: Ziran
authors.forename: Allison
authors.initials: A
authors.lastname: Williams
authors.forename: Wade
authors.initials: W
authors.lastname: Smith
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001860:Bone Plates; D001863:Bone Screws; D005260:Female; D005500:Follow-Up Studies; D005593:Fracture Fixation, Internal / Q000295:instrumentation*; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications / Q000453:epidemiology; D011379:Prognosis; D011475:Prosthesis Failure; D011859:Radiography; D012189:Retrospective Studies; D012784:Shoulder Fractures / Q000000981:diagnostic imaging / Q000601:surgery*