title: Complex proximal humerus fractures: Hertel's criteria reliability to predict head necrosis.
abstract: BACKGROUND
  The risk of post-traumatic humeral head avascular necrosis (AVN), regardless of the treatment, has a high reported incidence. In 2004, Hertel et al. stated that the most relevant predictors of ischemia after intracapsular fracture treated with osteosynthesis are the calcar length, medial hinge integrity and some specific fracture types. Based on Hertel's model, the purpose of this study is to evaluate both its reliability and weaknesses in our series of 267 fractures, assessing how the anatomical configuration of fracture, the quality of reduction and its maintenance were predictive of osteonecrosis development, and so to suggest a treatment choice algorithm.
  
  
  METHODS
  A retrospective study, level of evidence IV, was conducted to duly assess the radiographic features of 267 fractures treated from 2004 to 2010 following Hertel's criteria treated with open reduction and internal fixation by angular stability plates and screws. The average age was 65.2 years. The average follow-up was 28.3 ± 17.0 months. The percentage of AVN, the quality and maintenance of reduction obtained during surgery were evaluated.
  
  
  RESULTS
  The AVN incidence was 3.7 %. No significant correlation with gender, age and fracture type was found. At the last follow-up X-ray, only 30 % presented all Hertel's good predictors in the AVN group, 4.7 % in the non-AVN group (p < 0.05). About quality of reduction in the AVN group, it was poor in 50 %; while in the non-AVN group, it was poor in 3.4 % (p < 0.05). Four patients with AVN were symptomatic, and three needed a second surgery.
  
  
  CONCLUSIONS
  Hertel's criteria are important in the surgical planning, but they are not sufficient: an accurate evaluation of the calcar area fracture in three planes is required. All fractures involving calcar area should be studied with CT.
authors.affiliation: University Department of Orthopaedics, Modena, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Campochiaro
authors.affiliation: Department of Orthopaedics and Traumatology, Piacenza Hospital, Piacenza, Italy. Manuela.rebuzzi@libero.it.
authors.forename: M
authors.initials: M
authors.lastname: Rebuzzi
authors.affiliation: University Department of Orthopaedics, Modena, Italy.
authors.forename: P
authors.initials: P
authors.lastname: Baudi
authors.affiliation: University Department of Orthopaedics, Modena, Italy.
authors.forename: F
authors.initials: F
authors.lastname: Catani
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D005593:Fracture Fixation, Internal / Q000379:methods*; D006801:Humans; D006811:Humerus / Q000098:blood supply; D015994:Incidence; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D010020:Osteonecrosis / Q000453:epidemiology / Q000209:etiology*; D011183:Postoperative Complications / Q000453:epidemiology / Q000209:etiology*; D011859:Radiography; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012784:Shoulder Fractures / Q000000981:diagnostic imaging / Q000601:surgery*
keywords: Calcar; Hertel; Humerus fracture; Humerus head; Necrosis; Shoulder