title: Is radiographic measurement of acromiohumeral distance on anteroposterior view after reverse shoulder arthroplasty reliable?
abstract: BACKGROUND
  Reverse shoulder arthroplasty leads to arm lengthening. Different techniques have been described to determine postoperative lengthening. The purpose of this study was to evaluate the reliability of the acromiohumeral distance (AHD) in determining arm lengthening after reverse shoulder arthroplasty.
  
  
  METHODS
  At 2 centers, 44 patients who had received an onlay design reverse shoulder arthroplasty were observed for a minimum of 6 months. Examination followed a standardized protocol including preoperative and postoperative radiographs on anteroposterior view in neutral rotation. Two orthopedic surgeons independently performed the measurements in random order.
  
  
  RESULTS
  Mean arm lengthening averaged 2.5 cm (range, 0.3-3.9 cm) according to AHD measurement. Significant differences in interobserver and intraobserver variability for postoperative AHD measurements were found (P < .01). The mean intrapatient difference was 0.5 cm (range, 0.02-1.5 cm).
  
  
  CONCLUSIONS
  According to our study, the AHD is not a reliable measurement technique to determine arm lengthening after reverse shoulder arthroplasty.
authors.affiliation: Clinic for Shoulder and Elbow Surgery, Bad Neustadt a. d. Saale, Germany; Générale de Santé, Hôpital Jean Mermoz, Centre Orthopédique Santy, Lyon, France. Electronic address: birgitwerner@hotmail.com.
authors.forename: Birgit S
authors.initials: BS
authors.lastname: Werner
authors.affiliation: Orthopaedic and Traumatologic Surgery Department, Centre Chirurgical E. Gallé, Nancy, France.
authors.forename: Adrien
authors.initials: A
authors.lastname: Jacquot
authors.affiliation: Orthopaedic and Traumatologic Surgery Department, Centre Chirurgical E. Gallé, Nancy, France.
authors.forename: Daniel
authors.initials: D
authors.lastname: Molé
authors.affiliation: Générale de Santé, Hôpital Jean Mermoz, Centre Orthopédique Santy, Lyon, France.
authors.forename: Gilles
authors.initials: G
authors.lastname: Walch
mesh_terms: D000174:Acromion / Q000000981:diagnostic imaging*; D000368:Aged; D000072228:Arthroplasty, Replacement, Shoulder / Q000379:methods*; D005260:Female; D006801:Humans; D006811:Humerus / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D011859:Radiography; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012785:Shoulder Joint / Q000000981:diagnostic imaging* / Q000601:surgery
keywords: Shoulder; acromiohumeral distance; lengthening; measurement; radiograph; reverse arthroplasty