title: The acromial index is not predictive for failed rotator cuff repair.
abstract: BACKGROUND
  The main objective of this study was to evaluate the association between the acromial index (AI) and the incidence of recurrent tears of the rotator cuff (RC) in a cohort of patients with full thickness tears who underwent arthroscopic primary repair.
  
  
  METHODS
  A prognostic study of a prospective case series of 103 patients with full thickness RC tears was undertaken. The average age was 59.5 years (39-74) and follow-up was 30.81 months (12-72). True anterior-posterior X-rays were obtained during the pre-operative evaluation. Pre and post-operative magnetic resonance imaging (MRI) were recorded.
  
  
  RESULTS
  Eighteen cases with recurrent tears (17.4%) were seen on post-operative MRI. The average AI for patients with recurrent tears was 0.711 ± 0.065 and for patients without recurrent tears 0.710 ± 0.064 (p < 0.05). A positive association between age and recurrent tears of the RC was noted (average ages: recurrent tears group 63 ± 5.9 years; group without recurrent tears 58.8 ± 7.5 years) (r = -0.216; p = 0.029). We did not find an association between size of the primary tear and recurrent tears (r = -0.075; p < 0.05) or between degrees of retraction of the primary and recurrent tears of the cuff (r = -0.073; p < 0.05). We observed that 38.9% of the recurrent tears cases presented with more than one tendon affected before the arthroscopy. At follow-up, none of these recurrent tears showed more than one tendon affected on MRI evaluation.
  
  
  CONCLUSIONS
  In this study, we found that the AI radiological measurement is not a predictor for recurrent tears of the RC after primary arthroscopic repair.
authors.affiliation: Orthopaedics Department, Hospital del Trabajador, Santiago, Chile, patricio.melean@gmail.com.
authors.forename: Patricio
authors.initials: P
authors.lastname: Melean
authors.forename: Sven
authors.initials: S
authors.lastname: Lichtenberg
authors.forename: Fredy
authors.initials: F
authors.lastname: Montoya
authors.forename: Stephan
authors.initials: S
authors.lastname: Riedmann
authors.forename: Petra
authors.initials: P
authors.lastname: Magosch
authors.forename: Peter
authors.initials: P
authors.lastname: Habermeyer
mesh_terms: D000174:Acromion / Q000000981:diagnostic imaging* / Q000473:pathology; D000328:Adult; D000367:Age Factors; D000368:Aged; D001182:Arthroscopy / Q000379:methods*; D015331:Cohort Studies; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011379:Prognosis; D011446:Prospective Studies; D011859:Radiography; D012008:Recurrence; D012189:Retrospective Studies; D012307:Risk Factors; D017006:Rotator Cuff / Q000000981:diagnostic imaging / Q000601:surgery*; D000070636:Rotator Cuff Injuries; D013708:Tendon Injuries / Q000175:diagnosis* / Q000453:epidemiology / Q000601:surgery*; D017211:Treatment Failure