title: Incidence and prognostic factors for postoperative frozen shoulder after shoulder surgery: a prospective cohort study.
abstract: OBJECTIVE
  Frozen shoulder is a potential complication after shoulder surgery. It is a clinical condition that is often associated with marked disability and can have a profound effect on the patient's quality of life. The incidence, etiology, pathology and prognostic factors of postoperative frozen shoulder after shoulder surgery are not known. The purpose of this explorative study was to determine the incidence of postoperative frozen shoulder after various operative shoulder procedures. A second aim was to identify prognostic factors for postoperative frozen shoulder after shoulder surgery.
  
  
  METHODS
  505 consecutive patients undergoing elective shoulder surgery were included in this prospective cohort study. Follow-up was 6 months after surgery. A prediction model was developed to identify prognostic factors for postoperative frozen shoulder after shoulder surgery using the TRIPOD guidelines. We nominated five potential predictors: gender, diabetes mellitus, type of physiotherapy, arthroscopic surgery and DASH score.
  
  
  RESULTS
  Frozen shoulder was identified in 11% of the patients after shoulder surgery and was more common in females (15%) than in males (8%). Frozen shoulder was encountered after all types of operative procedures. A prediction model based on four variables (diabetes mellitus, specialized shoulder physiotherapy, arthroscopic surgery and DASH score) discriminated reasonably well with an AUC of 0.712.
  
  
  CONCLUSIONS
  Postoperative frozen shoulder is a serious complication after shoulder surgery, with an incidence of 11%. Four prognostic factors were identified for postoperative frozen shoulder: diabetes mellitus, arthroscopic surgery, specialized shoulder physiotherapy and DASH score. The combination of these four variables provided a prediction rule for postoperative frozen shoulder with reasonable fit.
  
  
  METHODS
  Level II, prospective cohort study.
authors.affiliation: Department of Orthopedics, Deventer Hospital, N. Bolkesteinlaan 75, 7416 SE, Deventer, The Netherlands. c.t.koorevaar@dz.nl.
authors.forename: Rinco C T
authors.initials: RCT
authors.lastname: Koorevaar
authors.affiliation: Teaching Hospital/Research Department, Deventer Hospital, N. Bolkesteinlaan 75, 7416 SE, Deventer, The Netherlands.
authors.forename: Esther
authors.initials: E
authors.lastname: Van't Riet
authors.affiliation: Department of Physiotherapy, Deventer Hospital, N. Bolkesteinlaan 75, 7416 SE, Deventer, The Netherlands.
authors.forename: Marcel
authors.initials: M
authors.lastname: Ipskamp
authors.affiliation: Department of Orthopedics, University Medical Center Groningen, University of Groningen, PO box 30.001, 9700 GB, Groningen, The Netherlands.
authors.forename: Sjoerd K
authors.initials: SK
authors.lastname: Bulstra
mesh_terms: D000328:Adult; D019540:Area Under Curve; D001182:Arthroscopy; D002062:Bursitis / Q000453:epidemiology*; D002968:Clavicle / Q000601:surgery; D015331:Cohort Studies; D019299:Decompression, Surgical; D003920:Diabetes Mellitus / Q000453:epidemiology; D005260:Female; D006801:Humans; D015994:Incidence; D007593:Joint Instability / Q000601:surgery; D008297:Male; D008875:Middle Aged; D019637:Orthopedic Procedures; D026741:Physical Therapy Modalities / Q000706:statistics & numerical data*; D011183:Postoperative Complications / Q000453:epidemiology*; D011379:Prognosis; D011446:Prospective Studies; D011788:Quality of Life; D012307:Risk Factors; D000070636:Rotator Cuff Injuries / Q000601:surgery; D017678:Sex Distribution; D012782:Shoulder / Q000601:surgery; D019534:Shoulder Impingement Syndrome / Q000601:surgery; D012785:Shoulder Joint / Q000601:surgery*
keywords: Incidence; Postoperative frozen shoulder; Prognostic factors; Shoulder surgery