title: The timing of elective shoulder surgery after shoulder injection affects postoperative infection risk in Medicare patients.
abstract: BACKGROUND
  The goal of this study was to employ a national database to evaluate the association of preoperative injection before shoulder arthroscopy and arthroplasty with the incidence of postoperative infection.
  
  
  METHODS
  A national database of Medicare patients was queried for patients who underwent shoulder arthroscopy or arthroplasty after ipsilateral shoulder injection. Three arthroscopy cohorts were created: arthroscopy within 3 months of injection (n = 3625), arthroscopy between 3 and 12 months after injection (n = 7069), and matched control arthroscopy without prior injection (n = 186,678). Three arthroplasty cohorts were created: arthroplasty within 3 months of injection (n = 636), arthroplasty between 3 and 12 months after injection (n = 1573), and matched control arthroplasty (n = 6211). Infection rates within 3 and 6 months postoperatively were assessed.
  
  
  RESULTS
  The incidence of infection after arthroscopy at 3 months (0.7%; odds ratio [OR], 2.2; P < .0001) and 6 months (1.1%; OR, 1.6; P = .003) was significantly higher in patients who underwent injection within 3 months before arthroscopy compared with controls. The incidence of infection after arthroplasty at 3 months (3.0%; OR, 2.0; P = .007) and 6 months (4.6%; OR, 2.0; P = .001) was significantly higher in patients who underwent injection within 3 months before arthroplasty compared with controls.
  
  
  CONCLUSIONS
  There was a significant increase in postoperative infection in Medicare patients who underwent injection within 3 months before shoulder arthroscopy and arthroplasty. This association was not noted when shoulder arthroscopy or arthroplasty occurred >3 months after injection.
authors.affiliation: Department of Orthopaedic Surgery, University of Virginia Health System, Charlottesville, VA, USA.
authors.forename: Brian C
authors.initials: BC
authors.lastname: Werner
authors.affiliation: Department of Orthopaedic Surgery, University of Virginia Health System, Charlottesville, VA, USA.
authors.forename: Jourdan M
authors.initials: JM
authors.lastname: Cancienne
authors.affiliation: Department of Orthopaedic Surgery, University of Virginia Health System, Charlottesville, VA, USA.
authors.forename: M Tyrrell
authors.initials: MT
authors.lastname: Burrus
authors.affiliation: Department of Orthopaedic Surgery, University of Virginia Health System, Charlottesville, VA, USA.
authors.forename: Justin W
authors.initials: JW
authors.lastname: Griffin
authors.affiliation: Department of Orthopaedic Surgery, University of Virginia Health System, Charlottesville, VA, USA.
authors.forename: F Winston
authors.initials: FW
authors.lastname: Gwathmey
authors.affiliation: Department of Orthopaedic Surgery, University of Virginia Health System, Charlottesville, VA, USA. Electronic address: sfb2e@virginia.edu.
authors.forename: Stephen F
authors.initials: SF
authors.lastname: Brockmeier
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001178:Arthroplasty / Q000009:adverse effects*; D001182:Arthroscopy / Q000009:adverse effects*; D017558:Elective Surgical Procedures; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D006278:Medicare; D010003:Osteoarthritis / Q000628:therapy*; D012785:Shoulder Joint / Q000601:surgery*; D013530:Surgical Wound Infection / Q000453:epidemiology* / Q000209:etiology; D014481:United States / Q000453:epidemiology
keywords: Shoulder arthroplasty; complications; postoperative infection; preoperative injection; shoulder arthroscopy; timing of injection