title: High Rates of Occult Infection After Shoulder Fracture Fixation: Considerations for Conversion Shoulder Arthroplasty.
abstract: BACKGROUND
  Existing hardware may contribute to increased risk of bacterial contamination and subsequent periprosthetic joint infection (PJI) in conversion shoulder arthroplasty performed for failed fracture fixation.
  
  
  OBJECTIVE
  This study examined the incidence of positive pre-operative aspiration and inflammatory marker data, along with correlation of pre-operative positive aspiration or inflammatory markers and subsequent infection following conversion shoulder arthroplasty for failed open reduction and internal fixation (ORIF) and the need for re-operation at 4.6-year follow-up.
  
  
  METHODS
  Twenty-eight patients who underwent conversion to shoulder arthroplasty for any reason after fracture fixation were retrospectively reviewed in a single center. A pre-operative aspiration was done in 17 patients; all patients had intra-operative tissue sampling. All procedures were single-stage removal of hardware and performance of the arthroplasty. In cases of pre-operative positive bacterial growth, a single-stage procedure was performed according to the septic ENDO-Klinik protocol.
  
  
  RESULTS
  In 4 of 17 pre-operative joint aspirations, bacterial growth was detected; one pre-operative negative aspiration demonstrated bacterial growth in intra-operative sampling. In three of them, the infection has been validated through intra-operatively results. Pre-operative aspiration showed a sensitivity of 75% and specificity of 92% (p < 0.005) for infection. No post-operative PJIs were observed. Six revisions were performed, most commonly for aseptic loosening (two cases) and conversion of hemiarthroplasty to a reverse design (two cases).
  
  
  CONCLUSIONS
  In conclusion, the risk of low-grade shoulder infection after fracture osteosynthesis may be higher than in hip and knee joints, based on limited study data. Adequate pre-operative testing is recommended to rule out occult shoulder infection in this setting.
authors.affiliation: Department of Trauma, Hand and Reconstructive Surgery, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany.
authors.forename: Till O
authors.initials: TO
authors.lastname: Klatte
authors.affiliation: Orthopaedic Surgery, Helios ENDO-Klinik Hamburg, Holstenstrasse 2, 22767 Hamburg, Germany.
authors.forename: Reza
authors.initials: R
authors.lastname: Sabihi
authors.affiliation: Trauma Department, Hannover Medical School (MHH), Hannover, Germany.
authors.forename: Daniel
authors.initials: D
authors.lastname: Guenther
authors.affiliation: Department of Orthopaedic Surgery, University of Pennsylvania, 3400 Spruce Street, 2 Silverstein Pavilion, Philadelphia, PA 19104 USA.
authors.forename: Atul F
authors.initials: AF
authors.lastname: Kamath
authors.affiliation: Department of Trauma, Hand and Reconstructive Surgery, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany.
authors.forename: Johannes M
authors.initials: JM
authors.lastname: Rueger
authors.affiliation: Orthopaedic Surgery, Helios ENDO-Klinik Hamburg, Holstenstrasse 2, 22767 Hamburg, Germany.
authors.forename: Thorsten
authors.initials: T
authors.lastname: Gehrke
authors.affiliation: Orthopaedic Surgery, Helios ENDO-Klinik Hamburg, Holstenstrasse 2, 22767 Hamburg, Germany.
authors.forename: Daniel
authors.initials: D
authors.lastname: Kendoff
keywords: bacterial contamination; infection shoulder arthroplasty; low-grade infection of fixation device; periprosthetic shoulder infection; post-traumatic arthritis; shoulder fracture