title: Cut-off values of latent infection in patients with rapid migration following bipolar hip hemiarthroplasty.
abstract: BACKGROUND
  Although most patients achieve favorable results following bipolar hip hemiarthroplasty (BHA), some experience rapid migration of the prosthesis. We retrospectively reviewed 18 patients with BHA that necessitated revision.
  
  
  METHODS
  We examined soft tissues obtained from periprosthetic lesions. In total, 18 patients with pain and acetabular migration of the BHA prosthesis were included. The patients were divided into a polymorphonuclear leukocyte (PMN)-positive (≥5 PMNs per high-power field [HPF]) and PMN-negative (<5 PMNs/HPF) group.
  
  
  RESULTS
  Pathological findings showed that 11 patients were PMN-positive, which was indicative of infection. All patients in the PMN-positive group showed no polyethylene particles or foreign body giant cells, while all patients in the PMN-negative group showed polyethylene debris or foreign body giant cells (p < 0.001). BHA survival, C-reactive protein (CRP) levels, and the Japanese Orthopaedic Association (JOA) hip score were significantly different between the PMN-positive and PMN-negative group (p < 0.01). A BHA survival cut-off value of 3270 days was diagnostic for PMN positivity (sensitivity: 100%; specificity: 100%). The cut-off values for CRP and the JOA hip score were 0.43 mg/dl and 56 points, respectively. Four of 11 PMN-positive patients showed no clinical symptoms of infection (asymptomatic PMN-positive group). BHA survival, CRP levels, and JOA hip scores were significantly different between the asymptomatic PMN-positive and PMN-negative group (p < 0.05). A BHA survival cut-off of 3270 days was diagnostic for asymptomatic PMN positivity (sensitivity: 100%; specificity: 100%). The cut-off values for CRP and the JOA hip score were 0.43 mg/dl and 57 points, respectively.
  
  
  CONCLUSIONS
  Our findings suggest that some portion of rapid BHA prosthesis migration is caused by mild infection. Careful pathological examination should be performed to identify infection before removal of the BHA prosthesis in patients who develop migration within 9 years.
authors.affiliation: The Near-Future Locomotor Organ Medicine Creation Course (Kusunoki Kai), Graduate School of Medical and Dental Sciences, Kagoshima University, 8-35-1 Sakuragaoka, Kagoshima, 890-8520, Japan. setoro@m2.kufm.kagoshima-u.ac.jp.
authors.forename: Takao
authors.initials: T
authors.lastname: Setoguchi
authors.affiliation: Department of Orthopaedic Surgery, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan.
authors.forename: Hirotaka
authors.initials: H
authors.lastname: Kawakami
authors.affiliation: Department of Medical Joint Materials, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan.
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Ishidou
authors.affiliation: Kagoshima University Hospital, Infection Control Team, Kagoshima, Japan.
authors.forename: Hideki
authors.initials: H
authors.lastname: Kawamura
authors.affiliation: Department of Microbiology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan.
authors.forename: Junichiro
authors.initials: J
authors.lastname: Nishi
authors.affiliation: Department of Molecular and Cellular Pathology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan.
authors.forename: Takako
authors.initials: T
authors.lastname: Yoshioka
authors.affiliation: Department of Orthopaedic Surgery, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan.
authors.forename: Hironori
authors.initials: H
authors.lastname: Kakoi
authors.affiliation: Department of Orthopaedic Surgery, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Nagano
authors.affiliation: Department of Orthopaedic Surgery, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Yokouchi
authors.affiliation: Department of Molecular and Cellular Pathology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan.
authors.forename: Akihide
authors.initials: A
authors.lastname: Tanimoto
authors.affiliation: Department of Orthopaedic Surgery, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan.
authors.forename: Setsuro
authors.initials: S
authors.lastname: Komiya
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects*; D005260:Female; D062785:Hemiarthroplasty / Q000009:adverse effects*; D006622:Hip Prosthesis / Q000009:adverse effects; D006801:Humans; D008297:Male; D008875:Middle Aged; D011475:Prosthesis Failure / Q000009:adverse effects* / Q000209:etiology*; D016459:Prosthesis-Related Infections / Q000150:complications* / Q000175:diagnosis*; D012189:Retrospective Studies