title: Early results of revision acetabular cup using antiprotrusio reconstruction rings and allografts.
abstract: BACKGROUND
  Hip arthroplasty is one of the most frequently performed orthopedic procedures with high scores of success while its most common complication is aseptic loosening of the acetabular component, which may result from host bone loss or even from pelvis discontinuity. The purpose of the study was to evaluate results in patients after revision acetabular arthroplasty with reconstruction rings and allografts.
  
  
  METHODS
  Retrospective data was collected from 69 revisions of acetabular components, performed in a group of 69 treated patients (the mean age 65.1 years). Before surgery, the patients had bone defects of type IIb (n = 5), IIc (n = 20), IIIa (n = 27) or IIIb (n = 17), according to Paprosky et al.
  
  
  RESULTS
  The mean followup period of the patients was 7.2 years (range 3-19 years). A Kaplan-Meier analysis showed that a 3- and 10 year survival rate was 92.8% and 84.8% respectively, using further revision for any reason of the acetabular device as an end point. Eight patients revealed implant related complications. Four patients presented with ring loosening, one with a loose acetabular polyethylene cup, two hips demonstrated recurrent dislocations and one patient was with deep infection. Regarding the remaining 61 patients without re-revision surgery, the mean Harris hip score improved from 30.5 to 73.8 points.
  
  
  CONCLUSIONS
  A modified, antiprotrusion cage provides an acceptable survival rate and radiological results, but complications could still be expected. It seems that the observed massive bone loss with pelvic discontinuity and an insufficient fixation of the cage to the ischium may result in implant loosening. Stable fixation of the ischial ring flange with screws is an essential condition to expect a good outcome.
authors.affiliation: Department of Orthopedics, Clinic of Orthopedics and Pediatric Orthopedics, Medical University of Lodz, Lodz, Poland.
authors.forename: Krzysztof
authors.initials: K
authors.lastname: Kmieć
authors.affiliation: Department of Orthopedics, Clinic of Orthopedics and Pediatric Orthopedics, Medical University of Lodz, Lodz, Poland.
authors.forename: Tomasz
authors.initials: T
authors.lastname: Dorman
authors.affiliation: Department of Orthopedics, Clinic of Orthopedics and Pediatric Orthopedics, Medical University of Lodz, Lodz, Poland.
authors.forename: Grzegorzewski
authors.initials: G
authors.lastname: Andrzej
authors.affiliation: Department of Orthopedics, Clinic of Orthopedics and Pediatric Orthopedics, Medical University of Lodz, Lodz, Poland.
authors.forename: Marek
authors.initials: M
authors.lastname: Synder
authors.affiliation: Department of Orthopedics, Clinic of Orthopedics and Pediatric Orthopedics, Medical University of Lodz, Lodz, Poland.
authors.forename: Piotr
authors.initials: P
authors.lastname: Kozłowski
authors.affiliation: Department of Orthopedics, Clinic of Orthopedics and Pediatric Orthopedics, Medical University of Lodz, Lodz, Poland.
authors.forename: Marcin
authors.initials: M
authors.lastname: Sibiński
keywords: Acetabular revision; Acetabulum; allograft; arthroplasty; hip; loosening; reconstruction ring