title: Long-Term Results After Total Knee Arthroplasty with Contemporary Rotating-Hinge Prostheses.
abstract: BACKGROUND
  Total knee arthroplasty (TKA) with a rotating-hinge prosthesis is considered a salvage procedure. While excellent immediate stability is achieved, the historically high failure rate has tempered its use. The goal of this study was to determine clinical outcomes, radiographic results, and survivorship after TKA with contemporary rotating-hinge components.
  
  
  METHODS
  We identified 408 consecutive TKAs performed with rotating-hinge components for nononcologic indications from 2002 to 2012 at a single academic institution. Two hundred and sixty-four knees (65%) had rotating-hinge TKA components implanted for aseptic etiologies, while 144 knees (35%) were managed with the components in 2-stage reimplantation following infection. Rotating-hinge TKA implants were used for complex primary procedures in 74 knees (18%) and as a revision construct in 334 knees (82%). Clinical outcomes were assessed with the Knee Society scoring system, survivorship analyses, and cumulative incidence of revision. The mean age of the patients at the time of the index arthroplasty was 69 years, and the mean duration of follow-up was 4 years (range, 2 to 12 years).
  
  
  RESULTS
  At the most recent follow-up, the mean Knee Society knee score had increased from 51 points preoperatively to 81 points (p < 0.0001), and the mean Knee Society functional score had increased from 26 to 36 points (p < 0.0001). At a mean of 4 years, loosening of components was observed in 13 (3.7%) of 349 knees. At the most recent follow-up, 59 revision procedures and 25 reoperations had been performed. The cumulative incidence of any revision was 9.7% at 2 years and 22.5% at 10 years. The cumulative incidence of revision for aseptic loosening was 1.7% at 2 years and 4.5% at 10 years. Metaphyseal cones were used in 114 knees (28%). Survivorship analysis revealed a trend toward a lower risk of revision (hazard ratio [HR] = 0.69; 95% confidence interval [CI] = 0.39 to 1.22; p = 0.20) and reoperation (HR = 0.51; 95% CI = 0.22 to 1.19; p = 0.12) in patients with metaphyseal cones, despite their use in the most severe of bone defects.
  
  
  CONCLUSIONS
  Contemporary rotating-hinge TKA implants had a low 10-year cumulative incidence of revision for aseptic loosening of 4.5%. Greater use of metaphyseal fixation has aided this improvement. Patients can expect substantial improvements in clinical outcomes with this revision strategy.
  
  
  METHODS
  Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.
authors.affiliation: 1Department of Orthopedic Surgery (U.C., M.P.A., K.I.P., D.G.L., and A.D.H.) and Division of Biomedical Statistics and Informatics (K.C.M.), Mayo Clinic, Rochester, Minnesota.
authors.forename: Umberto
authors.initials: U
authors.lastname: Cottino
authors.forename: Matthew P
authors.initials: MP
authors.lastname: Abdel
authors.forename: Kevin I
authors.initials: KI
authors.lastname: Perry
authors.forename: Kristin C
authors.initials: KC
authors.lastname: Mara
authors.forename: David G
authors.initials: DG
authors.lastname: Lewallen
authors.forename: Arlen D
authors.initials: AD
authors.lastname: Hanssen
mesh_terms: D000368:Aged; D019645:Arthroplasty, Replacement, Knee / Q000379:methods* / Q000706:statistics & numerical data; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D007719:Knee Joint / Q000601:surgery*; D007720:Knee Prosthesis; D008297:Male; D008875:Middle Aged; D011474:Prosthesis Design; D012086:Reoperation / Q000706:statistics & numerical data; D016896:Treatment Outcome