title: Revision knee arthroplasty with a rotating-hinge design in elderly patients with instability following total knee arthroplasty.
abstract: BACKGROUND
  Revision knee arthroplasty with a rotating-hinge design could be an option for the treatment of instability following total knee arthroplasty (TKA) in elderly patients.
  
  
  OBJECTIVE
  To evaluate the clinical and radiographic results of revision arthroplasties in TKAs with instability using a rotating-hinge design in elderly patients.
  
  
  METHODS
  We retrospectively reviewed 96 rotating-hinge arthroplasties. The average age of the patients was 79 years (range, 75-86 years); the minimum follow-up was 5 years (mean, 7.3 years; range, 5-10 years). Patients were evaluated clinically (Knee Society score) and radiographically (position of prosthetic components, signs of loosening, bone loss).
  
  
  RESULTS
  At a minimum followup of 5 years (mean, 7.3 years; range, 5-10 years), Knee Society pain scores improved from 37 preoperatively to 79 postoperatively, and function scores improved from 34 to 53. ROM improved on average from -15° of extension and 80° of flexion before surgery to -5° of extension and 120° of flexion at the last followup (p = 0.03). No loosening of implants was observed. Nonprogressive radiolucent lines were identified around the femoral and tibial components in 2 knees. One patient required reoperation because of a periprosthetic infection.
  
  
  CONCLUSIONS
  Revision arthroplasty with a rotating-hinge design provided substantial improvement in function and a reduction in pain in elderly patients with instability following TKA.
  
  
  METHODS
  Level IV, therapeutic study.
authors.affiliation: Department of Orthopaedic Surgery, La Paz University Hospital, Paseo de la Castellana 261, 28046 Madrid, Spain.
authors.forename: E Carlos
authors.initials: EC
authors.lastname: Rodríguez-Merchán
authors.affiliation: Department of Orthopaedic Surgery, La Paz University Hospital, Paseo de la Castellana 261, 28046 Madrid, Spain.
authors.forename: Primitivo
authors.initials: P
authors.lastname: Gómez-Cardero
authors.affiliation: Department of Orthopaedic Surgery, La Paz University Hospital, Paseo de la Castellana 261, 28046 Madrid, Spain.
authors.forename: Ángel
authors.initials: Á
authors.lastname: Martínez-Lloreda
keywords: Elderly patients; Instability; Revision arthroplasty; Rotating-hinge design; TKA