title: High early failure rate of the Columbus posterior stabilized high-flexion knee prosthesis.
abstract: BACKGROUND
  Most studies report high survivorship rates for TKAs, however, we observed higher than anticipated rates of dislocation and femoral component loosening after implanting a Columbus posterior stabilized prosthesis.
  
  
  OBJECTIVE
  We therefore determined (1) the incidence of dislocation and aseptic loosening that occurred after implantation of posterior stabilized high-flexion prostheses in TKAs, (2) the causative factors of dislocation and aseptic femoral component loosening when comparing two designs of prostheses, and (3) the mechanisms of dislocation.
  
  
  METHODS
  We retrospectively reviewed 319 patients who underwent 384 TKAs from May 2007 to July 2008. These patients had been assigned alternately to receive a Scorpio posterior stabilized knee prosthesis (Group I, 158 patients, 187 knees) or a Columbus posterior stabilized knee prosthesis (Group II, 161 patients, 197 knees). We followed the patients with clinical and radiographic evaluations for a minimum of 24 months (mean, 26 months; range, 24-38 months). Ten retrieved prostheses were examined visually.
  
  
  RESULTS
  Ten dislocations (5.1%; 10 of 197 knees) and seven aseptic loosenings of femoral components (3.6%; seven of 197 knees) occurred in Group II at a mean of 10.9 months postoperatively. However, no dislocation or loosening occurred in patients in Group I. Most dislocations were associated with varus flexion or flexion rotation movements during normal daily activities. The cam jump distance at 90º flexion for the Columbus prosthesis was lower than for the Scorpio prosthesis.
  
  
  CONCLUSIONS
  We observed a high rate of early failure during short-term followup after implantation of a Columbus posterior stabilized prosthesis. It appears that early failures of the Columbus design were related to a different cam-post design attributable to a low jump distance during knee flexion. We no longer recommend using this device.
  
  
  METHODS
  Level II, prognostic study. See the Guidelines for Authors for a complete description of levels of evidence.
authors: Department of Orthopaedic Surgery, Murup Hospital,  Changwon, South Korea.
authors: Woon-Hwa
authors: WH
authors: Jung
authors: Jae-Heon
authors: JH
authors: Jeong
authors: Yong-Chan
authors: YC
authors: Ha
authors: Young-Kyun
authors: YK
authors: Lee
authors: Kyung-Hoi
authors: KH
authors: Koo
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D019645:Arthroplasty, Replacement, Knee / Q000009:adverse effects / Q000295:instrumentation* / Q000379:methods; D017760:Bone Malalignment / Q000453:epidemiology / Q000209:etiology; D005260:Female; D006801:Humans; D007593:Joint Instability; D007719:Knee Joint / Q000503:physiopathology / Q000601:surgery*; D007720:Knee Prosthesis; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications; D011474:Prosthesis Design / Q000009:adverse effects*; D011475:Prosthesis Failure / Q000209:etiology*; D016059:Range of Motion, Articular; D012189:Retrospective Studies; D015996:Survival Rate; D013997:Time Factors