Follow-Up Studies

Painful or failed knee arthroplasties are evaluated with serial conventional radiographs. Most of these cases will show radiographic abnormalities. Exceptions include:

  • Acutely infected arthroplasties where the diagnosis has been made very early by clinical exam and arthrocentesis, before radiographic abnormalities have developed
  • Subtle rotational malalignment, which are better demonstrated on CT

Painful or failed arthroplasties may be due to a variety of problems (Table 1). These include:

  • Instability
  • Polyethylene problems
  • Osteolysis
  • Loosening
  • Infection
  • Fractures
  • Patellar complications
  • Heterotopic ossification
  • Malalignment

These and other conditions frequently require revision arthroplasty. In 1999, 22,000 knee revision operations were performed in the United States.8

Table 1: Percentage of patients with failure mechanism stratified into early and late subgroups.9 (PE=Polyethylene)

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