Background: There are limited population-based data on the
utilization and outcomes of total knee replacement. The aim of the present
study was to describe the rates of primary and revision total knee replacement
and selected outcomes in persons older than sixty-five years of age in the
Methods: Using Medicare claims, we computed annual incidence rates
of unilateral elective primary and revision total knee replacement among
United States Medicare beneficiaries in the year 2000. Poisson regression was
used to assess the relationships between demographic characteristics and the
incidence rates of primary and revision knee replacement. Proportional hazards
models were used to examine the relationships between the ninety-day rates of
complications and demographic and clinical factors.
Results: The rate of primary knee replacement was lower in blacks
than in whites and in those qualifying for Medicaid supplementation than in
those with higher incomes. The complications observed during the ninety days
following primary knee replacement included mortality (0.7%), readmission
(0.9%), pulmonary embolus (0.8%), wound infection (0.4%), pneumonia (1.4%),
and myocardial infarction (0.8%). The complications observed during the ninety
days following revision knee replacement were mortality (1.1%), readmission
(4.7%), pulmonary embolus (0.5%), wound infection (1.8%), pneumonia (1.4%),
and myocardial infarction (1.0%). Blacks had higher rates of mortality,
readmission, and wound infection after primary knee replacement than whites
did. Patients who qualified for Medicaid supplementation had higher
complication rates, particularly after primary knee replacement.
Conclusions: Overall, the rates of postoperative complications
during the ninety days following total knee replacement are low. In the United
States, blacks and individuals with low income undergo total knee replacement
less frequently and generally have higher rates of adverse outcomes following
primary knee replacement.
Level of Evidence: Prognostic Level II. See Instructions
to Authors for a complete description of levels of evidence.