What factors are associated with complication rates after simultaneous total knee arthroplasty (TKA)?” asked Bryan D. Springer, MD, who presented his study, “Factors Associated with Perioperative Complication Rates after Unilateral vs. Simultaneous TKA,” at the AAOS Annual Meeting yesterday.
Dr. Springer and his colleague, Susan M. Odum, MS, drew data from the Nationwide Inpatient Sample (NIS), a national claims database, from 2004 through 2007.
What are the odds?
The potential benefits of simultaneous bilateral TKA include decreased overall length of hospitalization, shorter anesthesia time, and decreased rehabilitation time in addition to a decreased cost to both the patient and the institution. These benefits may be offset, however, by the potential increase in morbidity and mortality that is associated with simultaneous bilateral TKAs.
During the 2004–2007 period, 407,070 TKAs were performed, based on the NIS dataset—24,574 simultaneous bilateral TKAs and 382,496 unilateral TKAs. Complications were determined using ICD-9 codes, and covariates included comorbidities, demographics, payer type, and hospital type.
Patients who underwent simultaneous bilateral TKAs had significantly increased odds for all types of complications. Of the 24,574 simultaneous TKAs, minor complications (such as peripheral vascular complications, phlebitis, or nonhealing surgical wounds) were reported in 1,682 cases (6.84 percent); minor complications were reported in 4.6 percent (17,582) of the 382,496 unilateral TKAs.
The proportion of major complications such as septic pulmonary embolisms was 1.49 percent for simultaneous TKAs and 1.19 percent for unilateral TKAs. The in-hospital mortality rate was 0.2 percent for simultaneous TKAs and 0.09 percent for unilateral TKAs.
In addition, a greater number of comorbidities were associated with complication rates in simultaneous bilateral TKAs than in unilateral TKAs (odds ratio 1.84 for minor complications, 2.63 for major complications, and 3.66 for mortality).
Overall, African Americans and Native Americans had significantly higher odds of incurring minor complications than Caucasians did, and women had significantly lower odds of incurring any type of complication than men. The patients younger than 45 years of age were the most likely to incur a major in-hospital complication.
Rural and urban non-teaching hospitals had lower complication rates overall than urban teaching hospitals, even though rural hospitals were associated with increased risk of mortality.
According to Ms. Odum, the higher risk of complications in teaching hospitals could have been driven by higher risk patients, who might have been referred or sought treatment at these hospitals.
Dr. Springer cautioned that, despite the large patient population involved in the study, a lack of patient-specific data made it difficult to quantitatively determine if patients who need both knees replaced would face a lower risk of complications in a simultaneous or a staged scenario.
Disclosure information: Dr. Springer—DePuy, Stryker, Convatec Surgical. Ms. Odum reported no conflicts.