The Occurrence of Pulmonary Embolism after Total Knee Arthroplasty

    Pulmonary embolism (PE) is a rare but potentially devastating complication of total knee arthroplasty (TKA).

    At the ICJR East meeting in New York, Nicholas B. Schraut, MD, from the University of Illinois at Chicago, and his colleagues presented their study of national trends in PE occurrence after TKA, including patient outcomes. Their poster was recognized as one of five winners of the ICJR East Abstract Awards, supported by an educational grant from Zimmer, Inc.

    Dr. Schraut and his colleagues used the National Hospital Discharge Survey (NHDS) to identify patients who had been admitted to United States hospitals after primary TKA. “We wanted to assess the efficacy of our nationwide effort to decrease PE after TKA,” said Dr. Schraut. “The NHDS offers a unique view of this issue because it includes data from hospitals in all of the states.”

    Of the 35,220 patients identified, 159 had developed an acute PE during the same admission. The mean age of patients with PE was 67.7 years (54 men and 105 women). The non-PE group had a mean patient age that was insignificantly lower at 66.6 years (p=0.21) and included 12,450 men and 22,611 women. Gender was also not significantly different (p=0.68) between PE groups.

    The number of medical comorbidities was significantly higher in those with PE (mean 6.42 diagnoses) than those without PE (mean 4.89 diagnoses, p<0.01). Average hospitalization length also varied based on PE status, with significantly longer stays for those with PE (8.2 days versus 3.7 days, p<0.01).

    The rate of DVT was higher in the PE group (12.7% versus 0.48%, p<0.01). Mortality was also significantly higher for the PE group (3.9% versus 0.09%, p<0.01). Discharge disposition did not significantly vary based on PE status, with 61.5% of PE patients and 64.0% of non-PE patients able to go directly home (p=0.59) after their inpatient stay.

    In this study, PE was associated with a 43-fold increase in mortality and a doubling of the inpatient length of stay. The risk of PE appeared to be greatest in patients with multiple medical comorbidities and established DVTs.

    Dr. Schraut and his colleagues also found that the PE rate varied based on hospital size, with the lowest rate seen in hospitals under 100 beds (0.23%) and the highest rate seen in those with over 500 beds (0.65%, p=0.01). No significant differences in PE incidence were noted based on U.S. region (p=0.38).

    Although PE remains a rare complication, efforts over the past 10 years to prevent or minimize it have not had a significant impact. As Dr. Schraut explained, “Even though the rate of PEs after TKA appears to be decreasing, we have not seen a statistically significant drop in the occurrence of PE.”

    Dr. Schraut noted that the data he and his colleagues examined did not include information about measures used to prevent PE. Asked what steps he takes to prevent DVT and PE in his practice, Dr. Schraut replied, “PE prevention is a part of every orthopaedic practice. First and foremost, it is our job to educate patients about the risk of PE and the preventative measures that we take. We aim to follow the guidelines of the American Academy of Orthopaedic Surgeons in our prophylaxis.”

    “PE will always be a risk after orthopaedic surgeries,” Dr. Schraut said, “and it is something that we will always have to address and inform our patients about.”