Incidence and Time Course of Thromboembolic Outcomes Following Total Hip or Knee Arthroplasty

TLDR

Incidence and timing of thromboembolic events after hip or knee arthroplasty, especially post‑discharge, remain poorly characterized. This study used California hospital discharge data to identify deep vein thrombosis or pulmonary embolism within three months of unilateral hip or knee arthroplasty. The study combined a surgeon survey on thromboprophylaxis practices with chart audits of 19,586 hip and 24,059 knee arthroplasties to estimate incidence and coding accuracy. Among 43,645 arthroplasties, 2.8% of hips and 2.1% of knees developed deep vein thrombosis or pulmonary embolism within three months, most diagnoses occurring after discharge (76% of hips, 47% of knees) with median times of 17 and 7 days, and the data suggest earlier, more intense prophylaxis for knees and prolonged prophylaxis for hips may further reduce events.

Abstract

Little is known about the incidence and time course of clinical thromboembolic events after total hip or knee arthroplasty, particularly after hospital discharge.We used a linked hospital discharge database provided by the State of California to identify cases diagnosed as having deep vein thrombosis or pulmonary embolism within 3 months of unilateral total hip or knee arthroplasty. Also, we surveyed orthopedic surgeons to estimate the frequency of postoperative thromboprophylaxis during July 1991 through June 1993. Medical charts were audited to determine the accuracy of the coded records.Among 19,586 primary hip and 24,059 primary knee arthroplasties, the cumulative incidence of deep vein thrombosis or pulmonary embolism within 3 months of surgery was 556 (2.8%) after hip arthroplasty and 508 (2.1%) after knee arthroplasty. The diagnosis of thromboembolism was made after hospital discharge in 76% and 47% of the total hip and total knee arthroplasty cases, respectively (P<.001), with a median time of diagnosis of 17 days and 7 days after surgery, respectively (P<.001). Questionnaire results indicated that 95% of all cases received thromboprophylaxis and that the frequency, type, and duration of thromboprophylaxis was virtually identical after hip and knee arthroplasty.There is a difference in the temporal patterns of clinically symptomatic thromboembolic complications after total hip and total knee arthroplasty, suggesting differences in pathogenesis or natural history. The findings suggest that to further reduce thromboembolic outcomes, earlier, more intense prophylaxis may be needed for total knee arthroplasty, and more prolonged prophylaxis may be required after total hip arthroplasty.