Characterization of Pulmonary Emboli in Orthopaedic Surgery Patients Compared to General Medical Patients

Introduction: A pulmonary embolus (PE) occurs frequently in medical patients and acutely in post surgical total joint patients. While the two groups seem vastly different, there has never been an analysis of the location, number of emboli a patient has and size of the emboli in post-operative total joint arthroplasty patients compared to general medical patients. Studies have looked at the size of PEs relative to symptomatic patients; recent data have suggested the timeline of PE development is usually within the first few days after total knee arthroplasty (TKA) or total hip arthroplasty (THA). Methods: We conducted a retrospective chart review at Providence Hospital from 2006 to 2011 of all THA and TKA patients who had a post-operative PE diagnosis and looked at their medical comorbidities, sex, age, procedure, post-operative day of PE, and size/location of PE using a novel pulmonary mapping tree database based on location of the PE on spiral computed tomography (CT). The same data, except for post-operative day, was collected for the medical population with a PE diagnosis. Size was defined based on level of blockage with small emboli occurring at different points within a lobe, medium being at the level of lobe, and large being either a saddle embolus or at the right or left pulmonary artery. Inclusion criteria for orthopaedic patients included THA or TKA performed prior to PE, PE within 1 month of surgery and CT confirming diagnosis of a PE. Medical patients meeting criteria had to have an admitting diagnosis of PE with CT confirmation of the PE. Exclusion criteria included V/Q scan alone to diagnose the PE. Results: Of the 2878 TKA (2024 women, 854 men) and 1270 THA (749 women, 521 men) patients reviewed between 2006 and the first half of 2011, 51 developed a PE. Although 67% of all total joint patients were women, they comprised 92% (n = 47) of all PE patients ( P P = .001) and also had larger emboli than the total joint arthroplasty group ( P = .01). Discussion: Our study showed an overwhelmingly disproportionate amount of PEs in female orthopaedic patients, thus making them a higher risk to develop PE post-operatively. When we analyzed the distribution of the PEs, multiple small emboli were more common than solitary emboli. The clinical significance of this is unknown. Medical patients, however, had fewer and larger emboli per patient. The treatment of PEs has largely been ascribed to radiologic reports documenting the PE. We postulate a different therapy may be warranted in post-operative total joint arthroplasty patients, given the difference in the characterization of their emboli. Conclusions: Women undergoing total joint arthroplasty had a significantly higher risk of developing a PE at our institution. The size and distribution of PEs have been elaborated in this study and may suggest that orthopaedic patients may not need the same anti-thrombotic therapy as medical patients with PE. A larger scale, descriptive analysis of PE is warranted in order to begin to question the appropriate anti-thrombotic therapy for post-operative THA or TKA patients compared to medical patients.