LMWH vs Aspirin for VTE Prophylaxis in Orthopaedic Oncology

Lower extremity orthopaedic surgery and malignancy are both known major risk factors for

venous thromboembolism (VTE). Guidelines from high quality data exist with regards to VTE

prophylaxis in patients undergoing orthopaedic surgery, particularly joint arthroplasty.

Far fewer data are available regarding the efficacy of various methods of pharmacologic

VTE prophylaxis in patients undergoing surgery for primary or metastatic musculoskeletal

malignancies as malignancy itself is known to confer a hypercoagulable state. The

existing data, including published data from our institution, are almost exclusively from

retrospective studies. Given the limited external validity of existing guidelines and

limitations inherent in applying data from retrospective studies, a randomized,

prospective study comparing two of the most common methods of pharmacologic VTE

prophylaxis would help to guide clinical care of this patient population. In addition,

large dead spaces susceptible to hematoma formation are often created from tumor

resections in orthopaedic oncology. Our retrospective data suggest that hematoma

formation may be an independent predictor of infection. An important risk of chemical VTE

prophylaxis is an increased incidence of bleeding into these dead spaces, leading to

hematomas. This illustrates the complexity of selecting a method of VTE prophylaxis in

patients at both high risk of VTE and hematoma formation and the need for high quality

data to guide clinical decision-making in this patient population.

The specific aim of this study is to compare the post operative incidence of symptomatic

deep vein thrombosis (DVT) and pulmonary embolus (PE) between patients who receive low

molecular weight heparin (LMWH) versus aspirin for prophylaxis after having undergone

pelvic or lower extremity orthopaedic oncology surgery (primary bone sarcomas, soft

tissue sarcomas, and metastatic osseous disease).

Our secondary aim is to compare the incidence of hematoma formation and wound

complications between these methods of pharmacologic prophylaxis in the aforementioned

patient population.

Our hypothesis is that there is no significant difference in the incidence rate of

symptomatic DVT/PE in patients administered LMWH versus aspirin for prophylaxis; however

there may exist a difference in the rate of wound complications between these prophylaxis

methods.