PREVENTion of Clot in Orthopaedic Trauma

Inclusion Criteria: * Patients who have a planned operative or non-operative pelvis or acetabular fracture, or any operative extremity fracture proximal to the metatarsals or carpals. * Patients at increased risk of blood clot(s) from their orthopaedic injury(ies) and will receive prophylactic blood thinner regimen per standard of care. * Patients 18 years or older. Exclusion Criteria: * Patients who present to the hospital more than 48 hours post injury * Patients who received more than 2 doses of LMWH or aspirin for initial VTE prophylaxis * Patients on long term blood thinners (other than low-dose aspirin or platelet inhibitors such as Plavix or Aggrenox) * Patients who have had a VTE within the last 6 months * Patients on therapeutic (as opposed to prophylactic) blood thinners for an acute issue at the time of admission * Patients who have a newly diagnosed indication for therapeutic blood thinners (for example vascular injury) that will require therapeutic anticoagulation for more than one week * Patients who cannot receive either of the study medications due to an allergy (history of heparin induced thrombocytopenia, allergy to aspirin, or NSAIDs) or other medical contraindication to blood thinners * Patients who are on higher dose aspirin (\>81 mg once a day or higher) for medical reasons or who will be treated with higher dose aspirin * Patients with underlying chronic clotting disorders (i.e. Factor V Leiden, hyperhomocysteinemia, Protein C and S deficiency) that require full dose anticoagulation or are a contraindication to venous thromboembolism chemoprophylaxis * Patients with end stage renal disease or impaired creatinine clearance \<30 ml/min at time of randomization(note: creatinine clearance does not need to be documented if prescribing physician would order medication without test as SOC) * Pregnant or lactating patients * Prisoners * Patients who do not speak either English or Spanish * Patients who are likely to have severe problems maintaining follow-up * Patients, based upon the clinical judgment of the treating clinician, NOT equally suited for treatment with either aspirin or low-molecular-weight heparin * Patients may be excluded for other reasons at the discretion of the treating physician; the reason for exclusion must be documented on the screening form * Patients who have a known COVID-19 diagnosis prior to fracture treatment or within 3 months of the index fracture