Current Concepts With DVT Prophylaxis
Pertinent Insights On Diagnosing DVT
The clinical presentation of DVT may be variable. Common clinical findings include persistent or unexplainable leg swelling. The clinical concern for DVT increases when leg swelling is unilateral. Erythema may also be a presenting sign. Homans’ sign is a physical test for the presence of DVT and is considered positive if the patient has pain in the calf with passive dorsiflexion of the foot. If a clinician suspects DVT, further diagnostic workup is indicated. When one diagnostically confirms DVT, the Homans’ sign is positive in only 8 to 56 percent of patients.3
While venography has been the historic gold standard for diagnosis of venous thrombosis, it has largely been replaced by duplex venous ultrasound for day-to-day clinical practice. Researchers have reported that venous Doppler is 89 percent sensitive and 94 percent specific for DVT.3 Laboratory testing, such as D-dimer, may be a useful part of a DVT workup. However, it is most useful as a tool to rule out DVT as it lacks specificity. In a patient with unexplained shortness of breath, fever, tachycardia or dizziness, one should expand the workup to include pulmonary embolism as well. If you suspect any form of VTE, perform an immediate workup.
What Studies Reveal About The Risk Of DVT After Foot And Ankle Surgery
While the risk of DVT following major orthopedic surgery has been well studied, there are only a few studies that address the risk of DVT following foot and ankle surgery. Complicating the decision making process is the wide variability of foot and ankle surgical procedures. The majority of studies regarding prophylaxis have examined these procedures as one group, which ranges from hammertoe arthroplasty to treatment of ankle and calcaneal fractures. The wide variation of biological insult inherent to these different procedures renders the information obtained from these studies less useful to the surgeon who is deciding whether to provide prophylaxis to the patient.
One of the most common procedures in foot surgery, the chevron osteotomy for hallux abducto valgus, has undergone specific study. In a study of 100 consecutive bunion surgery patients in Austria, researchers documented a DVT rate of 4 percent using contrast venography.5 Note that all of these DVTs were asymptomatic, were not detectable on clinical exam and none progressed to pulmonary embolism. While these patients were allowed to bear weight immediately after surgery, they were in the hospital for an average of six days. Exclusion of patients with a prior DVT or history of severe varicose veins or vein surgery probably understates the risk in this patient population.
Researchers have also specifically studied the rate of DVT in patients with Achilles tendon ruptures. In a study of 1,172 patients who sustained a complete rupture of the Achilles tendon, there was a DVT rate of 0.43 percent.6 In this same study population, the rate of pulmonary embolism was 0.34 percent. The patients in this study did not routinely receive prophylaxis.
A recent study in England examined 138,841 people who underwent foot and ankle surgery, and examined the rates of DVT for various procedures.7 The DVT rate for first metatarsal osteotomy was 0.006 percent. Hindfoot fusions demonstrated a DVT rate of 0.028 percent while ankle fractures had a rate of 0.117 percent and total ankle replacements had a DVT rate of 0 percent. The study analyzed multiple risk factors but was only able to identify increasing age and the presence of “multiple comorbidities following fracture surgery” as statistically significant risk factors. The authors do not recommend routine prophylaxis for foot and ankle surgery.