Individuals who undergo major orthopedic surgery such as total hip and total knee arthroplasties, are at risk of developing blood clots in the operated leg for at least 3-months after the surgery. Factors related to the surgery that may contribute to the development of blood clots include injury to leg veins during surgery, inflammation in the surgery site, and immobility after the surgery resulting in blood pooling in the veins. Acquired factors such as age, chronic kidney disease, and heavy smoking may also contribute. Blood clots occur in approximately 1-2% of orthopedic surgery patients who do not have a blood clotting disorder.
Blood Clotting Disorders
Approximately 5-8% of people in the United States have an inherited medical condition called thrombophilia. Thrombophilia is a blood disorder that increases an individual’s baseline risk of developing blood clots. This is of particular concern for individuals with thrombophilia who undergo orthopedic surgery because surgery can increase the risk of developing blood clots even more. Types of inherited thrombophilia include:
- Factor V Leiden thrombophilia (the most common type).
- Prothrombin thrombophilia (second most common type).
- Hereditary antithrombin deficiency.
- Protein C deficiency.
- Protein S deficiency.
Thrombophilia may also be acquired as a result of damage to the liver or the kidneys. These two organs help control how blood clots. The damage may result from an illness like cancer, a physical injury, or exposure to toxic chemicals. The most commonly acquired thrombophilia is called antiphospholipid syndrome.
Thrombophilia and Orthopedic Surgery
Medical researchers in the Netherlands reviewed the medical records of thousands of patients to determine how frequently blood clots developed after various orthopedic surgeries in both patients with and without thrombophilia. The researchers found that:
- Patients with thrombophilia had a 4x greater risk of developing blood clots than normal patients, even before surgery.
- Orthopedic surgery created a 6x greater risk of developing blood clots in normal patients.
- Orthopedic surgery created a 13x greater risk of developing blood clots in patients with thrombophilia than patients without thrombophilia and who did not have surgery.
Overall, patients with thrombophilia had a 3.5% risk of developing blood clots for at least one year after the operation, compared to a 1-2% risk in individuals without thrombophilia. The greatest risk of blood clots was in the first three months after surgery. Interestingly, knee surgeries had the greatest risk of developing blood clots in patients with thrombophilia. It’s not known for sure why thrombophilia increases the risk of blood clots after orthopedic surgery. It has been proposed that postoperative inflammation at the surgical site stimulates blood cells known as platelets, which help form clots, to clump together more easily. Surgery in individuals with thrombophilia may also disrupt the balance between mechanisms in the bloodstream that cause clots to form, and to dissolve, causing a shift toward forming blood clots.
Current strategies to prevent blood clots in individuals both with and without thrombophilia undergoing orthopedic surgery include blood thinning drugs, highly efficient and minimally invasive surgical techniques, reduced operation time, and early post-operative mobilization. However, individuals with thrombophilia are at a higher than normal risk of developing blood clots. Thrombophilia is a serious and complex medical condition that can complicate recovery from surgery. Individuals with thrombophilia who will be having orthopedic surgery may greatly benefit from a consultation with a Vascular Medicine specialist to develop personalized, pre- and post-surgical strategies for preventing blood clots.