Each year more than 800,000 Americans undergo hip or knee replacement surgery. Last week the American Academy of Orthopedic Surgeons (AAOS) Board of Directs released an updated clinical practice guideline with recommendation strategies for the reduction of potential blood clot formation following hip or knee replacement surgery. Suggestions include using preventive treatments and advice against routinely screening patients after surgery using ultrasound imaging.

According to Joshua Jacobs, MD, Academy second vice president, an orthopedic surgeon at Rush University Medical Center in Chicago, who was chairman of the workgroup that developed the guideline:

"Hip and knee arthroplasty (joint replacement surgery) is among the most successful of procedures in terms of restoring function and minimizing pain. However, one possible complication that orthopedic surgeons are concerned about is venous thromboembolic disease."

Thromboembolic disease incorporates two conditions. The first is deep vein thrombosis (DVT), a formation of a blood clot (thrombus) in a deep vein, for example in the thigh or calf. The second being a pulmonary embolism (PE), a fairly common event in which particles of a thrombus break lose and progress into the lung via the bloodstream where they obstruct the bloodstream blocking the lungs main artery or one of its branches. In very rare cases, PE can be fatal.

There are generally no warning signs for a PE, although possible symptoms include shortness of breath, chest pain, light-headedness or chest congestion. Likewise, many DVT patients also show no symptoms, however, in some patients swollen legs and pain necessitate further treatment or rehospitalization. The goal of the orthopedic surgeon is to prevent the occurrence of PE and DVT as best as possible following total hip and knee replacement.

The guidelines state that image detection revealed that approximately 37% of patients develop DVT if not administered with a prophylaxis.

Most of those patients will remain asymptomatic and will require no further treatment. According to recent studies in Denmark only 0.7 % of hip replacement patients and 0.9% of knee replacement patients needed to be hospitalized due to DVT in the first three months following their surgery.

Jacobs commented:

"After looking at all available scientific research evidence, in a rigorous fashion to minimize bias, we made recommendations that can help guide practitioners in the safest and most effective ways to prevent this potentially serious complication."

For the prevention of DVT, experts assessed the safety and efficacy of mechanical compression devices and drug therapies designed to improve the leg's blood flow after surgery. Drug therapy consists of anticoagulants (blood thinners) as well as aspirin, which prevent formation of blood clots by acting on platelets.

The work group also highlighted recommendations for future research on areas without sufficient supporting evidence that became apparent during their comprehensive and systematic review of the medical literature. Further research is considered as a vital necessity to optimize the safest and most efficient strategies for the prevention of venous thromboembolic disease.

After reviewing all evidence, the workgroup established the following recommendations for physicians treating patients prior to their hip or knee replacement:
  • Due to the increased risk of blood loss during surgery, antiplatelet (anticoagulant) drugs, such as, aspirin and clopidogrel (Plavix) should be discontinued prior to surgery. Advice on stopping any medication prior to surgery should be carried out under the guidance of the patient's physician.
  • Patients with previous DVTs or PEs are at additional risk for thromboembolic disease and it is therefore vital that the surgeon is made aware of any previous events. There is no sufficient evidence to recommend for or against routinely assessing patients for other possible risk factors.
  • Patients may require or opt for surgery under local anesthesia, such as epidural or spinal instead of having a general anesthesia and even though evidence suggests that local anesthesia does not affect the occurrence of DVT or PE, it does limit blood loss.
The workgroup also established the following aftercare recommendations after hip or knee replacement surgery:
  • Joint-replacement patients should not have routine postoperative screening for thromboembolic disease with duplex ultrasonography, which shows the blood's movement through arteries and veins. Ultrasound tests do not significantly reduce the rate of symptomatic DVT or PE or the rate of fatal PE.
  • Patients should receive anticoagulant therapy and/or mechanical compression devices after a hip or knee replacement surgery unless medical reasons, such as a bleeding disorder or active liver disease prevents them from using these drugs. There is no sufficient evidence to particularly recommend one preventive strategy or the duration of these treatments over the other. Duration and type of preventive treatment should be discussed with the patient's physician.
  • Joint-replacement patients should get up and be mobile as soon as safely possible after surgery. Even though there is insufficient evidence that "early mobilization" reduces DVT rates, early mobilization is low cost, carries minimal risk and is consistent with current practice.
Written by Petra Rattue