Current guidelines for DVT prophylaxis in joint arthroscopy appear adequate

Review of more than 20,000 knee arthroscopies suggests maintaining American College of Chest Physician guidelines.

LAS VEGAS – Early mobilization of patients who have undergone knee arthroscopy and who are not at risk for developing venous thromboembolism is a reasonable recommendation, one physician said here.

“Consensus standards with recommendations for thromboembolism prophylaxis have been developed for total joint arthroplasties, but no standards have been set for other orthopedic procedures,” Gregory B. Maletis, MD, said during the American Academy of Orthopaedic Surgeons 76th Annual Meeting.

: “As regulatory agencies take a more active role in dictating practice guidelines, it is important that these regulations [be] based on scientific data.”; — Gregory B. Maletis, MD

The Surgeon General has estimated that deep vein thrombosis (DVT) or pulmonary embolism (PE) will develop in 350,000 to 600,000 Americans this year.

“As regulatory agencies take a more active role in dictating practice guidelines, it is important that these regulations [be] based on scientific data,” Maletis said.

Citing current literature as being inconclusive regarding the overall benefit of thromboprophylaxis after knee arthroscopy, Maletis said that many of the DVTs identified in prospective studies may be clinically insignificant.

“Because the literature has been inconclusive, the American College of Chest Physicians, in their most recent publication, has not recommended prophylactic treatment but only early mobilization unless a patient has thromboembolic risk factors,” he said.

Previous study

In a previously published prospective randomized trial, Camporese and colleagues compared compression stockings with low-molecular-weight heparin (LMWH) to prevent thrombosis in patients undergoing knee arthroscopy.

They found a DVT rate of 4.4% in the compression stocking group, compared with a 1.5% rate in the LMWH group.

“When the results are limited to only proximal DVTs, though, the rate drops to 1.2% and 0.3%, respectively,” Maletis said.

There was no difference in PE incidence, but bleeding was more common in the LMWH group, he added.

“Based on their results, they recommended prophylaxis for all patients undergoing knee arthroscopy,” Maletis said.

Retrospective review

Maletis and colleagues conducted a retrospective chart review of all knee arthroscopies performed within Kaiser Permanente, a large prepaid health maintenance organization, over a 27-month period.

The group identified 21,794 procedures coded for knee arthroscopy, which included débridement, meniscus repair, cruciate reconstruction and synovectomy. Patients were excluded from the study if they had a previous history of DVT or PE or if they received any anticoagulation medicine within 2 weeks before or the day of surgery.

Electronic medical records were used to identify patients with DVT or PE, and those who died within 90 days of surgery. DVTs were confirmed by duplex ultrasound, and PEs were confirmed by either CT or pulmonary ventilation/perfusion scan. Charts were screened for any patient who had an ultrasound or was started on anticoagulation medicine within 90 days of surgery to ensure that no DVT or PE diagnoses were missed.

: “The risk of venous thromboembolism and fatal PE after knee arthroscopy is low.”�; — Gregory B. Maletis, MD

Ultimately, 21,401 knee arthroscopy patients were identified with no history of DVT or PE. Of these, 451 patients (2.1%) left the health plan within 90 days, leaving 20,950 patients in the study group. There were more men than women in the review, and average age was 44 years.

DVT developed in 52 patients (0.25%). Of these, 0.2% had proximal DVTs. Thirty-five patients (0.17%) had PE, making the overall combined incidence of venous thromboembolism 0.42%.

Patients older than 50 years of age had a higher incidence of venous thromboembolism, 0.51% vs. 0.33%, but no differences were noted based on gender or procedure code.

Eighteen patients died within 90 days of surgery; mean age of these patients was 66 years, significantly older than the mean age of the overall cohort. Of those who died, 11 had arthroscopic surgery for a diagnosis of septic arthritis, and all had multiple comorbidities.

There was one autopsy-proven fatal PE in a patient who underwent arthroscopy with subsequent open osteochondral allografting. The records for all patients who died were reviewed, and cause of death could not be determined in four patients.

“Therefore, the incidence of fatal PE may be as low as 0.005% or, if all those patients had fatal PE, as high as 0.024%,” Maletis said.

Strengths, weaknesses

Even though the study was limited in some respects, it also had a strong base for recommendation, Maletis said.

The study was limited by its retrospective nature and by its reliance on the accuracy of coding in the administrative database. Asymptomatic DVTs and PEs were not identified nor were secondary procedures that may have been performed at the same time as the arthroscopy. Also, factors that could affect development of DVT, such as time of surgery, tourniquet use, over-the-counter medication and smoking history, were not identified in the database.

Conversely, the large study population and the use of clinically relevant outcomes of symptomatic DVT, PE and death strengthen the study.

With multiple surgeons and a diverse and large patient population, the results of this study should be reflective of the general population, Maletis said.

“The risk of venous thromboembolism and fatal PE after knee arthroscopy is low and the recommendation of early mobilization in patients [who] do not have risk factors for venous thromboembolism, ... put forth by the American College of Chest Physicians, appear to be reasonable,” Maletis concluded.

For more information:

Gregory B. Maletis, MD, can be reached at Kaiser Baldwin Park, Department of Orthopedic Surgery, 1011 Baldwin Park Blvd, Baldwin Park, CA 91706; 626-851-5265; e-mail: Gregory.b.maletis@kp.org. He has no direct financial interest in any products or companies mentioned in this article.

References:

Camporese G, Bernardi E, Prandoni P, et al. Low-molecular-weight heparin versus compression stockings for thromboprophylaxis after knee arthroscopy. Ann Intern Med. 2008;149:73-82.
Maletis GB, Reynolds S, Inacio MCS. Incidence of thromboembolism after knee arthroscopy. Paper #340. Presented at the American Academy of Orthopaedic Surgeons 76th Annual Meeting. Feb. 25-28, 2009. Las Vegas.