Venous thromboembolism is a serious complication of total hip or knee arthroplasty. Deep vein thrombosis (DVT) occurs in 50% to 80% of patients who do not receive some form of prophylaxis. Prevention of this complication has developed in two directions: mechanical and pharmacological. Mechanical intervention, primarily the use of compression devices, has been proven to be an effective adjunctive treatment, but not a successful preventative therapy by itself. Pharmacological interventions have included heparin, dextran, adjusted-dose heparin, warfarin, low-molecular-weight heparin (LMWH), and aspirin. Recent prospective studies, however, have demonstrated only adjusted-dose warfarin, adjusted-dose heparin, and LMWH to be effective in preventing DVT. Unfortunately, adjusted-dose heparin has proven difficult to control. Thus, prevention of DVT has been limited to the use of warfarin or LMWH. The focus of this Symposium was the use of LMWH in the prevention of DVT following total hip and knee arthroplasty.
Because DVT is activated during surgery, effective prophylaxis should be operative early in the post-surgery period. Until recently, it was felt that prophylaxis could be discontinued at the time the patient was discharged from the hospital; however, with the implementation of shorter hospital stays it has become apparent that the period during which the patient is at increased risk for DVT extends into the post- discharge period. Thus, it would appear that successful prevention necessitates early intervention and continuation until the patient is independently ambulating.
Randomized, prospective studies have demonstrated enoxaparin to be clinically superior to warfarin during the postoperative period and more cost effective during the post-hospitalization period. Enoxaparin affords rapid protection, requires only limited monitoring, and bleeding complications with the 30 mg b.i.d. dose are no different from those experienced with warfarin. Two of the studies reported in this Symposium demonstrate the effectiveness of enoxaparin prophylaxis in the post-hospitalization period.
Much of the data presented in this Symposium emphasize the need for a large database on the prevention and treatment of venous thromboembolism and other serious complications of total hip or knee arthroplasty. Such a database will provide physicians with information required to make the critical treatment choices. Rhône-Poulenc Rorer, Collegeville, Pennsylvania, has provided a grant to assist the development of a total joint registry in North America. The total hip and knee registry is an outcome instrument that includes the SF36, a quality-of-life questionnaire, the WOMAC, a surgeon assessment form, and a standard form for documenting complications. To date, 700 surgeons have included their patients in the hip and knee registry, and approximately 3000 patients have been registered.
DVT and its ultimate complication, pulmonary embolism, are preventable complications that require active intervention by both the physician and surgeon.