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Saturday, March 18, 2000

Study finds MRV is reliable as a diagnostic technique

A study to determine the incidence of early proximal venous thrombosis following primary total hip arthroplasty found that magnetic resonance venogram (MRV) is a reliable diagnostic technique.

Ultrasound and venogram are of limited efficacy in detecting clots near or proximal to the inguinal ligament, said William B. Macaulay, MD, assistant professor of orthopaedic surgery, New York Presbyterian Hospital at Columbia University, presenter of poster exhibit 74.

Forty-two patients (21 male and 21 female; mean age, 72.4 years) underwent a complete MRV on post-op day 3-5. The patients ranged from low to high risk (ASA average = 2.21). Patients with a contra-indication to magnetic resonance imaging or who had had post-op warfarin prophylaxis recommended were excluded. Aspirin (325 mg bid) with or without pneumatic compression was used for thrombo-prophylaxis postoperatively.

Twelve of 42 (29 percent) of patients had an MRV-detected proximal clot on day 3-5. The non-occlusive clots averaged 2.4 cm in size and were located in the following veins: (11 ipsilateral and one contralateral); external iliac (nine patients), superficial femoral (one patient), profunda femoris (one patient) and the internal iliac (one patient). None were symptomatic. Analysis of variance revealed no association between risk for proximal DVT with age, pre-operative morbidity, estimated blood loss, operative time, drain output or use of intermittent pneumatic compression.

According to the study early proximal non-occlusive venous thrombosis occurred in 28 percent of patients in The Hospital for Special Surgery after primary total hip arthroplasty.

"Many of these clots would be missed by routine screening methods," said the study authors. "Their cause is probably related to the twisting of the proximal veins which occurs during femoral preparation. The extent and duration of this twisting should be kept to a minimum.

"MRV is a reliable technique for the diagnosis of bilateral proximal clots in patients in whom the diagnosis is entertained but routine screening methods have been negative. The main drawbacks of the technique remain its high cost and limited availability."

Other authors of the study are Hollis Potter, MD, chief, Magnetic Resonance Imaging section, Hospital for Special Surgery, associate professor of radiology, Weill Medical College of Cornell University; Geoffrey Westrich, MD, assistant attending orthopaedic surgeon, Hospital for Special Surgery, associate professor, Weill Medical College of Cor-nell University; Khaled Saleh, MD, assistant professor, department of orthopaedic surgery, School of Public Health, University of Minnesota Medical College; Thomas P. Sculco, MD, chief, surgical arthritis section, a nd director of orthopaedic surgery, Hospital for Special Surgery, professor of orthopaedic surgery, Weill Medical College of Cornell University; Kevin Palmer, MS, re-search assistant; and Eduardo Salvati, MD, attending orthopaedic surgeon, Hospital for Special Surgery, professor of clinical surgery, Weill Medical College of Cornell University.

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2000 Academy News March 18 Index B

Last modified 18/March/2000 by IS