Pa. Lotke et al., SIGNIFICANCE OF DEEP VENOUS THROMBOSIS IN THE LOWER-EXTREMITY AFTER TOTAL JOINT ARTHROPLASTY, Clinical orthopaedics and related research, (299), 1994, pp. 25-30
Thromboembolic disease continues to pose a significant risk to patient
s undergoing total joint arthroplasty, but the clinical significance o
f a deep venous thrombosis (DVT) in the postoperative period remains c
ontroversial. This report reviews the outcome of 920 patients undergoi
ng prospective obtained venograms after total hip and total knee surge
ry. Six hundred two patients also obtained postoperative ventilation p
erfusion scans (V/Q). All patients received one of the following forms
of prophylaxis: aspirin (79%), warfarin (16%), or low-molecular-weigh
t heparin (5%). The results show that 39% were without any clot, 36% h
ad small calf thrombi, 19% had large calf thrombi, 2.5% had popliteal
thrombi, and 3.8% had femoral thrombi. Calf thrombi occurred almost 2.
5 times more frequently after total knee arthroplasty than total hip a
rthroplasty (67% versus 27%), yet the incidence of pulmonary embolism
(PE) is the same in both groups. Intermediate or high probability V/Q
results occurred in 103 patients (15%). There was a positive associati
on between the size of a clot and the likelihood of an intermediate- o
r high-probability V/Q scan. Thromboembolic events resulted in five sy
mptomatic PE (0.5%) and two deaths (0.2%), one in the hospital on warf
arin, and one as an outpatient on aspirin. From these data, the author
s conclude that calf thrombi by themselves do not place a patient at r
isk and are not accurate markers of a patient being at risk. Larger cl
ots have a greater likelihood to embolize, but the size of the clot th
at is clinically significant is undetermined. A significant chance of
a PE after discharge from the hospital warrants some form of continuin
g prophylaxis in outpatients.