This is an observational study to analyze the influence of surgery duration and tourniquet time in the incidence of deep venous thrombosis (DVT) in patients that had undergone total knee arthroplasty (TKA).

Influence of Tourniquet Use and Surgery Duration on the Incidence of Deep Vein Thrombosis in Total Knee Arthroplasty

Tourniquet, Surgery Duration and DVT in TKA.

Abstract:

Objective: The occurrence of deep vein thrombosis (DVT) was evaluated in 78 patients submitted to total knee arthroplasty (TKA), followed by ascending venography (AV), between the seventh and twelfth days postoperative.

Methods: Patients received prophylaxis with oral anticoagulation for 12 days, maintaining INR at around 2.5.

Results: Results showed 45 cases (57.7%) of negative bilateral AV and 33 (42.3%) cases of positivity for DVT. Thirteen cases were of the proximal type DVT, making up 16.7% of the total. We compared the groups with and without DVT, and another which considered only cases with proximal DVT.

Conclusion: The statistical analysis didn't reveal significance in relation to tourniquet time, despite the higher likelihood of proximal DVT after 90 minutes (p=0.08) and surgery duration of more than 120 minutes increases its risk.

Keywords: Deep vein thrombosis. Prophylaxis. Thromboembolism. Tourniquet. Knee prosthesis.

Introduction Total knee arthroplasties (TKAs), together with total hip arthroplasties, are frequently the object of study regarding deep vein thrombosis (DVT) (1); however, DVT also commonly occurs in other knee procedures (2). Despite the importance of this problem and the interest in it, most researchers studying DVT generally focus on prophylaxis for prevention; surprisingly, there have been few studies of the isolated risk factors for DVT associated with TKA. Although there is some controversy about the role of TKA alone as a risk factor for DVT (3-7), some researchers believe that bone manipulation, reaming of the medullary canal, and the duration of the different procedures are relevant risk factors for DVT (8,9). Another important and controversial factor related to TKA is the use of surgical tourniquets. Although all these factors are mentioned in the literature, surgery duration as an isolated risk factor for DVT in TKA has received little attention.

We used ascending venography (AV) to evaluate the association between the use of tourniquets and total procedure duration and the occurrence of DVT during TKA.

Patients and Methods Seventy-eight consecutive patients from our institution underwent cemented TKA for degenerative knee disorders and then underwent AV, for which they gave informed consent, at a point between 7 and 12 days after surgery, after having been discharged from the hospital. Of the 78, 78.2% were women and 21.8% were men, with an average age of 65.1 years (range, 31-88 years; SD, 11.5 years). Osteoarthrosis was the diagnosis in 74.4%, rheumatoid arthritis in 21.8%, and other disorders in 3.8%.

All patients received prophylaxis for DVT with oral anticoagulants for 12 days, with an international normalized ratio being maintained at about 2.5 (range, 2.0-3.0) in all cases. Perioperatively, we recorded total pneumatic tourniquet time and total surgery duration, in minutes. In all cases, the use of a tourniquet was interrupted by hemostasis, after cementation of the implant and before wound closure. Five categories were established for total tourniquet time: <60, 61 to 90, 91 to 120, and >120 minutes. The total procedure duration was defined in the same way; we recorded the times of the initial incision and the last suture stitch made to close the incision. Three categories were defined for procedure duration: <120, 121 to 150, and >150 minutes. Only 2 patients (3.1%) were given a general anesthetic; all the others were given a spinal block.

The study end point was defined as the execution of bilateral AV at a point between 7 and 12 days after surgery, after hospital discharge. The AV was carried out by a specialist in vascular radiology. The technique applied was basically that described by Rabinov and Paulin (10). The presence of clinically manifested DVT and/or pulmonary embolism was also taken in to consideration. The clinical manifestations of DVT were greater edema of the lower limb than would be expected for the procedure, associated with intense pain on palpation of the calf and pain on passive dorsiflexion of the foot.

AV findings were considered positive for DVT in the presence of blood clots in the vein lumens (Figure 1). They were characterized as occurring on the operated side, contralateral or bilateral, and were diagnosed as proximal DVT (more severe) or distal DVT (less severe), depending on the contents of the radiologist's report.

Inclusion Criteria:

• patients that underwent cemented total knee arthroplasty

Exclusion Criteria:

• post-operative infection
• inadequate follow-up

Seventy-eight consecutive patients from our institution underwent cemented TKA for degenerative knee disorders and then underwent AV, for which they gave informed consent, at a point between 7 and 12 days after surgery, after having been discharged from the hospital.