To evaluate the preventive effect of deep vein thrombosis (DVT) by low molecular weight heparin (LMWH) after hip arthroplasty.

We analyzed 98 consecutive patients (107 cases) who were older than forty years of age and were scheduled to have elective primary or revision hip arthroplasty from August 1996 to March 1998. All of them received prophylactic LMWH, Nadroparin calcium (Fraxi-parine, Sanofi France). The effectiveness and safety of LMWH were evaluated in a prospective randomized trial. LMWH was injected subcutaneously once daily, from twelve hours before the operation to the tenth postoperative day with fixed dosage according to patient s body weight. For the detection of DVT after hip arthroplasty, patients were evaluated with color doppler image (CDI) preoperatively, postoperatively 7-10 days and six weeks consecutively.

DVT was detected in six patients (5.61%) and no symptomatic pulmonary embolism occurred. Asymptomatic isolated calf vein thrombosis was identified in four patients, they had no therapeutic treatment for the thrombosis but the thrombi were resolved spontaneously without any proximal propagation. Proximal vein DVT was identified in two patients and the thrombi were resolved within 6 weeks with additional treatment using Nadroparin calciurn administration. In three cases, late developing thrombi was detected at follow-up CDI carried out at the sixth postoperative week. There were three cases of bleeding complications.

Compared to our previous report of the incidence of DVT using low molecular weight dextran (12.2%) and warfarin (16.6%) with the incidence of DVT using low molecular weight heparin (5.61%), we considered that prophylaxis with LMWH is more effective in preventing DVT after hip arthroplasty. We also found that asymptomatic isolated calf vein thrombosis is resolved spontaneously. For the detection of late developing thrombosis, we recommend consecutive follow-up CDI.