We prospectively followed and reviewed the medical records of all 184 patients (148 women, 36 men) who underwent elective hip surgeries between August 2007 and January 2009 at two of our affiliated hospitals. The patients mean age at the time of surgery was 59 years (range, 23–84 years), and their mean body mass index (BMI) was 23 (range, 15–32). Preoperative diagnoses were osteoarthritis in 158 patients, osteonecrosis of the femoral head in 13, loosening of implants in 12, and rheumatoid arthritis in one. Primary THA was performed in 166 patients, revision hip arthroplasty in 12, and hip osteotomy in six. In primary THA, all cups were uncemented. Cementless stems were used in 102 patients, cemented stems in 40, and cemented femoral head resurfacing was performed in the remaining 24 patients. Simultaneous bilateral THAs were performed in seven patients. For revision THA, cementless stems were used in three patients, cemented stems were used in four, and only cups were revised in the remaining five patients. Three patients had a modified Chiari (dome) pelvic osteotomy whereas three had rotational acetabular osteotomy. The minimum followup was 6 months (mean, 15.2 months; range, 6.3–24.5 months). No patients were lost to followup. We had prior approval of this study by the institutional review board committees at both hospitals.
The day before surgery, we obtained blood analysis (platelet count) and coagulation assays (% prothrombin time [PT], international normalized ratio of prothrombin time [PT-INR], activated partial thromboplastin time [APTT], and fibrinogen levels). General anesthesia combined with epidural anesthesia was used in all patients. NSAIDs were given for postoperative pain control according to the complaints of patients. One hundred seventy-nine of these patients had no pharmacologic thromboprophylaxis, but five had therapeutic pharmacologic thromboprophylaxis because they were receiving agents before surgery for various reasons. Five patients taking aspirin (n = 2) or warfarin (n = 3) before surgery stopped administration 1 week before surgery and resumed it 5 to 7 days after surgery. The postoperative duplex ultrasonographic examination for DVT was performed on Postoperative Day 3 for all patients. Thus, the incidence of DVT on Postoperative Day 3 was not influenced by these drugs, and these patients were not excluded from the study.
For mechanical prophylaxis against DVT and PE, all patients were treated with bilateral elastic bandages during surgery. Postoperatively, an A-V Impulse System™ foot pump (Orthofix Vascular Novamedix, Andover, UK) was used on both feet for all patients except those with preoperative DVT. The slippers were fitted to both feet in the recovery room, and the machine was activated. The pneumatic compression cycle was set at 20 seconds with a pressure of 110 mm Hg applied for 1 minute.
Most of the patients took loxoprofen orally, 60 mg, three times a day for 3 to 5 days postoperatively, which we suspect could not have influenced the incidence of DVT or PE. Moreover, from the medical records, we found no patients took any kind of drugs that might have influenced the incidence of DVT or PE such as naproxen, raloxifene, or strontium ranelate.
The IPC device was used continuously for 1 to 2 days until the patient started to walk using aids. We advised patients to perform active ankle dorsiplantar flexion in bed for 2 weeks. On Postoperative Day 1, all patients who underwent primary THA or revision THA without structural bone grafting were allowed to walk with full weightbearing as tolerated. Physical therapists checked walking ability and advised each patient to use a walker, crutches, or a cane as appropriate. They also assisted in ROM and muscle strengthening exercises. Most patients could walk without a cane in 1 to 3 weeks and returned to their usual daily activities at 1 month. Patients who underwent THA with structural bone grafting or revision THA with structural bone grafting or osteotomy, were allowed to stand without weightbearing on the operated limb and used a wheelchair on Postoperative Days 1 and 2. On Postoperative Day 3, physical therapists assisted the patients with walking using a walker or crutches without weightbearing, and with ROM and muscle strengthening excises. At 1 month, patients were allowed partial weightbearing using crutches; full weightbearing was allowed at 3 months. These patients returned to their usual activities at 3 to 4 months.
To identify the presence of DVT, all patients underwent preoperative and postoperative routine duplex ultrasonography of both limbs. The preoperative examinations occurred 1 to 2 days before surgery, and the postoperative examinations were done on Postoperative Days 3 and 21. Color flow duplex scanners (Xario™ XG SSA-680A; Toshiba Medical Systems, Tochigi, Japan; or LOGIQ™ 7; GE Healthcare Japan, Tokyo, Japan) with 3.5-MHz convex and 7.5-MHz linear transducers were used. Real-time imaging information was obtained from the external iliac vein through the distal portion of the calf veins. Diagnostic criteria for DVT were observation of an intraluminal thrombus in a vein, loss of compressibility, and lack of flow. Patients who had postoperative DVT develop only in a calf vein distal to the popliteal vein were followed without thrombolytic therapy. If patients had DVT in a vein proximal to the popliteal vein, cardiovascular physicians were consulted. All patients who had postoperative DVT underwent additional duplex ultrasonography at 3-month intervals. Any readmission for DVT, PE, or thromboembolic complications was recorded.
All data were stored in a computer file and statistical analysis was performed using StatView™-J 5.0 software (Hulinks Inc, Tokyo, Japan). We determined differences in age, BMI, platelet count, %PT, PT-INR, APTT, fibrinogen level, duration of the operation, and volume of intraoperative blood loss between patients with and without development of DVT using the nonparametric method (Mann-Whitney U test).