Clinical Study On Deep Venous Thrombosis Of Lower Limbs After Spinal Surgery

Background Deep venous thrombosis of lower limbs is a common complication after orthopaedic surgeries, the mild outcome of which is to affect the rehabilitation of patients, the severe one to endanger their lives. Clinical workers in the world have done a lot of basic and clinical research on deep venous thrombosis of lower limbs with high incidence rate after the reconstruction of hip and knee joint and its prevention, and have gotten some achievement. However, the study on deep venous thrombosis of lower limbs after spinal surgery yet has not been carried out, so the reports about it in the international are not so many, which are only limited to the statistics about the incidence rate of symptomatic deep venous thrombosis of lower limbs notabout the non-symptomatic. Actually, the non-symptomatic also can cause severe outcomes such as fatal pulmonary embolism. At present, the data of the incidence rate of deep venous thrombosis after spinal surgery and the clinical study in our country yet have not been reported. Spinal diseases are common and frequently-occurring in the patients of Orthopaedics in our country and even in the international. How to improve its surgical effect and reduce the complications is a challenge for all surgeons in the spinal area. Therefore, to carry out the clinical study on deep venous thrombosis after spinal surgery is very necessary. Especially in the past few years, with the development of surgical technique and medical instrument, a lot of new technique, instrument and biomaterial have been extensively used for spinal surgery. Meanwhile the increase of surgical complexity and difficulty, the enlargement of surgical trauma and the prolongation of operation time will increase the risk of deep venous thrombosis of lower limbs after spinal surgery, severely interfere the process ofpostoperative rehabilitation and even endanger the patients' lives.Methods Criteria for selecting objects: 120 patients who had undergone surgery for spinal diseases in our hospital between October 2005 and January 2007 were divided into four groups including lumbar intervertebral disc protrusion, lumbar unsteadiness, thoracolumbar fractures with or without spinal nerve injury, and spinal tumors or tuberculosis. They were queried history in detail before operation and given each routine examination including blood clotting analysis, D-dipolymer test, blood viscosity test, and Doppler ultrasound examination of both lower extremities. Criteria for exclusion: 1) Having malignant tumors. 2) Peoperative blood clotting test was abnormal and had clinical significance. 3) With cerebrovascular disease. 4) Phlebothrombosis existed before operation. 5) Having the history of vascular surgery. 6) The function of liver, kidney and heart was abnormal and had clinical significance. 7) Hypertension was not well controlled. 8) With diabetes. 9)With hematological system diseases. 10) With chronic diseases of veins of lower extremity. In this study, there were 68 males and 52 females aged from 21 to 65 years (mean 42.4 years). All the operations were completed by the same group of surgeons. In the group of lumbar intervertebral disc protrusion, there were 40 cases purely performed the removal of nucleus pulposus by posterior approach in prone position under local infiltration anesthesia, including 32 cases in single segment and 8 in double segments. The operation time ranged from 30-90 minutes (mean 55 minutes). In the group of lumbar unsteadiness including spondylolysis and degeneration, there were 35 cases performed internal fixation, bone graft and fusion with pedicle screw system by posterior approach in prone position under general anesthesia (5 cases) and continuous epidural anesthesia (30 cases)continuous epidural anesthesia, including 17 in single segment, 10 in double segments, 5 in three segments and 3 in four segments. The operation time ranged from 120-230 minutes (mean 165 minutes). In thegroup of thoracolumbar fractures, there were 25 cases performed internal fixation, bone graft and fusion with pedicle screw system by posterior approach in prone position under general anesthesia (22 cases) and continuous epidural anesthesia (3 cases), including 14 cases with spinal nerve injury (according to Frankel Grading Criteria: 2 in Grade A, 3 in Grade B, 6 in Grade C and 3 in Grade D). Besides internal fixation, artificial bone filling via pedicle was also performed in 6 cases. The operation time ranged from 90-160 minutes (mean 124 minutes). In the group of thoracolumbar tumors or tuberculosis, there were 20 cases in pone (5 cases) and lateral position (15 cases) under general anesthesia (17 cases) and continuous epidural anesthesia (3 cases), including 13 performed focus clearance, bone graft and internal fixation, 2 performed focus clearance and bone cement filling and 5 performed focus clearance, artificial bone filling and internal fixation. The operation time ranged from 150-220 minutes (mean 180 minutes). Three to ten days after operation, upward contrast examination of deepveins of both lower extremities was performed by the same group of doctors, using 76% angiografm 40ml injected into each lower extremity.Results Analysis and diagnosis was given by the same group of radiologists. According to the diagnostic criteria of deep venous thrombosis raised by Lensing, the thrombus limited in the distal deep veins of cnemis was called distal thrombus, the one only involving the deep veins above popliteal vein was called proximate thrombus, and the one involving the both was called whole venous thrombus. In this study, 8 cases were detected thrombus in deep veins of lower limbs with mean age of 56.6 years and incidence rate of 6.67% and all had one lower limb involved, including 5 cases in the left and 3 in the right. There were 2 in proximate thrombus, 5 in distal thrombus and 1 in whole venous thrombus. There were complete embolism . There were 2 with clinical symptom (the swelling and pain of lower limbs) and 6 without clinical symptom. There was no pulmonary embolism occurring. The occurrence of thrombus indifferent groups: there were 1 case in lumbar intervertebral disc protrusion(2.5%), 2 in lumbar unsteadiness(5.71%), 3 in thoracolumbar fractures(12%), and 2 in thoracolumbar tumors or tuberculosis(10%). The occurrence of thrombus under different methods of anesthesia: there were 1 case under local anesthesia(2.5%), 2 under continuous epidural anesthesia(5.6%) and 5 under general anesthesia(11.4%). Discussion Three pathological factors for thrombosis are vessel wall injury, blood flow slow-moving and hypercoagulabale state of blood. Spinal surgery has risk factors as following: 1) wound and blood loss caused by the operation, 2) direct interference to the blood vessel due to the operative procedure such as anterior approach in lumbar spine, 3) oppression of inferior vena cave, vena iliaca and femoral vein due to the prone position, 4) implantation of artificial materials such as heat injury of blood vessel due to the heat release of bone cement or artificial bone, 5) anesthesia especially rachianesthesia or general anesthesia, 6) spinal trauma with spinal nerve injury or acroparalysis, and7) lying in bed or stopping moving for long time after operation. Any one or several factors above-mentioned can both cause deep venous thrombosis. Due to the different spinal surgeries under different anesthetic methods in different body positions and other factors such as the area of wound, the volume of bleeding, the operation time and surgical methods, the incidence rate of thrombus is different. The incidence rate of deep venous thrombosis of lower limbs is lower, which is difficult to find out in early time because without any clinical symptom or sign in most patients, so we should improve our knowledge about deep venous thrombosis after spinal surgery and its characteristics and the prediction, and think highly of the management during perioperative time and postoperative observation especially on the patients combined with high risk factors in order to prevent missed diagnosis. After spinal surgery especially lumbar surgery, most patients have radicular symptoms and signs on lower limbs which can be confused with those caused by deep venous embolism, so it needsDoppler ultrasound or contrast examination of deep veins oflower limbs to identify.Conclusion 1) The incidence rate of deep venousthrombosis of lower limbs after spinal surgery is lower thanthat of the replacement of hip and knee joint. 2) Surgicaltrauma and methods and anesthetic methods have thecorrelation with deep venous thrombosis of lower limbsafter spinal surgery.