Prevention of deep-vein thrombosis after total hip arthroplasty. Comparison of warfarin and dalteparin

The effectiveness and safety of warfarin were compared with those of a low-molecular-weight heparin (dalteparin) for the prevention of deep-vein thrombosis after total hip arthroplasty in a prospective, randomized, multi-institutional trial. Patients who were older than eighteen years of age and were scheduled to have an elective primary or revision total hip arthroplasty were eligible; 580 patients were randomized, 550 had the operation and received prophylaxis, and 382 had evaluable venograms. Prophylaxis was provided either with warfarin beginning the night before the operation or with dalteparin beginning two hours before the operation and was continued until venography was performed. Bleeding was assessed on the basis of intraoperative blood loss, transfusion requirements, a decrease in hematocrit, and clinically identified bleeding complications. The prevalence of deep-vein thrombosis was found to be significantly lower in the patients who had received dalteparin than in those who had received warfarin (twenty-eight [15 per cent] of 192 patients compared with forty-nine [26 per cent] of 190 patients; p = 0.006). Deep-vein thrombosis occurred in the calf veins of twenty-one patients (11 per cent) who had received dalteparin and of forty-three patients (23 per cent) who had received warfarin; this difference was significant (p = 0.003). Proximal deep-vein thrombosis occurred in ten patients (5 per cent) who had received dalteparin and in sixteen patients (8 per cent) who had received warfarin; however, with the numbers available, no significant difference could be detected (p = 0.185). We also could not detect a significant difference with regard to the intraoperative and postoperative blood loss, the decrease in hematocrit, and the prevalence of major bleeding complications between the two groups; however, the patients who had received dalteparin had a significantly higher prevalence of bleeding complications involving the operative site (p = 0.03), and a significantly greater percentage required postoperative transfusions (p = 0.001). We concluded that preoperative prophylaxis with dalteparin is significantly more effective than that with warfarin in preventing deep-vein thrombosis after total hip arthroplasty. The greater effectiveness of dalteparin must be considered, however, in light of an increased need for postoperative transfusions and an increase in the prevalence of wound-related bleeding complications.     

Cost effectiveness of low-molecular weight heparin versus warfarin following hip replacement surgery

Little information is available on the efficacy of low-molecular-weight heparin (enoxaparin) versus warfarin for treatment of deep vein thrombosis and pulmonary embolism following hip replacement surgery. Still less is known of the comparative cost effectiveness of these two therapies. A retrospective study was done on 56 patients who underwent elective hip surgery at an urban medical center between 1991 and 1996. All patients received enoxaparin or warfarin for purposes of thromboprophylaxis. An analysis of medication cost, therapy, laboratory monitoring, and bleeding events of the two antithrombolytic agents was undertaken. Total savings with enoxaparin averaged $1253 per patient, or $137,886 over the study period. The incidence of deep vein thrombosis or pulmonary embolism was 0% with enoxaparin and 3% with warfarin. These data indicate that enoxaparin is a more cost-effective and efficacious regimen for thromboprophylaxis following hip replacement surgery than warfarin.     

Thromboembolic disease in patients undergoing total knee replacement

In a prospective study fo the incidence of deep-vein thrombosis in thirty patients undergoing total knee replacement, all patients had clinical examinations and 125I fibrinogen scanning, while those suspected of having deep venous thrombosis also had confirmatory venography. Sixteen (53 per cent) of the thirty patients had thromboembolic disease; nine had thrombi only in the limb operated on; four had bilateral deep venous thrombi; and three had pulmonary embolism. In nine patients who took aspirin regularly the incidence of thromboembolism was 11 per cent, while in the eight who did not take aspirin or any other antiplatelet drug the incidence was 88 per cent, a difference which was highly significant (p = 0.003).     

A clinical trial of vena caval filters in the prevention of pulmonary embolism in patients with proximal deep-vein thrombosis. Prévention du Risque d'Embolie Pulmonaire par Interruption Cave Study Group

BACKGROUND: The efficacy and safety of vena caval filters in the prevention of pulmonary embolism in patients with proximal deep-vein thrombosis is still a matter of debate. METHODS: Using a two-by-two factorial design, we randomly assigned 400 patients with proximal deep-vein thrombosis who were at risk for pulmonary embolism to receive a vena caval filter (200 patients) or no filter (200 patients), and to receive low-molecular-weight heparin (enoxaparin, 195 patients) or unfractionated heparin (205 patients). The rates of recurrent venous thromboembolism, death, and major bleeding were analyzed at day 12 and at two years. RESULTS: At day 12, two patients assigned to receive filters (1.1 percent), as compared with nine patients assigned to receive no filters (4.8 percent), had had symptomatic or asymptomatic pulmonary embolism (odds ratio, 0.22; 95 percent confidence interval, 0.05 to 0.90). At two years, 37 patients assigned to the filter group (20.8 percent), as compared with 21 patients assigned to the no-filter group (11.6 percent), had had recurrent deep-vein thrombosis (odds ratio, 1.87; 95 percent confidence interval, 1.10 to 3.20). There were no significant differences in mortality or the other outcomes. At day 12, three patients assigned to low-molecular-weight heparin (1.6 percent), as compared with eight patients assigned to unfractionated heparin (4.2 percent), had had symptomatic or asymptomatic pulmonary embolism (odds ratio, 0.38; 95 percent confidence interval, 0.10 to 1.38). CONCLUSIONS: In high-risk patients with proximal deep-vein thrombosis, the initial beneficial effect of vena caval filters for the prevention of pulmonary embolism was counterbalanced by an excess of recurrent deep-vein thrombosis, without any difference in mortality. Our data also confirmed that low-molecular-weight heparin was as effective and safe as unfractionated heparin for the prevention of pulmonary embolism.     

The effect of active movement of the foot on venous blood flow after total hip replacement

Surgeons often encourage patients to move their feet in an attempt to prevent venous stasis, but there is little evidence that this measure is beneficial. We investigated the effect of active movement of one foot on the venous blood flow four days after total hip replacement. The actual venous outflow at rest was measured with use of venous occlusion strain-gauge plethysmography in thirty-eight patients. The patients were randomly allocated to the control group (eighteen patients) or the exercise group (twenty patients). A baseline measurement was followed by a one-minute period of rest (control group) or of maximum plantar flexion and dorsiflexion of the foot, ankle, and toes at a rate of thirty cycles per minute (exercise group). The venous outflow was measured again at two, seven, twelve, and thirty minutes in both groups. Movement of the foot for one minute produced a significant and sustained increase (p < 0.002) in the venous outflow (mean maximum increase, 22 per cent). The value remained greater than the baseline level for thirty minutes (mean increase, 6.5 per cent) (p < 0.2). The increase was gradual, reaching a maximum twelve minutes after the completion of exercise. Our results confirm the beneficial hemodynamic effects of active movement of the foot in the postoperative period and suggest that patients should move the feet and ankles postoperatively as part of a prophylactic regimen directed at decreasing the risk of venous thrombosis.     

Ultrasound surveillance for asymptomatic deep venous thrombosis after total joint replacement

Prospective data on 202 consecutive patients who had a total of 123 total hip and ninety-four total knee arthroplasties were collected from two university medical centers. The findings of routine surveillance for deep venous thrombosis performed with ascending contrast venography were compared with those of surveillance with duplex ultrasonography complemented with color-flow Doppler imaging. All of the studies were performed between the third and seventh postoperative days. Of the 202 patients (342 extremities) who were examined, fifty-five (27 per cent) were found to have deep venous thrombosis; fifty-two (95 per cent) of the thrombi were in the calf and three (5 per cent) were in the proximal veins. All of the thrombi were clinically asymptomatic and all were nonocclusive, allowing passage of contrast medium around an intraluminal filling defect. Duplex ultrasonography with color-flow Doppler imaging correctly identified two of the three proximal thrombi and five of the fifty-two thrombi in the calf (sensitivity, 10 per cent). The sensitivity for the detection of thrombi in the calf was zero of sixteen at one of the institutions involved in the study and 14 per cent (five of thirty-six) at the other. There were two false-positive findings on ultrasonographic examination; one involved a proximal thrombus and one, a distal thrombus. We believe that the interinstitutional variability and insensitivity of duplex ultrasonography with color-flow Doppler imaging for the detection of asymptomatic deep venous thrombi in the calf after total joint replacement make it unreliable as a routine surveillance tool after total hip or knee arthroplasty.     

Cuff-impedance phlebography and 125I fibrinogen scanning versus roentgenographic phlebography for diagnosis of thrombophlebitis following hip surgery. A preliminary report

Seventy-eight limbs of forty-eight patients undergoing total hip replacement were studied by roentgenographic phlebography, cuff-impedance phlebography, and 125I fibrinogen scanning. Compared with roentgenographic phlebography, cuff-impedance phlebography detected seven of ten thrombi in the thigh but none of nine thrombi in the calf and popliteal veins, giving an over-all accuracy of 80 per cent. The 125I fibrinogen scanning technique detected none of the ten thrombi in the thigh and seven of the nine in the calf and popliteal veins, giving an over-all accuracy of 78 per cent. Combining the results of the two techniques, fourteen of the nineteen thrombi were detected. Cuff-impedance phlebography appears to be a useful method for the diagnosis of thrombi in the thigh after hip surgery.     

Hydroxyapatite-coated total hip femoral components in patients less than fifty years old. Clinical and radiographic results after five to eight years of follow-up

One hundred and thirty-three patients (152 hips) who were an average of thirty-nine years old (range, sixteen to forty-nine years old) received a proximally hydroxyapatite-coated femoral prosthesis as part of a total hip arthroplasty and were followed for a minimum of five years (average, 6.4 years; range, five to 8.3 years) or until revision. The average Harris hip score was 47 points (range, 22 to 77 points) preoperatively and 93 points (range, 49 to 100 points) at the time of the latest clinical evaluation. Two patients who had a well fixed femoral implant had activity-limiting pain in the thigh at the time of the most recent examination. Radiographic changes consistent with bone-remodeling (cortical hypertrophy and bone condensation) typically were seen around the mid-part of the shaft of the prosthesis. Forty-eight (32 per cent) of the 148 hips that were included in the radiographic analysis demonstrated a small amount of erosive scalloping in either zone 1 or zone 7 of Gruen et al., and intramedullary osteolysis was suspected in only one hip. All stems were radiographically osseointegrated according to a modification of the criteria described by Engh et al. Four stems were revised, but none of the revisions were performed because of mechanical failure (two stems were revised in conjunction with a revision of the cup because of pain; one, because of an infection; and one, after a traumatic femoral fracture that occurred six years postoperatively). Thus, the rates of aseptic and mechanical failure were both 0 per cent. The combined rate of failure, which included the two stems that were revised because of pain and the two stems that were associated with pain that limited activity, was 2.6 per cent (four of 152 stems). The over-all clinical results associated with hydroxyapatite-coated femoral components were excellent in this group of young patients after intermediate-term follow-up. A review of serial radiographs showed mechanically stable implants with osseous ingrowth, evidence of stress transmission at the middle part of the stem, and minimum endosteal osteolysis.     

Ruptured Baker's cyst causes ecchymosis of the foot. A differential clinical sign

Three consecutive patients with ruptured Baker's cysts, verified by duplex scan, were found to have ecchymosis on the dorsum of the foot. The appearance of ecchymosis can be helpful in differentiating a ruptured cyst from cellulitis or deep-vein thrombosis.     

Total hip arthroplasty with cement in patients who have rheumatoid arthritis. A minimum ten-year follow-up study

One hundred and six consecutive total hip arthroplasties with cement were performed by one surgeon, at least ten years before the time of the present clinical and radiographic review, in seventy-five patients who had adult-onset rheumatoid arthritis. Two patients (three hips) were lost to follow-up. Seven (7 per cent) of the remaining 103 hips were revised. The revisions were performed because of infection (three hips), dislocation (two hips), or aseptic loosening (two hips). Of the ninety-eight hips that were not lost to follow-up or revised because of infection or dislocation, eight (8 per cent) had radiographic loosening of the acetabular component and two (2 per cent) had radiographic loosening of the femoral component. Although the prevalence of radiographic loosening of the acetabular component was four times greater than the prevalence of radiographic loosening of the femoral component, the prevalence of revision because of aseptic loosening of the acetabular component was identical to that for the femoral component (one component each). These results compared favorably with those of total hip arthroplasty with cement, performed by the same surgeon, for the treatment of other diagnoses. Loosening of the acetabular component was significantly associated with a younger age at the time of the index operation (p = 0.03) and with acetabular osteolysis (p = 0.0006). Of forty-eight hips in thirty-two patients who survived for at least ten years, 96 per cent (forty-six hips) were considered by the patients to have a satisfactory result. At the time of the latest follow-up, twenty-four (75 per cent) of the patients had no pain in the hip. Although eighteen patients (56 per cent) could walk without support at a minimum of ten years after the operation, we found that the functional results for patients who had rheumatoid arthritis were inferior to those observed for patients who had had a total hip arthroplasty with cement, performed by the same surgeon, for the treatment of other diagnoses.     

Clinical and hemodynamic criteria for use of the intra-aortic balloon pump in patients requiring cardiac surgery

In order to establish criteria for elective use of the intra-aortic balloon pump (IABP) in patients having cardiac surgery, we conducted a retrospective study of 43 patients who required counterpulsation, because of inability to be weaned from cardiopulmonary bypass, between May, 1972, and June, 1974. Patients in cardiogenic shock preoperatively were excluded. The 43 patients included 23 (Group A) who had severe preoperative left ventricular dysfunction with a mean cardiac index less than 1.8 L. per minute per square meter, ejection fraction less than 30 per cent, and end-diastolic pressure greater than 22 mm. Hg; 20 patients (Group B) had a combination of moderate cardiac dysfunction (cardiac index less than 2.2, ejection fraction less than 40, end-diastolic pressure less than 18) in the presence of acute infarction or severe aortic stenosis (gradient greater than 80 mm. Hg) with or without coronary disease. An inverse relationship was noted between survival and delay from completion of operation to the use of 1ABP. Thirty-two of 43 patients were weaned off bypass and were balloon assisted for 12 to 96 hours postoperatively; 25 patients were discharged (58 per cent). In Subgroup A, 14 of 23 (60 per cent) and, in Subgroup B, 9 of 20 (45 per cent) were long-term survivors. Based on these findings, 45 patients were operated upon between June, 1974, and December, 1975, with elective use of 1ABP and were assessed by serial hemodynamic studies. Sixteen had severe preoperative left ventricular dysfunction similar to Subgroup A and 29 had moderate dysfunction in combination with pathology similar to Subgroup B. Fifteen of these patients were hemodynamically unstable at time of arrival in the operating room; 1ABP was inserted under local anesthesia. Thirty-nine patients (87 per cent) were weaned off bypass and were hospital survivors. In Subgroup A, 13 of 16 (81 per cent) and, in Group B, 21 of 29 (72 per cent) were long-term survivors. Criteria for elective use of 1ABP in cardiac surgery should include severe preoperative left ventricular dysfunction or a combination of moderate dysfunction with coronary or valvular pathology. Elective 1ABP improves the survival with trivial iatrogenic morbidity.     

Proximal femoral osteotomy as the primary operation for young adults who have osteoarthrosis of the hip

We report the results of proximal femoral osteotomy that was performed to treat osteoarthrosis in twenty-three consecutive young adults (twenty-five hips) who had a mean age of thirty-eight years (range, eighteen to fifty-three years). The mean duration of follow-up was seven years (range, two to twelve years). With conversion to a total hip replacement as the end point, the rate of survival at twelve years was 67 per cent (95 per cent confidence interval, 37 to 88 per cent). Four hips (16 per cent) were converted to a total hip replacement at a mean of eight years after the osteotomy. For the patients who did not have conversion to a total hip replacement, the mean score for pain, according to the system of Merle d'Aubigné and Postel as modified by Charnley, improved from 3.4 points preoperatively to 5.1 points postoperatively, the mean score for walking ability improved from 3.9 to 4.7 points, and the mean score for range of motion improved from 3.2 to 4.2 points. These results compare favorably with those following other forms of operative treatment of osteoarthrosis of the hip in young adults. In addition, the osteotomy does not preclude subsequent replacement arthroplasty if one is necessary.     

Combined use of leg scanning and impedance plethysmography in suspected venous thrombosis. An alternative to venography

Venography is the standard method for the diagnosis of venous thrombosis but is invasive and may cause discomfort. We evaluated the combination of impedance plethysmography and 125I-fibrinogen leg scanning as an alternative to venography in 200 symptomatic patients. One or both of these less invasive tests was positive in 81 of 86 patients with positive venograms (sensitivity of 94 per cent) and both were negative in 104 of 114 patients with negative venograms (specificity of 91 per cent). These two tests detected all 60 patients with popliteal or more proximal venous thrombosis and 21 of 26 patients with calf-vein thrombosis. In addition, this approach detected 21 of 22 patients with calf-vein thrombosis with symptoms for eight days or less. These results suggest that the combination of these two less invasive tests can be used as an alternative to venography in selected patients with clinically suspected venous thrombosis.     

Thromboembolism following total hip-replacement arthroplasty. The efficicy of dextran-aspirin and dextran-warfarin in prophylaxis

The efficacy of two antithrombotic regimens, combined dextran and aspirin and combined dextran and warfarin, was analyzed by comparing the incidence of thromboembolism following total hip replacement in two groups of similar patients. Of the 427 who received dextran and aspirin, 7 per cent had thromboembolic complications, including one case of fatal pulmonary embolus and one case of recurrent emboli that required vena caval ligation, and 15 per cent had wound-healing complications. Of the 197 patients who received dextran and warfarin, 5 per cent had thromboembolism and 24 per cent had wound healing complications. Although both prophylactic regimens seemed effective, dextran and aspirin appeared less effective in reducing thromboembolic complications than dextran and warfarin, but there were fewer wound complications in that group. One-fourth of the patients on dextran-warfarin were not adequately anticoagulated despite close supervision. In forty-five patients with a history of thromboembolism who were excluded from the study and analyzed separately, warfarin alone and the two described regimens were equally ineffective in preventing thromboembolism, and the incidence of thromboembolic complications was high. Dextran-aspirin and dextran-warfarin appear to be satisfactory and relatively simple methods of thromboembolic prophylaxis.     

Postoperative mortality after total hip arthroplasty. An analysis of deaths after two thousand seven hundred and thirty-six procedures

We retrospectively determined the prevalence and nature of mortality as many as ninety days after 2736 primary and revision total hip arthroplasties performed in 2002 patients by one surgeon at a teaching hospital between January 1969 and December 1996. All but seventy-one of the patients had received prophylaxis against venous thromboembolic disease. There were no intraoperative deaths, and no events during the operation could be linked directly to postoperative mortality. Eight deaths (mortality rate, 0.3 per cent) occurred within ninety days after the 2736 procedures. Four deaths (mortality rate, 0.15 per cent) occurred during the initial hospitalization. The cause of seven of the deaths was determined. Three patients died as a result of preexisting disease (severe hepatorenal disease, metastatic esophageal cancer, or severe cardiac disease), and one patient died from sepsis with a gram-negative organism during a thoracotomy eight days postoperatively. A bleeding complication that occurred while the patient was receiving warfarin therapy led to the death of two other patients; one of these deaths occurred in 1974 and the other, in 1982. At the time that these patients were managed, the desired prothrombin time was considered to be twice the control value. The remaining patient, who had had a clip placed on the inferior vena cava after a pulmonary embolus occurred in 1970, died secondary to acute, severe thrombosis of this vessel after a total hip arthroplasty in 1971. The patient for whom the cause of death was not determined had had an artificial aortic valve and had been receiving chronic warfarin therapy. She died suddenly eighty-nine days postoperatively; no autopsy was performed. No patient died as the direct result of a known pulmonary embolus. No deaths related to venous thromboembolic disease or its prophylaxis or treatment occurred after 1982 (1458 operations). We attribute this, in part, to reduced levels of warfarin prophylaxis and improved management with warfarin. The ninety-day postoperative mortality rate after 2736 procedures performed over nearly three decades was low (0.3 per cent). This span of time included the period before the introduction of many current improvements in perioperative care, such as routine intubation of patients under general anesthesia, continuous monitoring of the electrocardiogram intraoperatively, and blood-gas determinations. When the patients who died as a result of known, severe preexisting disease were excluded, the mortality rate was 0.18 per cent (five of 2733).     

Giving both enoxaparin and dextran increases the need for transfusion in revision hip arthroplasty

OBJECTIVE: To find out if the need for transfusion was increased by volume substitution with dextran 70 in patients receiving prophylaxis against thrombosis with low molecular weight heparin. DESIGN: Open randomised controlled trial. SETTING: University hospital, Sweden. SUBJECTS: 40 patients undergoing revision hip arthroplasty. INTERVENTIONS: Enoxaparin 40 mg was given daily. Intraoperative normovolaemia was maintained with albumin (n = 20) or dextran 70 (n = 20). Intraoperative autotransfusion was used. Packed cell volume was kept above 0.29, if necessary with homologous blood. MAIN OUTCOME MEASURES: External blood loss, red cell balance. RESULTS: Dextran patients received 0.64 (0.2) g/kg of dextran (mean (SD)) and required more (p < 0.05) homologous blood (3.8 (2.4) units) than those receiving albumin (2.3 (1.6) units). The initial and final packed cell volumes were similar (0.40 and 0.32 compared with 0.41 and 0.32, respectively). The calculated loss of red cells was larger in the dextran group (1401 (511) compared with 1077 (374); p < 0.05). CONCLUSION: The combination of enoxaparin and dextran appreciably increased the need for transfusion compared with enoxaparin alone.     

A common mutation in the methylenetetrahydrofolate reductase gene (C677T) increases the risk for deep-vein thrombosis in patients with mutant factor V (factor V:Q506)

Hyperhomocysteinemia is a frequent risk factor for deep-vein thrombosis. A common mutation (C677T) in the gene encoding for methylenetetrahydrofolate reductase (MTHFR) is responsible, in the homozygous state, for decreased enzyme activity and mild hyperhomocysteinemia and is associated with increased risk for cardiovascular disease. We studied the prevalence of C677T MTHFR in 77 patients with deep-vein thrombosis and in 154 age- and sex-matched healthy control subjects. In the same individuals, we also evaluated the frequency of the coexistence of C677T MTHFR with mutant factor V:Q506, a common risk factor for deep-vein thrombosis. Sixteen patients (20.8%) and 35 control subjects (22.7%) were homozygous for the C677T MTHFR mutation (odds ratio [OR] = 0.8, 95% confidence interval [CI] = 0.4-2.0). Sixteen patients (20.8%) and 4 control subjects (2.6%) had factor V:Q506; of them, 10 patients and 3 control subjects had isolated factor V:Q506 (adjusted OR = 6.3, 95% CI = 1.6-25.3) and 6 patients and 1 control subject also had C677T MTHFR (adjusted OR = 17.3, 95% CI = 2.0-152.9). The OR for the coexistence of the two mutations was 65% to 75% higher than the expected joint effect calculated by either an additive (OR = 6.0) or multiplicative (OR = 4.4) model. The homozygous C677T mutation of MTHFR per se is not a risk factor for deep-vein thrombosis but increases the risk associated with factor V:Q506. Due to the high prevalence of C677T MTHFR, it is likely that previous studies, which did not look for this mutation, overestimated the relative risk of thrombosis associated with factor V:Q506 alone.     

Prevention of thromboembolic phenomena

The leading cause of death from total hip replacement is pulmonary embolism. Prophylactic anticoagulation has been effective in decreasing thromboembolic phenomena but has been associated with a high rate of complications. A low dose warfarin prophylaxis combined with anti-embolic hose, elevation of the legs and early ambulation was employed in 415 total hip replacements. Clinical thrombosis occurred in 2.4 per cent and there was 1.45 per cent pulmonary emboli but none resulted in death. Two deaths from non-embolic causes occurred for a mortality rate of 0.49 per cent. Systemic complications of the warfarin were few with 5 mild gastroentestinal hemorrhages but no deaths related to the medication. Wound hemorrhage occurred in 4.6 per cent of patients and it is recommended that severe, deep superficial hematomas be treated with early surgical evacuation. The management program appeared to be safe and effective in preventing postoperative mortality from pulmonary emboli but close monitoring is essential.     

Complications and long-term results of ankle arthrodeses following trauma

A review of sixty patients who had undergone ankle fusion for post-traumatic arthritis revealed that thirty-five (58 per cent) had the procedure performed within the first year after injury. A total of forty-eight complications occurred in twenty-nine (48 per cent) of the patients. Frequent complication were infection (23 per cent), non-union (23 per cent), inadequate surgical alignment or early loss of position (15 per cent), malunion (12 per cent), and delayed union (7 per cent). The lateral transfibular approach had the highest incidence of complications, and a two-incision approach using the Charnley compression apparatus was the procedure with the fewest complications. Forty-one patients were followed for an average of 7.5 years after operation. Of these, thirty-four (83 per cent) were satisfied with the procedure. Examination of thirty of the forty-one patients at an average of 7.3 years after surgery revealed virtually no subtalar motion but motion of 13 degrees at Chopart's joint. With shoes, patients had a near-normal gait. The roentgenograms revealed a minimum amount of degenerative arthritis at Chopart's joint, which may worsen with time. Varus or valgus angulation of the hind part of the foot was associated with a greater degree of symptoms in the subtalar area as well as the middle of the foot. The neutral position in varus-valgus angulation as well as dorsiflexion-plantar flexion was the optimum position for both men and women. The results of the procedure did not deteriorate with time.     

Accuracy of clinical assessment of deep-vein thrombosis

The clinical diagnosis of deep-vein thrombosis is generally thought to be unreliable. From experience, we hypothesised that this widely held view might be incorrect. We developed a clinical model and prospectively tested its ability in three tertiary care centres to stratify symptomatic outpatients with suspected deep-vein thrombosis into groups with high, moderate, or low probability groups of deep-vein thrombosis. We evaluated our clinical model in combination with venous ultrasonography to determine the potential for an improved and simplified diagnostic approach in patients with suspected deep-vein thrombosis. All patients were clinically assessed to determine the probability for deep-vein thrombosis before they had ultrasonography and venography. All tests were performed and interpreted by independent observers. In 529 patients, the clinical model predicted prevalence of deep-vein thrombosis in the three categories: 85% in the high pretest probability category, 33% in the moderate, and 5% in the low category. There was no statistical difference in the performance of the model in the three centres. The model demonstrated excellent interobserver reliability (Kappa = 0.85). There were important differences with ultrasonography between the high and low pretest probability groups for both positive predictive values (100% (95% CI, 94-100%) vs (63% [35-85%], respectively). Thus, use of the clinical model combined with ultrasonography would decrease the number of false positive and negative diagnosis if venography were done when the ultrasound result and pretest probability were discordant. The diagnostic process could be simplified by excluding those patients with low pretest probability and normal ultrasound results from serial testing.