Cardiorespiratory and vascular dysfunction related to major reconstructive orthopedic surgery

Long-term effects of cemented and cementless fixations of total knee arthroplasty: a meta-analysis and systematic review of randomized controlled trials

BACKGROUND

To determine the long-term effects (a minimum follow-up time 8.8 years) of cemented and cementless fixations used for total knee arthroplasty (TKA).

METHODS

PubMed, EMBASE, Ovid, Cochrane Library, CINAHL, China National Knowledge Infrastructure and China Wangfang database were interrogated for appropriate randomized controlled trials (RCTs) through July 2020. Data were extracted and assessed for accuracy by 2 of the authors acting independently. Any controversial discrepancies were resolved after discussion with a third author.

RESULT

Eight RCTs were included with low to moderate bias risks. The cemented fixation of TKA was comparable to cementless fixation in terms of implant survival (relative risk, 1.016; 95% CI 0.978 to 1.056; P = 0.417), Knee Society (KS) knee score (standardized mean difference (SMD), - 0.107; 95% CI - 0.259 to 0.045; P = 0.168), KS function score (SMD - 0.065; 95% CI - 0.238 to 0.109; P = 0.463), KS pain score (SMD - 0.300; 95% CI - 0.641 to 0.042; P = 0.085), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score (SMD - 0.117; 95% CI - 0.307 to 0.073; P = 0.227), HSS score (SMD - 0.027; 95% CI - 0.270 to 0.217; P = 0.829), range of motion (SMD 0.061; 95% CI - 0.205 to 0.327; P = 0.652) at ≥ 8.8 years of follow-up. In terms of radiographic outcomes at ≥ 8.8 years of follow-up, the incidence of a radiolucent line in the cementless group was lower than for the cemented group (SMD 3.828; 95% CI 2.228 to 6.576; P < 0.001). However, the maximum total point motion (MTPM) of the cementless group was greater than for the cemented group (SMD - 0.739; 95% CI - 1.474 to - 0.005; P = 0.048).

CONCLUSIONS

Long-term follow-up verified that cementless and cemented fixation have similar prosthesis survival rates, clinical scores and mobility. However, radiography suggested that each technique had an advantage with regard to the radiolucent line and MTPM.

Cement pulmonary embolism after percutaneous kyphoplasty: An unusual culprit for non-thrombotic pulmonary embolism

Non-thrombotic pulmonary embolism can occur from rare but diverse etiology and is not well understood. Increasing prevalence of osteoporosis in the aging population has contributed to increased utilization of percutaneous vertebral augmentation procedures of vertebroplasty and its recent modification, kyphoplasty. Though these procedures are relatively well tolerated, there is risk of potentially fatal complication of bone cement embolization to distant vasculature. We report a case of symptomatic pulmonary cement emboli developed 2 day's post kyphoplasty and its successful treatment with novel anticoagulant for 6 months. We also summarize evidence to assist clinicians and radiologists for early identification, treatment, and prevention of cement pulmonary emboli.

Postoperative respiratory failure necessitating transfer to the intensive care unit in orthopedic surgery patients: risk factors, costs, and outcomes

Background

Postoperative pulmonary complications in orthopedic surgery patients have been associated with worse clinical outcomes. Identifying patients with respiratory risk factors requiring enhanced monitoring and management modifications is an important part of postoperative care. Patients with unanticipated respiratory decompensation requiring transfer to the intensive care unit (ICU) have not been studied in sufficient detail.

Methods

A retrospective case-control study of elective orthopedic surgery patients (knee, hip, shoulder, or spine, n = 51) who developed unanticipated respiratory failure (RF) necessitating transfer to the ICU over a 3-year period was conducted. Controls (n = 153) were frequency matched to cases by gender, age, and surgical procedure. Patient and perioperative care factors, clinical outcomes, and cost of care were examined.

Results

Transfer to the ICU occurred within 48 h of surgery in 73 % of the cases, 31 % required non-invasive ventilation, and 18 % required mechanical ventilation. Cases had a higher prevalence of chronic obstructive pulmonary disease (COPD), obstructive sleep apnea (OSA), and regular psychotropic medication use than controls. Cases received more intravenous opioids during the first 24 postoperative hours, were hospitalized 4 days longer, had higher in-hospital mortality, and had excess hospitalization costs of US$26,571. COPD, OSA, preoperative psychotropic medications, and anesthesia time were associated with risk of RF in a multivariate analysis.

Conclusions

Unanticipated RF after orthopedic surgery is associated with extended hospitalization, increased mortality, and higher cost of care. Hospital protocols that include risk factor assessment, enhanced monitoring, and a cautious approach to opioid use in high-risk patients may reduce the frequency of this complication.

The proportion of perioperative mortalities attributed to cemented implantation in hip fracture patients treated by hemiarthroplasty

INTRODUCTION

Bone cement for fixation of prostheses, comorbidity and age have been previously shown to be associated with increased relative risk of mortality within the first day of surgery. However, the proportion of mortalities associated to each of these exposures is not adequately expressed by relative risk estimates.

MATERIALS AND METHODS

The attributable fraction (AF), i.e., the fraction of diseased individuals attributed to a given risk factor, was estimated for cemented fixation of hip prostheses in the elderly (>65 years) with a hip fracture. Dementia, symptomatic comorbidity (American Society of Anesthesiologists (ASA)≥ 3), old age (≥85 years), male gender, and a delay of 24 hours or more from fracture to operation were considered as additional risk factors for a fatal outcome in close proximity to surgery.

RESULTS

In the entire study population (n = 11210), the unadjusted and adjusted population AFs of cemented fixation on mortalities within the first day after surgery were 0.58 (95% CI 0.28-0.76) and 0.59 (95% CI 0.29-0.76), respectively. Symptomatic comorbidity and old age as risk factors had population AFs of 0.71 (95% CI 0.51-0.83) and 0.55 (95% CI 0.39-0.67), respectively. Male gender, dementia and time from fracture to operation all had considerably lower population AFs.

CONCLUSIONS

The estimated AFs on perioperative mortality in hip fracture patients treated by hemiarthroplasty showed that about half of the mortalities within the first day of surgery could be associated with the use of bone cement.

No difference in mortality between cemented and uncemented hemiprosthesis for elderly patients with cervical hip fracture. A prospective randomized study on 334 patients over 75 years

INTRODUCTION

Laboratory and human mechanical studies indicated that chemical substances in bone cement had toxic and prothrombotic effects. Impaction of cement added a mechanical trauma to the reaming and broaching procedure and contributed to a substantial local and systemic thrombin generation. Case reports and materials have indicated bone cement as the immediate trigger of cardiorespiratory and vascular dysfunction, occasionally fatal, and described as the bone cement implantation syndrome. In spite of this knowledge, bone cement has gained popularity and is widely used for prosthesis fixation, possibly due to a lack of clinical evidence supporting the basic science indicating bone cement as a mortality risk factor.

METHOD

This is a prospective, randomized study comparing cemented and non cemented hemiprosthesis on patients suffering a dislocated cervical hip fracture. Perioperative characteristics and 1 year mortality differences between the groups were estimated.

PATIENTS

Hundred and thirty-four patients over 75 years were enrolled from two hospitals in Norway. Average age was 84 years, 75 % were female and 60 % had symptomatic comorbidities.

RESULTS

We find no difference in mortality between cemented and uncemented hemiprosthesis up to 1 year (HR 0.77, 95 % CI 0.51-1.18, p = 0.233). However, statistically significant reduced operation time and blood loss were found in the non-cemented group. (mean difference of 13 min, 95 % CI 4-22, p = 0.004 and 92 ml 95 % CI 3-181, p = 0.043, respectively).

CONCLUSION

Installation of non-cemented hemiprostheses in elderly with hip fracture may have benefits perioperatively regarding operation time and bleeding, and do not seem to influence 1 year mortality relative to cemented implants.

Perioperative mortality in hip fracture patients treated with cemented and uncemented hemiprosthesis: a register study of 11,210 patients

PURPOSE

Adverse events associated with the use of bone cement for fixation of prostheses is a known complication. Due to inconclusive results in studies of hip fracture patients treated with cemented and uncemented hemiprostheses, this study was initiated.

METHODS

Our study is based on data reported to the Norwegian Hip Fracture Register on 11,210 cervical hip fractures treated with hemiprostheses (8,674 cemented and 2,536 uncemented).

RESULTS

Significantly increased mortality within the first day of surgery was found in the cemented group (relative risk 2.9, 95 % confidence interval 1.6-5.1, p=0.001). The finding was robust giving the same results after adjusting for independent risk factors such as age, sex, cognitive impairment and comorbidity [American Society of Anesthesiologists (ASA) score]. For the first post-operative day the number needed to harm was 116 (one death for every 116 cemented prosthesis). However, in the most comorbid group (ASA worse than 3), the number needed to harm was only 33.

CONCLUSIONS

We found increased mortality for the cemented hemiprosthesis the first post-operative day compared to uncemented procedures. This increased risk is closely related to patient comorbidity estimated by the patient's ASA score.

Biochemical lung, liver and kidney markers and early death among elderly following hip fracture

INTRODUCTION

In the elderly, hip fracture is a common injury associated with high early mortality dominated by cardiorespiratory and thromboembolic events. Identification of risk factors that can be modified by treatment has caught attention over the last years. This study was conducted to assess biological markers on perioperative organ dysfunction and its association with early mortality within 3 months after surgery.

METHOD

Blood samples were collected before, during and until 4 days after surgery. Analyses on PaO(2), alanine aminotransaminase (ALAT), gamma-glutamyl transpeptidase (g-GT) and creatinine were performed and used as markers on lung, liver and kidney functions.

PATIENTS

Three hundred and two patients over 75 years of age with acute dislocated hip fracture were consecutively enrolled from two hospitals in Norway.

RESULTS

We found a positive correlation between the plasma levels of ALAT, creatinine and death, and an inverse relationship between PaO(2) and death. After controlling for confounding factors such as sex, age and comorbidity, ALAT and creatinine levels were shown to be significantly and independently related to risk for fatal outcome.

CONCLUSION

Our results provide data on clinically important biomarkers in patients undergoing hip fracture surgery. We suggest a stronger emphasis on monitoring and correcting these biomarkers when possible.

Osteoblast response to polymethyl methacrylate bioactive glass composite

Polymethylmethacrylate (PMMA) has been used in many orthopedic and dental applications since the 1960s. Biocompatibility of newly developed surface porous fiber reinforced (SPFR) PMMA based composite has not been previously proven in cell culture environment. Analysis of rat bone marrow stromal cells grown on the different test materials showed only little difference in normalized cell activity or bone sialoprotein (BSP) production between the test materials, but the osteocalcin (OC) levels remained higher (P < 0.015-0.005) through out the test with SPFR-material when compared to tissue culture poly styrene (TCPS). The cells grown on SP-FRC material also showed highest calcium depletion from the culture medium (P < 0.026-0.001) when compared to all other test substrates. SEM images of the cultured samples confirmed that all the materials enabled cell spreading and growth on their surface, but the roughened surface remarkably enhanced this process of cell attachment, division and calcified nodule formation. This study shows that the SP-FRC composite material does not elicit harmful/toxic reactions in cell cultures more than neutral TCPS and can be considered biocompatible. The material possesses good capabilities to form new mineralized tissue onto its surface, and through that a possibility to bond directly to bone. Rough surface seems to enhance osteoblast proliferation and formation of mineralized extracellular matrix.

The ACCP guidelines for thromboprophylaxis in total hip and knee arthroplasty

The 1986 National Institutes of Health consensus conference Prevention of Venous Thrombosis and Pulmonary Embolism emphasized the high rates of venous thromboembolic disease (VTE), including deep vein thrombosis (DVT) and pulmonary embolism (PE), associated with orthopedic surgery of the lower extremity when performed without thromboprophylaxis. Total joint arthroplasty patients treated with placebo or as controls have, based on studies conducted between 1908 and 2002, a total DVT prevalence of 41% to 85% and a proximal DVT prevalence of 5% to 36% when examined by venography at 7 to 14 days. Prevalence of PE is less certain, but clinical studies have reported a range of 0.9% to 28% for all PE and 0.1% to 2% for fatal PE in control or placebo patients. As the number of total joint arthroplasties in the United States has grown - nearing 1,000,000 annually and expected to increase significantly over the next 20 years as the population ages - so too has interest in appropriate thromboprophylaxis. Methods of preventing VTE are either pharmacologic or mechanical. Guidelines from the American College of Chest Physicians make evidence-based recommendations for both pharmacologic and nonpharmacologic prophylaxis in the settings of total hip and total knee arthroplasty. These recommendations and their underlying rationale are discussed herein.

Anaesthesia for hemipelvectomy--a series of 49 cases

We undertook an audit of 49 consecutive hemipelvectomies performed for primary or secondary malignancy. Combined epidural and general anaesthesia was used in 41 patients. The operations were long (range 90 to 600 minutes). The median crystalloid requirement was 8500 ml (range 1000 to 42000 ml) and a median of seven units of packed red blood cells were transfused (range 0 to 44 units). All measures of coagulation were normalised by the first postoperative day using fresh frozen plasma, platelets and cryoprecipitate. Warmed blood was administered at high flow rates using a custom designed system consisting of a roller pump and high capacity fluid warmer Thirty-five patients were managed postoperatively in the intensive care unit, of whom 31 remained intubated for postoperative ventilation. In 41 patients, postoperative pain management was by a continuous epidural infusion of local anaesthetic and opioid. The average duration of infusion was 4.25 days (range 3 to 6 days). One patient died during surgery from complications relating to massive blood loss, 14 had wound infections and one had an acute brain syndrome. There was significant utilisation of resources involving anaesthesia, surgery, intensive care and blood transfusion services. Anaesthesia for hemipelvectomy is challenging because of the extensive tissue trauma involved, the potential for massive blood loss and the potential for severe postoperative pain. The perioperative management necessitates care from a well coordinated, directed and focused healthcare team.

Delayed presentation of pulmonary polymethylmethacrylate emboli after percutaneous vertebroplasty

STUDY DESIGN

Literature review concerning pulmonary embolism of polymethylmethacrylate (PMMA) material following percutaneous vertebroplasty and a report on 2 new cases.

OBJECTIVE

To inform clinicians about delayed clinical manifestation of pulmonary embolism of polymethylmethacrylate material after percutaneous vertebroplasty, pathophysiology, precautions, and therapeutic management of this complication.

SUMMARY OF BACKGROUND DATA

Percutaneous vertebroplasty is a minimal invasive intervention used to treat vertebral fractures, which yields good therapeutic results and rarely produces complications. Nevertheless, serious complications may occur. Pulmonary PMMA embolism, which has been recently reported in some cases, is one of these.

METHODS AND RESULTS

We report on 2 cases of pulmonary embolism of PMMA material after percutaneous vertebroplasty. In the case of a 45-year-old female patient, symptoms of pulmonary embolism arose with a delay of 3 days following percutaneous vertebroplasty. A therapy with low-molecular-weight heparin, Enoxaparin, enabled recovery from pulmonary failure. The second case occurred without detection of any cement leakage into the paravertebral venous system, neither intraoperatively nor perioperatively. The existence of PMMA in pulmonary vessels was detected 1 year later and remained asymptomatic.

CONCLUSION

These 2 cases allow us to conclude that the risk of pulmonary embolism of PMMA might be underestimated. We propose routine chest radiograph following every vertebroplasty, in order to detect pulmonary PMMA embolism and thereby prevent serious delayed cardiopulmonary failures.

Reduction of Toxic Effect of Methyl Methacrylate on Human Cells in Culture Containing Sodium Hypochlorit

The effect of sodium hypochlorite (SH) upon toxic response of cultured human fibroblasts to methyl methacrylate (MMA) which is a part of bone cement «Polacris» has been studied. Toxic effect of MMA in clinically adequate concentrations demonstrated dose-dependant suppression of total activity of mitochondrial enzymes and that was one of the showings of stress at the cellular level. MMA:SH mixture in volume ratio 1:1 and 10:1 caused reliable reduction of toxic effect on cultured cells as compared with pure MMA of the similar concentration. On the contrary, MMA: SH mixture in volume ratio 1:10 resulted in true decrease of fibroblasts viability as compared with the state of cells in presence of pure MMA. Thus it was shown that chemical experimental in vitro inactivation of MMA could be achieved only when MMA concentration was either higher or equal to SA concentration. That provided the reduction of metabolic disturbances in cells.

Orthopaedic Surgery as a Model for Drug Development in Thrombosis

Venous thromboembolism after total hip replacement or total knee replacement represents a significant complication of these surgical techniques, with profound clinical and economic consequences. As the detection of venous thromboembolism is particularly difficult in this setting, its prevention with thromboprophylactic agents is the most appropriate strategy. The anticoagulants currently used for thromboprophylaxis in orthopaedic surgery are injectable low-molecular-weight heparins (LMWHs) and oral coumarin derivatives such as warfarin. Orthopaedic surgery provides a good model with which to investigate the antithrombotic potential of novel agents, because of the relatively high venous thromboembolism event rates, and the opportunity to detect and quantify bleeding. This paper provides an overview of the clinical burden of venous thromboembolism in orthopaedic surgery and the benefits and limitations of current thromboprophylactic modalities. In addition, geographical differences in treatment regimens regarding the choice of agent, timing of initiation and duration of thromboprophylaxis, and how these influence the incidence of venous thromboembolism, will be discussed.

Prevention of Venous Thromboembolism Following Orthopaedic Surgery

Patients undergoing total hip or total knee replacement are at high risk of venous thromboembolism (VTE), and are therefore considered to be populations well suited for the evaluation and dose optimisation of new anticoagulants. Deep vein thrombosis may lead to life-threatening pulmonary embolism, disabling morbidity in the form of the post-thrombotic syndrome, and risk of recurrent thrombotic events. There is increasing evidence that anticoagulant treatment for the prevention of VTE should be extended from 1 to at least 4 weeks after surgery. Anticoagulation with vitamin K antagonists (such as warfarin), low molecular weight heparin or unfractionated heparin effectively lowers the risk of VTE, but these anticoagulants have limitations such as the need for coagulation monitoring and subsequent dose adjustment (vitamin K antagonists), difficulty of continuing prophylaxis out of hospital because of the requirement for parenteral administration, and risk of heparin-induced thrombocytopenia. The development of new anticoagulants has been pursued with the aim of finding more effective, safer and/or more convenient therapies. Thrombin is a central regulator in the coagulation and inflammation process and several direct thrombin inhibitors (DTIs) with distinct pharmacological profiles, as well as pharmacological differences from the conventional anticoagulants, are currently in clinical use for certain indications or are under development. Clinical experience with parenterally administered DTIs has accumulated since the mid 1990s, although only desirudin (a recombinant hirudin) is currently approved for use in patients undergoing orthopaedic surgery. Two oral DTIs, ximelagatran and dabigatran etexilate, are in clinical development. Dabigatran etexilate has recently been evaluated in phase II clinical trials in patients undergoing total hip replacement. Several large phase III trials have now demonstrated the efficacy and safety of ximelagatran in the prevention of VTE following total hip or knee replacement. Ximelagatran can be used with an oral fixed dose without the need for coagulation monitoring or dose adjustment. Hence, it offers significant potential to facilitate the management of anticoagulation in or out of hospital.

Cardiopulmonary complications of intramedullary fixation of long bone metastases

Intramedullary fixation of long bone metastases is an effective method of treating or preventing pathologic fractures. An important complication of this technique is the development of pulmonary embolism, which may occur at any number of steps during bone manipulation. Passage of normal marrow contents or tumor into the pulmonary circulation is thought to cause various biochemical, hemodynamic, or physical responses that lead to hypotension, arrythmia, and O2 desaturation. Death is a known risk of this procedure. Numerous surgical and anesthetic strategies have been developed to prevent or treat pulmonary embolic phenomena; however, the most important prophylaxis may be a heightened awareness of this possibility during any procedure that involves intramedullary manipulation of tumor containing bone.

Platelet activation after in vitro contact with seven acrylic bone cements

Seven acrylic bone cements were evaluated: Cemex Rx (Tecres S.p.a., Italy), Cemex Isoplastic (Tecres S.p.a., Italy), Zimmer Low Viscosity Cement (L.V.C., Zimmer, IN, USA), Zimmer bone cement - dough type (Zimmer, IN, USA), CMW (DePuy International Ltd., UK), Cerim LT (Cremascoli S.r.l., Italy), and Palacos (Merck, Wehreim, Germany). The cements after polymerization were put in contact in vitro with platelet-rich plasma. Plasma in contact only with siliconated glass was used as the negative control. After contact, platelet number, beta-thromboglobulin (beta-TG), and transforming growth factor-beta1 (TGF-beta1) were determined. The Wilcoxon signed rank test showed Palacos R and L.V.C. induced a significant decrease of platelet number compared with the negative control. All cements determined a significant increase in beta-TG. CMW 3, Palacos, L.V.C., and Zimmer dough type determined a significant increase in TGF-beta1 compared with the negative control.

Ten-year follow-up of a proximal circumferential porous-coated femoral prosthesis: radiographic evaluation and stability

We studied the radiographic findings on 48 hips in 48 patients to determine the stability of a proximal circumferential porous-coated femoral prosthesis in cementless total hip replacement. The patients had coxarthrosis related to acetabular dysplasia. The follow-up interval in the study was 10 to 13 years. In 36 patients, migration of the femoral component was equal to or less than 2 mm. No patient showed progressive migration. Revision surgery was performed in 37 patients because of migration of the acetabular components. Intraoperatively, no femoral components demonstrated visible motion under stress of the implant-bone interface, and none had been revised. During the follow-up period, two patients had mild thigh pain. Two others sustained fracture of the femur 11 years after surgery due to a fall. Pedestal formation was observed in 39 patients and calcar rounding in 21. The mean diameter of the medullary cavity around the distal part of the prosthesis increased from 13.6 to 16.3 mm average. We conclude that the proximal circumferential porous-coated femoral prosthesis is stable for more than ten years after surgery. The risk of subsequent periprosthetic fractures in elderly patients, however, is a matter of concern.

Thrombomodulin expression in endothelial cells after contact with bone cement

The expression of thrombomodulin after contact with CMW 1 bone cement extracts was studied in human umbilical vein endothelial cells. Cement extracts after 1 h and 7-day curing induced no significant variations in thrombomodulin antigen levels and in mRNA expression. Significant increase of thrombomodulin was observed when endothelial cells were treated with all-trans retinoic acid (ATRA). ATRA induced the increase of thrombomodulin also in cells incubated with cement extracts. These results suggest that CMW 1 bone cement does not impair the expression of thrombomodulin in endothelial cells.

Platelet release of transforming growth factor-beta and beta-thromboglobulin after in vitro contact with acrylic bone cements

Three methacrylate-based bone cements used for the fixation of joint prostheses were evaluated: Sulfix-60 (Sulzer Orthopedic Inc., Baar, Switzerland). CMW1 (DePuy International Ltd., England). and CMW2 (DePuy International Ltd., England). The cements after polymerization were put in contact in vitro with platelet-rich plasma. Plasma, in contact only with siliconized glass, was used as a negative control. After contact, platelet number. beta-thromboglobulin (beta-TG), and transforming growth factor-beta1 (TGF-beta1) were determined. The Student's paired t test showed that the ccments induced no significant modifications of platelet number. CMWI and Sulfix-60 determined a significant increase in beta-TG compared with the negative control. All cements determined a significant increase in TGF-beta1. Significant differences were also seen in the levels of beta-TG and TGF-beta1 between cements with a content of benzoyl peroxide < 1 (Sulfix-60) and those with a content > 1 (CMW1 and CMW2). The cement with zirconium dioxide (Sulfix-60) produced higher levels of beta-TG and TGF-beta1, compared to those with barium sulphate (CMW1 and CMW2). In conclusion, all the cements induced the secretion of TGF-beta1 CMW1 and Sulfix-60 determined also a significant release of beta-TG. Platelet activation induced by the cements from one side could contribute to the pathogenesis of deep venous thrombosis, that often occurs after prosthetic implant and is caused also by other factors, including surgical trauma and venous stasis. From the other side, activated platelets can release growth factors favoring bone formation.

No effect of methacrylate-based bone cement CMW 1 on the plasmatic phase of coagulation, red blood cells and endothelial cells in vitro

The compatibility of a methacrylate-based bone cement (CMW 1, DePuy International Ltd, England) used for the fixation of joint prostheses was evaluated on plasma, an erythrocyte suspension and cultured human endothelial cells. The extract of the cement was tested, following 1 hour and 7 days of curing. After the contact in vitro of the extract with plasma, activated partial thromboplastin time, antithrombin III, thrombin-antithrombin complexes and fibrin degradation products were assayed. Hemolytic activity was tested by adding the cement extracts to a suspension of erythrocytes. After 4 hours of incubation at 37 degrees C, the hemoglobin concentration was determined on the supernatants by the colorimetric method. The effect of the cement on tissue factor and thrombomodulin production was evaluated on human umbilical vein endothelial cell cultures. Tissue factor was determined in cell lysates by enzyme immunoassay, following 4 hours' incubation of cultures with the cement extract. Thrombomodulin was assayed in cell lysates by enzyme immuno assay, after 24 hours' incubation with the cement extract. The response to all trans-retinoic acid (ATRA) was tested. The cement caused no significant modifications of the coagulation tests, had no hemolytic activity, did not determine tissue factor production and did not modify thrombomodulin, compared to the negative control. The response to stimulation with ATRA was similar to that of the negative control. We conclude that the cement extract does not affect the plasmatic phase of coagulation, has no effect on erythrocytes, does not induce the expression of procoagulant activity by endothelial cells and does not impair their antithrombotic property, within the limits of the tests performed.

The incidence of acute cardiorespiratory and vascular dysfunction following intramedullary nail fixation of femoral metastasis

Intramedullary nail fixation is a common treatment for metastatic tumors of the femur with overt or impending femoral fracture. This procedure sometimes causes severe cardiorespiratory and vascular dysfunction. The clinical relevance of this is not dear. We reviewed 45 operations in 43 patients, where intramedullary nail fixation was used to treat metastatic femoral fractures and impending fractures. We studied the incidence of intraoperative oxygen desaturation and hypotension associated with intramedullary manipulation as markers of cardiorespiratory and vascular dysfunction. Acute oxygen desaturation and hypotension occurred in 11 of our 45 patients. Of these, 3 died, 2 required intensive care postoperatively and 6 made uneventful recoveries. We hope to highlight a serious complication in this patient group.

Thromboprophylaxis in hip arthroplasty. New frontiers and future strategy

Coagulation-related complications are a frequent cause of death following hip replacement surgery. Venographically-proven deep vein thrombosis (DVT) is found in a high frequency. Most cases have no symptoms. Fatal pulmonary embolism (PE) may develop from subclinical thrombi. In addition, arterial thromboses may induce serious cardiovascular events and an unknown number of patients may develop cardiorespiratory insufficiency, due to non-fatal venous PE. Finally, several patients may develop venous insufficiency. Recent prospective double-blind studies have shown that the frequency of deep vein thrombosis increased after hospital discharge in patients undergoing hip replacement surgery. Prolonged thrombo-prophylaxis with low-molecular-weight heparin (dalteparin or enoxaparin) is recommended for at least 5 weeks after the operation.