Intra-operative collapse or death related to the use of acrylic cement in hip surgery

Bone Cement and Its Anesthetic Complications: A Narrative Review

The concept of bone cement implantation syndrome (BCIS) is not yet fully understood. In patients undergoing cemented hip arthroplasty, it is a significant factor in intraoperative mortality and morbidity. It may also manifest in a milder form postoperatively, resulting in hypoxia and confusion. In the older population, hip replacement surgery is becoming more prevalent. The risks of elderly patients suffering BCIS may be increased due to co-existing conditions. In this article, we present a narrative review of BCIS including its definition, incidence, risk factors, etiology, pathophysiology, clinical features, prevention, and management, all from an anesthetic point of view.

The Bone Cement Hypercoagulation Syndrome: Pathophysiology, Mortality, and Prevention

Since Charnley introduced acrylic cement to seal metallic hip prostheses in the 1950s, reports of perioperative fatal cardiorespiratory and vascular dysfunctions have been published. Studies on humans and animals have shown neurogenic stimulation and substantial local and systemic activation of coagulation are caused by surgical bone marrow damage and chemical cell destruction by toxic monomeric methyl methacrylate from the implanted cement and other tissue-released substances. Venous blood-borne cell fragments and conjugates of activated cells from the surgical site are sequestered and trapped in the pulmonary microcirculation. A substantial hypercoagulation occurs in the lung circulation. Hypercoagulable blood is passed over to the arterial side and may cause vessel obliteration and organ damage. This process may affect the brain, heart, and kidneys and, through the release of vasoactive substances, introduce hemodynamic imbalances that can lead to fatal outcomes in susceptible populations such as elderly patients with hip fractures. The main underlying pathophysiologic processes leading to these occasionally devastating outcomes are a substantial activation of coagulation and cell destruction caused by the toxic substance released by curing bone cement and several vasoactive substances.

Does the Risk of Death Within 48 Hours of Hip Hemiarthroplasty Differ Between Patients Treated with Cemented and Cementless Implants? A Meta-analysis of Large, National Registries

BACKGROUND

Although current recommendations suggest that hip hemiarthroplasties performed for femoral neck fractures be implanted with bone cement, it is known to cause cardiorespiratory and hemodynamic reactions that in some patients can be fatal. Older patients may be at particular risk of this complication, but because of its relative infrequency, large studies-perhaps even larger than can be achieved in the context of single-country national registries-are needed to get reasonably precise estimates as to its frequency. Pooling results from national registries reporting on death within 48 hours of cement exposure in this setting may therefore be helpful.

QUESTION/PURPOSE

In a systematic review of studies based on large national registries, we asked: Does the risk of death within 48 hours of hip hemiarthroplasty differ between patients treated with cemented and cementless implants?

METHODS

MEDLINE and Embase data sources were searched for cohort studies on patients with hip fractures treated with cement or cementless hip hemiprostheses based on results from national registries that tracked perioperative deaths within 48 hours of surgery, from 2010 or later (to include only studies that used contemporary cement techniques). We excluded registry research on elective THAs for other indications (such as degenerative joint disease), mixed populations (registries that combined patients having arthroplasty for fracture and for other diagnoses like osteoarthritis, such that we could not separate them), and overlapping data from the same registers (to avoid double and triple publications of similar data). Five studies met our inclusion criteria. The cohorts ranged from about 11,000 to about 25,000 patients. About 31% of the patients were in the cementless group. Two studies reported the age ranges of participating patients, and three studies communicated mean ages (which were 82 years for both sexes). Twice as many females as males were present in both the cemented and cementless group. When reported, more than 50% in both groups were in the American Society of Anesthesiologists physical status classification 3 or 4. Study quality was deemed good according to the Newcastle-Ottawa Scale. Publication bias was assessed using a funnel plot and the Egger test, and study heterogeneity was evaluated using the I2 heterogeneity statistic and Cochran Q heterogeneity test. There was some heterogeneity between the studies, with a Cochran Q statistics of 8.13 (degrees of freedom = 4; p = 0.08) and an I2 statistic of 50.8%. There was evidence for a small amount of publication bias (Egger test; p = 0.02). The pooled risk ratio (RR) from a random-effects model is presented with 95% confidence intervals. The primary endpoint was the occurrence of any fatalities within 48 hours of hip fracture treatment with cementless compared with cemented prostheses. We performed a sensitivity analysis to assess the needed association of a potential unmeasured or uncontrolled confounding, and we made an estimate of the amount of unmeasured confounding that would need to be present in order to change the direction of the result. We summarized this using a parameter known as the "E-value." Based on that sensitivity analysis, we found it unlikely that an unmeasured hypothetical confounder could explain the significant association between cemented and cementless implants and risk of death within 48 hours of hip hemiarthroplasty.

RESULTS

Compared with the cementless group, mortality was increased in the cemented group (RR 1.63 [95% CI 1.31 to 2.02]; p < 0.001). The number needed to harm from the pooled data was 1 of 183 operated patients; that is, for every 183 patients treated with cemented implants, one death would be expected.

CONCLUSION

Bone cement is associated with a higher risk of fatalities within 48 hours of surgery compared with cementless prostheses. However, numerous prior studies have found a higher risk of serious complications resulting in additional surgical procedures associated with cementless devices in this population; those complications, as well, may result in death. Based on our study alone, we cannot recommend cementless implants in this setting. Large, national registries should evaluate fixation choice in older patients with hip fractures, and those studies should consider both early death and the potential for later harms.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Inhaled prostacyclin for the prevention of increased pulmonary vascular resistance in cemented hip hemiarthroplasty-A randomised trial

BACKGROUND

Bone cementation may cause pulmonary vasoconstriction and ventilation/perfusion abnormalities in patients undergoing cemented hip hemiarthroplasty. In this randomised trial, we tested the hypothesis that intra-operative inhalation of prostacyclin could attenuate the increase in pulmonary vascular resistance index (PVRI, primary endpoint) when compared to inhaled saline in this group of patients.

METHODS

Twenty-two patients with displaced femoral neck fractures were allocated to receive inhaled aerosolised prostacyclin (20 ng/kg/min) (n = 11) or inhaled saline (NaCl, 9 mg/mL) (n = 11). All patients received total intravenous anaesthesia and were catheterised with radial and pulmonary artery fast response thermodilution catheters, for measurements of arterial and pulmonary arterial pressures, cardiac output, right ventricular ejection fraction and effective pulmonary arterial elastance. Haemodynamic measurements were performed after induction of anaesthesia, during surgery before and immediately after bone cementation and prosthesis insertion, 10 and 20 min after insertion and during skin closure.

RESULTS

During the surgical procedure, PVRI increased both in the saline (44%, P < 0.001) and the prostacyclin (36%, P = 0.019) groups, with a less pronounced increase in the prostacyclin group (P = 0.031). Effective pulmonary arterial elastance increased both in the saline (44%, P < 0.001) and the prostacyclin groups (29%, P = 0.032), with a trend for a less pronounced increase in the prostacyclin group (P = 0.084). Right ventricular ejection fraction decreased significantly in both groups with no difference between the groups.

CONCLUSION

Inhalation of prostacyclin attenuates the increase in pulmonary vascular resistance in patients undergoing cemented hip hemiarthroplasty and could potentially attenuate/prevent haemodynamic instability induced by an increase in right ventricular afterload seen in this procedure.

Sudden death during hip replacement surgery: A case series

Hip arthroplasty (hip replacement) surgery is a very common procedure and is particularly common in elderly individuals, where it is typically performed following traumatic hip fracture. As with any surgical procedure, hip arthroplasties are associated with a certain degree of morbidity and mortality, with many deaths occurring in the post-operative period. As most of these cases result from trauma (fractured hips), they are typically referred for medicolegal death investigation. Occasionally, sudden cardiorespiratory collapse and death occurs during hip arthroplasty surgery. In certain medicolegal jurisdictions, all intra-operative deaths must be investigated. Although many post-operative arthroplasty-related deaths might not require autopsy, those that occur intra-operatively may require autopsy. While clinical decision-making during recent years has resulted in fewer arthroplasty-related deaths, intraoperative deaths may still occur. In this review, the authors present their experience with three intra-operative arthroplasty-related deaths, followed by a discussion related to possible mechanisms involved in the deaths.

Pulmonary haemodynamics and right ventricular function in cemented vs uncemented total hip arthroplasty-A randomized trial

BACKGROUND

Bone cement implantation syndrome (BCIS) is a feared complication in orthopaedic surgery with a huge impact on post-operative morbidity. In this randomized trial, we evaluated the effects of bone cement on pulmonary and systemic haemodynamics in patients receiving either cemented or uncemented hip arthroplasty for isolated femoral neck fracture.

METHODS

Twenty-two patients were randomized to receive either cemented (n = 10) or uncemented (n = 12) total hip arthroplasty. Surgery was performed under total intravenous anaesthesia in the lateral position. All patients were catheterized with radial- and pulmonary artery catheters, for continuous measurements of mean arterial pressure (MAP), pulmonary arterial pressure (PAP), cardiac output, right ventricular (RV) end-diastolic volume (RVEDV) and RV ejection fraction (RVEF). Haemodynamic measurements and blood gas analyses were performed after induction of anaesthesia, during surgery before and immediately after bone cementation and prosthesis insertion, 10 and 20 minutes after insertion and during skin closure.

RESULTS

Pulmonary vascular resistance index (PVRI) increased during and after prosthesis insertion by 45% and 20% in the cemented and uncemented group, respectively (P < 0.005). Systolic and mean PAP increased by 18% and 17% in the cemented group, which was not seen in the uncemented group (P < 0.001). There was a trend for a more pronounced fall in RVEF in the cemented group, while there were no differences in cardiac output or stroke volume between groups.

CONCLUSION

The use of bone cement in total hip arthroplasty increases pulmonary vascular resistance and the afterload of the RV with potentially negative effects on RV performance.

Intraoperative blood pressure changes during cemented versus uncemented bipolar hemiarthroplasty for displaced femoral neck fracture: a multi-center cohort study : The effect of bone cement for bipolar hemiarthroplasty in elderly patients

INTRODUCTION

The purpose of this study was to compare the cemented bipolar hemiarthroplasty with uncemented about the change of intraoperative blood pressure and the incidence of major complications in elderly patients with femoral neck fracture.

MATERIALS AND METHODS

This multiple center prospective cohort study included only patients with acute displaced femoral neck fracture (Garden stage III or IV). All patients were treated with cemented or uncemented bipolar hemiarthroplasty using modified Hardinge or Watson-Jones approach in the lateral decubitus position. Baseline data, medical history, type of anesthesia, FiO₂ value, the number of vasopressor using during operation, femoral component, intraoperative blood pressure, SaO₂, and major complications were evaluated.

RESULTS

Of 164 patients (45 males and 119 females), 86 underwent cemented and 78 underwent uncemented bipolar hemiarthroplasty. Baseline medical histories were similar in both groups. In both the cemented and uncemented groups, intraoperative systolic blood pressure significantly decreased during cementing or rasping (106.3 and 103.6 mmHg) and after femoral component insertion (103.3 and 99.1 mmHg) compared to before rasping (120.7 and 116.4 mmHg) (p < 0.0001, respectively). Donaldson's grade seemed more favorable in uncemented group than in cemented group during cementing or rasping, during stem insertion; however, no patients experienced the lethal complication in both groups.

CONCLUSIONS

Intraoperative blood pressure did not change during cemented and uncemented bipolar hemiarthrplasty for displaced femoral neck fracture. If the standard modern cement technique was performed during operation, bone cement is a safe and acceptable for elderly patients who have a lot of medical histories.

Evaluation of the incidence of pulmonary embolus in the early postoperative period following cemented hemiarthroplasty

PURPOSE

Little is known regarding the incidence of early postoperative pulmonary embolus (PE) following hip fracture surgery. Clinical suspicion of PE mandates therapeutic anticoagulation, adding a further insult to those of trauma and surgery in a physiologically frail population. The aim of the study was to evaluate for the presence of PEs by performing postoperative CT pulmonary angiography (CTPA) in patients who demonstrated intraoperative, or early postoperative cardiorespiratory lability following surgery with a cemented prosthesis for intracapsular hip fracture.

METHODS

All patients undergoing cemented hemiarthroplasty for displaced intracapsular neck of femur fracture were recruited during a 6-month period, and signed consent obtained from the patient or their next of kin for CTPA in the event of any cardiorespiratory instability. Patient demographics, comorbidities were reviewed, and premorbid mobility status documented.

RESULTS

18 of the 66 patients in the study having cemented hemiarthropalsty demonstrated intra- or early postoperative lability, all had early postoperative CTPA scans. 6 of the 18 were noted to have PE. All had more than 1 risk factor for VTE on admission (excluding their injury). Patients diagnosed with PE had a higher ASA grade, and lower mobility scores than those who did not have a PE.

CONCLUSIONS

Clinical suspicion alone is inadequate to diagnosis PE in patients undergoing cemented hip arthroplasty. Only 1 in 3 patients suspected of PE on account of intraoperative or immediate postoperative cardiorespiratory lability was found to have a PE based on CTPA. Early postoperative CTPA is helpful to prevent unnecessary anticoagulation for suspected PE.

An Experimental Study to Determine the Role of Inferior Vena Cava Filter in Preventing Bone Cement Implantation Syndrome

BACKGROUND

Inferior vena cava filters (IVCF) are frequently used for preventing pulmonary embolism (PE) following deep venous thromboembolism.

OBJECTIVES

The present study was designed to investigate whether IVCF could prevent or impede the occurrence of bone cement implantation syndrome (BCIS), since PE is considered as the central mechanism of BCIS.

MATERIALS AND METHODS

Fifteen sheep were divided into three groups: bone cement free (BCF) group, cement implantation (CI) group and IVCF group. In all the groups, an osteotomy proximal to the greater trochanter of left femur was carried out. In BCF group, the femoral canal was not reamed out or packed with any bone cement. In CI and IVCF groups, the left femoral canals were packed with bone cement, to simulate the cementing procedures carried out in hip replacement. An OptEase(®) filter was placed and released in inferior vena cava, prior to packing cement in the femoral canal in IVCF group, while the IVCF was not released in the CI group. The BCF group was considered as control.

RESULTS

Systolic blood pressure (SBP), saturation of oxygen (SaO2) and partial pressure of carbon dioxide (PaCO2) declined significantly 10 min after the bone cement packing, in CI group, compared to those in BCF group. This was accompanied by a rise in the arterial pH. However, IVCF prevented those changes in the CI group. On ultrasonography, there were dotted echoes in right atrium in the CI group, after bone cement packing, while such echoes were hardly seen in the IVCF group.

CONCLUSION

This study demonstrates that IVCF could prevent BCIS effectively, and, as a corollary, suggests that PE represents the leading cause of the constellation of BCIS symptoms.

Comparison of hemodynamic changes between old and very old patients undergoing cemented bipolar hemiarthroplasty under spinal anesthesia

Background

The old age population, including the very old aged (≥ 85 years), is rapidly increasing, and femur neck fracture from accidents is commonly seen in the elderly. Use of bone cement during bipolar hemiarthroplasty can cause bone cement implantation syndrome.

Methods

This study was prospectively conducted on the elderly who were scheduled to undergo elective cemented bipolar hemiarthroplasty under spinal anesthesia. Patients were divided into 2 groups: the old age (65-84 years) and very old age groups (≥ 85 years). Hemodynamic parameters were recorded at the following time points: the start of the operation, femoral reaming, cement insertion, every 2 minutes after cement insertion for 10 minutes, femoral joint reduction, and the end of operation. When hypotension occurred, ephedrine was given.

Results

Sixty-five patients in the old age group and 32 patients in the very old age group were enrolled. Mean ages were 78.9 and 89.4 years, respectively, in the old age and very old age groups. The very old age group showed constantly decreased levels of cardiac index and stroke volume from cementing until the end of the operation compared to the old age group. To maintain hemodynamic stability after cement insertion, the requirement of ephedrine was higher in the very old age group than in the old age group (13.52 ± 7.76 vs 8.65 ± 6.38 mg, P = 0.001).

Conclusions

Bone cement implantation during bipolar hemiarthroplasty may cause more prominent hemodynamic changes in very elderly patients. Careful hemodynamic monitoring and management are warranted in very elderly patients undergoing cemented bipolar hemiarthroplasty.

Management of skeletal metastases: An orthopaedic surgeon's guide

Skeletal metastasis is a common cause of severe morbidity, reduction in quality of life (QOL) and often early mortality. Its prevalence is rising due to a higher rate of diagnosis, better systemic treatment, longer lives with the disease and higher disease burden rate. As people with cancer live longer and with rising sensitivity of body imaging and surveillance, the incidence of pathological fracture, metastatic epidural cord compression is rising and constitutes a challenge for the orthopedic surgeon to maintain their QOL. Metastatic disease is no longer a death sentence condemning patients to "terminal care." In the era of multidisciplinary care and effective systemic targeted and nontargeted therapy, patient expectations of QOL, even during palliative end of care period is high. We lay emphasis on proving the diagnosis of metastasis by biopsy and histopathology and discuss imaging modalities to help estimate fracture risk and map disease extent. This article discusses at length the evidence and decision-making process of various modalities to treat skeletal metastasis. The modalities range from radiation including image-guided, stereotactic and whole body radiation, systemic targeted or hormonal therapy, spinal decompression with or without stabilization, extended curettage with stabilization, resection in select cases with megaprosthetic or biological reconstruction, percutaneous procedures using radio frequency ablation, cementoplasties and discusses the role of emerging modalities like high frequency ultrasound-guided ablation, cryotherapy and whole body radionuclide therapy. The focus lies on the role of multidisciplinary care, which considers complex decisions on patient centric prognosis, comorbidities, cost, feasibility and expectations in order to maximize outcomes on QOL issues.

Bone cement implantation syndrome in cemented hemiarthroplasty for femoral neck fracture: incidence, risk factors, and effect on outcome

BACKGROUND

Bone cement implantation syndrome (BCIS) is characterized by hypoxia, hypotension, and loss of consciousness occurring around the time of bone cementation. Using a recently proposed severity classification of BCIS, we estimated the incidence of and risk factors for BCIS and its impact on mortality in cemented hemiarthroplasty for femoral neck fractures.

METHODS

In this retrospective study, 1016 patients undergoing cemented hemiarthroplasty were included. Medical history and medication were obtained from medical records. Anaesthesia charts for all patients were reviewed for mean arterial pressure, arterial oxygen saturation, and heart rate before, during, and after cementation. Each patient was classified as having no BCIS (grade 0) or BCIS grade 1, 2, or 3, depending on the degree of hypotension, arterial desaturation, or loss of consciousness around cementation.

RESULTS

The incidence of BCIS grade 1, 2, and 3 were 21%, 5.1%, and 1.7%, respectively. Early mortality in BCIS grade 1 (9.3%) did not differ significantly from BCIS grade 0 (5.2%), while early mortality in BCIS grade 2 (35%) and grade 3 (88%) were significantly higher when compared with grades 0 and 1. Early mortality was also higher in BCIS grade 3 when compared with grade 2. Independent predictors for severe BCIS were: ASA grade III-IV, chronic obstructive pulmonary disease, and medication with diuretics or warfarin. Severe BCIS was associated with 16-fold increase in mortality.

CONCLUSIONS

BCIS is a commonly occurring phenomenon in cemented hemiarthroplasty and severe BCIS has a huge impact on early and late mortality.

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.

Bone cement embolism attached to central venous catheter

We report on a rare complication of poly(methyl methacrylate) (PMMA), injected into the spine, which then inadvertently leaked into the venous system. This resulted in an embolism of PMMA and produced a mass surrounding a triple lumen central venous catheter located in the superior vena cava. The catheter as well as the attached mass of PMMA was retrieved safely by cardiothoracic surgery. This case emphasizes the importance of prompt diagnosis and treatment and illustrates the need for close monitoring of patients undergoing any spinal surgery that includes vertebroplasty.

Transient thermal sympathectomy as a possible mechanism for hypotension after kyphoplasty: a case report

BACKGROUND

Vertebroplasty and kyphoplasty are minimally invasive treatments for vertebral compression fractures. Although infrequent, both transitory and persistent adverse effects have been reported. They range from asymptomatic to severe neurological deficits that are caused directly by polymethylmethacrylate (PMMA) leakage or may be related to local or general reactions not due to PMMA leakage. Transitory hypotension after the procedure has been observed, but the characteristics and etiology of this phenomenon are not defined.

OBJECTIVE

To describe a case of prolonged hypotension after kyphoplasty and suggest a possible mechanism.

METHODS

Six months after L2 kyphoplasty, a 63-year-old woman with severe osteoporosis developed a new back pain due to compression fracture of L1 and compression deformity of the superior L3 endplate. The patient underwent bilateral kyphoplasty at the L1 and L3 levels. She developed persistent hypotension for approximately 46 hours immediately after the procedure. Common causes of hypotension were ruled out and the event resolved spontaneously.

RESULTS

On the basis of needle placement, the temporal relationship between the procedure and blood pressure change, and the lack of other identifiable causes, thermal sympathectomy from heating of the PMMA adjacent to the paravertebral sympathetic chain is proposed as a potential mechanism.

LIMITATIONS

Single case report based on clinical observation.

DISCUSSION

Prolonged hypotension can complicate kyphoplasty at upper lumbar levels. Two days of severe hypotension has not been described as a complication of kyphoplasty. Although the mechanism is unknown, a transient thermal sympathectomy may be the cause.

Safety and efficacy of non-cemented femoral fixation in patients 75 years of age and older

The aim of this study was to assess peri-operative complications, safety and efficacy of non-cemented femoral fixation in total hip arthroplasty (THA) as compared to cemented femoral fixation in the elderly population. Fifty-two matched pair analysis of patients with 75 years of age and older (104 patients), who underwent primary THA from June 1997 to December 2004, was performed based on age, sex, BMI, and Charnley classification. Mean age was 81 years (75-101) and the average follow up was 3.1 ± 2.9 years (1.2-6.4). There was no difference in peri-operative cardiopulmonary complications, pulmonary failures, deep venous thrombosis, pulmonary embolus, length of stay, or discharge deposition between the two groups. Non-cemented fixation is safe and effective in patients older than 75 years of age.

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.

Is there a difference in perioperative mortality between cemented and uncemented implants in hip fracture surgery?

INTRODUCTION

Although cemented implants have proven beneficial over uncemented implants for treatment of displaced sub-capital proximal femoral fractures, there are concerns regarding the haemodynamic consequence of using cemented implants in hip fracture patients. National Patient Safety Agency recently issued an alert regarding the use of cement in hip fracture surgery. We compared the incidence and pattern of 48 h perioperative mortality between patients receiving cemented and uncemented implants after hip fracture surgery.

METHODS

Using data prospectively recorded in hospital care records, we retrospectively reviewed the case records of all patients who died in hospital following hip fracture surgery between January 2005 and April 2010. We recorded demographic variables, type of fracture, implant used, medical co-morbidity, seniority of operating surgeon and anaesthetist, perioperative haemodynamic status, time and cause of death.

RESULTS

We identified 15 cases of perioperative death (PoD) over a 64-month period. PoD was 1% (15/1402). Eight of 15 deaths occurred following cemented hemiarthroplasty insertion. There were four cases of intra-operative death, two of them were following cemented hemiarthroplasty insertion. PoD following cemented hemiarthroplasty was 2.54% (8/314) and nil (0/168) following uncemented Austin-Moore hemiarthroplasty. Operations were performed by both trainees (six) and consultants (two). Both trainees (five) and consultants (three) anaesthetised the patients. None of the patients belonged to American Society of Anesthesiologists (ASA) I or II (ASA III 5 and IV 3). All patients had significant cardiovascular or pulmonary co-morbidity. Apart from the cases of immediate haemodynamic collapse and death, cemented implant insertion was followed by intra-operative haemodynamic instability in 2/15 and perioperative instability in 3/15 patients. Post-mortem was performed in 3/8 patients: 2/3 demonstrated pulmonary embolism (PE), 1/3 bronchopneumonia. Of the rest, 3/5 had suspected myocardial infarction (MI).

CONCLUSION

There was 1% risk of perioperative death after hip fracture surgery. Risk of perioperative death was significantly higher following cemented implant insertion. Mortality risk was exacerbated in patients with pre-existing cardiovascular morbidity and was independent of the seniority of the surgeon or the anaesthetist.

Phosphorylated Pullulan Bioadhesive for Regeneration and Reconstruction of Bone and Tooth

A biodegradable material that bonds to hard tissues such as bones and teeth is urgently needed for medical and dental applications. However, such materials are not available in today’s clinical practice of orthopedics and dentistry. Therefore, we synthesized biodegradable phosphorylated pullulan to develop a biomaterial that combines primary properties such as high biocompatibility, good bonding potential to hard tissue, high strength, biodegradability, and osteoconductivity. The pharmacopoeial polysaccharide pullulan was chemically functionalized with dihydrogen phosphate groups. Phosphorylated pullulan was formed network by adding calcium ion, making the composite less soluble in water. Adhesive force measurement revealed that adhesiveness of the pastes before setting can be controlled through optimization of additives. In addition, histological evaluation revealed that phosphorylated pullulan-based composite possesses high biocompatibility. These results indicate that phosphorylated pullulan can be used as a key material for regeneration and reconstruction of bone and tooth.

Noise-enhanced clustering and competitive learning algorithms

Noise can provably speed up convergence in many centroid-based clustering algorithms. This includes the popular k-means clustering algorithm. The clustering noise benefit follows from the general noise benefit for the expectation-maximization algorithm because many clustering algorithms are special cases of the expectation-maximization algorithm. Simulations show that noise also speeds up convergence in stochastic unsupervised competitive learning, supervised competitive learning, and differential competitive learning.

Predictors of intensive care unit admission after total joint arthroplasty

Total joint arthroplasty (TJA) is a relatively safe orthopedic procedure. However, complications do occur, and some may necessitate admission to the intensive care unit (ICU). Our purpose was to determine risk factors associated with admittance to ICU after TJA. We evaluated 22,343 primary and revision total hip and knee arthroplasties from 1999 to 2008. One hundred thirty patients were admitted to the ICU. Cases were matched 1:2 for date of surgery, surgeon, and type of surgery. The causes for admission to ICU were recorded. Independent risk factors for ICU admission were smoking, cemented arthroplasty, general anesthesia, allogenic transfusion, higher C-reactive protein, lower hemoglobin level, higher body mass index, and older age. Proper identification and management of these "at-risk" patients may decrease the incidence of ICU admittance after TJA.

Perioperative pulmonary circulatory changes during bilateral total hip arthroplasty under regional anesthesia

BACKGROUND AND OBJECTIVES

The transient and rarely clinically relevant effect of bone and cement embolization during unilateral joint arthroplasty is a known phenomenon. However, available studies do not address events surrounding bilateral total hip arthroplasties, during which embolic load is presumably doubled. To elucidate events surrounding this increasingly used procedure and assess the effect on the pulmonary hemodynamics in the intraoperative and postoperative periods, we studied 24 subjects undergoing cemented bilateral total hip arthroplasty during the same anesthetic session.

MATERIALS

Twenty-four patients without previous pulmonary history undergoing cemented bilateral total hip arthroplasty under controlled epidural hypotension were enrolled. Pulmonary artery catheters were inserted and hemodynamic variables were recorded at baseline, 5 mins after the implantation of each hip joint, 1 hr and 1 day after surgery. Mixed venous blood gases and complete blood counts were analyzed at every time point.

RESULTS

An increase in pulmonary vascular resistance was observed after the second but not the first hip implantation when compared with values at incision. Pulmonary vascular resistance remained elevated 1 hr after surgery. Pulmonary artery pressures were significantly elevated on postoperative day 1 compared with those at baseline. The white blood cell count increased in response to the second hip implantation but not the first compared with incision.

CONCLUSIONS

The embolization of material during bilateral total hip arthroplasty is associated with prolonged increases in pulmonary artery pressures and vascular resistance, particularly after completion of the second side. Performance of bilateral procedures should be cautiously considered in patients with diseases suggesting decreased right ventricular reserve.

Influence of the pre-operative time in upright sitting position and the needle type on the incidence of post-dural puncture headache (PDPH) in patients receiving a spinal saddle block for anorectal surgery

BACKGROUND

A spinal saddle block can be a safe method for anorectal surgery with a low rate of complications when performed with the right technique. A dreaded complication is the post-dural puncture headache (PDPH), which can be decreased by the use of non-cutting spinal needles. Regrettably, cutting Quincke (Q)-type needles are still widely used for economic reasons. Besides size and design of a spinal needle, the pre-operative time in upright sitting position may also influence the incidence of PDPH after spinal saddle block.

METHODS

Within 4 months, 363 patients undergoing anorectal surgery in saddle block technique were randomised to receive either a 27-gauge (G) pencil-point (PP) or a 27-G Q spinal needle and were pre-operatively left in upright sitting position for 10 or 30 min, respectively. The incidence of PDPH was assessed 1 week after the operation via a telephone interview.

RESULTS

Three hundred sixty three patients (219 males/144 females) were analysed. Fifteen patients (4.1%) developed PDPH. Patients receiving spinal anaesthesia with a Q needle suffered significantly more frequently from PDPH [Q: n = 12 (6.6%) vs. PP: n = 3 (1.7%), p = 0.02], but there was no association between PDPH and pre-operative time in the upright position (p = 0.20).

CONCLUSIONS

These data prove that using 27-G PP needles is the method with the fewest side effects caused by spinal saddle block, and suggest that the time spent sitting in the upright position is not clinically relevant.

Pulmonary haemodynamics and right ventricular function during cemented hemiarthroplasty for femoral neck fracture

BACKGROUND

Bone cement implantation syndrome (BCIS) is characterised by hypoxia, hypotension and loss of consciousness occurring early after bone cementation. The haemodynamic perturbations during BCIS have not been extensively studied, particularly not in patients with femoral neck fracture. We evaluated the effects of cemented hemiarthroplasty, in these patients, on pulmonary haemodynamics, right ventricular performance, intrapulmonary shunting and physiological dead space.

METHODS

Fifteen patients undergoing cemented hemiarthroplasty because of femoral neck fracture were included. Surgery was performed under total intravenous anaesthesia in the lateral position. All patients were catheterised with a radial and pulmonary artery catheter, for continuous measurements of mean arterial pressure (MAP), pulmonary arterial pressure (PAP), cardiac output, mixed venous oxygen saturation, right ventricular end-diastolic volume (RVEDV) and right ventricular ejection fraction (RVEF). Haemodynamic measurements and blood gas analyses were performed after induction of anaesthesia, during surgical stimulation before and immediately after bone cementation and prosthesis insertion, 10 and 20 min after insertion and during skin closure.

RESULTS

After bone cementation and prosthesis insertion, MAP (-10%), cardiac index (-10%) and stroke volume index (-10%) decreased, while PAPs (10-15%) and the pulmonary vascular resistance index (45%) increased. RVEF decreased by 10-20%, while the RVEDV index increased by 10%. Pulmonary haemodynamic and RV variables changed progressively with time, while intra-pulmonary shunting and physiological dead space increased immediately after prosthesis insertion and then returned to baseline.

CONCLUSIONS

Cemented hemiarthroplasty in patients with femoral neck fracture causes a pronounced pulmonary vasoconstriction and an impairment of RV function accompanied by pulmonary ventilation/perfusion abnormalities.

Perioperative mortality in patients with pulmonary hypertension undergoing major joint replacement

BACKGROUND

There is a paucity of perioperative outcomes data for patients with chronic pulmonary hypertension (PHTN) undergoing noncardiac surgery. Clinicians, therefore, have little information on which to evaluate the risk for morbidity and mortality in this patient population. In this study, we evaluated the incidence and risks of perioperative morbidity and mortality in patients with PHTN undergoing primary total hip arthroplasty (THA) and total knee arthroplasty (TKA).

METHODS

Using the largest inpatient database in the United States (National Inpatient Sample), we identified entries for THA and TKA between the years of 1998 and 2006. Patients with the diagnosis of PHTN were identified and matched to those without the disease based on health-related demographic variables. Perioperative mortality was considered the primary outcome. Multivariate logistic regression models were fitted to assess the impact of PHTN on in-hospital mortality.

RESULTS

We identified 670,516 entries for TKA and 360,119 for THA. Of those patients, 2184 (0.3%) and 1359 (0.4%), respectively, had the diagnosis of PHTN (average annual rate of 1180 for TKA [range, 507-2073] and 739 for THA [range, 467-1054]). Patients with PHTN undergoing THA experienced an approximately 4-fold increased adjusted risk of mortality (2.4% vs 0.6%), and those undergoing TKA a 4.5-fold increased adjusted risk of mortality (0.9% vs 0.2%) compared with patients without PHTN in the matched sample (P < 0.001 for each comparison). Patients with primary PHTN undergoing THA experienced the highest mortality rate (5% [95% CI, 2.3%-7.7%]).

CONCLUSIONS

This analysis demonstrates that patients with PHTN are at increased risk for perioperative mortality after THA and TKA.

Cemented versus uncemented hemiarthroplasty for displaced femoral neck fractures

Hemiarthroplasty is the most commonly used treatment for displaced femoral neck fractures in the elderly. There is limited evidence in the literature of improved functional outcome with cemented implants, although serious cement-related complications have been reported. We performed a randomized, controlled trial in patients 70 years and older comparing a cemented implant (112 hips) with an uncemented, hydroxyapatite-coated implant (108 hips), both with a bipolar head. The mean Harris hip score showed equivalence between the groups, with 70.9 in the cemented group and 72.1 in the uncemented group after 3 months (mean difference, 1.2) and 78.9 and 79.8 after 12 months (mean difference, 0.9). In the uncemented group, the mean duration of surgery was 12.4 minutes shorter and the mean intraoperative blood loss was 89 mL less. The Barthel Index and EQ-5D scores did not show any differences between the groups. The rates of complications and mortality were similar between groups. Both arthroplasties may be used with good results after displaced femoral neck fractures.

R-wave Changes in Fatal Air Embolism During Bone Cementation

Holter monitoring during cementation of a hip prosthesis showed sudden R-wave loss. At post mortem, demonstration of a large intracardiac air embolus may explain the ECG changes.

Bone cement implantation syndrome

Bone cement implantation syndrome (BCIS) is poorly understood. It is an important cause of intraoperative mortality and morbidity in patients undergoing cemented hip arthroplasty and may also be seen in the postoperative period in a milder form causing hypoxia and confusion. Hip arthroplasty is becoming more common in an ageing population. The older patient may have co-existing pathologies which can increase the likelihood of developing BCIS. This article reviews the definition, incidence, clinical features, risk factors, aetiology, pathophysiology, risk reduction, and management of BCIS. It is possible to identify high risk groups of patients in which avoidable morbidity and mortality may be minimized by surgical selection for uncemented arthroplasty. Invasive anaesthetic monitoring should be considered during cemented arthroplasty in high risk patients.

Surgical applications of methyl methacrylate: a review of toxicity

Methyl methacrylate (MMA) is a monomer of acrylic resin widely used in a variety of medical, dental, and industrial applications. Its extensive use in surgery, particularly for arthroplasties, has often raised concerns regarding potential human toxicity for orthopaedic surgeons, surgical nurses, and other operating-room staff who are occupationally exposed to the compound. The main toxic effects of MMA exposure appear to involve the cardiovascular system. When exposed to MMA in the work environment, surgical staff have been reported to suffer from hypersensitivity, asthmatic reactions, local neurological symptoms, irritations and local dermatological reactions. The integrity of latex gloves may also be compromised following exposure to MMA during surgical procedures. At present, MMA is not thought to be carcinogenic to humans under normal conditions of use. Nevertheless, sound occupational hygiene practices should still be used to help reduce workplace exposure to MMA during orthopaedic and other medical procedures. Surgical staff should avoid direct contact with MMA mixtures wherever possible, and room ventilation and adequate airflow should also be optimized. In the present article, the authors review studies relating to MMA toxicity in surgical practice, updating in part a previous literature review and expanding on the toxicity of MMA within the surgical setting.

Intraoperative embolism and hip arthroplasty: intraoperative transesophageal echocardiographic study

OBJECTIVES

Cardiopulmonary complications are well known in orthopaedic surgery. The aim of the present study was to evaluate the relevance and the origin of embolization, to correlate the event with the procedure and to establish the clinical relevance of this phenomenon.

METHODS

We performed transesophageal echocardiography (TEE) on 40 patients during total hip arthroplasty, 19 males and 21 females, average age 66 years, with a negative medical history for heart and lung diseases, who underwent an operation for hip prosthesis (22 patients) or surgery for medial fracture (18 patients). Of these, 22 patients received a cemented prosthesis and 18 patients received an uncemented one.

RESULTS

During the placement of the acetabular and femoral components, and during the relocation of the hip joint, a snow flurry appearing in the right heart was followed by several highly echogenic and mobile emboli of various sizes.

CONCLUSIONS

Our data suggest that the presence of emboli detected by TEE in the right heart and pulmonary artery appears to derive principally from the reaming of the femoral canal and the placement of the femoral stem, particularly during the placement of cemented prostheses. However, the passage of embolic material had no adverse sequelae. For these reasons routine, intraoperative TEE cannot be recommended in orthopaedic surgery.

Critical care issues in the patient after major joint replacement

Admission rates of orthopedic patients to intensive care units are increasing. Thus, an intensivist's familiarity with specific problems associated with major joint replacement surgery is of utmost importance in order to meet the needs of this particular patient population. In this article, the authors review the most commonly encountered complications after major hip and knee arthroplasty. Perioperative risk factors for morbidity and mortality and the epidemiology, diagnosis, and treatment of cardiopulmonary complications in this patient population are discussed. Procedure-specific complications such as fat embolism and acrylic bone cement-related issues are reviewed.

Perioperative morbidity and mortality after reconstruction for metastatic tumors of the proximal femur and acetabulum

An observational cohort study was performed on 90 hip arthroplasties performed in 84 patients for metastatic disease of the hip. Significant improvement was noted with both 3-month and 6-month function scores vs preoperative function scores (P < .001). Complications included 1 intraoperative femur fracture, 2 cases of deep venous thrombosis, 1 peroneal nerve palsy, 1 deep infection, and 5 dislocations. Eight (8.8% of 90 procedures, 9.4% of 84 patients) patients died during the initial hospital stay. Although the risk of mortality after hip arthroplasty for metastatic diseases is perhaps higher than previously expected, improvement in postoperative function scores in surviving patients was significant and perioperative morbidity in this complex patient population was acceptably low.

Complications of cemented long-stem hip arthroplasties in metastatic bone disease

It is controversial whether a cemented long-stem femoral arthroplasty is a safe surgical option for patients with meta-static bone disease of the hip. Cemented long stems increase the risk of embolic cascades and may cause subsequent cardiopulmonary complications, particularly in patients with metastatic disease. We retrospectively reviewed results of 29 long-stem cemented femoral arthroplasties in 27 patients in which surgical techniques that minimized intramedullary debris and canal pressurization were used. The surgical techniques minimized intraoperative cement-related emboli with aggressive medullary lavage, intraoperative canal suctioning during cementation, use of early low-viscosity polymethylmethacrylate, and slow, controlled insertion of the long-stem prosthesis. Cement-associated hypotension occurred in four (14%) patients, sympathomimetics were administered in nine (31%) patients, and a worsening mental status occurred postoperatively in one (3%) patient. There were no cement-associated desaturation events, cardiac arrests, or intraoperative deaths. No patients required prolonged intubation, and there were no postoperative cardiopulmonary events. Cemented long-stem femoral arthroplasty is a safe procedure for patients with high-risk metastatic disease. Increased awareness of cement-related cardiopulmonary pathophysiology, and modifying conventional surgical techniques can minimize cement-associated complications.

LEVEL OF EVIDENCE

Therapeutic study, Level IV (case series). See the Guidelines for Authors for a complete description of levels of evidence.

Influence of Novel Resin Monomer on Viability of L-929 Mouse Fibroblasts in vitro

We have previously synthesized a novel acrylic resin monomer, methacryloyloxyethyl methyl succinate (TA). The aim of this in vitro study, therefore, was to examine its influence on cell viability using L-929 mouse fibroblasts and then compare the results with MMA, EMA, and LMA. Medium containing each monomer was changed every 15 minutes as some monomers were volatile. After one hour of exposure, these mediums were replaced with a normal medium and cells were further incubated for 72 hours. IC50 value for each monomer was determined, and chronological cell viability and cytomorphologic observation were evaluated. Viability was impaired in a dose-dependent manner. All monomers, except TA, tended to correlate between molecular weight and cell viability. On the other hand, TA showed excellent viability and did not impair growth abruptly. These results thus demonstrated that cellular damage by TA was much lower than that by other monomers.

Polymethylmethacrylate causes prolonged pulmonary hypertension during fat embolism: a study in sheep

BACKGROUND

Fat embolism (FE), the release of bone marrow contents into the circulation and the subsequent cardiovascular changes, is still a potentially fatal com-plication during orthopedic surgery. Different causative factors have been suggested, but the exact pathomechanism of FE still remains unclear. We investigated the role of polymethylmethacrylate (PMMA) in FE during vertebroplasty in sheep.

METHODS

In 8 sheep, two vertebral bodies were augmented alternatively with PMMA or bone wax. Pulmonary and cardiovascular parameters were monitored during the procedure.

RESULTS

The peak response was similar for both groups and characterized by hypotension, a drop in cardiac output and pulmonary hypertension. However, the recovery in pulmonary arterial pressure and pulmonary vascular resistance was quicker in the wax group.

INTERPRETATION

The injection of PMMA may cause prolonged pulmonary hypertension during vertebro-plasty and also arthroplasty. Surgeons should be aware of this potential cardiovascular complication, especially in patients with impaired pulmonary and cardiovascular function.

[Surgical treatment of a displaced femoral head fracture with a cement-free dual-headed prosthesis using a minimally invasive approach. Clinical and radiographic outcome]

One hundred patients treated with a cementless bipolar prosthesis for a displaced subcapital hip fracture were prospectively evaluated for clinical and radiographic outcome. All patients were operated via a minimally invasive approach; in every case we implanted a Zweymuller stem. There were 77 women and 33 men with a mean age of 80 years (29-98 years). The mean duration of the operation was 29 min (20-95 min). Full weight bearing on crutches was allowed 1 day after the operation. The mean follow-up was 2.5 years (6 months to 7 years). Two years after the operation there were 40% of the remaining 65 patients who scored between 90 and 100 on the Harris hip score, 23% between 80 and 89, 20% between 70 and 79, and 17% below 70. No patient complained about thigh pain and up to now there has been no need for femoral revision due to loosening. There was no infection or nerve lesion. In three patients there was a luxation of the prosthesis which could be reduced by closed means. Radiographs from 81 patients showed stress shielding in 97.5% mainly in Gruen zones 1 and 7. Radiolucent lines in two or more Gruen zones were found in two patients. These findings suggest that the noncemented, pressfit, grit-blasted bipolar prosthesis demonstrated similar stability and radiographic results to cemented bipolar prostheses. Stress shielding was common but did not influence longevity of the implant. We did not find any signs of protrusion. Especially in older patients with a history of cardiac disease, the noncemented bipolar prosthesis is a rational alternative to avoid intra- and postoperative complications despite the higher costs for the implant. The minimally invasive approach helps to reduce operation time and intraoperative blood loss.

Endogenous cannabinoids are candidates for lipid mediators of bone cement implantation syndrome

Acute hypotension, hypoxemia, cardiac arrhythmias, cardiac arrest, (or a combination of these), and sudden death are well-recognized complications of the cemented hip arthroplasty procedure. Collectively, these are known as the bone cement implantation syndrome (BCIS). The endogenous cannabinoids, anandamide (ANA) and 2-arachidonylglycerol (2-AG), are reported to be strong vasodilators and play a role in the hypotension associated with hemorrhagic and septic shock. In the present study, a potential role for the endogenous cannabinoids in influencing hemodynamic variables in BCIS was investigated. Thirty-five patients (35 hips) entered a prospective, randomized clinical trial. The patients were divided into two groups. Group 1 comprised 16 patients who had the component inserted using a conventional cementing technique, whereas group 2 consisted of 19 patients who had the femoral component inserted without cement. Blood samples were taken at six consecutive time points: before anesthesia, after reaming the femur, 2 min after insertion of stems with or without cement into the femur, and 10 min, 20, and 30 min after stem insertion. In group 1 (with cement), the mean levels of ANA and 2-AG significantly increased after stem insertion. In a comparison of each group after stem insertion, mean ANA and 2-AG levels in group 1 also significantly differed from those in group 2. By contrast, in group 2 (without cement) neither ANA nor 2-AG levels exhibited a significant increase or change at any point in time. In conclusion, we have shown for the first time that endogenous cannabinoids are candidates for lipid mediators of BCIS.

Angiotensin-converting enzyme activity: a novel way of assessing pulmonary changes during total knee arthroplasty

Emboli after tourniquet release (TR) during total knee arthroplasty (TKA) occur in all patients. This may lead to fat embolism syndrome with lung injury. Angiotensin-converting enzyme (ACE) lines the pulmonary endothelium, and a decrease in ACE metabolism or hydrolysis of (3)HBPAP ((3)H-benzoyl-Phe-Ala-Pro; a substrate specific for ACE) has been associated with lung injury. We evaluated the association of this assay with pulmonary changes during TKA. Eleven consecutive patients undergoing bilateral TKA had the ACE assay performed perioperatively. We determined substrate hydrolysis and pulmonary capillary surface area (capillary perfusion index; CPI) and correlated it with pulmonary vascular resistance (PVR) and clinical outcome. Ten of the 11 patients demonstrated an increase in substrate hydrolysis and CPI along with a decrease in PVR after first or second TR when compared with baseline values (P < 0.05). In the other patient, PVR continued to increase even after TR, whereas CPI and substrate hydrolysis decreased after surgery. Whereas all others did well clinically, this patient developed confusion and hypoxemia. In previous studies, a decrease in PVR with an increase in CPI, as exhibited by the 10 patients, has been associated with pulmonary capillary recruitment. We believe this to be an important mechanism by which the lungs are able to accommodate the burden of emboli at the time of TR.

Fatal Intraoperative Pulmonary Fat Embolism During Cemented Total Hip Arthroplasty in a Dog

A 3-year-old, German shepherd dog died suddenly during cemented total hip arthroplasty. Gross necropsy findings included severe pulmonary edema and congestion as well as congestion of the liver and kidneys. Acute pulmonary embolism was suspected as the cause of death. Microscopic examination of hematoxylin and eosin-stained, formalin-fixed, and oil red O-stained frozen tissue sections confirmed the presence of large numbers of fat globules in blood vessels in the lungs, liver, and kidneys. Fat embolism during total hip arthroplasty is a common surgical complication in humans, but it is uncommon in veterinary cases and is rarely a cause of death.

Spinal Anesthesia Performance Conditions and Side Effects Are Comparable Between the Newly Designed Ballpen and the Sprotte Needle: Results of a Prospective Comparative Randomized Multicenter Study

In this study, we examined the characteristics of a newly designed spinal needle (Ballpen [B]) with a pencil-like tip formed by a stylet that is withdrawn after penetration of the dura. The main goal was to examine whether the use of the B needle could reduce performance time by improved puncture conditions in comparison with the Sprotte (S) needle. Seven-hundred patients at 4 hospitals received single-dose spinal anesthesia with a 25-gauge B or S needle and 0.5% bupivacaine. The performance time of spinal anesthesia was defined as the time between insertion of the introducer needle and the first identification of cerebrospinal fluid in the hub of the spinal needle. Failed spinals were assessed when patients required general anesthesia. On postoperative Day 2-4, all patients were visited and interviewed. Groups did not differ with respect to demographics, puncture site, and dose of bupivacaine. Performance time was 98 +/- 145 s in Group B and 103 +/- 159 s in Group S (P = 0.68). The failure rate in Groups B and S was 3.8% and 3.9%, respectively, and the incidence of postdural puncture headache was 1.8% and 0.9% (P = 0.50), respectively. We conclude that there was no difference in technical variables or outcome between the B and S needles.

IMPLICATIONS

This multicenter study examined characteristics of the newly designed Ballpen needle with the Sprotte needle in 700 patients undergoing lower abdominal or extremity surgery in single-dose spinal anesthesia. Technical variables and side effects were comparable between both noncutting spinal needles.