The relationship between pneumatic tourniquet time and the amount of pulmonary emboli in patients undergoing knee arthroscopic surgeries

Personalized tourniquet pressure versus uniform tourniquet pressure in orthopedic trauma surgery of extremities: A prospective randomized controlled study protocol

Background

In the field of orthopedic surgery, tourniquets are often used to achieve a clear operative field, expedite operations, and minimize hemorrhagic events. However, determining the optimal tourniquet inflation pressure is a topic of debate. The current approach involves using a constant tourniquet pressure, although this is associated with the potential to augment the risk of tourniquet-associated complications. The Association of Surgical Technologists recommends a tourniquet pressure of systolic blood pressure plus 50 mm Hg for the upper limb and 100 mm Hg for the lower limb. Nevertheless, this method lacks robust support from high-quality medical literature. Therefore, the study aimed to compare the hemostatic efficacy and disparities in tourniquet pressure settings based on systolic blood pressure versus those using the constant-pressure method. The findings might outline the theoretical framework necessary for advocating for tourniquet pressure setups guided by systolic blood pressure.

Methods/design

This randomized controlled study classified the tourniquet pressure regimen into two groups: one based on the patient's systolic blood pressure (the study group) and the other using a constant pressure (the control group). The study included patients aged between 16 and 70 who presented with fresh fractures (less than 3 weeks) of the lower and upper limbs. All the included patients required surgical treatment involving the intraoperative use of a tourniquet and had no contraindications to this surgery. Our primary outcome was to assess the surgeon's satisfaction with the hemostasis achieved in the operative field. We also examined the changes in the circumference of the limb where the tourniquet was applied and tracked any postoperative complications and their incidence. The study ultimately encompassed 144 patients.

Discussion

Despite the prevalent use of tourniquets in surgical operations related to limb fractures, conflicting viewpoints persist concerning the adjustments in pressure and other elements. The study aimed to compare the hemostatic efficacy and disparities in tourniquet pressure settings based on systolic blood pressure versus those using the constant-pressure method.

Study registration

The study was duly recorded in the Chinese Clinical Trial Registry on May 13, 2022 (Registration number: ChiCTR2200059867).

Registration website

https://www.chictr.org.cn/showproj.aspx?proj=162504.

Cemented total knee arthroplasty provides greater knee range of motion at 2 years than cementless technique

INTRODUCTION

Optimal fixation method between cemented, cementless, and hybrid techniques for total knee arthroplasty (TKA) is still debated. The purpose of this study is to evaluate the clinical outcomes of patients undergoing cemented versus cementless TKA.

METHODS

We reviewed 168 patients who underwent a primary TKA at a single academic institution between January 2015 and June 2017. Patients were categorized into cemented (n = 80) or cementless (n = 88) groups. Only patients with greater than or equal to 2-year follow-up were included in the study. Multivariate regressions were performed to analyze the relationship between the surgical fixation technique and the clinical outcomes.

RESULTS

There were no differences in demographics or baseline operative characteristics between the two groups. The cemented group had fewer manipulations under anesthesia (MUA) (4 vs. 15, p = 0.01), longer intraoperative tourniquet times (101.30 vs. 93.55 min, p = 0.02), and increased knee range of motion (ROM) at final follow-up (111.48 vs. 103.75°, p = 0.02) compared to the cementless group.

DISCUSSION AND CONCLUSION

Both cemented and cementless component fixation are viable options for (TKA). This study found that patients who underwent a cemented TKA required fewer MUA's and had greater final ROM compared to patients undergoing cementless TKA. Additional research is required regarding cementless and cemented fixation. We believe that the choice of which fixation technique to use ultimately comes down to patient characteristics and surgeon preference.

Retrospective review of complications following long tourniquet time in foot and ankle surgery

BACKGROUND

Tourniquet use is ubiquitous in orthopaedic surgery to create a bloodless field and to facilitate safe surgery, however, we know of the potential complications that can occur as a result of prolonged tourniquet time. Experimental and clinical research has helped define the safe time limits but there is not much literature specific to foot and ankle surgery.

METHODS

A retrospective review of the postoperative course of patients with prolonged tourniquet time (longer than 180 min) for foot and ankle procedures was done. Data related to the patient factors and the surgical procedure was collected. The length of stay, re-admissions and complications were the important indicators of the individual patient's recovery.

RESULTS

Twenty patients were identified with longer than 180-min tourniquet times for complex foot and ankle procedures. The average uninterrupted tourniquet time was 191 min. Eight of the twenty procedures were revision surgeries. The average length of stay was 3 days and there were no re-admissions within 30 days. Eight patients (40%) had at least one recorded complication. The complications seen in this group were transient sensory loss, wound issues, superficial infection, ongoing pain and non-union.

CONCLUSIONS

This case series has not revealed any major systemic complications resulting from the prolonged tourniquet such as pulmonary embolism or renal dysfunction. Unlike past literature on knee procedures with extended tourniquet times, no major nerve palsies were seen in our patient group. Our understanding of the local and systemic effects of tourniquet is not complete and this study demonstrates that the complications do not necessarily increase in a linear fashion in relation to the tourniquet time.

Tourniquet use for extremity fractures has no adverse effect on number of ventilator days for patients who are treated with reamed femoral or tibial shaft nails

INTRODUCTION

Concern exists regarding the pulmonary effects of using tourniquets for secondary extremity fractures in patients also undergoing intramedullary nail (IMN) fixation of femoral or tibial shaft fractures. Our hypothesis was that tourniquet use would be associated with increased ventilator days.

METHODS

At a Level I trauma center, we conducted a retrospective review of 1966 patients with 2018 fractures (1070 femoral shaft and 948 tibial shaft) treated with IMN from December 2006 to September 2014. Medical record review and bivariate and multiple variable regression analyses were conducted, and the main outcome measurement was number of ventilator days.

RESULTS

No statistically significant negative association was found between use of a tourniquet and number of ventilator days in the femoral or tibial fracture group. Use of tourniquets in the upper extremities showed a statistically significant decrease in amount of ventilator days in the femoral group (-2.2 days, p = 0.003) but no association in the tibial group (1.1 days, p = 0.36). Use of tourniquets concurrently in both upper and lower extremities of both femoral and tibial groups also had a protective effect (-6.8 days, p < 0.001 and -2.3 days, p = 0.009, respectively). Stratified and sensitivity analyses (to account for effects of mortality and missing data) showed consistently similar results.

CONCLUSION

Tourniquet use for secondary extremity fractures, in patients also undergoing IMN fixation for femoral or tibial shaft fractures, was not associated with an increased number of ventilator days. A potential protective effect of tourniquet use was shown in patients with upper extremity fractures and in those with both upper and lower extremity fractures.

LEVEL OF EVIDENCE

Therapeutic Level III (Retrospective cohort study).

A matched cohort study between cementless TKA and cemented TKA shows a reduction in tourniquet time and manipulation rate

Introduction

Cementless total knee arthroplasty (TKA) is now becoming more acceptable with the advent of newer ongrowth constructs and better initial fixation. It has been proposed that cementless TKA may save OR time and result in a lower incidence of manipulation. This study was designed to assess the difference between cemented and cementless TKA.

Methods

Our hospital statistician performed a matched cohort analysis between 127 cementless TKAs and 127 cemented TKRs performed by a single surgeon. Patients were matched on age and BMI. Mean tourniquet time between the cemented and cementless TKAs was assessed as well as the rate of manipulation between these groups. Of note, a tourniquet was routinely used in both the cementless and cemented cohorts to reduce confounding bias.

Results

A total of 127 cementless TKAs with a mean age of 60.8 years and mean BMI 32.2 were compared to 127 cemented TKAs with a mean age of 61.5 years and mean BMI of 32.2 at an average follow-up of 2.0 years. There was a statistically significant reduction in tourniquet time in the cementless TKA cohort at 45.7 min compared to the cemented TKA cohort at 54.8 min (p = 0.001). Estimated blood loss was similar in both the cementless (179.5 ml) and cemented (196 ml) cohorts (p = 0.3) and postoperative outcomes, including UCLA score.In addition, the cementless TKA cohort had a manipulation rate of 0% compared to 3.1% for the cemented TKA group (p = 0.044).

Discussion and conclusion

While cementless and cemented TKA have shown similar PROMs and survivorship, we demonstrated a significant reduction in tourniquet time with cementless TKRs, with similar estimated blood loss, and a lower incidence of manipulation with cementless TKRs in this matched cohort study. The increased cost of a cementless implant may be negated if one considers the cost savings of not using cement, the cost savings of not performing manipulations, and the shorter operative time.

Determination of Pneumatic Tourniquet Pressure of Lower Limb by Ultrasonic Doppler

OBJECTIVE

The aim of this study was to investigate the clinical effect of tourniquet inflation pressure setting by ultrasonic Doppler on lower limb operation.

METHODS

Ninety-six patients with total knee arthroplasty were selected in this study from January 2015 to December 2015. The patients were randomly divided into the study group and the control group with 48 cases in each group. In the control group, the tourniquet pressure is determined by the doctor's request for the patient's condition, but all the tourniquet pressure values should be 80 KPa or less. In the study group, ultrasonic Doppler was used to monitor the popliteal artery blood flow of surgery limb with the maximum systolic velocity in artery as a reference value. The pressure of pneumatic tourniquet gradually increased until the maximum systolic velocity was reduced to 0. At this time, the popliteal artery blood flow was not present. The 2 groups of patients with lower extremity tourniquet pressure, hemostatic effect of intraoperative tourniquet, and the incidence of adverse reaction using tourniquets were observed and recorded.

RESULTS

In the study group, the lower extremity tourniquet pressure and the incidence of adverse reaction using tourniquets were all better than that in control group; the difference between 2 groups was significant (P < 0.05). There was no significant difference between the 2 groups in the effect of hemostasis and the time of tourniquet operation (P > 0.05).

CONCLUSIONS

The method of ultrasonic Doppler setting lower extremity tourniquet pressure during the operation could not only ensure the hemostatic effect, but it could also provide the optimum individual pneumatic tourniquet pressure value for patients. In the meanwhile, it could reduce the incidence of adverse reaction using tourniquets effectively as well as improve the safety of the tourniquet. This method played an important role in the recovery of patients.

Use of Tourniquets in Limb Trauma Surgery

Although tourniquets are commonly used in patients with limb trauma patients, both in the acute and elective settings, no set protocols exist for their indications, contraindications, or proper use. This article addresses the current literature on optimal pressure, timing, cuff design, and complications of tourniquets in trauma patients. General issues are discussed, followed by those specific to upper and lower extremities. Lastly, serious complications, such as pulmonary embolism, are described.

A study on dynamic monitoring, components, and risk factors of embolism during total knee arthroplasty

BACKGROUND

Fat embolism is a common complication of orthopedic surgery. However, the exact component and risk factor responsible for this complication remains unelucidated. This study aimed to detect the origin of the pulmonary embolus and identify relevant risk factors of pulmonary embolism in total knee replacement.

METHODS

A total of 40 osteoarthritis patients who underwent primary unilateral TKA were recruited into this study. Transesophageal echocardiography (TEE) was utilized to dynamically monitor the embolism. Pulmonary arterial pressure was recorded and biopsies were obtained from the medullary cavity during surgery.

RESULTS

After tourniquet release, the arterial embolism was observed by TEE to have a peak signal at 30 seconds when pulmonary arterial pressure was increased by 25% to 40% (P = .002). The pathology study of the embolism revealed its bone marrow origin. Total embolus quantity was positively correlated with age (P = .021), body mass index (BMI, P = .041), and fat content of the bone marrow (P = .003). Logistic regression analysis revealed that the fat content of the marrow (OR: 1.432, 95% CI: 1.335-1.592), age (OR: 1.632, 95% CI: 1.445-1.832), and BMI (OR: 1.231, 95% CI: 1.032-1.381) were risk factors for pulmonary hypertension.

CONCLUSION

This study revealed that the embolus detected in the right atrium was derived from bone marrow tissues, and this led to pulmonary arterial pressure fluctuations after tourniquet release. Therefore, elderly patients who have high BMI or bone marrow fat content are at high-risk for pulmonary fat embolism during TKA.

A prospective randomized study to compare systemic emboli using the computer-assisted and conventional techniques of total knee arthroplasty

BACKGROUND

Conventional total knee arthroplasty is performed with use of an intramedullary alignment guide, which produces elevated intramedullary pressure that can create fat emboli. Total knee arthroplasty performed via computer-assisted surgery does not require an intramedullary femoral rod, raising the question of whether computer-assisted surgery generates less embolic material than conventional total knee arthroplasty. The purpose of this study was to compare the emboli produced in the two techniques.

METHODS

Fifty-seven patients were randomized into two groups: the computer-assisted surgery group (n = 29) and the conventional total knee arthroplasty group (n = 28). An intramedullary femoral alignment jig was used in the conventional total knee arthroplasty group but not in the computer-assisted surgery group. Intraoperative invasive monitoring was performed with use of transesophageal echocardiography and a pulmonary artery catheter.

RESULTS

The mean embolic score was 6.21 points for the conventional technique group and 5.48 points for the computer-assisted surgery group (p = 0.0161). After tourniquet deflation, fat emboli were observed in the blood of five patients in the conventional surgery group and one patient in the computer-assisted surgery group.

CONCLUSIONS

The patients in the computer-assisted surgery group had lower embolic loads compared with the patients in the conventional total knee arthroplasty group. In patients with an uncompromised cardiopulmonary system, the embolic load difference between the techniques was not clinically relevant.

LEVEL OF EVIDENCE

Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence.

Does intramedullary canal irrigation reduce fat emboli? A randomized clinical trial with transesophageal echocardiography

The effect of medullary cavity irrigation on fat emboli during total knee arthroplasty (TKA) was evaluated. Thirty female patients with osteoarthritis were randomly assigned to undergo conventional TKA without irrigation (conventional group) or with medullary canal saline irrigation (irrigation group). The four-chamber view was monitored by transesophageal echocardiography (TEE) and echogenic reflections of fat emboli were observed. The grey-scale score and area ratio of fat emboli were calculated during TKA. Hemodynamic parameters were simultaneously monitored and showed no obvious change between two groups (P>0.05). The average grey-scale score (P=0.016) and area ratio (P=0.033) of emboli were significantly decreased in irrigation group. Removal of medullary contents by irrigation could significantly reduce the formation of fat emboli during TKA.

Tourniquet in knee surgery

INTRODUCTION

The tourniquet is a surgical device composed of a round pneumatic cuff in which air at high pressure can be inflated with an automatic programmable pump to avoid bleeding and technical impediment.

SOURCES OF DATA

Comprehensive searches of Medline, Cochrane and Google Scholar databases were performed for studies regarding tourniquet application in arthroscopic and open surgery of the knee. The methodological quality of each study was evaluated using the Coleman methodology score (CMS).

AREAS OF AGREEMENT

The use of a tourniquet does not lead to significant increase in the risk of major complications, and there is no difference in clinical outcome in the medium term. The inflated cuff does prevent intraoperative blood loss, but hidden blood loss is not avoided completely. There is a statistically significantly higher occurrence of deep vein thrombosis in patients who undergo surgery with tourniquet, but the clinical relevance of this finding is uncertain.

AREAS OF CONTROVERSY

The heterogeneity in terms of inflating pressure and duration of application of tourniquet in the single studies makes it very difficult to compare the outcomes of different investigations to draw definitive conclusions.

GROWING POINTS

Standardization of pressure and application time of the cuff could allow a comparison of the data reported by the trials. Better study methodology should be also implemented since the mean CMS considering all the reviewed articles was 57.6 of 100.

RESEARCH

More and better designed studies are needed to produce clear guidelines to standardize the use of tourniquet in knee procedures.

The effect of tourniquet use on operative performance and early postoperative results of anatomic double-bundle anterior cruciate ligament reconstruction

PURPOSE

The purpose of this study was to examine the effect of tourniquet use on operative performance and early postoperative results of anatomic double-bundle anterior cruciate ligament (ACL) reconstruction.

METHODS

Fifty-one patients who underwent scheduled ACL reconstruction for unilateral ACL deficiency from June 2010 to October 2011 were included in this study. The mean age at surgery was 26.3 years (range 14-45 years). An anatomic bundle reconstructive procedure with an autogenous hamstring tendon graft was performed in all cases. These patients were randomly divided into two groups: the tourniquet group (T group) and no tourniquet group (NT group). The reconstructive procedure was performed with the use of a tourniquet for 28 patients in the T group, while a tourniquet was inflated only during the graft harvest for 23 patients in the NT group. The surgical procedure and postoperative management were identical for both groups. Inter-group comparison was conducted for intra- and peri-operative clinical parameters as well as early postoperative results (functional recovery at 3 months).

RESULTS

The arthroscopic visual field during the procedure was not compromised even without the use of a tourniquet. There was no significant difference in operative time between the groups (P = 0.10). The amount of blood corrected through the intraarticular drain was significantly larger in the T group (P = 0.02), while total blood loss calculated by the postoperative reduction of the hemoglobin value was not significantly different between the groups (P = 0.74). Although the VAS value for postoperative numbness was significantly higher in the T group (P = 0.0002), the VAS value for pain was not significantly different (P = 0.30). Additionally, recovery of muscle strength at 3 months was not significantly different between the groups.

CONCLUSION

This comparative study showed that arthroscopic procedures could be uneventfully performed without the use of a tourniquet. The clinical parameters when not using a tourniquet were not significantly different, but the use of a tourniquet resulted in an increase in postoperative intraarticular bleeding and VAS for numbness.

LEVEL OF EVIDENCE

Prospective randomized study, Level II.

Paradoxical cerebral embolism after total knee arthroplasty

Deep vein thrombosis is a frequent complication following total joint arthroplasty and other major orthopedic procedures. Pulmonary embolism occurs with or without a diagnosis of deep vein thrombosis, although infrequently (1.5%-10%). In patients with congenital cardiac defects, such as a patent foramen ovale, paradoxical cerebral embolism may also occur. This article describes a case of a 52-year-old woman who sustained a paradoxical cerebral embolism following total knee arthroplasty. In the workup of a patient with a known murmur and stroke symptoms, paradoxical cerebral embolism should be included in the differential. The initial evaluation should incorporate transesophageal echocardiography because of its accuracy in the demonstration of the cardiac physiology. An abnormal intracardiac or intrapulmonary shunt is essential for paradoxical cerebral embolism, allowing the entrance of the thrombus into cerebral circulation from the venous system. No clear consensus has been reached on the management of patients at risk for paradoxical cerebral embolism prior to orthopedic procedures. However, when an embolic stroke is diagnosed acutely, ideal management includes thrombolytic therapy, but further research is needed to confirm that this is the correct management. Due to the risk of recurrence, postoperative thromboprophylaxis is recommended with or without closure of the foramen ovale. Most importantly, and as demonstrated by the current patient, who partially recovered but did not require walking assistance after 2-year follow-up, treating physicians should be prepared to counsel patients through a lengthened physical rehabilitative process.

The prevalence of cognitive dysfunction after conventional and computer-assisted total knee replacement

Post operative cognitive dysfunction (POCD) is common following lower limb arthroplasty. The prevalence varies from 41-75% at 7 days to 18-45% at 3 months post operatively. The wide range of prevalence is due to inconsistencies in defining and quantifying POCD. The aim of this study is to ascertain an accurate prevalence of POCD in patients who had either conventional TKR (n=31) or computer-assisted TKR (n=30). Cognition was assessed pre-operatively, 6 days and at 6 months post-operatively by a battery of 11 validated neuropsychological tests. We found the mean prevalence of POCD to be 72% at 6 days and 30% at 6 months post-operatively. When comparing the prevalence of POCD between the two groups, we found no statistically significant difference at 6 days or at 6 months post-operatively. The only statistically significant factor between the two groups was the mean procedure time which was longer in the computer-assisted TKR group (p=< 0.001). We found a correlation between procedure time and the prevalence of POCD at 6 days (p=0.02) but not 6 months (p=0.26). POCD occurs in approximately one-third of TKR patients at 6 months post-operatively. The cause is undoubtedly multi-factorial; however we have demonstrated that procedure time may be a contributing factor. Our results suggest that using an intra-medullary femoral jig has no effect on POCD. Further research into the cognitive effects following TKR with and without a tourniquet would be of benefit.

Thromboembolic complications after bilateral knee arthroscopic surgery patients

Deep venous thrombosis and pulmonary embolism are rare complications after arthroscopic knee procedures. Most of the cases of thromboembolic complications reported to have involved unilateral knee arthroscopic patients; here, we report the cases of patients with bilateral knee arthroscopy. The patients were treated with anticoagulants and thrombolytics and subjected to necessary laboratory monitoring. All the patients recovered well after the treatment and were symptom-free during a 6-month follow-up. The purpose of this article was to increase the awareness of knee arthroscopists of this complication.

An autopsy case of intraoperative death due to pulmonary fat embolism—possibly caused by release of tourniquet after multiple muscle-release and tenotomy of the bilateral lower limbs

We report a case of a juvenile male with muscle rigidity caused by cerebral palsy who experienced intraoperative sudden death due to pulmonary fat embolism after multiple muscle-release and tenotomy of the bilateral lower limbs. Data were obtained through review of the surgical and anesthesia records, as well as from autopsy and histopathological examination. All surgical procedures were performed within the same operation, beginning with the right lower limb and then proceeding with the left lower limb, with application of a pneumatic tourniquet to avoid intraoperative hemorrhage. Slight changes in the hemodynamics were noticed after release of the right tourniquet. Further, sudden onset of hypotension, severe bradycardia, and a marked decrease in percutaneously monitored oxygen saturation occurred just after release of the left tourniquet when the left limb was raised for casting. The patient died despite immediate and vigorous cardiopulmonary resuscitation. At autopsy performed 20 h after death, examination of the lungs revealed a pale surface, slight edema, and obvious fat droplets in the vessels at the cut surfaces. Histopathological examination with fat staining was notable for the presence of pulmonary fat embolism. These results suggest that restoration of venous return after removal of the tourniquet combined with massive fat embolism from dead spaces was the likely cause of death.

An unusual case of pulmonary embolism after arthroscopic meniscectomy

Although the incidence of pulmonary embolism (PE) following arthroscopic knee surgery has not been well established, such occurrences place the patient at high risk. In this report we present a case of PE following arthroscopic meniscectomy. The patient was a 63-year-old woman, with no definite risk factors for PE, who underwent successful arthroscopic meniscectomy. However, on the postoperative 9th day she developed dyspnea and tachycardia. Investigations carried out in the emergency department, including EKG, echocardiography, and CT angiography, supported the diagnosis of a PE. Heparin therapy was initiated, and the patient's condition then improved sufficiently to allow follow-up at our outpatient department.

Prévention de la maladie thromboembolique en orthopédie et traumatologie

Orthopaedic and trauma surgery are classified according 3 groups of venous thromboembolic risk. Elective total hip replacement (THR) or total knee replacement (TKR), hip fracture surgery or trauma patients are at high risk. Isolated lower extremity injury with fracture is at moderate risk whereas this risk is low without fracture as well as with knee arthroscopy. In THR and TKR, low molecular weight heparin (LMWH), fondaparinux or melagatran-ximelagatran are strongly recommended. The routine use of other anticoagulants, in particular vitamin K antagonist are not recommended. In patients at high risk of venous thromboembolism as for example trauma patients, optimal use of intermittent pneumatic compression is an alternative option in case of contra-indication to anticoagulant prophylaxis. Graduated compression stockings enhance the efficacy of pharmacological methods. In schedule surgery, initiation of prophylaxis with LMWH may be started postoperatively. To reduce the haemorrhagic risk of anticoagulants, timing of first postoperative dose is essential and is proper to each drug. Duration of prophylaxis depends on the surgical and the individual patients' risk. Extended prophylaxis in THR for up to 42 days with LMWH and up to 35 days with fondaparinux in hip fracture surgery is recommended. However extended prophylaxis after 14 days in TKR has not demonstrated a higher efficacy and should only be considered for patients with additional risk factors. In patients with isolated lower extremity injury or undergoing knee arthroscopy, LMWH should not be routinely used according to a low or a moderate risk and/or the duration of prophylaxis required. But LMWH has to be considered for patients with additional risk factors. Prophylaxis in other orthopedic procedures has not been assessed and will be extrapolated from the above recommendations.

Thromboembolic events after arthroscopic knee surgery

We present a case of fatal pulmonary embolus after knee arthroscopy to raise awareness of the frequency of this complication and the need for consideration of thromboembolic prophylaxis before knee arthroscopy.

The Use of Bone Cement Induces an Increase in Serum Astroglial S-100B Protein in Patients Undergoing Total Knee Arthroplasty

Cerebral microemboli can occur during arthroplasty with the use of bone cement. Astroglial S-100B protein is a sensitive marker of cerebral damage. Therefore, we designed this study to determine the effect of bone cement on the brain by investigating serum levels of S-100B protein in patients undergoing bone surgery with or without bone cement. Fourteen patients undergoing knee arthroplasty (n = 7) or reamed intramedullary nailing for tibial fracture (n = 7) requiring a pneumatic tourniquet were enrolled in this study. Bone cement containing polymethyl methacrylate and methyl methacrylate was used for every patient undergoing knee arthroplasty. Serum samples were obtained from venous blood before the induction of general anesthesia, 15 min after deflation of a pneumatic tourniquet, and 3 days after the operation. The serum level of S-100B protein was significantly increased 15 min after a pneumatic tourniquet deflation in the knee arthroplasty group compared with the tibial fracture group (0.41 and 0.08 ng/mL, respectively; P < 0.05). In all patients studied, no neurological abnormalities were noted in the postoperative period. These results suggest that, in patients undergoing knee arthroplasty, bone cement may transiently induce astroglial injury, although it does not alter neurological outcome.

IMPLICATIONS

Serum S-100B protein was significantly increased 15 min after a pneumatic tourniquet deflation in patients undergoing knee arthroplasty with bone cement, but not in those undergoing reamed intramedullary nailing for tibial fracture without bone cement. These results suggest that bone cement may transiently induce astroglial injury.

Single dose of acetylsalicylic acid prevents thromboxane release after tourniquet ischemia

BACKGROUND

Ischemia, such as that caused by a tourniquet, stimulates thromboxane (Tx) A(2) synthesis. TxA(2) might sensitize the operated limb to various complications, such as compartment syndrome and thromboembolic events.

METHODS

We studied the effect of pretreatment with a single dose of acetylsalicylic acid (ASA) (25, 100, and 500 mg) given 3 hours before surgery on the formation of TxB(2), a stable metabolite of TxA(2), after tourniquet deflation in 32 knee or ankle surgery patients.

RESULTS

Tourniquet time varied between 60 +/- 8 to 71 +/- 7 (SE) minutes. In control patients without ASA pretreatment, the platelet-produced femoral vein serum TxB(2) concentration over 30 minutes in vitro coagulation increased remarkably (from 40.0 +/- 20 ng/mL to 73.5 +/- 39 ng/mL) immediately after tourniquet deflation. Plasma concentrations increased similarly, approximately threefold. Pretreatment with 100 or 500 mg ASA prevented the increase in TxB(2) concentrations. Radial artery concentrations of TxB(2) were similar to venous concentrations in the different treatment groups.

CONCLUSION

Pretreatment with a single 100-mg dose of ASA prevents the release of TxB(2) after tourniquet deflation.

Paradoxic cerebral embolism after cemented knee arthroplasty: a report of 2 cases and prophylactic option for subsequent arthroplasty

Major orthopaedic procedures that involve instrumentation of the medullary canal are well known to produce showers of embolic debris including fat, bone fragments, marrow constituents, and cement. A growing literature has identified paradoxic cerebral embolism as a rare but serious consequence of the passage of these emboli through an intracardiac right-to-left shunt to the cerebral arterial circulation. We report 2 cases of paradoxic cerebral embolism after cemented total knee arthroplasty and propose a novel treatment plan to prevent recurrent stroke during subsequent surgery.

Quantification and comparison of pulmonary emboli formation after pneumatic tourniquet release in patients undergoing reconstruction of anterior cruciate ligament and total knee arthroplasty

The amount of emboli formed (percentage of total emboli area to the right atrial area [%Ae]) after tourniquet release in invasive procedures of the medullary cavity is empirically much larger than that in noninvasive procedures, even if the tourniquet duration is similar. Thus, we compared %Ae between arthroscopic reconstruction of the anterior cruciate ligament (ACL, n = 20) and total knee arthroplasty (TKA, n = 20). The right atrium was continuously monitored by transesophageal echocardiography to assess %Ae. Peak %Ae +/- SD (ACL, 4.1% +/- 3.4%; TKA, 20.7% +/- 16.7%) appeared 30-40 s after tourniquet release in both groups. However, %Ae in the TKA group was always larger than the peak %Ae in the ACL group. In addition, although the ET(CO(2)) significantly increased after tourniquet release in both groups, increase of ET(CO(2)) (1.1% +/- 0.3%) in the ACL group was significantly larger than that in the TKA group (0.5% +/- 0.2%). An increase in ET(CO(2)) was inversely proportional to peak %Ae (P < 0.01; r = 0.703). Therefore, the present data suggest that the risk of acute pulmonary embolism after tourniquet release may be more frequent during TKA than ACL.

IMPLICATIONS

We compared emboli formation after tourniquet release in patients undergoing arthroscopic reconstruction of the anterior cruciate ligament (ACL, n = 20) and total knee arthroplasty (TKA, n = 20) using transesophageal echocardiography. The present data suggest that the risk of acute pulmonary embolism after tourniquet release could be more frequent during TKA than ACL.