Bone marrow fat in the circulation: clinical entities and pathophysiological mechanisms

Relationship between fat embolism and endothelial glycocalyx

Fat embolism (FE) is acknowledged as one of the significant causes of sudden death following traumatic injury. To clarify the relevance of vascular endothelial glycocalyx (EGC) damage and FE, temporal changes in the mRNA levels of inflammatory cytokines associated with EGC components were investigated in an experimental fat embolization rat model. Nine-week-old rats were used as FE models through triolein injection (TO) and femoral fracture (FX), and physiological saline was administered to the control group. RT-qPCR and fat staining were performed. The target genes were Il6, Il10, Tnf, Elane, Sdc1, Sdcbp, Vcan, Hyal1, Fn1, and CD14. Notably, FE was detected in 100% and 5.6% of the TO and FX groups, respectively, using fat staining. Bimodal peaks in the mRNA expression levels of Sdc1, Tnf, Elane, IL6, and IL10 were observed 4 and 20 h after treatment in both groups. In the TO group, mRNA expression peaked at 4 h and then declined to the lowest level at 16 h. The incidence of fat emboli due to trauma was consistent with that reported in previous studies. Bimodal mRNA peaks may correspond to FE progression, in which physical obstructions are followed by biochemical reactions. The fluctuation in Sdc1 expression suggests that the initial peak resulted from physical EGC damage. The subsequent peak could be because of EGC damage caused by the secretion of inflammatory cytokines induced by oleic acid from lipid droplet decomposition. These results suggest that EGC disorders caused by lipid droplets may induce lung damage during FE.

Femoral nailing associated with bone marrow emboli in pigs induced a specific increase in blood IL-6 and broad inflammatory responses in the heart and lungs

Introduction

Bone marrow embolization may complicate orthopedic surgery, potentially causing fat embolism syndrome. The inflammatory potential of bone marrow emboli is unclear. We aimed to investigate the inflammatory response to femoral intramedullary nailing, specifically the systemic inflammatory effects in plasma, and local tissue responses. Additionally, the plasma response was compared to that following intravenous injection of autologous bone marrow.

Methods

Twelve pigs underwent femoral nailing (previously shown to have fat emboli in lung and heart), four received intravenous bone marrow, and four served as sham controls. Blood samples were collected hourly and tissue samples postmortem. Additionally, we incubated bone marrow and blood, separately and in combination, from six pigs in vitro. Complement activation was detected by C3a and the terminal C5b-9 complement complex (TCC), and the cytokines TNF, IL-1β, IL-6 and IL-10 as well as the thrombin-antithrombin complexes (TAT) were all measured using enzyme-immunoassays.

Results

After nailing, plasma IL-6 rose 21-fold, compared to a 4-fold rise in sham (p=0.0004). No plasma differences in the rest of the inflammatory markers were noted across groups. However, nailing yielded 2-3-times higher C3a, TCC, TNF, IL-1β and IL-10 in lung tissue compared to sham (p<0.0001-0.03). Similarly, heart tissue exhibited 2-times higher TCC and IL-1β compared to sham (p<0.0001-0.03). Intravenous bone marrow yielded 8-times higher TAT than sham at 30 minutes (p<0.0001). In vitro, incubation of bone marrow for four hours resulted in 95-times higher IL-6 compared to whole blood (p=0.03).

Discussion

A selective increase in plasma IL-6 was observed following femoral nailing, whereas lung and heart tissues revealed a broad local inflammatory response not reflected systemically. In vitro experiments may imply bone marrow to be the primary IL-6 source.

A case of fatal fulminant fat embolism syndrome saved by VA-ECMO in the acute phase of multiple trauma

Fat embolism syndrome (FES) is a rare complication of long bone fractures, with fulminant FES developing within 12 h of injury and often proving fatal (Shaikh, 2009 [1]). Here, we present a case of fulminant FES in a patient who developed sudden right heart failure after undergoing external fixation of a lower leg fracture and required veno-arterial extracorporeal membrane oxygenation (VA-ECMO). A 79-year-old woman injured in a traffic accident was transferred to our emergency department. Upon arrival, her level of consciousness deteriorated, and she developed circulatory failure. We promptly performed transcatheter arterial embolization for the pelvic fracture and external fixation of the tibiofibular fracture. Within four hours of the injury, she was admitted to our intensive care unit (ICU). Two hours after ICU admission, her hemodynamic status worsened, necessitating the administration of maximum catecholamine dose. Echocardiography revealed petechial hemorrhage of the palpebral conjunctiva and enlargement of the right ventricle. Despite maximal supportive care, the patient remained cardiovascularly unstable. Therefore, VA-ECMO was initiated to stabilize her hemodynamic status. Thereafter, her hemodynamics stabilized, and ECMO support was weaned off and removed on day 3. Subsequent magnetic resonance imaging revealed evidence of cerebral fat embolism. On day 9, she underwent open reduction of the left lower leg with internal fixation and was transferred to another hospital on day 29. This report documents the successful management of fulminant FES during the acute phase of multiple traumas. Clinicians should consider VA-ECMO when suspecting uncontrolled circulatory failure due to fulminant FES, even in the acute phase of multiple trauma.

Fat embolism syndrome associated with atraumatic compartment syndrome of the bilateral upper extremities: An unreported etiology

Fat embolism syndrome (FES) is a potentially life-threatening condition that develops when fat embolism leads to clinical symptoms and multisystem dysfunction. The classic triad of respiratory distress, neurologic symptoms, and petechial rash are non-specific, and the lack of specific laboratory tests makes the diagnosis of FES difficult. Although FES is most common after long bone fractures, multiple conditions some of which are atraumatic have been associated with the development of FES. We report a case of FES that occurred in the setting of a non-traumatic compartment syndrome of the upper extremities. The pathologic and clinical findings, pathophysiology, diagnostic challenges, and pathologic methods to properly diagnose FES are discussed with a review of the relevant literature. This case highlights the importance of the autopsy in making a diagnosis of FES in cases where death could otherwise be incorrectly attributed to multi-organ system failure, shock, or sepsis.

Fat Pulmonary Embolism With Crazy-Paving Pattern Opacities and Pneumothorax: A Rare Complication of Liposuction

Fat embolism syndrome (FES) is a rare multiorgan disease caused by microvascular obstruction by fat globules and free fatty acid-mediated endothelial injury leading to pro-inflammatory cytokine release. We present a rare case of a 54-year-old woman who underwent elective aesthetic liposuction and developed FES and pneumothorax within 12 hours of the procedure.

Orthobiologics: a review

PURPOSE

The use of biologic materials in orthopaedics (orthobiologics) has gained significant attention over the past years. To enhance the body of the related literature, this review article is aimed at summarizing these novel biologic therapies in orthopaedics and at discussing their multiple clinical implementations and outcomes.

METHODS

This review of the literature presents the methods, clinical applications, impact, cost-effectiveness, and outcomes, as well as the current indications and future perspectives of orthobiologics, namely, platelet-rich plasma, mesenchymal stem cells, bone marrow aspirate concentrate, growth factors, and tissue engineering.

RESULTS

Currently available studies have used variable methods of research including biologic materials as well as patient populations and outcome measurements, therefore making comparison of studies difficult. Key features for the study and use of orthobiologics include minimal invasiveness, great healing potential, and reasonable cost as a nonoperative treatment option. Their clinical applications have been described for common orthopaedic pathologies such as osteoarthritis, articular cartilage defects, bone defects and fracture nonunions, ligament injuries, and tendinopathies.

CONCLUSIONS

Orthobiologics-based therapies have shown noticeable clinical results at the short- and mid-term. It is crucial that these therapies remain effective and stable in the long term. The optimal design for a successful scaffold remains to be further determined.

Fat Embolism Syndrome After Knee Arthroscopy in a Pediatric Patient

Fat embolism syndrome describes a constellation of symptoms that follow an insult and that results in a triad of respiratory distress, neurologic symptoms, and petechia. The antecedent insult usually entails trauma or orthopedic procedure, most frequently involving long bone (especially the femur) and pelvic fractures. The underlying mechanism of injury remains unknown but entails biphasic vascular injury with vascular obstruction from fat emboli followed by an inflammatory response. We present an unusual case of a pediatric patient with acute onset of altered mental status, respiratory distress, hypoxemia, and subsequent retinal vascular occlusions after knee arthroscopy and lysis of adhesions. Diagnostic findings most supportive of the fat embolism syndrome included anemia, thrombocytopenia, pulmonary parenchymal, and cerebral pathologic findings on imaging studies. This case highlights the importance of fat embolism syndrome as a diagnostic consideration after an orthopedic procedure, even absent major trauma or long bone fracture.

Fat Embolism Syndrome Without Bone Fracture: Is It Possible?

BACKGROUND: Fat embolism syndrome is a life challenge syndrome. Early diagnosing and treatment can significantly improve the patient’s prognosis and likelihood of success. This syndrome occurs mainly after long bones fractures or orthopedic surgery up to 95% of diagnosed cases, but in unusual situation can be faced as well. These rare situations include diabetes mellitus, video-assisted thoracoscopies, fatty liver, and fat injection in plastic and cosmetic procedures. The likelihood of this syndrome can be increased if multiplex long bones fractures occur in the same patient simultaneously. This syndrome is usually manifested with respiratory changes (hypoxemia and ARDS), neurological focal symptoms (confusion, headache, aphasia, and hemiplegia), and skin abnormalities (petechias, and rush in conjunctiva and oral mucosa). The clinical scenario begins typically after 24−72 h of injury, and mainly, respiratory changes are the first, followed by neurological abnormalities and finally petechias as the most significant sign. CASE REPORT: In this case, we report a rare case of unexpected fat embolism syndrome after soft-tissue minimal trauma. This is the first case that we faced according to literature, and the aim of reporting this case is to emphasize that fat syndrome embolism can happen perhaps in every trauma patient even in minor soft-tissue trauma in absence of bone fractures. CONCLUSION: We strongly suggest that this case should make the physicians taking in consideration fat embolism syndrome even if bone fracture missed, to early diagnosing and adequately treating the patient, and optimizing his chances to survive.

Filler-induced non-thrombotic pulmonary embolism after genital aesthetic injection

Genital aesthetic procedures have increased in popularity among women and men. Many clinicians tried to expand the application of fill injection by using it for genital aesthetic injection. However, this procedure is not so safe as imagined and may lead to a fatal complication of pulmonary embolism. This article summarizes the clinical manifestations and proposed mechanism of the filler-induced non-thrombotic pulmonary embolism (FINTPE) cases. A literature review was performed with the search keywords including "genital aesthetic injection, vaginal injection, vaginoplasty, vaginal tightening, penile augmentation, penis injection, hyaluronic acid, fat grafting, pulmonary embolism, alveolar hemorrhage, hypoxemia, and dyspnea." Among the 14 cases from 11 articles enrolled, 12 patients were female, and two were male. Eight patients received silicone injection, followed by two received fat grafting and hyaluronic acid injection, respectively. All the female patients had one single injection site, including 11 cases for the vaginal wall and one for G-spot, while all the male patients received injections into the penis and scrotum. The main symptoms were dyspnea and chest pain. Almost 60% of FINTPE patients presented respiratory disorders within 12 hours post-operation. Treatment includes oxygen therapy, corticosteroids, and anticoagulation. Five patients improved with an average of 14.6-day treatment, and seven died due to organ failures. Genital aesthetic filler injections are experimental procedures without being strictly reviewed or approved. As a severe complication following these procedures, FINTPE requires cautious performance, careful prevention, timely identification, and treatment to decrease its incidence and mortality.

Concomitant post-traumatic ocular and cerebral fat embolism syndrome and thrombotic pulmonary embolism: A case report

RATIONALE

Fat embolism syndrome (FES) is composed of a triad of symptoms, including respiratory distress, neurologic deficit, and petechiae. Respiratory distress usually presents first before the other symptoms. Thrombotic pulmonary embolism (TPE) is a differential diagnosis of FES. Trauma is a risk factor for both diseases; however, co-occurrence is rare.

PATIENT CONCERNS

A 35-year-old male patient presented with altered consciousness, focal neurologic deficit, and respiratory distress after a left femoral subtrochanteric fracture and subsequent open reduction and internal fixation with an intramedullary nail.

DIAGNOSIS

Computed tomography pulmonary angiography (CTPA) revealed lower pulmonary artery filling defects and ground-glass opacities in bilateral lung, indicating TPE and FES, respectively.

INTERVENTIONS

Heparin was initially added and subsequently switched to apixaban. The symptoms improved quickly without major bleeding complications.

LESSION SUBSECTIONS

Concomitant TPE and FES after trauma are rare and require different treatment approaches. Due to clinical similarities, prompt chest CTPA was advised to detect TPE that was treated with anticoagulant therapy instead of supportive care for FES.

Non-thrombotic pulmonary embolism of brain, liver, or bone marrow tissues associated with traumatic injuries in free-ranging neotropical primates

From 2016 to 2019, Southeastern Brazil faced an outbreak of yellow fever (YF) affecting both humans and New World primates (NWP). The outbreak was associated with a marked increase in traumatic lesions in NWP in the affected regions. Non-thrombotic pulmonary embolization (NTPE) can be a consequence of massive traumatic events, and it is rarely reported in human and veterinary medicine. Here, we describe NTPE of the brain, liver, and bone marrow in free-ranging NWP, highlighting the epidemiological aspects of these findings and the lesions associated with this condition, including data on traumatic injuries in wild NWP populations during the course of a recent YF outbreak. A total of 1078 NWP were necropsied from January 2017 to July 2019. Gross traumatic injuries were observed in 444 marmosets (44.3%), 10 howler monkeys (23.2%), 9 capuchins (31.0%), 1 titi-monkey (50.0%), and 1 golden lion tamarin (33.3%). NTPE was observed in 10 animals, including 9 marmosets (2.0%) and 1 howler monkey (10.0%). NTPE was identified in the lung and comprised hepatic tissue in 1 case, brain tissue in 1 case, and bone marrow tissue in 8 cases. Although uncommon, it is important to consider NTPE with pulmonary vascular occlusion during the critical care of traumatized NWP. In addition, this study highlights the importance of conservational strategies and environmental education focusing on One Health, not only to protect these free-ranging NWP populations but also to maintain the efficacy of epidemiological surveillance programs.

Autologous Bone Marrow Mononuclear Cells (BMMCs) for the Treatment of Uncomplicated Grade 2 Ununited Anconeal Process (UAP) in Six Dogs: Preliminary Results

The aim of this study was to report the results of autologous bone marrow mononuclear cell (BMMC) transplantation as a minimally invasive treatment for grade 2 UAP in dogs. This was an observational case series on six German shepherd dogs affected by grade 2 UAP as defined according to their clinical condition as well as radiographic and CT findings. Bone marrow was collected from the iliac crest and the mononuclear fraction was separated with density gradient centrifugation. Cells were suspended in fibrin glue before BMMC administration and implanted via transcutaneous injection under IB or CT guidance, using a spinal needle directly inserted into the ossification centre between the anconeal process and the olecranon. Clinical and radiographic follow-up was performed for up to 6 months. Microradiographic assessment was performed on one dog that died of other causes. A progressive reduction of pain within 3 weeks after BMMC administration was observed in all dogs, with gradually increased weight bearing on the affected limb. Radiographic and CT follow-up revealed the progressive fusion of the ossification centre at 90 days without any signs of secondary OA. The examination of microradiographs showed newly formed bone tissue in which a residue of calcified cartilage was present at the site of BMMC implantation. On the basis of these results, BMMC therapy for grade 2 UAP may be considered to be an effective and minimally invasive treatment option for dogs.

Early acute fat embolism syndrome caused by femoral fracture: A case report

BACKGROUND

Fat embolism syndrome (FES) is a rare complication caused by the presence of fat particles in the microcirculation, which usually occurs within 12-72 h after trauma. At present, there have been few cases of fat embolism presenting within 3 h after trauma. Here, we report a case of femoral fracture complicated with an acute fat embolism caused by a car accident.

CASE SUMMARY

A 29-year-old woman with pain, swelling and limited movement of her left lower limb after a car accident was taken by ambulance to our hospital. X-ray examination showed fracture of the middle and lower part of the left femur and fracture of the base of the left fifth metatarsal bone. She was hospitalized and admitted to the orthopedic ward. After the attending doctor performed tibial tubercle bone traction, the patient became confused, followed by respiratory distress. Finally, she was transferred to the intensive care unit. After nearly a month of treatment in the intensive care unit, the patient's cognitive function gradually recovered over 6 mo.

CONCLUSION

For patients with early traumatic fractures, young emergency physicians and orthopedics should be aware of the possibility of FES.

Arterial Fat Embolism in a Pediatric Patient with Femur Fracture: A Case Report

CASE

Here, we present the case of a pediatric polytrauma patient found to have lower extremity intra-arterial fat embolism causing ischemic necrosis and ultimately necessitating below-the-knee amputation.

CONCLUSION

Fat embolism, a common complication of long bone fractures in adults, can be associated with significant morbidity. Although rare, it should be considered among the possible etiologies for a pulseless limb after trauma. Early fracture stabilization may prevent fat embolism and fat embolism syndrome; however, there is no known definitive treatment, and management is supportive.

Adolescent Fat Embolism Syndrome after Closed Tibial Shaft Fracture: Treatment with Emergent External Fixation

Case

An adolescent male developed fat embolism syndrome 24 hours after sustaining a closed right tibial shaft fracture in a football game. The patient was treated with emergent external fixator application due to declining respiratory and mental status and experienced swift recovery after stabilization. He was treated with an intramedullary nail within 1 week of injury.

Conclusion

Pediatric fat embolism syndrome is uncommon, and a high index of suspicion is required to facilitate appropriate orthopaedic involvement. External fixation can be performed emergently with minimal fracture manipulation. Rapid provisional fixation appears to have facilitated recovery in this example.

Fat Embolism Syndrome - A Qualitative Review of its Incidence, Presentation, Pathogenesis and Management

Fat Embolism Syndrome (FES) is a poorly defined clinical phenomenon which has been attributed to fat emboli entering the circulation. It is common, and its clinical presentation may be either subtle or dramatic and life threatening. This is a review of the history, causes, pathophysiology, presentation, diagnosis and management of FES. FES mostly occurs secondary to orthopaedic trauma; it is less frequently associated with other traumatic and atraumatic conditions. There is no single test for diagnosing FES. Diagnosis of FES is often missed due to its subclinical presentation and/or confounding injuries in more severely injured patients. FES is most frequently diagnosed using the Gurd and Wilson criteria, like its rivals it is not clinically validated. Although FES is a multi-system condition, its effects in the lung, brain, cardiovascular system and skin cause most morbidity. FES is mostly a self-limiting condition and treatment is supportive in nature. Many treatments have been trialled, most notably corticosteroids and heparin, however no validated treatment has been established.

Use of venovenous extracorporeal membrane oxygenation for perioperative management of acute respiratory distress syndrome caused by fat embolism syndrome: A case report and literature review

INTRODUCTION

Fat embolism syndrome (FES) is a known complication of long bone fracture and can affect multiple organs. The organ most commonly affected with FES is the lung. Severe cases of FES from long bone fracture can cause acute respiratory distress syndrome (ARDS). Although the treatment of ARDS remains challenging, it is reported that a lung protection strategy and prone positioning are effective. In addition, early fixation is reported to be beneficial in respiratory failure due to FES, though it may exacerbate respiratory failure during the perioperative period. We report the use of venovenous extracorporeal membrane oxygenation (VV-ECMO) for the successful perioperative management of a patient diagnosed with ARDS due to FES.

PATIENT CONCERNS

A 24-year-old man injured in a traffic accident was brought to our emergency department due to shock and consciousness disorder.

DIAGNOSIS

After examining the patient, we noted bilateral pneumothorax, liver and spleen injuries, and multiple long bone fractures. Four days after admission, he was diagnosed with FES due to a prolonged consciousness disorder, progressive hypoxia with diffuse lung damage, and cutaneous and mucosal petechiae.

INTERVENTION

As respiratory failure progressed, VV-ECMO was initiated on the 6th day. To improve the respiratory failure caused by ARDS, prone position therapy was necessary. Thus, we performed osteosynthesis on the 9th day under ECMO. Prone position therapy was started after surgery.

OUTCOMES

Subsequently, his respiratory condition and chest radiographs improved steadily. VV-ECMO was discontinued on the 17th day and the ventilator was removed on the 28th day. His consciousness levels improved without residual central nervous system complications.

CONCLUSION

Our study reveals the successful improvement of FES-induced ARDS by osteosynthesis and prone positioning under VV-ECMO. This strategy prioritizes supportive treatment over pharmacologic interventions.

Fat embolism syndrome in blunt trauma patients with extremity fractures

OBJECTIVE

This study sought to provide a national, descriptive analysis to determine fat embolism syndrome (FES) risk factors, hypothesizing that femur fractures and multiple fractures are associated with an increased risk.

METHODS

The Trauma Quality Improvement Program was queried (2010-2016) for patients with extremity fractures. A multivariable logistic regression analysis model was used.

RESULTS

From 324,165 patients, 116 patients (0.04%) were diagnosed with FES. An age ≤30, closed femur fracture, and multiple long bone fractures were associated with an increased risk of FES.

CONCLUSION

Future research to validate these findings and develop a clinical risk stratification tool appears warranted.

Analysis of Changes in Right Ventricular Systolic Function by Point-of-Care Ultrasound in Patients Undergoing Corrective Surgeries for Femur Fracture

Background:

Fat embolism syndrome (FES) following major orthopedic injuries and surgeries is a well-known phenomenon where acute depression of right ventricular (RV) systolic function is a potential possibility. Clinical presentation of FES may vary from mild self-limiting nature to severe life-threatening multiorgan dysfunction syndrome with pulmonary manifestations being most common.

Aims:

This study was aimed to know whether perioperative assessment of RV function by measuring tricuspid annular plane systolic excursion (TAPSE) with point-of-care transthoracic echocardiogram will identify patients at risk of developing FES and its sequelae.

Settings and Design:

This was a prospective observational study.

Materials and Methods:

This study was carried out in 142 patients with femur fractures posted for correction surgeries of both genders who require intramedullary (IM) reaming. TAPSE was recorded four times perioperatively. Time taken for IM reaming was also recorded.

Statistical Analysis Used:

Recorded data were analyzed using professional statistics package Epi Info 7.0 version for Windows. Descriptive data were represented as mean ± standard deviation for numeric variables, percentages, and proportions for categorical variables. Repeated-measure ANOVA was applied to assess the changes in TAPSE from baseline to immediate postoperative, after 6-h postoperative, and after 24-h postoperatively. Pearson's correlation was utilized to be applied to assess the relationship between TAPSE and other numerical variables.

Results:

All four readings of TAPSE were well above 17 mm (mean of 19.06, 19.05, 19.04, and 19.04, respectively). Mean reaming time was found to be 6.92 min. None of the patients developed any postoperative pulmonary complications.

Conclusion:

Assessment of RV function can be done with relative ease using TAPSE as a noninvasive method without any complications. Reaming time not exceeding 12 min did not produce any changes in RV function as measured by TAPSE as well as any postoperative pulmonary complications.

Fat Embolism and Fat Embolism Syndrome

Fat embolism (FE) occurs frequently after trauma and during orthopaedic procedures involving manipulation of intramedullary contents. Classically characterized as a triad of pulmonary distress, neurologic symptoms, and petechial rash, the clinical entity of FE syndrome is much less common. Both mechanical and biochemical pathophysiologic theories have been proposed with contributions of vascular obstruction and the inflammatory response to embolized fat and trauma. Recent studies have described the relationship of embolized marrow fat with deep venous thrombosis and postsurgical cognitive decline, but without clear treatment strategies. Because treatment is primarily supportive, our focus must be on prevention. In trauma, early fracture stabilization decreases the rate of FE syndrome; however, questions remain regarding the effect of reaming and management of bilateral femur fractures. In arthroplasty, computer navigation and alternative cementation techniques decrease fat embolization, although the clinical implications of these techniques are currently unclear, illustrating the need for ongoing education and research with an aim toward prevention.

Cerebral fat embolism syndrome (FES): similar cases with different outcomes

Fat embolism syndrome (FES) is a rare multisystem, clinical syndrome occurring in 0.9%-2.2% of long-bone fractures. The severity of FES can vary from subclinical with mild respiratory changes and haematological aberrations to a fulminant state characterised by sudden onset of severe respiratory and neurological impairment. Here we present two patients with cerebral FES secondary to femur fracture. Both patients exhibited profound neurological impairment with varied outcomes. Our cases highlight the importance of a high clinical suspicion of FES in patients with long-bone fractures and neurological deterioration. We recommend early plate osteosynthesis to prevent additional emboli in patients with FES and situational placement of intracranial pressure monitoring. Finally, cerebral FES has low mortality even in a patient with tentorial herniation and fixed, dilated pupils.

Fulminant Cerebral Fat Embolism: Case Description and Review of the Literature

The release of fat and bone marrow fragments is a common occurrence following traumatic and nontraumatic events. In most cases, they go symptomless or cause only minor disturbances, but occasionally they can determine a multiorgan dysfunction whose severity ranges from mild to fatal. The authors describe the case of a patient who became deeply comatose and ultimately died after a traffic accident in which he suffered the exposed right femoral and tibial fracture in the absence of other injuries. He underwent the external fixation of the fractured bones 2 hours after the admission under general anesthesia. Three hours later, he failed to awake at the suspension of the anesthetic agents and became anisocoric; a CT scan demonstrated a diffuse cerebral edema with the herniation of the cerebellar tonsils; these abnormalities were unresponsive to the treatment and the brain death was one day later. The causes, the mechanisms, the symptoms, the prevention, and the treatment of the syndrome are reviewed and discussed.

A systematic review of the concept and clinical applications of bone marrow aspirate concentrate in tendon pathology

Tendon pathologies are a group of musculoskeletal conditions frequently seen in clinical practice. They can be broadly classified into traumatic, degenerative and overuse-related tendinopathies. Rotator cuff tears, Achilles tendinopathy and tennis elbow are common examples of these conditions. Conventional treatments have shown inconsistent outcomes and might fail to provide satisfactory clinical improvement. With the growing trend towards the use of mesenchymal stem cells (MSCs) in other branches of medicine, there is an increasing interest in treating tendon pathologies using the bone marrow MSC. In this article, we provide a systematic literature review documenting the current status of the use of bone marrow aspirate concentrate (BMAC) for the treatment of tendon pathologies. We also asked the question on the safety of BMAC and whether there are potential complications associated with BMAC therapy. Our hypothesis is that the use of BMAC provides safe clinical benefit when used for the treatment of tendinopathy or as a biological augmentation of tendon repair. We followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) checklist while preparing this systematic review. A literature search was carried out including the online databases of PubMed, EMBASE, ClinicalTrial.gov and the Cochrane Library from 1960 to the end of May 2015. Relevant studies were selected and critically appraised. Data from eligible studies were extracted and classified per type of tendon pathology. We included 37 articles discussing the application and use of BMAC for the treatment of tendon pathologies. The Critical Appraisal Skills Program (CASP) appraisal confirmed a satisfactory standard of 37 studies. Studies were sub-categorised into: techniques of extraction, processing and microscopic examination of BMAC (n = 18), where five studies looked at the evaluation of aspiration techniques (n = 5), augmentation of rotator cuff tears (n = 5), augmentation of tendo-achilles tendon (n = 1), treatment of gluteal tendon injuries (n = 1), management of elbow epicondylitis (n = 2), management of patellar tendinopathy (n = 1) and complications related to BMAC (n = 5). Multiple experimental studies investigated the use of BMAC for tendon repair; nonetheless, there are only limited clinical studies available in this field. Unfortunately, due to the scarcity of studies, which were mainly case series, the current level of evidence is weak. We strongly recommend further future randomised controlled studies in this field to allow scientists and clinicians make evidence-based conclusions.

Fat attacks!: a case of fat embolisation syndrome postliposuction

Liposuction is a procedure commonly performed in the UK usually with a low incidence of serious sequelae; however with larger patients and increased volumes of lipoaspirate, complications have been reported more frequently. One of the rare but very serious complications postliposuction is fat embolism syndrome (FES), a life-threatening condition difficult to diagnose and limited in treatment.The authors present the case of a 45-year-old woman who was admitted to the intensive care unit postelective liposuction for bilateral leg lipoedema. She presented with the triad of respiratory failure, cerebral dysfunction and petechial rash requiring a brief period of organ support. This case highlights that with the recent increase in liposuction procedures worldwide, FES is a differential to always consider. Although still a rare condition this article emphasises the importance of thinking outside the box and how to identify and manage such a life-threatening complication.

A systematic review of the clinical applications and complications of bone marrow aspirate concentrate in management of bone defects and nonunions

PURPOSE

Fracture healing encompasses a succession of dynamic multifactorial metabolic events, which ultimately re-establishes the integrity of the biomechanical properties of the bone. Up to 10% of the fractures occurring annually will need additional surgical procedures because of impaired healing. The aim of this article is to review the current literature regarding the use of bone marrow aspirate concentrate (BMAC) and its effectiveness in the management of bone defects.

METHODS

We have included all published clinical literature investigating the development, techniques and applications of BMAC. Language, design and risk of bias did not deter the initial inclusion of any study. Our search was exclusively limited to studies involving human subjects. A PRISMA compliant search was carried out as published in 2009. This included the online databases: PubMed, EMBASE, clinical trial.gov and the Cochrane library from 1960 to the end of May 2015. MeSH terms used included: "Bone" AND "Marrow" AND "Aspirate" AND "Concentrate" AND "Bone Defects" AND "NONUNION". Eligible studies were independently appraised by two authors using the Critical Appraisal Skills Program checklist. For the purpose of narrative review, relevant studies were included irrespective of methodology or level of evidence.

RESULTS

Thirty-four of the 103 (48 PubMed and 55 EMBASE) results yielded by the preliminary search were included. Exclusions included three duplicate records, six letters, 17 non-orthopaedics related studies and four records irrelevant to our search topic. The CASP appraisal confirmed a satisfactory standard of 31 studies. They all had clearly defined objectives, were well designed and conducted appropriately to meet them. The published studies reported the use of BMAC in non-union and fracture healing (15 studies), bone defects (nine studies), spine fusion (two studies), distraction osteogensis (two studies) and complications related to the use of BMAC (seven studies).

CONCLUSIONS

Stem cells found in BMAC have the potential to self-renew, undertake clonal expansion and differentiate into different musculoskeletal tissues. The commercial processing of BMAC needs to be optimized in order to achieve a consistent end product, which will provide predicable and translatable results. The future potential of cell characterization in order to determine the optimum cell for repair/regeneration of bone also needs to be explored.

LEVEL OF EVIDENCE

Systematic Review of minimum level IV studies.

Timing of definitive fixation of major long bone fractures: Can fat embolism syndrome be prevented?

Fat embolism is common in patients with major fractures, but leads to devastating consequences, named fat embolism syndrome (FES) in some. Despite advances in treatment strategies regarding the timing of definitive fixation of major fractures, FES still occurs in patients. In this overview, current literature is reviewed and optimal treatment strategies for patients with multiple traumatic injuries, including major fractures, are discussed. Considering the multifactorial etiology of FES, including mechanical and biochemical pathways, FES cannot be prevented in all patients. However, screening for symptoms of FES should be standard in the pre-operative work-up of these patients, prior to definitive fixation of major fractures.

Fat emboli syndrome and the orthopaedic trauma surgeon: lessons learned and clinical recommendations

PURPOSE

Fat emboli syndrome is a rare but well-described complication of long-bone fractures classically characterised by a triad of respiratory failure, mental status changes and petechial rash. In this paper, we present the case of a patient who sustained bilateral femoral fractures and subsequently developed FES. Our aim was to review and summarise the current literature regarding the pathophysiology and management of fat emboli syndrome (FES) and propose an algorithm for treating patients with bilateral femoral fractures to reduce the risk of FES.

METHODS

A literature analysis was performed to determine implications in the clinical setting.

RESULTS

Currently, there exists little high-quality evidence to guide the orthopaedic surgeon in identifying patients at highest risk of FES or in preventing FES in patients with multiple long-bone fractures. However, the literature does suggest that the risk is directly related to the volume of marrow displaced and inversely related to both the time to fracture stabilisation and the respiratory reserve of the patient. Based on these correlations, we propose an algorithm for treating patients with bilateral femoral fractures, taking into consideration haemodynamic and pulmonary stability.

CONCLUSIONS

Our algorithm for managing bilateral femoral fractures prioritises early stabilisation with external fixation, staged intramedullary nailing and conversion to plate fixation if FES develops. This protocol is meant to be the basis of future investigations of optimal treatment strategies.

Fat embolism syndrome: What have we learned over the years?

Although its original clinical description dates from the nineteenth century, fat embolism syndrome remains a diagnostic challenge for clinicians. Fat emboli occur in all patients with long-bone fractures, but only few of them develop a multisystem disorder affecting the lung, brain, and skin, also known as fat embolism syndrome (FES). The incidence of FES varies and is often underestimated. Mechanical and biochemical theories have been proposed for the pathophysiology of FES. Clinical manifestations consist of respiratory and cerebral dysfunction and a petechial rash. Diagnosis of FES is difficult and based mainly on clinical criteria. FES is a self-limiting disease and treatment needs to be mainly supportive. Surgical treatment of the coexistent injuries is still obscured by controversies and the treatment methods used provide inconclusive results. In this context, prevention focuses on the early identification of predisposing factors.

Fat embolism syndrome: State-of-the-art review focused on pulmonary imaging findings

BACKGROUND

Fat embolism syndrome (FES) is a rare but potentially fatal complication of trauma or orthopedic surgery, which presents predominantly with pulmonary symptoms. Modern intensive care has improved the mortality rates, however diagnosis remains difficult, relying predominantly on a combination of a classic triad of symptoms and non-specific, but characteristic radiological features. The aim of this review is to describe the main clinical and imaging aspects of FES, ranging from pathophysiology to treatment with emphasis on pulmonary involvement.

METHODS

We reviewed the currently published literature on the main characteristics of FES.

RESULTS

In a hypoxic patient with recent trauma or orthopedic surgery, the presence of diffuse, well-demarcated ground glass opacities or ill-defined centrilobular nodules on computed tomography (CT) of the chest are suggestive of FES.

CONCLUSIONS

Combination of the classic clinical syndrome in the appropriate clinical setting, together with the characteristic imaging findings on chest CT, can help to achieve the correct diagnosis. Management remains predominantly supportive care, and the benefit of medical therapies such as corticosteroids and heparin remains unclear.

Fat Intravasation from Intraosseous Flush and Infusion Procedures

STUDY HYPOTHESIS

The primary study objective was to delineate the procedural aspects of intraosseous (IO) infusions responsible for fat intravasation by testing the hypothesis that the fat content of effluent blood increases during IO infusions.

METHODS

IO cannulas were inserted into the proximal tibiae of 35 anesthetized swine (Sus scrofa, 50.1 ± 3.5 kg) and intravasated fat was assessed using a lipophilic fluoroprobe (Nile red) and by vascular ultrasound imaging. Effluent blood bone marrow fat was assessed at baseline, during flush, and with regimens of controlled infusion pressures (73-300 mmHg) and infusion flow rates (0.3-3.0 mL per second). Fat intravasation was also assessed with IO infusions at different tibial cannulation sites and in the distal femur. In 7 animals, the lipid uptake of alveolar macrophages and lung tissue assessed for fat embolic burden using oil red O stain 24 hours post infusion. Additionally, bone marrow shear-strain was assessed radiographically with IO infusions.

RESULTS

Fat intravasation was observed during all IO infusion regimens, with subclinical pulmonary fat emboli persisting 24 hours post infusion. It was noted that initial flush was a significant factor in fat intravasation, low levels of intravasation occurred with infusions ≤300 mmHg, fat intravasation and bone marrow shear-strain increased with IO infusion rates, and intravasation was influenced by cannula insertion site. Ultrasound findings suggest that echogenic particles consistent with fat emboli are carried in fast and slow venous blood flow fields. Echo reflective densities were observed to rise to the nondependent endovascular margins and coalesce in accordance with Stoke's law. In addition, ultrasound findings suggested that intravasated bone marrow fat was thrombogenic.

CONCLUSION

Results suggest that in swine the intravasation of bone marrow fat is a common consequence of IO infusion procedures and that its magnitude is influenced by the site of cannulation and infusion forces. Although the efficacy and benefits of IO infusions for emergent care are well established, emergency care providers also should be cognizant that infusion procedures affect bone marrow fat intravasation.

Intramedullary fat globules related to bone trauma: a new MR imaging finding

OBJECTIVE

The purpose of this study is to describe intraosseous fat globules related to bone trauma that are detectable with magnetic resonance imaging (MRI), to define the relationship of this finding to fracture and bone contusion, to establish the frequency and associated findings. A proposed pathogenesis is presented.

MATERIALS AND METHODS

We retrospectively reviewed 419 knee MRI examinations in patients with a history of recent injury and MRI findings of fracture or bone contusion. As a control population, 268 knee MRI examinations in patients without MRI findings of recent bone injury were also reviewed.

RESULTS

Eight of 419 (1.9%) patients with acute or subacute knee injury with positive findings of osseous trauma on MRI demonstrated intraosseous fat globules. The mean age of patients with fat globules was greater than that of those without fat globules, and the finding was more commonly seen in women. Fat globules were hyperintense to the normal fatty marrow present elsewhere in the bone on TI-weighted imaging and had a surrounding halo of high signal intensity on fluid-sensitive imaging.

CONCLUSIONS

Intramedullary fat globules related to bone injury visible on MRI are thought to be due to coalesced fat released by the necrosis of fatty marrow cells. The pathogenesis is supported by histologic studies of fat globules related to osteomyelitis, bone contusions and fractures. As the medullary cavity of long bones in older patients contains more fat than hematopoetic bone marrow, it is likely that this finding is more common with advancing age.

What the Intensive Care Doctor Needs to Know about Blast-Related Lung Injury

Explosions are currently the primary cause of military combat injuries. A minority of civilian trauma is also caused by explosions. People hurt by explosion are likely to present with complex injuries. The aim of the article is to explain the mechanism underlying these injuries and the associated physiology to help the intensive care clinician manage these casualties properly. The generic term ‘blast injury’ is applied to a collection of injuries caused by explosion. Components of blast injuries have precise definitions relating to the elements of the explosion that caused the injuries: primary blast injury is due to a shock wave, secondary blast injury is caused by fragments and debris colliding with the victim and tertiary blast injury is due to the casualty being thrown against solid objects. Primary blast injury results in damage principally in gas-containing organs, eg the lungs (blast lung) and can lead to impaired pulmonary gas transfer and hypoxaemia. Secondary blast injuries are often penetrating and can lead to haemorrhage while tertiary blast injuries are often blunt and involve substantial tissue damage. Survivors of explosions in confined spaces are more likely to exhibit primary blast injury than those injured in open spaces. The current military approach to immediate management is to apply the C ABC principle (arrest catastrophic haemorrhage first and then deal with airway, breathing and circulation) to achieve Damage Control Resuscitation. Early administration of blood products (plasma as well as red cells) is advocated for those suffering significant haemorrhage. Initial resuscitation is hypotensive to minimise risk of dislodging nascent clots. However, if evacuation is protracted (longer than one hour) then consideration should be given to improving blood flow / oxygen delivery by adopting a revised normotensive blood pressure target to reverse the deleterious consequences of the hypotensive shock state. Animal studies have shown that titrating FiO2 to a target SaO2 of 95% can improve survival and ‘buy time’ during hypotensive resuscitation. Ventilator strategies should use a lung-protective approach with permissive hypercapnia if necessary. Blast casualties are often a challenging group of patients needing expert, tailored, care. Outcome can be good especially in young, otherwise fit, casualties with more than 96% surviving to ICU discharge, although this figure may be lower with a mixed civilian group.

Lateral drill holes decrease strength of the femur: an observational study using finite element and experimental analyses

Background

Internal fixation of femoral fractures requires drilling holes through the cortical bone of the shaft of the femur. Intramedullary suction reduces the fat emboli produced by reaming and nailing femoral fractures but requires four suction portals to be drilled into the femoral shaft. This work investigated the effect of these additional holes on the strength of the femur.

Methods

Finite element analysis (FEA) was used to calculate compression, tension and load limits which were then compared to the results from mechanical testing. Models of intact femora and fractured femora internally fixed with intramedullary nailing were generated. In addition, four suction portals, lateral, anterior and posterior, were modelled. Stresses were used to calculate safety factors and predict fatigue. Physical testing on synthetic femora was carried out on a universal mechanical testing machine.

Results

The FEA model for stresses generated during walking showed tensile stresses in the lateral femur and compression stresses in the medial femur with a maximum sheer stress through the neck of the femur. The lateral suction portals produced tensile stresses up to over 300% greater than in the femur without suction portals. The anterior and posterior portals did not significantly increase stresses. The lateral suction portals had a safety factor of 0.7, while the anterior and posterior posts had safety factors of 2.4 times walking loads. Synthetic bone subjected to cyclical loading and load to failure showed similar results. On mechanical testing, all constructs failed at the neck of the femur.

Conclusions

The anterior suction portals produced minimal increases in stress to loading so are the preferred site should a femur require such drill holes for suction or internal fixation.

Effects of systemically transplanted allogeneic bone marrow multipotent mesenchymal stromal cells on rats' recovery after experimental polytrauma

BACKGROUND

The aim of this study was to evaluate impact of transplantation of bone marrow mesenchymal stromal cells (BM MMSCs) on recovery after polytrauma and bone fracture repair.

METHODS

A total 27 Wistar-Kyoto rats were divided into three groups (n = 9): normal control (A), polytrauma (B), and polytrauma treated with BM MMSC transplantation (C). The experimental polytrauma model was made on male rats by causing multiple fractures and hemorrhagic shock. At 36 hours 9 days after surgery, nine rats received allogeneic BM MMSCs (1 × 10(6) cells per kilogram) intravenously. The day before operation and at Days 3 and 10 after surgery as well as at the end of the experiment, blood analysis was carried out. At 10, 20, and 30 days after surgery the rats' locomotor activity was assessed in an open-field test. At Day 30, rats were euthanized, and macroscopic and histologic observations of rats' lower extremities was performed.

RESULTS

The treated animals gained weight faster regained their physical activity earlier. These outcomes were associated with locomotor activity test results, blood glucose and lactate ratios, as well as less marked muscle atrophy.Rat treatment with BM MMSC transplantation stimulated bone fracture healing-bone edge consolidation and enhanced callus formation, as well as the size and maturity of newly formed trabeculae.Red blood cell analysis results showed delayed recovery after hemorrhage in the rats receiving allogeneic BM MMSCs: restoration of red blood cell counts, hematocrit level, and hemoglobin level was slower in the untreated animals.

CONCLUSION

Allogeneic BM MMSC transplantation improved rats rehabilitation scores after experimental polytrauma.

Two variants of fat embolism syndrome evolving in a young patient with multiple fractures

Fat embolism syndrome (FES) is a continuum of fat emboli. Variants of FES: acute fulminant form and classic FES are postulated to represent two different pathomechanisms. Acute fulminant FES occurs during the first 24 h. It is attributed to massive mechanical blockage pulmonary vasculature by the fat emboli. The classic FES typically has a latency period of 24-36 h manifestation of respiratory failure and other signs of fat embolism. Progression of asymptomatic fat embolism with FES frequently represents inadequate treatment of hypovolaemic shock. We present a rare case of two variants of FES evolving in a patient with multiple fractures to emphasis the importance of adequate and appropriate treatment of shock in preventing the development of FES. Since supportive therapy which is a ventilatory support remains as the treatment of FES, it is appropriate to treat FES in the intensive care unit setting.

Systemic fat embolism and the patent foramen ovale--a prospective autopsy study

A fat embolism is a known and common complication of blunt force injuries, especially pelvic and long bones fractures. The aim of this study was to determine the importance of a patent foramen ovale (PFO) in developing systemic fat embolism (SFE) and eventually fat embolism syndrome (FES) in patients suffering from orthopaedic blunt injuries and consequent lung fat embolism. The sample was divided: 32 subjects with a sealed foramen ovale (SFO), and 20 subjects with a PFO. In our sample, there was no difference in either the incidence of renal fat embolism in subjects with PFO compared to those with SFO (Fisher's exact test 0.228, p=0.154) or in the grade of renal fat embolism (Pearson Chi-square 2.728, p=0.435). However, there was a statistically significant correlation between the grade of lung fat embolism and the number of fractured bones for the whole sample (Spearman's rho 0.271, p=0.052), but no correlation between the grade of lung fat embolism and the ISS or NISS (Pearson correlation 0.048, p=0.736, and 0.108, p=0.445, respectively). In our study, the presence of fat emboli in the kidney, i.e. SFE, could effectively be predicted by the grade of lung fat embolism (the moderate and slight grades of lung fat embolism were better predictors than the massive one: logistic regression - Wald. Coeff.=11.446, p=0.003, Wald. Coeff.=10.553, p=0.001, and Wald. Coeff.=4.128, p=0.042), and less effectively by presence of PFO (Wald. Coeff.=2.850, p=0.091). This study pointed out that lung and SFE are not pure biomechanical events, so the role of a PFO is not crucial in developing a lung fat embolism into a systemic embolism: the fat embolism is more of a biochemical and pathophsyiological event, than a biomechanical one. The appearance of a patent foramen ovale associated with a systemic fat embolism should be less emphasised: maybe arteriovenous shunts and anastomosis between the functional and nutritive, i.e. systemic circulation of lungs play a more important role in developing a SFE than a PFO.

A minimally invasive technique for the detection and analysis of pulmonary fat embolism: a feasibility study

We investigated the feasibility of postmortem percutaneous needle biopsy (PNB) for obtaining pulmonary samples adequate for the study of pulmonary fat embolism (PFE). Samples of both lungs were obtained from 26 cadavers via two different methods: (i) PNB and (ii) the double-edged knife technique, the gold standard at our institute. After water storage and Sudan III staining, six forensic pathologists independently examined all samples for the presence and severity of PFE. The results were compared and analyzed in each case regarding the vitality of the PFE and its relationship to the cause of death. The results showed that PFE was almost identically diagnosed and graded on the samples obtained via both methods. The discrepancies between the two techniques did not affect the diagnoses of vitality or cause of death related to PFE. This study demonstrates the feasibility of the PNB sampling method for the diagnosis and interpretation of PFE in the postmortem setting.

Intravasation of bone marrow content. Can its magnitude and effects be modulated by low pressure reaming in a porcine model?

INTRODUCTION

Intramedullary orthopaedic procedures may increase the intramedullary pressure (IMP) and thereby cause intravasation of bone marrow contents. In recent studies by the authors the reamer-irrigator-aspirator (RIA) has been demonstrated to reduce IMP and coagulation-, fibrinolysis- and cytokine responses, but did not prove any significant difference in cardiopulmonary function parameters or numbers of emboli when compared to a traditional reaming (TR) system. The correlations between IMP increase, regardless type of reamer, and inflammatory- and coagulation responses, pulmonary embolization, and cardiopulmonary alterations have, however, not previously been analyzed in this material. Our hypothesis was that a lower IMP would result in reduced occurrence of pulmonary embolization, reduced inflammatory-and coagulation responses, as well as reduced cardiopulmonary alterations.

MATERIALS AND METHODS

Twenty-eight young Norwegian landrace pigs were exposed to femoral intramedullary reaming, with either the TR (n = 10) or the RIA (n = 10) system, or used as controls (n = 8). IMP was recorded during reaming and nailing. Serial blood samples for demonstration of coagulation-, fibrinolysis-, and cytokine activation were withdrawn peroperatively and until 72 hours post nail insertion. Circulatory and pulmonary effects were monitored peroperatively and until two hours postoperatively. The animals were sacrificed 72 hours post nail insertion and lung tissue biopsies were harvested and examined for lung emboli.

RESULTS AND CONCLUSIONS

A strong correlation between increased IMP and increased coagulation-and cytokine responses was found. The number of emboli was not significantly correlated to IMP, but was strongly correlated to changes in the coagulation- and cytokine responses. No clinical relevant correlations were observed between increased IMP or numbers of lung emboli and changes in hemodynamic- or pulmonary function parameters. A correlation between coagulation activation and cytokine activation was observed. This study confirms the connection between increased IMP, increased coagulation activation and the magnitude of pulmonary emboli in a model evaluating the effects of intramedullary reaming of intact pig femora. In this model, the lowering of IMP during reaming, as obtained with RIA, reduced the magnitude of and the effects of bone marrow extravasation.

Diagnosis of fatal pulmonary fat embolism with minimally invasive virtual autopsy and post-mortem biopsy

We report a case of a 78-year-old female with a proximal femur fracture caused by an accidental fall who died suddenly 1h after orthopaedic prosthesis insertion. Post-mortem computed tomography (CT) scan and histological examination of samples obtained with post-mortem percutaneous needle biopsies of both lungs were performed. Analysis of the medical history and the clinical scenario immediately before death, imaging data, and biopsy histology established the cause of death without proceeding to traditional autopsy. It was determined to be acute right ventricular failure caused by massive pulmonary fat embolism. Although further research in post-mortem imaging and post-mortem tissue sampling by needle biopsies is necessary, we conclude that the use of CT techniques and percutaneous biopsy, as additional tools, can offer a viable alternative to traditional autopsy in selected cases and may increase the number of minimally invasive forensic examinations performed in the future.

The Early Effects of Intramedullary Reaming of the Femur on Bone Mineral Density; an Experimental Study in Pigs

Background and Aims:

Both fracture and fracture treatment affect bone mineral density (BMD). BMD after standard intramedullary reaming of the femoral cavity and after reaming with a reamer-irrigator-aspirator (RIA) system were studied with the hypothesis that the RIA technique would lead to lower BMD levels.

Material and Methods:

Dual-energy X-ray absorptiometry (DXA) was performed on the third day after operation with standard intramedullary nailing technique (n = 6)or RIA technique (n = 7) in intact femora of young Norwegian landrace pigs.

Results and conclusion:

Significantly lower BMD were found in the mid-shaft and total femur after reaming with the RIA technique compared to the non-operated femur. Traditional reaming technique resulted in significantly higher BMD in the distal femur.

Interpretation:

The results of this study indicate that standard reaming increased BMD in the distal femur, suggesting compressive effects on trabecular bone. The RIA technique decreased BMD in the femoral diaphysis and total femur, suggesting removal of trabecular bone. A possible clinical impact of the findings remains to be investigated.

Fat marrow embolism during intramedullary bone endoscopy: an experimental study in sheep

We present a study designed to investigate whether the intramedullary bone endoscopy (IBE) procedure within the cavity of an intact long bone will create embolic loads on the lungs similar to that of other orthopedic procedures (e.g., stem implantation in total hip arthroplasty [THA]). In a sheep model, 10 animals underwent the IBE procedure with complete perioperative anesthesiology monitoring. The lungs were harvested postoperatively and examined for fat embolisms. One animal showed evidence of intraoperative fat embolism with temporary increases in mean pulmonary arterial pressure (MPAD) and the mean CO(2)-gradient. The histological examination in this animal revealed fat embolism with a 2% surface area of the investigated fields covered with fat vacuoles. All peri- and postoperative data on the other nine animals were normal. Our findings indicate that, as with other intramedullary manipulation in intact long bones, there is a potential risk for systemic fat excavation during IBE. However, the embolic load is much lower than the rates reported for other orthopedic interventions.