Fifty-five adults who had sustained a tibial fracture, or a femoral fracture, or both, were subjected to a double-blind randomised study to determine the efficacy of methylprednisolone in treating the fat embolism syndrome. This drug maintained arterial oxygen levels, stabilised or reduced the serum level of free fatty acids, and decreased the risk of the fat embolism syndrome in a statistically significant proportion of patients. Gurd's criteria for the diagnosis of the fat embolism syndrome were found inadequate. Other more sensitive criteria for early diagnosis and effective management were determined. There were no deaths or serious morbidity in our series

Several experimental models have been used to produce intravascular fat embolism. We have developed a simple technique to induce fat embolism using corn oil emulsified with distilled water to form fatty micelles. Fat embolism was produced by intravenous administration of these fatty micelles in anaesthetised rats, causing alveolar oedema, haemorrhage and increased lung weight. Histopathological examination revealed fatty droplets and fibrin thrombi in the lung, kidney and brain. The arteriolar lumen was filled with fatty deposits. Following fat embolism, hypoxia and hypercapnia occurred. The plasma phospholipase A. 2. , nitrate/nitrite, methylguidanidine and proinflammatory cytokines were significantly increased. Mass spectrometry showed that the main ingredient of corn oil was oleic acid. This simple technique may be applied as a new animal model for the investigation of the mechanisms involved in the fat embolism syndrome

Aims. The aim of this study was to assess whether it is possible to predict the mortality, and the extent and time of neurological recovery from the time of the onset of symptoms and MRI grade, in patients with the cerebral fat embolism syndrome (CFES). This has not previously been investigated. Methods. The study included 34 patients who were diagnosed with CFES following trauma between 2012 and 2018. The clinical diagnosis was confirmed and the severity graded by MRI. We investigated the rate of mortality, the time and extent of neurological recovery, the time between the injury and the onset of symptoms, the clinical severity of the condition, and the MRI grade. All patients were male with a mean age of 29.7 years (18 to 70). The mean follow-up was 4.15 years (2 to 8), with neurological recovery being assessed by the Glasgow Outcome Scale and the Mini-Mental State Examination. Results. In all, seven who had early-onset CFES (< 24 hours), and a severe Takahashi grade on MRI, died. There was a significant association between the time of onset of neurological signs and mortality (p = 0.035). Mortality was also significantly associated with a severe Takahashi grade (p < 0.001). Among the 27 surviving patients, 26 (96.3%) recovered completely. One (3.7%) had a cognitive deficit. The mean time to recovery was 4.7 weeks (2 to 13), with late recovery aftereight eight weeks being recorded in three patients. Conclusion. There was a significantly increased rate of mortality in patients with CFES who had an early onset of symptoms and a severe grade on MRI. Complete neurological recovery can be expected in most patients with CFES who survive. Cite this article: Bone Joint J 2022;104-B(1):142–149

Aims. Previous research has demonstrated increased early complication rates following total hip arthroplasty (THA) in obese patients, as defined by body mass index (BMI). Subcutaneous fat depth (FD) has been shown to be an independent risk factor for wound infection in cervical and lumbar spine surgery, as well as after abdominal laparotomy. The aim of this study was to investigate whether increased peritrochanteric FD was associated with an increased risk of complications in the first year following THA. Methods. We analyzed prospectively collected data on a consecutive series of 1,220 primary THAs from June 2013 until May 2018. The vertical soft tissue depth from the most prominent part of the greater trochanter to the skin was measured intraoperatively using a sterile ruler and recorded to the nearest millimetre. BMI was calculated at the patient’s preoperative assessment. All surgical complications occuring within the initial 12 months of follow-up were identified. Results. Females had a significantly greater FD at the greater trochanter in comparison to males (median 3.0 cm (interquartile range (IQR) 2.3 to 4.0) vs 2.0 cm (IQR 1.7 to 3.0); p < 0.001) despite equivalent BMI between sexes (male median BMI 30.0 kg/m. 2. (IQR 27.0 to 33.0); female median 29.0 kg/m. 2. (IQR 25.0 to 33.0)). FD showed a weak correlation with BMI (R² 0.41 males and R² 0.43 females). Patients with the greatest FD (upper quartile) were at no greater risk of complications compared with patients with the lowest FD (lower quartile); 7/311 (2.3%) vs 9/439 (2.1%); p = 0.820 . Conversely, patients with the highest BMI (≥ 40 kg/m. 2. ) had a significantly increased risk of complications compared with patients with lower BMI (< 40 kg/m. 2. ); 5/60 (8.3% vs 18/1,160 (1.6%), odds ratio (OR) 5.77 (95% confidence interval (CI) 2.1 to 16.1; p = 0.001)). Conclusion. We found no relationship between peritrochanteric FD and the risk of surgical complications following primary THA. Cite this article: Bone Joint J 2020;102-B(9):1146–1150

1. Blood from forty-one healthy volunteers, seventy-one patients with fractures but without symptoms of fat embolism and seven patients with clinical evidence of fat embolism was examined microscopically for fat droplets and chemically for triglycerides. 2. Fat droplets, after Millipore filtration of the blood, were seen evenly distributed in all three groups. 3. There was no significant difference in triglyceride concentration between serum and filtrate in the three groups. 4. The results do not support the thesis that the Gurd test is a reliable aid in the diagnosis of fat embolism

1. A distinction must be made between the fat embolism syndrome, a clinical entity, and fat embolism demonstrated pathologically, which may be found after death following fracture with no prior evidence of the syndrome. 2. One hundred cases of the syndrome encountered over a period of four years have been studied in detail and the diagnostic criteria have been defined. These include one major feature, four minor features and fat macroglobulaemia. 3. Sixteen of the patients died–eight from severe pulmonary insufficiency of the syndrome, eight from other traumatic causes. 4. The prevention of shock is the best measure for prevention of the syndrome. The role of proteases in the production of shock and the place of protease inhibition in treatment of the syndrome are briefly discussed. 5. For the established case the aim of treatment is to ensure an adequate pressure of arterial oxygen

1. A diagnostic procedure is described which is specific for fat embolism. It allows identification of the pathological fat globules On a stained slide. 2. The amount of pathological fat can be estimated by comparing the serum triglyceride levels before and after filtration. 3. The method is simple, reproducible and inexpensive

1. Fat embolism occurs in a high percentage of all cases of injury and it is a relatively frequent complication of fractures of the long bones in civilian accidents as well as battle casualties. 2. The diagnosis can usually be established by the clinical features together with certain physical signs which must however be sought deliberately. 3. Important clinical features are the mental disturbance, alternation of coma with full consciousness, petechial haemorrhages in the conjunctiva and skin, and typical changes in the retina. 4. Evidence is still conflicting as to whether the fat arises by embolism from an injured bone, or by general metabolic disturbance. 5. The fat is harmful not so much by reason of mechanical obstruction of vessels as by erosion and rupture of the vessel wall clue to the liberation of fatty acids. 6. Preventive treatment appears to be of some value but no satisfactory specific treatment is yet available for the established case. 7. Ligation of the profunda vein has been tried in two patients, one of whom recovered and the other died

1. Reports of the lipaemia-clearing effect of heparin suggested that this drug might be of therapeutic value in fat embolism. 2. In an experimental trial with rats, heparin was found both to accelerate death and to increase the number of deaths after fat embolism. 3. It is accordingly concluded that a clinical trial of heparin in human fat embolism would not be warranted

The changes in a number of haemostatic factors after fractures of the tibia or femur were compared with those observed in patients with fat embolism complicating such fractures. After fractures uncomplicated by fat embolism there was a rise in the fibrinogen, α. 1. -antitrypsin and serum activation inhibitor. The plasminogen level and platelet count initially fell, but later increased to above the initial levels. Patients whose fractures were complicated by fat embolism had the same pattern of changes but quantitatively greater

An experimental study performed in 16 mongrel dogs is presented, which shows that when venous stasis is combined with the local injection of non-esterified fatty acid an intense thrombosis results. This response is not produced by venous stasis alone, nor by the combination of venous stasis and triacylglycerol. Histologically it is quite different from the response produced by an inert intraluminal foreign body. It does resemble venous thrombosis described experimentally and in patients. The clinical relevance of these findings is that during accidental or operative trauma to a long bone, fat is commonly forced into the local venous circulation. If this event is combined with venous stasis or a tourniquet is used, then the circumstances of this experiment are reproduced. It is suggested that the venous thrombosis which commonly complicates long-bone injury or operation is in part caused by the thrombogenic nature of the introduced fat

An episode of hypotension is common during cemented joint replacement, and has been associated with circulatory collapse and sudden death. We studied the mechanism of hypotension in two groups of six dogs after simulated bilateral cemented arthroplasty. In one group, with no lavage, the insertion of cement and prosthesis was followed by severe hypotension, elevated pulmonary artery pressure, decreased systemic vascular resistance and a 21% reduction in cardiac output. In the other group, pulsatile intramedullary lavage was performed before the simulated arthroplasties. Hypotension was less, and although systemic vascular resistance decreased, the cardiac output did not change. The severity of the hypotension, the decrease in cardiac output and an increase in prostaglandin metabolites were related to the magnitude of pulmonary fat embolism. Pulsatile lavage prevents much of this fat embolism, and hence the decrease in cardiac output. The relatively mild hypotension after lavage was secondary to transient vasodilation, which may accentuate the hypotension caused by the decreased cardiac output due to a large embolic fat load. We make recommendations for the prevention and management of hypotension during cemented arthroplasty

1. Three cases of acute peptic ulceration are reported after cerebral fat embolism complicating skeletal injuries. In two instances death occurred after perforation of an ulcer, and in the third intestinal haemorrhage led to death. 2. Although intracranial lesions and peptic ulceration have been reported on many occasions, so far as we know cerebral fat embolism as a cause has not been previously recognised. 3. The possible pathogenesis is discussed

1. Three patients are reported in whom a sudden acute internal derangement of the knee was caused by torsion of a pedunculated portion of the infrapatellar fat pad. 2. The symptoms and signs are described. 3. The pathological changes and the pathogenesis are discussed

We examined the roles of methylmethacrylate (MMA) monomer and cementing technique in the formation, and haemodynamic outcome, of pulmonary fat emboli. The preparation of the femoral canal and the cementing technique were studied in four groups of adult dogs as follows: control (no preparation); lavage; cement pressurisation; and cement pressurisation after lavage. We measured the intramedullary pressure, pulmonary artery pressure (PAP), pulmonary capillary wedge pressure and bilateral femoral vein levels of triglyceride, cholesterol and MMA monomer at rest and after reaming, lavage, and cementing. Femoral vein triglyceride and cholesterol levels did not vary significantly from resting levels despite significant elevations in intramedullary pressure with reaming, lavage and cementing (p = 0.001). PAP was seen to rise significantly with reaming (p = 0.0038), lavage (p = 0.0031), cementing (p = 0.0024) and cementing after lavage (p = 0.0028) while the pulmonary capillary wedge pressure remained unchanged. MMA monomer was detected in femoral vein samples when cement pressurisation was used. Intramedullary lavage before cementing had no significant effect on the MMA level. Haemodynamic evidence of pulmonary embolism was noted with reaming and intramedullary canal preparation, irrespective of the presence of MMA monomer. We found no relationship between MMA monomer level and intramedullary pressure, PAP or pulmonary capillary wedge pressure. Our findings suggest that the presence of MMA monomer in femoral venous blood has no effect on the formation of fat emboli or their pulmonary haemodynamic outcome during cemented hip arthroplasty

Twenty young men with displaced fractures of one or more long bones in the lower limb, but with no evidence of cranial, thoracic or abdominal injury, were studied prospectively. Although all the patients became hypoxaemic, the six who developed signs of respiratory distress (Group 1) were found to have a significantly lower arterial oxygen tension and a significantly higher rate of urinary urea excretion than the remaining 14 patients whose pulmonary function appeared to be clinically normal (Group 2). Circulating fat macroglobules were identified in three cases, only one of whom was in Group 1, and hence the tests for fat embolism were not of prognostic value. Although an immunodeficient state is considered to contribute to the pulmonary insufficiency which occurs after major trauma, convincing evidence of a lymphocyte-suppressive agent was found in only one patient

Multipotential processed lipoaspirate (PLA) cells extracted from five human infrapatellar fat pads and embedded into fibrin glue nodules, were induced into the chondrogenic phenotype using chondrogenic media. The remaining cells were placed in osteogenic media and were transfected with an adenovirus carrying the cDNA for bone morphogenetic protein-2 (BMP-2). We evaluated the tissue-engineered cartilage and bone using in vitro techniques and by placing cells into the hind legs of five severe combined immunodeficient mice. After six weeks, radiological and histological analysis indicated that the PLA cells induced into the chondrogenic phenotype had the histological appearance of hyaline cartilage. Cells transfected with the BMP-2 gene media produced abundant bone, which was beginning to establish a marrow cavity. Tissue-engineered cartilage and bone from infrapatellar fat pads may prove to be useful for the treatment of osteochondral defects

Asymptomatic cyst-like cortical defects appearing after fractures in children have been occasionally reported. Typically, these defects appear during fracture consolidation, within the newly formed subperiosteal bone, proximal to the fracture line, do not enlarge, and progressively disappear. We have previously shown a fatty density on CT scan within the early cortical defect. We now present two additional cases in which early CT scans appeared to confirm that these transient cortical defects may consist of fat, and probably result from the inclusion of medullary fat within the subperiosteal haematoma

The cavities left after resection of bone bridges for partial closure of growth plates in children have commonly been filled with free fat grafts. Such cavities have been seen to elongate and thus enlarge during growth after the operation, but the fate of the grafts has been unknown. Similar cavities, made in the tibiae of growing pigs were filled with autogenous fat and studied by radiography for periods of up to 9 1/2 months. These cavities elongated in a manner similar to those in the clinical cases, and histological section showed them to be filled with living adipose tissue. The volume of this tissue had continuously increased in parallel with the growth in length of the bone. The fate of the grafts used in children may be similar to that seen experimentally

The operative technique and result of treatment of traumatic radio-ulnar synostosis in two patients are described. In both, the treatment was excision of the cross-union and interposition of a free non-vascularised fat transplant. The functional result was excellent, and there was no evidence of regrowth of the synostosis at two and three years respectively