Aims. The aim of this study was to investigate the global and local impact of fat on bone in obesity by using the diet-induced obese (DIO) mouse model. Methods. In this study, we generated a diet-induced mouse model of obesity to conduct lipidomic and 3D imaging assessments of bone marrow fat, and evaluated the correlated bone adaptation indices and bone mechanical properties. Results. Our results indicated that bone mass was reduced and bone mechanical properties were impaired in DIO mice. Lipidomic sequencing and bioinformatic analysis identified 373 differential lipids, 176 of which were upregulated and 197 downregulated. Functional enrichment analysis revealed a significant downregulation of the pathways: fat digestion and absorption (ko04975) and lipolysis regulation in adipocytes (ko04923) in DIO mice, leading to local fat accumulation. The use of 3D imaging confirmed the increase in fat accumulation within the bone marrow cavity of obese mice. Conclusion. Our study sheds light on the intricate interplay between fat and bone, and provides a non-toxic and non-invasive method for measuring marrow adipose tissue. Cite this article: Bone Joint Res 2023;12(9):580–589

Background. Although there are predictive equations that estimate the total fat mass obtained from multiple-site ultrasound (US) measurements, the predictive equation of total fat mass has not been investigated solely from abdominal subcutaneous fat thickness. Therefore, the aims of this study were; (1) to develop regression-based prediction equations based on abdominal subcutaneous fat thickness for predicting fat mass in young- and middle-aged adults, and (2) to investigate the validity of these equations to be developed. Methods. The study was approved by the Local Research Ethics Committee (Decision number: GO 19/788). Twenty-seven males (30.3 ± 8.7 years) and eighteen females (32.4 ± 9.5 years) were randomly divided into two groups as the model prediction group (19 males and 12 females) and the validation group (8 males and 6 females). Total body fat mass was determined by dual-energy X-ray absorptiometry (DXA). Abdominal subcutaneous fat thickness was measured by US. The predictive equations for total fat mass from US were determined as fat thickness (in mm) × standing height (in m). Statistical analyses were performed using R version 4.0.0. The association between the total fat mass and the abdominal subcutaneous fat thickness was interpreted using the Pearson test. The linear regression analysis was used to predict equations for total body fat mass from the abdominal subcutaneous fat thickness acquired by US. Then these predictive equations were applied to the validation group. The paired t-test was used to examine the difference between the measured and the predicted fat masses, and Lin's concordance correlation coefficient (CCC) was used as a further measure of agreement. Results. There was a significant positive moderate correlation between the total fat mass and the abdominal subcutaneous fat thickness × height in the model prediction group of males (r = 0.588, p = 0.008), whereas significant positive very strong correlation was observed in the model prediction group of females (r = 0.896, p < 0.001). Predictive equations for DXA-measured total body fat mass from abdominal subcutaneous fat thickness using US were as follows: for males “Fat mass-DXA = 0.276 × (Fat thickness-US × Height) + 17.221” (R. 2. = 0.35, SEE = 3.6, p = 0.008); for females “Fat mass-DXA = 0.694 x (Fat thickness-US × Height) + 7.085” (R. 2. = 0.80, SEE = 2.8, p < 0.001). When fat mass prediction equations were applied to the validation groups, measured- and estimated-total fat masses in males and females were found similar (p = 0.9, p = 0.5, respectively). A good level of agreement between measurements in males and females was attained (CCC = 0.84, CCC = 0.76, respectively). Conclusion. We developed and validated prediction equations that are convenient for determining total fat masses in young- and middle-aged adults using abdominal subcutaneous fat thickness obtained from the US. The abdominal subcutaneous fat thickness obtained from a single region by US might provide a noninvasive quick and easy evaluation not only in clinical settings but also on the field

Introduction:. Primary functions of heel and forefoot fat pad - shock absorber at heel strike, energy dissipation, load bearing, grip and insulation. •Reliability of weight bearing heel pad thickness measurements by ultrasound has been determined by Rome et al. Importance of soft tissue fillers has been recently popularised by Coleman. Methods and materials:. Harvesting done by standard low pressure liposuction using small cannula. Grafting using small needle depositing the small globules of fat in multiple layers of soft tissue. There is an expectation that up to 50% of the fat will be lost and so upto 19mls of fat placed per foot. Patients were kept NWB for 4–6 weeks post op and then allowed to mobilise fully. Case notes were prospectively collated and analysed. Pre and post-op ultrasound scans were performed to document the depth of the heel/forefoot fat pad. Clinical pictures were taken and post-op patient satisfaction scores were done as well. Results:. We treated 9 feet in 5 patients. 5 heel fat pad transfers and 4 forefoot. Pain completely relieved in all feet. No complications. Average pre-op VAS - 3/ Post-op – 9. Average pre-op AOFAS score - 70/ post-op - 105. Follow-up 6months - maximum 23 months. Conclusion:. Fat transfer is usually used for cosmetic reasons and occasionally to improve scars. Very few reports from South America have been published for patients using high heels giving pain but none for patients with a pathological anomaly. The technique seems to highly effective with no complications so far. It is currently being used on other painful problems in other areas of the sole with equal success. Abdominal fat transfer is an innovative technique aimed at getting rid of the ‘heel pad syndrome’

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

Abstract. Introduction. Patella Baja is a known complication of TKR. In this study, we report the effect of the senior author's change of practice from total excision to minimal resection of Hoffa's fat pad on patellar height. Methods. Retrospective analysis of a prospective series of TKRs performed or directly supervised by the senior author. Group 1 included 72 patients performed before April 2011 who had complete excision of Hoffa's fat pad to improve exposure during their TKR procedures. Group 2 included 138 patients performed after April 2011 who had the minimum excision of Hoffa's fat pad to allow exposure. There were no other changes in surgical technique, implant choice or rehabilitation protocol during this time. Patellar height was measured using the Caton–Deschamps Index (CDI) on standard lateral radiographs immediately postoperative and at a minimum follow up of 1 year. Results. Group 1 included 28 males, 44 females with mean age 68.36 years. The mean CDI in this group changed from 0.54 immediately post-operatively to 0.46 at minimum one year follow-up (P=0.001) indicating progressive Patella Baja. Group 2 included 56 males, 82 females with mean age 65 years. The mean CDI changed from 0.67 immediately post-operative to 0.68 at minimum one year post follow-up (P= 0.32) indicating no statistically or clinically relevant post-operative change in patellar height. Conclusions. Total excision of Hoffa's fat pad is associated with progressive post-operative patella baja which can be avoided by resecting the minimum amount of fat pad to allow adequate exposure

Elevated fat pads on a paediatric elbow radiograph may represent an intraarticular fracture. If no obvious fracture is visible, the injury may be treated with a collar and cuff until discomfort resolves. In some centres these patients are discharged directly from A&E, easing the load on fracture clinics and reducing the number of visits required by the patient. A retrospective study was carried out to review patient journey for children referred to clinic with elevated fat pads only and to investigate whether such a protocol could be established locally. Notes for all children attending fracture clinic in May 2018 were reviewed. X-rays for patients with any elbow injury were then reviewed. Patients with raised fat pads only were included in the study. Outcome following clinic review was recorded. 818 patients (315 new referrals) attended 15 clinics. 31 were referred with raised fat pads only. Mean age was 7.7 years with mean time to clinic of 4 days. 74.2% required no further treatment and were discharged at first clinic appointment. 8 patients were kept in cast for another 1–2 weeks due to parental apprehension, patient apprehension or patient being uncomfortable without cast. None of our patients required surgical intervention or re-attended following discharge. This study showed that patients with raised fat pads only can be treated with collar and cuff, analgesia and discharged from A&E with an advice leaflet. This would reduce the number of patients unnecessarily attending clinics thereby reducing patient distress and enabling more efficient use of clinic appointments

Introduction. Previous research has demonstrated increased early complication rates following total hip arthroplasty in obese patients, as defined by body mass index (BMI). Subcutaneous fat depth 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 peri-trochanteric fat depth was associated with increased risk of early complication following total hip arthroplasty. Methods. We analysed prospectively collected data on a consecutive series of 1220 patients undergoing primary total hip arthroplasty 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 using a sterile ruler and recorded to the nearest millimetre. BMI was calculated at the patient's pre-operative assessment review. All complications (infection, dislocation and peri-prosthetic fracture) occuring within the initial 12 month follow-up were identified. Results. Females had a significantly greater fat depth at the greater trochanter in comparison to males (median 3.0cm (IQR 2.3–4.0) versus 2.0cm (IQR 1.7–3.0), p<0.001) despite equivalent BMI between genders (males median BMI 30.0 (IQR 27.0–33.0); female median 29.0 (IQR 25.0–33.0). Fat depth had a weak correlation with BMI (R. 2. 0.41 males and R. 2. 0.43 females). Patients with the greatest fat depth (upper quartile) were at no greater risk of developing a complication compared to patients with the lowest fat depth (lower quartile); 2% vs 1.8%, p=0.829. Conclusions. Peri-trochanteric fat depth is only weakly correlated with BMI. We found no correlation between increased fat depth and risk of early complication following primary total hip arthroplasty

The knee joint has also a periarticular adipose tissue, which is known as Hoffa's fat pad (IPFP). IPFP has a dual function in the joint it reduces the concentration of Nitric Oxide, the release of glycosaminoglycans and the expression of MMP1 in the cartilage, but it also contains MSC and macrophages. Our hypothesis is that synovial fluid contains elements, not all of which are understood, which act as messengers and alter the “homeostasis” of the knee and the metabolism of all the cellular components of the joint, including the MSC of Hoffa's fat pad, thus making them another piece in the puzzle as far as OA of the knee is concerned. The IPFP of 37 patients with OA and 36 patients with ACL rupture were analyzed. Isolation, primary culture, and a functional and proteomic study of MSCs from IPFP were performed. Our results show that OA of the knee, in its more severe phases, also affects the MSC's of IPFP, which is a new actor in the OA degenerative process and which can contribute to the origin, onset and progression of the disease. A differential protein profile between OA and ACL patients were identified. Infrapatellar pad should be regarded as an adipose tissue with its own characteristics and it´s also able to produce and excrete important inflammatory mediators directly into the knee joint

Objectives. Although many clinical and experimental investigations have shed light on muscle atrophy and intramuscular accumulation of fat after rotator cuff disruption, none have reported on their onset in the absence of muscle retraction. Methods. In 30 rabbits, we detached one supraspinatus (SSP) tendon and repaired it immediately, thus preventing muscle retraction. The animals were killed in groups of 10 at one, two and six weeks. Both shoulders of 15 non-operated rabbits served as controls. We measured the weight and volume of SSP muscles and quantified the cross-sectional area of intramuscular fat (i-fat) histologically. Results. There was significant loss of muscle weight and volume after one week (p = 0.004 and 0.003, respectively), and two weeks (both p < 0.001) in the experimental group; which recovered to control values after six weeks. I-fat accumulated one week after immediate repair, greater than in the control group and statistically significant at the mid-part of the muscle (mean 2.7% vs 1.5%, p = 0.008). I-fat continued to accumulate up to six weeks at all sites of the SSP muscle (all 3, p < 0.001). More fat accumulated closer to the musculotendinous junction than at the mid-part after two and six weeks (p = 0.012 and 0.019, respectively). Conclusion. Muscle atrophy and i-fat accumulation occur early after SSP tendon tear and immediate repair. While early repair benefitted muscle recovery, it did not prevent fat accumulation. SSP muscle retraction was not essential to the muscle alterations. The divergent evolution of muscle and fat points to different pathophysiologies. Cite this article: Bone Joint Res 2014;3:117–22

Hip and knee replacements are common and successful surgeries in orthopaedics. One of the known complications is fat embolism. Cemented implants used in arthroplasty allow good implant fixation and excellent long term results. However this has been associated with an increased incidence of fat embolism. This experimental animal study compared the amount of fat embolism following three different surgeries in 30 Sprague Dawley rats. These surgeries simulated hip replacement procedures and included a control surgery, an un-cemented implant and a cemented implant. These animals were then sacrificed at 24 hours. All the lungs were fixed in formalin and then stained using Osmium Tetroxide. The amount of fat was then counted using a light microscope at 40x power. Both the uncemented implant group (p < 0.001) and the cemented implant groups (p < 0.003) had significantly higher fat emboli from the surgical control group. There were also a significantly higher number of emboli (p < 0.05) in the cemented implant group compared to the uncemented implant group. We conclude that fat embolism occurs in both the un-cemented and cemented hip replacement. The amount of emboli created by un-cemented hip replacement is less than the cemented hip replacement. The cement itself does not cause the complication of fat embolism. It is the high intramedullary pressure associated with the insertion of the implant, and the cementing process, that contributes to fat embolism. Devices or surgery that minimise this rise in pressure could reduce the amount of fat embolism

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

The purpose of this study in to investigate the role of infrapatellar fat pad on primary total knee arthroplasty. We evaluated 100 patients who had been undergone TKA from August 2002 to July 2003, with open box posterior substituting femoral component implant (Scorpio PS Knee. ™. ). The study was performed prospectively and randomly allocated. We divided two groups. Group 1 (50 knees) was preserved infrapatellar fat pad and repaired fad at wound closure. Group 2 (50 knees) was excised infrapatellar fat pad as possible and repaired only joint capsule. We analyzed and compared clinical results of Knee Society knee (KS) score, function score, patellar score and Insall-Salvati ratio in both groups. The complications of each group were evaluated. Patients were followed up for mean 40 months(17~52 months). Mean KS score was 91.9 (91.94±5.58) in Group 1 and 90.9(90.92±6.38) in Group 2. Mean function score was 81.6(81.64±13.18) in Group 1 and 83.7(83.79±17.71) in Group 2. Mean patellar score was 29.9(29.89±9.10) in Group 1 and 27.9(27.90±1.80) in Group 2. And mean patellar height as Insall-Salvati ratio was 1.19(1.19±0.17) in Group 1 and 1.23(1.23±0.11) in Group 2. The differences between the Group 1 and Group 2 in all of index were statistically insignificant. In complications, 2 cases of recurrent hemarthrosis were observed in Group 1 patients. We concluded The difference of clinical outcomes whether infrapatellar fat pad was excised or not were statistically insignificant. However, preservation of infrapatellar fat pad on open boxed PS TKA showed unique complications such as recurrent hemarthrosis which might be caused by fat pad adhesion to intercondylar notch. We propose that infrapatellar fat pad on primary PS TKA with open box design would like to be excised for prevention of unique complications

Background. Carpometacarpal osteoarthritis is a degenerative disease of the hand that causes pain, stiffness and weakness. Currently, no drugs are available to prevent progression or cure this disease. Ultimately, the last treatment option is the surgical removal of the trapezium bone. In order to this limited treatment options, the utilization of autologous fat injections or adipose-derived stem progenitor cells (ADSPCs) provides a novel treatment option to inhibit the progression of this disease and potentially regenerate the damaged tissue. Objective. By utilizing next-generation-sequencing (NGS), we aim to uncover novel factors, released by ADSPCs or whole-fat aspirates, that might be involved into the metabolism of osteoarthritic cartilage. Materials and Methods. Human fat tissue was collected from five patients undergoing abdominal liposuction. Fat- and ADSPCs-conditioned medium was prepared by incubating fat and ADSPCs for 48 h in culture medium with and without TNFα to stimulate the secretion of immunomodulatory factors. The transcriptome of stimulated and non-stimulated fat and ADSPCs was analyzed by NGS. Chondrocytes from osteoarthritic cartilage from seven patients undergoing trapeziectomy were isolated, expanded and pooled. Chondrocytes were treated with six different conditions for 72 h. While standard culture medium with and without TNFα served as control groups. Fat-conditioned medium with and without TNFα, as well as ADSPCs-conditioned medium with and without TNFα served as experimental groups. Before and after cultivation of osteoarthritic chondrocytes with conditioned medium, chondrocytes were analyzed by NGS to evaluate the effect of fat- and ADSPCs-conditioned medium onto transcriptional changes in osteoarthritic chondrocytes. Results. To determine which factors might be involved in the anti-inflammatory effect of fat- and ADSPCs- conditioned medium, stimulated and non-stimulated fat and ADSPCs were analyzed by NGS. The most promising genes are cytokines, tissue inhibitors of matrix metalloproteinases and growth factors. In order to see the effect of conditioned medium from fat and ADSPCs on chondrocytes before and after cultivation with conditioned medium, NGS was performed. The gene expression of matrix metalloproteinases, cytokines, suppressors of cytokine signaling and cartilage specific proteins is of special interest. Conclusion. We aimed to investigate in our study if the clinically approved fat injection into osteoarthritic joints has the same therapeutical effect as the not yet clinically approved injection of isolated ADSPCS. Since the use of autologous fat injections is not only clinically approved but also much more convenient for a clinical approach, it is of utmost interest to know if both injection methods have a sufficient treatment effect on osteoarthritis

Introduction: The infrapatellar fat pad was first described in 1904 by Albert Hoffa. Sometimes disregarded, it is apparent that the infrapatellar fat pad is of importance to knee joint function as fat at this site is only lost in severely emaciated individuals. Also, recent MRI studies have described various pathological changes affecting the fat pad. This study examined the anatomy of the infrapatellar fat pad in relation to knee symptoms and surgical approaches. Materials and Methods: 8 preserved knees were dissected via semicircular parapatellar incisions extending from the tibial tubercle to the superior patellar border and including the quadriceps muscle 13 cm above the superior border of the patella. The synovial membrane of the joint and the ligamentum mucosum were divided and the tibial tubercle was then excised. The resultant tissue complex was removed and the fat pad dissected away from surrounding structures. The appearance, volume and presence of any clefts in the pad were recorded. The cadaveric dissections were then compared to direct observation of the fat pad during total knee replacement, during arthroscopy and on MR imaging. Results: The infrapatellar fat pad was found to be present in all cases. It had a consistent shape consisting of a central mass with medial and lateral extensions. The ligamentum mucosum was attached to the intercondylar notch of the femur in all cases and measured an average of 15.7mm at its base. A horizontal cleft was found in 6 cases and a vertical cleft was found in 7 cases. Both have been previously noted. A tag extended superiorly from the posterior aspect of the fat pad in 7 cases. The volume of the fat pad had quite a large range among individual cadavers (average volume was 24 ml, range: 12–36ml). The intra-individual variation was smaller with an average difference of 4ml (range:2.7ml) between knees. Discussion: The infrapatellar fat pad has been implicated in a wide variety of conditions affecting the knee joint. It has been shown to be involved in arthofibrosis of the knee following surgery, patellar tendonitis, formation of intra-articular fibrous bands, and a site of an ossifying chondroma. It seems that fat pad pathology is usually secondary to other knee joint pathology and primary involvement is rare. The presence of clefts in the fat pad is of importance as a distended cleft may mimic an abnormality and an abnormality in the cleft may be overlooked on imaging of the knee joint. The appearance of the fat pad on direct visualisation in the living person presented a fat pad with a more globular appearance than that seen in the cadaver. The clefts were clearly visualised on MRI. Conclusion: The infrapatellar fat pad is a structure that is consistently present in the knee joint. It consists of a central body with medial and lateral and medical extensions. It usually contains a vertical cleft located superiorly and a horizontal cleft located inferiorly as well as a tag of fat extending superiorly, which forms the roof of the vertical cleft. The infrapatellar fat pad is attached to the intercondylar notch of the femur by the ligamentum mucosum and is firmly anchored to the patella by dense fibrous tissue

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

This study was undertaken to assess the contribution of pulmonary fat embolism to systemic platelet activation in a rabbit model of fat embolism. Fifteen NZW rabbits were randomly assigned into one of two groups: fat embolism and control. Fat embolism was induced via intramedullary canal pressurization with a 1–1.5 ml bone cement injection. Only the animals that underwent fat embolism displayed consistent platelet activation, as demonstrated by platelet degranulation and procoagulatory surface expression. These findings suggest that fat embolism plays a role in platelet activation and in the overall activation of hemostasis following trauma. The objective of this study was to use a recently developed rabbit model of fat embolism to assess the systemic hemostatic response to pulmonary fat embolism. Our findings demonstrate platelet activation following forced liberation of bone marrow contents into the circulation only in the FE group, as demonstrated by CD62P elevation (a marker of platelet degranulation) and annexin V elevation (a marker of procoagulatory surface expression). Platelet activation also coincided with significantly lower platelet counts in the FE group at two and four hours post embolism, suggesting platelet aggregation. These findings suggest that fat embolism plays a role in platelet activation and in the overall activation of hemostasis following trauma. Platelet count decreased significantly at two and four hours post knee manipulation only in the FE group. Annexin V expression increased significantly in the FE group at two and four hours post knee manipulation. Lastly, CD62P expression only increased significantly in the FE group at two hours post knee manipulation. Fifteen New Zealand White male rabbits were randomly assigned into one of two groups: control and fat embolism (FE). In FE group (n=8), the intramedullary cavity was drilled, reamed and pressurized with a 1–1.5 ml bone cement injection. In the control group (n=7), a sham knee incision was made, exposing both femoral condyles, but was immediately closed without further manipulations. All animals were mechanically ventilated for an additional monitoring period of four hours post-surgical closure. For flow cytometric evaluation of platelet activation, blood samples were stained with fluorescence-conjugated antibodies against CD41 (FITC), CD62P (P-selectin) and annexin V (FITC). Platelet events were identified by their characteristic CD41 staining and size and were analyzed using a flow cytometer. All animals were mechanically ventilated for four hours post surgical closure. The implications of platelet activation following fat embolism are numerous, ranging from adherence and aggregation, to secretion of key components of both the coagulation and inflammatory cascades

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