Hemodynamically unstable pelvic fracture: A damage control surgical algorithm that fits your reality / Trauma pélvico e inestabilidad hemodinámica: Un algoritmo quirúrgico de control de daños que se adapta con su realidad

Abstract Pelvic fractures occur in up to 25% of all severely injured trauma patients and its mortality is markedly high despite advances in resuscitation and modernization of surgical techniques due to its inherent blood loss and associated extra-pelvic injuries. Pelvic ring volume increases significantly from fractures and/or ligament disruptions which precludes its inherent ability to self-tamponade resulting in accumulation of hemorrhage in the retroperitoneal space which inevitably leads to hemodynamic instability and the lethal diamond. Pelvic hemorrhage is mainly venous (80%) from the pre-sacral/pre-peritoneal plexus and the remaining 20% is of arterial origin (branches of the internal iliac artery). This reality can be altered via a sequential management approach that is tailored to the specific reality of the treating facility which involves a collaborative effort between orthopedic, trauma and intensive care surgeons. We propose two different management algorithms that specifically address the availability of qualified staff and existing infrastructure: one for the fully equipped trauma center and another for the very common limited resource center.

Resumen Las fracturas de pelvis ocurren en más del 25% de los pacientes con trauma severo y su mortalidad es alta, a pesar de los avances en la resucitación hemodinámica y las técnicas quirúrgicas. Esta mortalidad se explica por la hemorragia inherente y las lesiones extra pélvicas asociadas, las fracturas o las disrupciones ligamentarias de la pelvis aumentan el volumen del espacio pélvico, y conlleva a que la hemorragia pélvica se acumule en el espacio retroperitoneal. En poco tiempo, esto conduce a la inestabilidad hemodinámica y el rombo de la muerte. La hemorragia pélvica es un 80% venosa proveniente de los plexos pre-sacro / pre-peritoneal. El restante 20% es arterial por sangrado de las ramas de la arteria iliaca interna. Esta realidad podría ser cambiada a través de un manejo secuencial enfocado según la disposición de recursos del centro de atención y de un trabajo colaborativo entre ortopedistas, cirujanos de trauma e intensivistas. Este articulo propone dos algoritmos de manejo que están enfocados según la disponibilidad de un equipo calificado e infraestructura existente: uno para un centro de trauma totalmente equipado, y el otro para un centro con recursos limitados.

Pathological fracture after radiotherapy: systematic review of literature

SUMMARY OBJECTIVE: To evaluate the epidemiological data and available treatments for fractures secondary to radiotherapy treatment. METHODS: Identification of publications on pathological skeletal fractures previously exposed to ionizing radiation. RESULTS: The incidence of fractures after irradiation varies from 1.2% to 25% with a consolidation rate of 33% to 75%, being more frequent in the ribs, pelvis, and femur. The time elapsed between irradiation and fracture occurs years after radiotherapy. Risk factors include age above 50 years, female gender, extensive periosteal detachment, circumferential irradiation, tumor size, and anterior thigh location. The etiology is still uncertain, but cellular disappearance, reduction of bone turnover and activity were observed hematopoietic as possible causes of failure of consolidation. CONCLUSION: There is no consensus in the literature on the factors related to the development of fractures, with radiation dose, previous tumor size and periosteal detachment being suggested as potential factors.

RESUMO OBJETIVO: Avaliar dados epidemiológicos e tratamentos disponíveis para fraturas secundárias ao tratamento radioterápico. MÉTODOS: Identificação de publicações sobre as fraturas patológicas ocorridas em esqueleto previamente exposto à radiação ionizante. RESULTADOS: A incidência de fraturas após irradiação varia de 1,2% a 25% com taxa de consolidação de 33% a 75%, sendo mais frequente em costelas, pelve e fêmur. O tempo decorrido entre a irradiação e a fratura ocorre anos após a radioterapia. Os fatores de risco incluem idade acima de 50 anos, sexo feminino, descolamento periosteal extenso, irradiação circunferencial, tamanho do tumor e localização anterior na coxa. A etiologia ainda é incerta, mas foram observados desaparecimento celular, redução do turnover ósseo e da atividade hematopoiética como possíveis causas da falha de consolidação. CONCLUSÃO: Não há consenso na literatura avaliada sobre os fatores relacionados ao desenvolvimento de fraturas, sendo a dose de radiação, o tamanho prévio do tumor e o descolamento periosteal sugeridos como fatores potenciais.

Swimming training potentiates the recovery of femoral neck strength in young diabetic rats under insulin therapy

OBJECTIVE: To test whether swimming training benefits femoral neck strength in young diabetic rats under insulin therapy. METHODS: A total of 60 male Wistar rats (age: 40 days) were divided equally into the following six groups: control sedentary, control exercise, diabetic sedentary, diabetic exercise, diabetic sedentary plus insulin and diabetic exercise plus insulin. Diabetes was induced with a unique intraperitoneal injection (60 mg/kg body weight) of streptozotocin. Seven days after the injection and after 12 hours of fasting, the animals with blood glucose levels ≥300 mg/dL were considered diabetic. Seven days after the induction of diabetes, the animals in the exercise groups were subjected to progressive swimming training (final week: 90 min/day; 5 days/week; 5% load) for eight weeks. The animals in the insulin groups received a daily dose of insulin (2-4 U/day) for the same period. RESULTS: Severe streptozotocin-induced diabetes reduced the structural properties of the femoral neck (trabecular bone volume, trabecular thickness and collagen fiber content). The femoral neck mechanical properties (maximum load and tenacity) were also impaired in the diabetic rats. Insulin therapy partially reversed the damage induced by diabetes on the structural properties of the bone and mitigated the reductions in the mechanical properties of the bone. The combination of therapies further increased the femoral neck trabecular bone volume (∼30%), trabecular thickness (∼24%), collagen type I (∼19%) and type III (∼13%) fiber contents, maximum load (∼25%) and tenacity (∼14%). CONCLUSIONS: Eight weeks of swimming training potentiates the recovery of femoral neck strength in young rats with severe streptozotocin-induced diabetes under insulin therapy.

TSH-receptor antibodies may prevent bone loss in pre- and postmenopausal women with Graves' disease and Graves' orbitopathy

ABSTRACT Objective Thyrotoxicosis is established risk factor for osteoporosis due to increased bone turnover. Glucocorticoids often administered for Graves' orbitopathy (GO) have additional negative effect on bone mineral density (BMD). Our aim was to examine the influence of thyroid hormones, TSH, TSH-receptor antibodies (TRAb) and glucocorticoid treatment on bone in women with Graves' thyrotoxicosis and Graves' orbitopathy (GO). Subjects and methods Forty seven women with Graves' disease, mean age 55.6 ± 12.8 (23 women with thyrotoxicosis and 24 hyperthyroid with concomitant GO and glucocorticoid therapy) and 40 age-matched healthy female controls were enrolled in the study. We analyzed clinical features, TSH, FT4, FT3, TRAb, TPO antibodies. BMD of lumbar spine and hip was measured by DEXA and 10-year fracture risk was calculated with FRAX tool. Results The study showed significantly lower spine and femoral BMD (g/cm2) in patients with and without GO compared to controls, as well as significantly higher fracture risk. Comparison between hyperthyroid patients without and with orbitopathy found out significantly lower spine BMD in the first group (p = 0.0049). Negative correlations between FT3 and femoral neck BMD (p = 0.0001), between FT4 and BMD (p = 0.049) and positive between TSH and BMD (p = 0.0001), TRAb and BMD (p = 0.026) were observed. Fracture risk for major fractures and TRAb were negatively associated (p = 0.05). We found negative correlation of BMD to duration of thyrotoxicosis and cumulative steroid dose. Conclusions Our results confirm the negative effect of hyperthyroid status on BMD. TRAb, often in high titers in patients with GO, may have protective role for the bone, but further research is needed.

Oral motor and electromyographic characterization of adults with facial fractures: a comparison between different fracture severities

OBJECTIVES: To characterize the oral motor system of adults with facial injuries and to compare the oral motor performance/function between two different groups. METHODS: An observational, descriptive, cross-sectional study was conducted in 38 patients presenting with facial trauma who were assigned to the Division of Orofacial Myology of a Brazilian School Hospital. Patients were divided into two groups: Group 1 (G1) consisted of 19 patients who were submitted to open reduction of at least one facial fracture, and Group 2 (G2) consisted of 19 individuals who were submitted to closed fracture reduction with maxillomandibular fixation. For comparison purposes, a group of 19 healthy volunteers was recruited. All participants underwent a clinical assessment that included an oral motor evaluation, assessment of the mandibular range of motions, and electromyographic assessment of the masticatory muscles. RESULTS: Clinical assessment of the oral motor organs indicated that G1 and G2 presented deficits related to the posture, position, and mobility of the oral motor organs. Patients also presented limited mandibular ranges of movement. Deficits were greater for individuals in G1, especially for maximal incisor opening. Additionally, patients in G1 and G2 presented a similar electromyographic profile of the masticatory muscles (i.e., patients with facial fractures presented lower overall muscle activity and significant asymmetrical activity of the masseter muscle during maximum voluntary teeth clenching). CONCLUSION: Patients in G1 and G2 presented similar functional deficits after fracture treatment. The severity of facial fractures did not influence muscle function/performance 4 months after the correction of fractures.

Diabetes mellitus affects the biomechanical function of the callus and the expression of TGF-beta1 and BMP2 in an early stage of fracture healing

Transforming growth factor beta 1 (TGF-β1) and bone morphogenetic protein-2 (BMP-2) are important regulators of bone repair and regeneration. In this study, we examined whether TGF-β1 and BMP-2 expressions were delayed during bone healing in type 1 diabetes mellitus. Tibial fractures were created in 95 diabetic and 95 control adult male Wistar rats of 10 weeks of age. At 1, 2, 3, 4, and 5 weeks after fracture induction, five rats were sacrificed from each group. The expressions of TGF-β1 and BMP2 in the fractured tibias were measured by immunohistochemistry and quantitative reverse-transcription polymerase chain reaction, weekly for the first 5 weeks post-fracture. Mechanical parameters (bending rigidity, torsional rigidity, destruction torque) of the healing bones were also assessed at 3, 4, and 5 weeks post-fracture, after the rats were sacrificed. The bending rigidity, torsional rigidity and destruction torque of the two groups increased continuously during the healing process. The diabetes group had lower mean values for bending rigidity, torsional rigidity and destruction torque compared with the control group (P<0.05). TGF-β1 and BMP-2 expression were significantly lower (P<0.05) in the control group than in the diabetes group at postoperative weeks 1, 2, and 3. Peak levels of TGF-β1 and BMP-2 expression were delayed by 1 week in the diabetes group compared with the control group. Our results demonstrate that there was a delayed recovery in the biomechanical function of the fractured bones in diabetic rats. This delay may be associated with a delayed expression of the growth factors TGF-β1 and BMP-2.

Efectos óseos de la cirugía bariátrica / Effects of bariatric surgery on bone

La cirugía bariátrica es un recurso terapéutico cuyo uso para el manejo de la obesidad mórbida crece rápidamente. La intervención induce varios cambios en el perfil hormono-metabólico de los pacientes: disminuye la absorción de calcio, caen los niveles de vitamina D, se produce un hiperparatiroidismo secundario que acelera el recambio óseo, aumentan algunas citoquinas como la adiponectina, el GLP-1 y la esclerostina, y disminuyen otras como la leptina, la ghrelina, el GIP y la amilina. El estradiol cae por disminución de la aromatización periférica de la testosterona. Hay disminución de la carga mecánica en el esqueleto, especialmente en los miembros inferiores. Todo esto lleva a pérdida de la masa ósea, que es variable y más marcada en el fémur proximal que en la columna. El riesgo de fractura aumenta, aunque no todas las series lo han demostrado. Los pacientes con marcada disminución del peso corporal poscirugía deberían ser controlados, procurandoun buen aporte de calcio y otros nutrientes, la suplementación con vitamina D y el monitoreo de la densitometría ósea. (AU)

Bariatric surgery is a therapeutic resource for the management of morbid obesity; its use is growing rapidly. The intervention induces several changes in the hormonal and metabolic profile of patients: decreased calcium absorption, falling levels of vitamin D, secondary hyperparathyroidism which accelerates bone turnover; increased level of some cytokines such as adiponectin, GLP-1 and sclerostin, and decreased levels of others such as leptin, ghrelin, GIP and amylin. Estradiol falls due to decreased peripheral aromatization of testosterone. There is a decrease in the mechanical load on the skeleton, especially in the lower limbs. All this leads to loss of bone mass, which is variable and more marked in the proximal femur than in the spine. The risk of fracture increases, although it has not been shown in all series. Patients with marked decrease in body weight after bariatric surgery should be controlled carefully to insure a good supply of calcium and other nutrients, vitamin D supplementation, and the monitoring of bone mineral density. (AU)

The vascular and neurogenic factors associated with erectile dysfunction in patients after pelvic fractures

ABSTRACT Erectile dysfunction (ED) is a common complication of pelvic fractures. To identify the vascular and neurogenic factors associated with ED, 120 patients admitted with ED after traumatic pelvic fracture between January 2009 and June 2013 were enrolled in this study. All patients answered the International Index of Erectile Function (IIEF-5) questionnaire. Nocturnal penile tumescence (NPT) testing confirmed the occurrence of ED in 96 (80%) patients on whom penile duplex ultrasound and neurophysiological testing were further performed. Of these ED patients 29 (30%) were demonstrated only with vascular abnormality, 41 (42.7%) were detected only with neural abnormality, 26 (27.1%) revealed mixed abnormalities. Of the 55 patients (29+26) with vascular problems, 7 patients (12.7%) with abnormal arterial response to intracavernous injection of Bimix (15mg papaverine and 1mg phentolamine), 31 (56.4%) with corporal veno-occlusive dysfunction and 17 (30.9%) had both problems. Of the 67 (41+26) patients with abnormal neurophysiological outcomes, 51 (76.1%) with abnormal bulbocavernosus reflex (BCR), 20 (29.9%) with pathological pudendal nerve evoked potentials (PDEPs) and 25 (37.3%) with abnormal posterior tibial somatosensory nerve evoked potentials (PTSSEPs). Our observation indicated that neurogenic factors are important for the generation of ED in patients with pelvic fracture; venous impotence is more common than arteriogenic ED.

Effect of hyperbaric oxygen therapy combined with autologous platelet concentrate applied in rabbit fibula fraction healing

OBJECTIVES: The purpose is to study the effects of hyperbaric oxygen therapy and autologous platelet concentrates in healing the fibula bone of rabbits after induced fractures. METHODS: A total of 128 male New Zealand albino rabbits, between 6-8 months old, were subjected to a total osteotomy of the proximal portion of the right fibula. After surgery, the animals were divided into four groups (n = 32 each): control group, in which animals were subjected to osteotomy; autologous platelet concentrate group, in which animals were subjected to osteotomy and autologous platelet concentrate applied at the fracture site; hyperbaric oxygen group, in which animals were subjected to osteotomy and 9 consecutive daily hyperbaric oxygen therapy sessions; and autologous platelet concentrate and hyperbaric oxygen group, in which animals were subjected to osteotomy, autologous platelet concentrate applied at the fracture site, and 9 consecutive daily hyperbaric oxygen therapy sessions. Each group was divided into 4 subgroups according to a pre-determined euthanasia time points: 2, 4, 6, and 8 weeks postoperative. After euthanasia at a specific time point, the fibula containing the osseous callus was prepared histologically and stained with hematoxylin and eosin or picrosirius red. RESULTS: Autologous platelet concentrates and hyperbaric oxygen therapy, applied together or separately, increased the rate of bone healing compared with the control group. CONCLUSION: Hyperbaric oxygen therapy and autologous platelet concentrate combined increased the rate of bone healing in this experimental model. .

Disability appraisal for common peroneal nerve injury in traffic accidents: 8 cases analysis / 法医学杂志

OBJECTIVE@#To investigate the characteristics of forensic clinical identification on common peroneal nerve injury in traffic accident.@*METHODS@#Eight cases of common peroneal nerve injury in traffic accidents were analyzed, including general condition of the wounded, the way of injury, the imaging results, the EMG results, and the degree of injury, etc.@*RESULTS@#In 8 cases, 2 cases of complete common peroneal nerve injury were determined to grade 9 (disability degree) and 6 cases of partial common peroneal nerve injury were determined to grade 10 (disability degree).@*CONCLUSION@#By comparison, the disability degree of complete common peroneal nerve injury is higher than that of partial common peroneal nerve injury. The forensic clinical identification of common peroneal nerve should be made with synthetical consideration of medical history, symptoms, and auxiliary examinations.

Osteoporose no climatério I: epidemiologia, definição, rastreio e diagnóstico / Osteoporosis in climacteric I: epidemiology, definition, screening and diagnosis

A osteoporose é um distúrbio osteometabólico caracterizado pela diminuição da densidade mineral óssea (DMO), com deterioração da microarquitetura óssea, levando a um aumento da fragilidade esquelética e do risco de fraturas, pelo comprometimento da resistência e/ou da qualidade óssea. Sua incidência pode variar de 14 a 29% em mulheres acima de 50 anos e chegar até 73% em mulheres acima de 80 anos. O objetivo do nosso artigo é estudar a osteoporose relacionada ao período pós-menopausa, mas vale ressaltar que os riscos de fraturas em algumas condições independem da quantidade de massa óssea mensurada, e sim da qualidade óssea. Atualmente dispomos de uma ferramenta muito útil, denominada FRAXtm (Fracture Risk Assessement tool), para avaliação do risco de fraturas; por meio dela, é possível calcular a probabilidadede, em dez anos, ocorrer fratura no quadril e em outros sítios, não somente pela quantidade de massa óssea, mas pela associação de outros fatores clínicos de risco. Isso poderá nos ajudar a tomar decisões clínicas quanto à prevenção e tratamento da osteoporose na mulher na pós-menopausa, na nossa prática diária, quando validada para uso no Brasil

Osteoporosis is a metabolic disorder characterized by decreased bone mineral density (BMD), with deterioration of bone microarchitecture. It leads to an increase in skeletal fragility and fracture risk, by compromising the strength and/or quality of bone. Its incidence varies from 14 to 29% in women over 50 years and reaches 73% in women over 80 years. The objective of our paper is to study osteoporosis related to post-menopause. But, it is noteworthy that the risk of fractures in some conditions depends on the bone quality. Currently, we have a very useful tool called FRAXtm (Fracture Risk Assessment tool), to evaluate the risk of fractures. The probability to occur hip fracture, or another bone fracture, in ten years is calculated, not only by the amount of bone mass, but by the association of other clinical risk factors. This may help us make clinical decisions about prevention and treatment of osteoporosis in postmenopausal women in our daily practice, when validated for use in Brazil

Advancement in methods of evaluation on bone fracture healing and its application in forensic medicine / 法医学杂志

It is frequently encountered to identify the time of bone fracture in forensic medicine. Hence it is important to develop the methods for evaluating the time of bone fracture. This article reviews the applications and values of the methods such as ultrasonic evaluation, impulse measurement, digital imaging technology and bone mineral density testing technology, etc. It is proposed that to use these methods jointly may provide more scientific evidence in determine the time of bone fracture.

The mast cell and trauma / 法医学杂志

Mast cell(MC) takes an important role in trauma and the process of wound healing, and the pathophysiology reaction has a relationship to the time since trauma, which is helpful to determine the post-trauma and postmortem interval, and to distinguish the wound shaped whether before or after death. In this paper, the role of MC and its chemic medium in the process of wound healing, scar shaping, postburns inflammatory response, healing of bone fracture, as well as the signification for forensic medicine and the progress of researching in this field were reviewed.

Análisis tomográfico original de las intercorrelaciones músculo-hueso en el raquis humano / Analyses of musculoskeletal interactions in humans by Quantitative Computed Tomography (QCT)

Hemos analizado las propiedades seccionales de los cuerpos vertebrales (contenido y densidad mineral volumétricos BMC, vBMD de hueso total, cortical y trabecular) y de los músculos periespinales (áreas seccionales libres de grasa por filtrado, FFMA) en scans de Tomografía Computada Cuantitativa (TCC) tomados al nivel L3 en 93 mujeres normales de 32-74 años, y adicionalmente en 5 hombres normales como referencia, y los comparamos con el "ángulo de cifosis" de Cobb (Ka, proporcional a la curvatura ántero-posterior raquídea) determinado entre las vértebras T4 y T12 en radiografías laterales. La vBMD trabecular (indicadora de la rigidez estructural de la trama), el BMC total (proporcional a la resistencia a la compresión) y las FFMA (estimadoras de la fuerza de contracción) variaron paralelamente y correlacionaron negativamente con el Ka. Las curvas fueron contínuas y monotónicas para mujeres y hombres en conjunto, pero el tiempo de post-menopausia (TPM) afectó la posición gráfica de los datos. Análisis de regresión múltiple mostraron que la vBMD trabecular y el BMC total fueron los predictores independientes más significativos del Ka, y que las FFMA y el TPM fueron los únicos determinantes independientes de las propiedades óseas, sin participación de la edad per-se ni de los datos antropométricos. Los resultados confirman nuestra hipótesis de que la calidad ósea está normalmente determinada por el estado muscular regional y perturbada por el entorno endocrino-metabólico del sujeto, en forma independiente de la edad, la conformación corporal y el sexo

Stimulation of Fracture Healing in a Canine Ulna Full-defect Model by Low-intensity Pulsed Ultrasound

Because no report has been issued on the healing effects of low-intensity pulsed ultrasound on moderate to large fracture gaps, we performed an experimental study using acanineulna full-defect model. Ten mongrel male dogs were divided into two groups: a small defect group and large defect group. The defects were made on the middle one third of both ulnae and one side only was randomly selected for ultrasound sonication, at 1 MHz, 200 microsecond bursting sine wave in 50 mW/cm2 spacial average and temporal average. Sonication was started on the day after surgery and applied for 15 minutes once a day for six days a week. In the small defect group, the means of the radiologic scores, as described by Lane and Sandhu, were 0.6, 4.4, and 8.4 in the control side and 1.8, 6.0, and 10.4 in the treatment side one, three, and five months after the operation, respectively (p=0.0372). In the large defect model, the corresponding means were 2.2, 3.4, and 6.0 in the control side and 3.3, 5.4, and 9.2 in the treatment side (p= 0.009). Low-intensity pulsed ultrasound enhanced new bone formation in small and large full-defects and decreased the incidence of nonunion in the large defect model.

The clavicular fracture: a biomechanical study of the mechanism of clavicular fracture and modes of the fracture.

A clavicle is an S-shaped long bone whose biomechanical behavior is unlike that of a straight tubular long bone. When a clavicle is under a compression load along the axis, the force produces a middle one-third clavicular fracture. The present study is a biomechanical study to confirm the clinical observations of the mechanism of the fracture and to discover the tension site and compression site of the fracture, using 12 fresh cadaveric clavicles, a universal testing machine and two special grips. One grip was constructed with a contour like a sternoclavicular articulation. The grip was mounted at the medial end of the clavicle. Another grip was constructed with a contour like an acromioclavicular articulation. The grip was mounted at the lateral end of the clavicle. A load was applied to the lateral clavicle like a force transmitting from the weight of the shoulder girdle. A load was also applied to the medial clavicle like a force from the sternocleidomastoid muscle. A compression load was applied along the axis of the testing clavicle through the upper grips by using a universal testing machine. The result found that the average load of the clavicular fracture was 1526.19 N. The fracture occurred at the middle one-third of the clavicle in the region of the curve of the lateral clavicle changing to the curve of the medial clavicle. While primatic cross section of the clavicle at the fracture site determined a tension and a compression site of the fracture, the fracture took the superoanterior aspect of the clavicle as a tension site and posteroinferior aspect as a compression site. The fracture had a ratio of length of the lateral fragment to the total length of the clavicle of 0.49. This study confirmed that a compression load along the axis of the clavicle produces a middle one-third clavicular fracture as in clinical observation and the fracture took the superoanterior aspect of the clavicle as a tension site.

La osteoporosis en el varón es un riesgo frecuentemente ignorado / Osteoporosis in the male is a frequently ignored risk

Durante muchos años la osteoporosis se ha considerado una enfermedad que afecta al sexo femenino, sin embargo en el hombre, el envejecimiento y la disminución de las concentraciones de testosterona se encuentran asociados a la disminución de la masa ósea. Al igual que en la mujer, la osteoporosis en el hombre debe tratarse con suplementos de calcio y vitamina D. Recientemente se ha demostrado que el alendronato, un bisfosfonato ha tenido éxito para mejorar la densidad ósea y disminuir la incidencia de fracturas en el hombre. La terapia de reemplazo con andrógenos se espera tenga efecto benéfico sobre el hueso, pero se requieren estudios clínicos controlados que lo comprueben.

Issues in electromagnetic field-biointeractions.

Low level electromagnetic fields have been found to produce a variety of biological effects, though the mechanism of such interaction is still not completely understood. Cell membrane of the brain is a critical structure perceiving the action of microwaves, which has received greater attention in the recent past. The interactions of EMF with the living cells are considered as stochastic resonance, cooperative effects, non-equilibrium thermodynamic process and non-linear interactions. The living cells derive the energy from noise and pumps it into the modes of excitation at the driving frequency of an electromagnetic wave which give sufficient amplification of the signal and increase the signal to noise ratio. The non-linear mechanism plays their main role in the process of transmembrane coupling of the signal to the cytoplasm. The criteria for safe exposure limits of electromagnetic field to humans is also discussed.