Geometrical approach to tumor growth

Tumor growth has a number of features in common with a physical process known as molecular beam epitaxy. Both growth processes are characterized by the constraint of growth development to the body border, and surface diffusion of cells/particles at the growing edge. However, tumor growth implies an approximate spherical symmetry that makes necessary a geometrical treatment of the growth equations. The basic model was introduced in a former article [C. Escudero, Phys. Rev. E 73, 020902(R) (2006)], and in the present work we extend our analysis and try to shed light on the possible geometrical principles that drive tumor growth. We present two-dimensional models that reproduce the experimental observations, and analyse the unexplored three-dimensional case, for which new conclusions on tumor growth are derived

Fracturas Pélvicas: una visión moderna

Las fracturas pélvicas se presentan con severidad variable, desde lesiones de baja energía, habitualmente por compresión lateral, hasta lesiones secundarias a un traumatismo de alta energía con inestabilidad del anillo pélvico, frecuentes lesiones asociadas y altas tasas de morbilidad y mortalidad. El tratamiento inicial de estas severas lesiones se sustenta en la aplicación de protocolos de soporte vital avanzado, disminuir el sangrado pélvico con medidas que reduzcan el volumen de la pelvis y estabilicen la lesión, como la fijación externa y ante inestabilidad persistente técnicas de angiografía-embolización o empaquetamiento. Tras la estabilización inicial del paciente el objetivo será la restauración anatómica del anillo pélvico predictora de la recuperación funcional. Las técnicas de estabilización definitiva actuales evolucionan hacía técnicas menos invasivas y percutáneas con el paciente preferentemente decúbito supino. A pesar de los avances en el tratamiento, el dolor, la disfunción sexual o persistencia de problemas neurológicos crónicos se asocian a las lesiones más graves1-3.Pelvic fractures have a wide spectrum of severity depending on the strength of the trauma, ranging from low energy injuries, usually by lateral forces, until secondary lesions to high-energy trauma with pelvic ring instability, and high rates of morbidity and mortality. High-energy pelvic fractures require advanced life support and the first step in treatment is to reduce pelvic bleeding with external fixation and to continuing instability embolization angiography techniques or packing. Later, when patient is hemodynamically stable the goal is to achieve an anatomical reconstruction of pelvic ring which is considered nowadays the most powerful predictor of functional recovery. Less invasive and percutaneous stabilization techniques have emerged in recent years. Nevertheless, despite the progress in treatment, pain, sexual dysfunction or chronic persistent neurological problems are associated with more severe injuries1-3

Tratamiento del choque femoroacetabular mediante miniabordaje anterior. Resultados a corto plazo

El tratamiento quirúrgico del choque femoroacetabular (CFA) es un práctica clínica cada vez más frecuente en nuestra especialidad. Objetivo. Analizar los resultados clínicos y radiológicos de una primera serie de pacientes diagnosticados de CFA intervenidos mediante miniabordaje anterior. Material y métodos. Estudio prospectivo de 30 pacientes con una edad media de 36,2 años y un seguimiento mínimo de 12 meses. La valoración clínica se ha realizado mediante las escalas SF-36, WOMAC y NAHS. Evaluamos la corrección radiológica de la deformidad y la progresión o no del grado de coxartrosis. Resultados. Se obtuvo una corrección adecuada de la deformidad en el 93% de los casos, 27 de los 30 pacientes presentaron una mejoría clínica significativa en los test realizados. La complicación más frecuente fue la meralgia parestésica del femorocutáneo (5 casos), 1 paciente precisó de sustitución protésica por evolución del grado de coxartrosis. Conclusiones. El tratamiento del CFA mediante mini abordaje anterior es un procedimiento seguro y reproducible. Permite la corrección de las anormalidades anatómicas y la obtención de resultados clínicos satisfactorios en una cohorte de pacientes jóvenes.Surgical treatment of femoroacetabular impingement (FAI) is an increasingly common clinical practice in our speciality. Aim. To analyze the clinical and radiological results of a first series of patients diagnosed with a FAI treated with anterior mini-open approach. Material and methods. Prospective study of 30 patients with a mean age of 36.2 years with a minimum follow-up of 12 months was made. Clinical assessment was performed using the SF-36, WOMAC and NAHS scales. We evaluate the correction of the radiologic deformity and progression of the osteoarthritis grade. Results. An adequate correction of the deformity in 93% of cases was obtained, 27 of the 30 patients showed significant clinical improvement in all tests performed. The most common complication was meralgia paresthesia of the femoro-cutaneous nerve (5 cases), 1 patient required prosthetic replacement for progression of the osteoarthritis grade. Conclusions. FAI treatment by mini-open approach is a safe and reproducible procedure. This technique allows correction of anatomical abnormalities and obtains satisfactory clinical outcomes in a cohort of young patients

Tratamiento quirúrgico de las metástasis diafisarias de huesos largos en pacientes oncológicos estadio IV

La incidencia de enfermedad metastásica ósea se ha incrementado debido a la mayor supervivencia de los pacientes con cáncer. El esqueleto es la tercera localización mas frecuente de metástasis procedentes de tumores primarios. Se evalúan las indicaciones quirúrgicas para evitar la aparición de fracturas patológicas y los resultados obtenidos en metástasis diafisarias de huesos largos. Cincuenta lesiones han sido tratadas en 48 pacientes. En todos los casos se estabilizó con un clavo intramedular. La supervivencia media fue de 11 meses (2 días-48 meses). Al final del seguimiento la puntuación media en la escala MSTS fue 25/30 y 27/30 para miembro superior e inferior respectivamente. Debe considerarse la radioterapia postoperatoria para disminuir la progre - sión de la enfermedad. Hay múltiples factores a tener en cuenta en el tratamiento de pacientes con metástasis óseas incluyendo comorbilidades, características histológicas del tumor primario, la expectativa de vida y acti - vidad del paciente y el dolor.The incidence of metastatic bone disease is increasing as patients with cancer living longer. The skeleton is the third most common site for metastasis that originates from primary carcinomas. We evaluated the indications for surgery to prevent pathological fractures and the results obtained in metastases of the diaphyseal long bones. Fifty metastases bone lesion were treated in 48 patients. In all cases an intramedullary nail was in - serted. The chance of surviving was 11 moths average (2 days-48 moths). At follow-up, the MSTS average was 25/30 and 27/30 for superior and inferior limb respectively. To minimize disease progression postoperative ex - ternal-beam irradiation should be considered. There are multiples factors to consider in the treatment of patients with bone metastasic, including comorbidities, the histological characteristics of the primary tumor, the expected life span of the patient, the patient ?s activity level and pain

Prótesis de pirocarbono en fracturas complejas de cabeza de radio.

Presentamos los resultados de un estudio observacional retrospectivo sobre 23 casos de fracturas complejas de cabeza de radio tratadas mediante la implantación de una prótesis cabeza radio de pircocarbono (Mo - Pyc). La distribución por sexos fue 10 hombres y 13 mujeres, y la edad media de 54 años. El seguimiento medio fue de 70 meses (48-93 meses). La principal causa fue una fractura de cabeza de radio no reconstruible con inestabilidad asociada de codo. La evaluación clínica se realizó con la Mayo Elbow Performance Score (MEPS). Radiográficamen - te se valoró la congruencia articular, el tamaño de la prótesis, la radiolucencia periprotésica, la osificación heterotópica y la osteoartritis. Al final del seguimiento la media de la escale MEPS fue 82/100, con 84 % resultados de excelentes y buenos. La flexión media fue de 130º, extensión -30º, pronación 76º y supinación 77º. La estabilidad del codo fue buena en todos los casos y no observamos migración proximal del radio. Observamos radiolucencia alrededor del vástago en 5 pacientes, pero sin aparente repercusión clínica. Las complicaciones fueron una paresia del nervio interóseo posterior con recuperación funcional al cabo de 11 semanas, 2 pacientes presentaron "overstuffing" con subluxación posterior asociada que necesitó realizar exéresis de la cabeza y una osificación heterotópica con repercu - sión sobre el balance articular que necesitó 2 cirugías, todos ellos con resultados clínicos aceptables. Los resultados son alentadores.The authors present the results of a retrospective observational study of 23 cases of a complex radial head fractures treated by pyrocarbon radial head prosthesis (MoPyc). This modular radial head prosthesis is compo - sed of a cementless titanium stem and a 15º angulated neck. The gender distribution was 10 men and 13 women, ave - rage age 54 years. The mean follow-up was 70 months (48-93 months). The main etiology was a radial head fracture with elbow instability. Clinical evaluation was performed using the Mayo Elbow Performance Score (MEPS). Was assessed radiographically joint congruity, the size of the prosthesis, periprosthetic radiolucency, heterotopic ossifica - tion and osteoarthritis. At follow-up, the MEPS average was 82/100, with 84% of good and excellent results. Elbow flexion averaged 130º, extension -30º, pronation 76º and supination 77º. Elbow stability was good in all the cases, and no proximal migration of the radius occurred. Asymptomatic bone lucencies were found in five cases around the stem. Complications included paresis of the posterior interosseous nerve with functional recovery after 11 weeks, 2 patients had "overstuffing" associated with posterior subluxation and they need to perform excision of the head and one heterotopic ossification with articular impact on balance that needs two surgeries, all of them with acceptable clinical results. The preliminary results are encouragin

A reaction-diffusion model for the growth of avascular tumor

A nutrient-limited model for avascular cancer growth including cell proliferation, motility and death is presented. The model qualitatively reproduces commonly observed morphologies for primary tumors, and the simulated patterns are characterized by its gyration radius, total number of cancer cells, and number of cells on tumor periphery. These very distinct morphological patterns follow Gompertz growth curves, but exhibit different scaling laws for their surfaces. Also, the simulated tumors incorporate a spatial structure composed of a central necrotic core, an inner rim of quiescent cells and a narrow outer shell of proliferating cells in agreement with biological data. Finally, our results indicate that the competition for nutrients among normal and cancer cells may be a determinant factor in generating papillary tumor morphology.Comment: 9 pages, 6 figures, to appear in PR

Vástagos monobloque de recubrimiento completo en cirugía de revisión femoral. Resultados a largo plazo de 80 casos.

Bone stock lost and anatomical changes in the proximal femur make femoral revision surgery a complex procedure where the implant chooses will be essential. With the aim of evaluating the clinical and radiological results of the fully coated monoblock stems, we retrospectively studied 80 consecutive cases of femoral revision surgery operated by our hip team. The mean follow-up was 8.6 years. The average score on the Harris Hip Score was 81,2 points. We achieved better results in patients with less bone defects (Paprosky I, II and IIIA) in contrast to those with Paprosky type IIIB defects (p=0.005), in patients with a single previous surgery (p=0.031), in patients under 65 years (p=0.009) and in those who did not suffer complications (p=0.024). The survival rate was 96.1% at 10 years if we consider as failure the removal of the stem due to aseptic loosening and 89.9% if we consider revision of the stem as a failure due to any cause. After the results obtained, we think that fully coated stems provide a solid and stable fixation in femoral revision surgery. However, worst results obtained in patients with bigger bone defects make other options to be considered

Relaciones talla peso del barbul Pimelodus clarias en la Cuenca del Río Sinú, Colombia.

Piscicultur

Choque extraarticular de cadera secundario a consolidación viciosa tras fractura-avulsión de la espina ilíaca antero inferior : a propósito de un caso

The anterior inferior iliac spine (AIIS) avulsion fractures are uncommon, caused by a sudden contraction of the rectus femoris muscle with hyperextension of the hip and knee flexion. We present the clinical case of a 32-year-old mansuffering from pain in his right hip for several years with a history of a AIIS avulsion fracture in his childhood. He presented pain with flexion and internal rotation of the right hip. Physical examination and imaging tests revealed an extra-articular hip impingement secondary to a malunited fracture of AIIS. The patient underwent surgery performing AIIS osteoplasty and excision of the ossification by an anterior mini-open approach. After surgery he was able to re-join sports activity. Malunited fracture of AIIS can cause an extra-articular hip impingement in young sports patients. The treatment by surgical excision of the hypertrophic spine through an anterior mini-open approach allows the correction of the deformity and an early reincorporation to sports activities

Tracking tumor evolution via prostate-specific antigen: an individual post-operative study

<p>Abstract</p> <p>Background</p> <p>The progress of the prostate-specific antigen (PSA) level after radical prostatectomy is observed for a patient in order to extract information about the mode of tumor cell growth. Although PSA values are determined routinely to find the doubling time of the prostate marker, to our knowledge, this analysis is the first in the literature.</p> <p>Results</p> <p>The prostate tumor marker values were determined regularly after the surgery and plotted on a logarithmic scale against time. An initial rapid-growth mode changed to a slower power-law regime within two years of surgery. Our analysis associates this observation with a transition in the growth mode from unrestricted growth of dispersed cells to their clumping into macroscopic structures.</p> <p>Conclusions</p> <p>Such studies may help determine the appropriate time window for postoperative therapies in order to increase the life expectancy of the patient.</p