Achieving Specified Laxity in a Noncruciate Total Knee: A Laboratory Design Study.

BACKGROUND: Noncruciate total knee arthroplasty designs, including ultracongruent, medially congruent, and medial pivot, are gaining increasing attention in total knee arthroplasty surgery. However, there is no consensus for the bearing surface design, whether there should be different medial, lateral, anterior, and posterior laxities, or whether the medial side should be a medial pivot. This study proposes the criterion of reproducing the laxity of the anatomic knee, defined as the displacements and rotations of the femur on the tibia in the loaded knee when shear and torque are applied. The purpose of this study was to determine the ideal tibial radii to achieve that goal. METHODS: The femoral component was based on the average knee from 100 mild arthritic knee scans. There were 8 tibial components that were designed with different sagittal radii: antero-medial, antero-lateral, postero-medial, and postero-lateral. Radii were defined as the percent height reduction from full conformity with the femoral profile. Components were 3-dimensional-printed. A test rig was constructed where the tibial component was fixed and shear and torque were applied to the femoral component. Displacements and rotations of the femoral component were measured at 0 and 45° of flexion, the latter representing any flexion angle due to the constant femoral sagittal radius. RESULTS: Displacements ranged from 0 to 11 mm, and rotations ranged from 1 to 11°. Anterior femoral displacements were higher than posterior due to the shallow distal-anterior femoral profile. The final femoral and tibial components with the most closely matched anatomic laxity values were designed and tested. CONCLUSIONS: A steeper distal-anterior femoral radius was an advantage. High medial-anterior tibial conformity was important. However, on the lateral side, the posterior sagittal tibial radius had to be shallower than ideal to allow femoral rollback in high flexion. This meant that the posterior laxity displacements on the lateral side were higher than anatomic, and there was no guidance for lateral femoral rollback.

Principles of a 3D printed mechanical device for total knee balancing.

Implant alignment and soft-tissue balancing are important factors in total knee arthroplasty (TKA). The purpose of this study was to design a mechanical balancing device, which measures deflections resulting from forces applied on each condyle to provide numerical data indicating the extent of ligament release needed, or angular changes in the bone cuts required to achieve a balanced knee. Two mechanical devices were designed and 3D printed, Pistol Grip and In-line. The Pistol Grip design consisted of a lever system that indicated the difference between lateral and medial forces with a single pointer. The In-line design allows for the quantification of the absolute force applied on each individual condyle. The two designs were evaluated on a test rig designed to model balance and imbalance conditions in the knee. For the Pistol Grip design maximum pointer deflection indicates a 2 mm change in elevation per condyle and/or a 3 degrees angular change of the condyles which can be corrected by adjusting the ligament lengths equivalent to 2 mm and/or by modifying the proximal or distal femur bone cut by 3 degrees. For the In-line design, maximum pointer deflection represented a 40 N load on the condyle. Our mechanical balancer designs were successful in providing information that can guide surgeons to accurately achieve balance through ligamentous releases and/or modification to bone cuts. The balancer designs are easy to use, do not require any electronics or software, and can be incorporated into the surgical procedure.

Relationship Between Ligament Forces and Contact Forces in Balancing at Total Knee Surgery.

BACKGROUND: Spacer blocks, tensors, or instrumented tibial trials are current methods of balancing the knee during surgery but there are no current techniques for measuring ligament forces. Our goal was to study the relationship between the collateral ligament forces and the condylar contact forces to determine whether there was equivalence. METHODS: A test rig was constructed modeling an artificial knee joint with collateral ligaments. The ligament forces as well as the lateral and medial tibial contact forces were measured during flexion for different positions of the femoral component on the femur, producing a set of forces for the simulated conditions. A regression analysis was used to study the correlation between the ligament and contact forces. RESULTS: The combined medial and lateral ligament and contact forces showed a linear relation with a correlation coefficient of 0.98. For the medial and lateral sides separately, the correlations were 0.85 and 0.88, respectively, with more than 80% of points within a ±25% deviation from the linear relations. This deviation from the linear correlation is linked to differences in medial-lateral femoral-tibial contact point locations at different flexion angles. CONCLUSION: Within balancing accuracies generally achieved at surgery, the collateral ligament forces were linearly correlated to the condylar contact forces. These forces can also be equally correlated to the distraction forces as well as the moments at which condylar liftoff would occur from varus-valgus moments. This indicated a unification of the different balancing parameters, and hence such quantitative methods can be used interchangeably.

Effects of femoral component placement on the balancing of a total knee at surgery.

Misalignment and soft-tissue imbalance in total knee arthroplasty (TKA) can cause discomfort, pain, inadequate motion and instability that may require revision surgery. Balancing can be defined as equal collateral ligament tensions or equal medial and lateral compartmental forces during the flexion range. Our goal was to study the effects on balancing of linear femoral component misplacements (proximal, distal, anterior, posterior); and different component rotations in mechanical alignment compared to kinematic alignment throughout the flexion path. A test rig was constructed such that the position of a standard femoral component could be adjusted to simulate the linear and rotational positions. With the knee in neutral reference values of the collateral tensions were adjusted to give anatomic contact force patterns, measured with an instrumented tibial trial. The deviations in the forces for each femoral component position were then determined. Compartmental forces were significantly influenced by 2 mm linear errors in the femoral component placement. However, the errors were least for a distal error, equivalent to undercutting the distal femur. The largest errors mainly increase the lateral condyle force, occurred for proximal and posterior component errors. There were only small contact force differences between kinematic and mechanical alignment. Based on these results, surgeons should avoid overcutting the distal femur and undercutting the posterior femur. However, the 2-3 degrees varus slope of the joint line as in kinematic alignment did not have much effect on balancing, so mechanical or kinematic alignment were equivalent.

Evaluación de la calidad de vida en pacientes con enfermedad renal crónica en tratamiento sustitutivo / Quality of life evaluation in chronic kidney disease patients under replacement treatment

Introducción: El objetivo fue evaluar la calidad de vida de pacientes con enfermedad renal crónica sometidos a terapia sustitutiva. Enfermedad que impacta la calidad de vida de los pacientes y afecta el estado biopsicosocial del individuo. Materiales y métodos: Estudio analítico transversal. Un total de 206 pacientes del Hospital Carlos Andrade Marín y del centro de hemodiálisis Contigo Da Vida SOCIHEMOD que asistieron a la consulta entre junio y octubre de 2015 fueron entrevistados mediante un cuestionario de datos sociodemográficos y el cuestionario KDQOL SFtm 1,3 para valorar la calidad de vida. Resultados: De acuerdo al puntaje global del cuestionario de calidad de vida el grupo de trasplante renal obtuvo 88,91 puntos, el grupo de diálisis peritoneal 75,50 puntos y el grupo de hemodiálisis 55,93 puntos. En lo que respecta a calidad de vida, se encontró correlación significativa entre edad, nivel de instrucción, situación laboral y tiempo de tratamiento. Discusión: A mayor nivel de instrucción educativa y mejor situación laboral, mejor calidad de vida; mientras que a mayor edad y más tiempo de tratamiento, menor calidad de vida. Los pacientes con trasplante renal presentaron mejor calidad de vida que aquellos en diálisis peritoneal o hemodiálisis.

Introduction: The main goal was assessing the quality of live of Chronic kidney Disease patients. This disease impact the quality of life and affects physical, mental, emotional status and social conditions. This study aimed to determine the quality of life in patients undergoing replacement therapy. Methods: This is a cross-sectional analytical study.We studied 206 patients from Carlos Andrade Marín and hemodialysis center, SOCIHEMOD ContigoDaVida from June to October 2015. Two questionnaires were used: a sociodemographic data questionnaire and the KDQOL SFTM 1.3 to assess quality of life. Results: According to the overall score for quality of life, the kidney transplant group scored 88.91 point, peritoneal dialysis group 75.50 points and hemodialysis group 55.93 points. Regarding quality of life, a significant correlation was found between age, education level, employment status, long term treatment duration and quality of life overall scores. Discusion: Quality of life scored higher with higher literacy, and better employment status, and scored lower with long lasting therapy with older patients.

Planificación familiar en mujeres en condiciones de vulnerabilidad social / Family planning for women in vulnerable social

Introducción: La planificación familiar es un componente esencial en el cuidado de la salud primaria y reproductiva desatendida en poblaciones socialmente vulnerables. Objetivo: Evaluar los conocimientos básicos sobre planificación familiar y su aplicación con mujeres en edad reproductiva que viven en condiciones de pobreza y vulnerabilidad en un barrio de la ciudad de Medellín, Colombia. Metodología: Estudio descriptivo de corte transversal, en donde se aplicó una entrevista personal semi-estructurada a 100 mujeres elegidas por muestreo abierto. Resultados: Las mujeres encuestadas tenían conocimientos básicos sobre la existencia de diferentes métodos de planificación familiar. El 93% de las mujeres no deseaba concebir más hijos, de estas el 38,7% no planificaba en el momento de la entrevista. El 42% tenía un nivel bajo de escolaridad; se halló relación entre este hecho y el número de hijos, donde el 31% de las madres tenía entre 3 y 7 hijos (p<0,001; O.R: 5,8). El 68% de las mujeres tenía vida sexual activa; de estas 69,1% planificaba. El 33% de las mujeres inició su vida sexual antes de los 15 años, además, esto se suma con la no utilización de métodos anticonceptivos, el número de hijos y la no planeación de los embarazos; (p<0,02). Conclusión: El nivel de conocimientos de los métodos de planificación familiar es aceptable, sin embargo, esto no se ve reflejado en el uso. La edad de inicio de relaciones sexuales temprana es un factor determinante de vulnerabilidad, dado que está influenciado por la condición de pobreza de estas mujeres. Salud UIS 2011; 43 (3): 241-248.

Introduction: Family planning is an essential component of primary health care and reproductive, unattended in socially vulnerable populations. Objective: To evaluate the basic knowledge about family planning and its implementation, in women of reproductive age living in poverty and vulnerability in a neighborhood of the city of Medellín, Colombia in 2010. Materials and methods: It was performed a cross sectional study, which applied a semi-structured interview to 100 women elected by open sampling. Results: The women surveyed had basic knowledge about the existence of different methods of family planning. 93% of women did not want to conceive more children, the 38.7% of these, did not plan at the time of the interview. 42% had low level of schooling relation was found between this and the number of children, where 31% of the mothers had children between 3 and 7 (p <0.001, OR: 5.8). 68% of the women were sexually active, 69.1% of these planned. 33% began sex before age 15 year old, relating to failure to use contraception, the number of children and not planning pregnancies; (p <0.02). From the women using some form of planning 82% received medical advice for their use, however only 14% belong to the family planning program. Conclusion: The level of knowledge of family planning methods is acceptable, however this is not reflected in their use. The age of first sexual intercourse early, is a determinant of vulnerability, because it is influenced by the poverty status of these women. Salud UIS 2011; 43 (3): 241-248.

Introdução: A planificação familiar é um componente essencial no cuidado da saúde primaria e reprodutiva desconsiderada em populações socialmente vulneráveis. Objetivo: Avaliar os conhecimentos básicos sobre o planejamento familiar e a sua aplicação em mulheres na idade reprodutiva que estejam em situação de pobreza e vulnerabilidade num bairro da cidade de Medellín, Colômbia; 2010. Métodos: Foi realizado um estudo descritivo de corte transversal, onde foi aplicada uma entrevista pessoal semi-estruturada em cem mulheres eleitas por amostragem aberta. Resultados: As mulheres entrevistadas tinham conhecimentos básicos sobre a existência de diferentes métodos de planejamento familiar. O 93% das mulheres não desejavam conceber mais filhos, destas o 38,7% não usava métodos de planejamento familiar no momento da entrevista. O 42% tinha baixo nível de escolaridade; encontrou-se relação entre este dado e o número de filhos, onde o 31% das mães tinham entre três e sete filhos (p<0,001; O.R: 5,8). O 68% das mulheres tinham vida sexual ativa; destas 69,1% usavam métodos de planejamento familiar. O 33% iniciou a sua vida sexual antes dos 15 anos, tendo relação com o não uso de métodos de planejamento familiar, o número de filhos e o não planejamento da gravidez; (p<0,02). Das mulheres que usavam algum método de planejamento familiar, o 82% recebeu conselho porem somente o 14% pertencem ao programa de planejamento familiar. Conclusão: O nível de conhecimentos dos métodos de planejamento familiar é aceitável, porem isto não esta se refletindo no seu uso. A idade de inicio das relações sexuais de forma prematura é um fator determinante de vulnerabilidade, devido a que isto esta influenciado pela situação de pobreza destas mulheres.