Objectivethe objective of this study was to present an analog method for preoperative planning of primary total hip arthroplasty procedures based on measuring the components by overlaying the transparencies of the prosthesis on the preoperative radiographs and checking the accuracy, both for predicting the size of the acetabular and femoral components used and for restoring the offset and correcting the dysmetria.Methodsbetween March 2005 and July 2009, 56 primary total hip arthroplasty procedures performed on 56 patients at the Mario Covas State Hospital in Santo André were analyzed. The measurements on the femoral and acetabular components obtained through planning were compared with those that were used in the surgery. The offsets measured through the preoperative planning were compared with those measured on the postoperative radiographs. Dysmetria was evaluated before and after the operation.Resultsaccuracy of 78.6% (p < 0.001) in predicting the size of the acetabular component and 82.2% (p < 0.001) in predicting the femoral nail was observed. The offsets measured through preoperative planning were statistically similar to the offsets measured on the postoperative radiographs. After the operation, we observed absolute equalization in 48.2% of the cases. In 87.5%, the dysmetria was less than or equal to 1 cm and in 69.6%, it was less than or equal to 0.5 cm.Conclusionsthe accuracy was 78.6% and 82.2%, respectively, for the acetabular and femoral components. The offsets that were planned preoperatively were statistically similar to those measured on postoperative radiographs. We found absolute equalization in 48.2% of the cases.

There are situations which the tomographic exam is done on the affected hip or situations where the contralateral hip presents abnormalities that make it impossible to compare. In this study we aimed to evaluate a tomographic index that does not require comparison between the both hips. Twenty two patients with unilateral acetabular fracture dislocation with fracture of posterior wall were studied. We established the relationship between the remaining posterior wall and the femoral head diameter (head/wall index-H/W index). We evaluated 45 two-dimensional computed tomography scan in normal hips and established the H/W index. In 45 normal hips we simulated a posterior wall fracture with involvement of 25% and 30% of the posterior wall and calculated the H/W index. We divided into five groups with five different H/W index (fractured group with non surgical treatment; fractured group; normal group; normal group with simulated fracture of 25% and; 30% of the posterior wall). 2.4 was the lowest limit of confidence interval of the group with 25% of the posterior wall fracture. When we analyzed the confidence interval of the 30% fracture group the upper limit of the confidence interval was 2.7, close to the lower limit of the surgical group that was 2.9. Thus, we suggest the 2.4 the H/W index limit as an auxiliary criteria to indicate whether or not to operate. H/W index is helpful to decide whether or not surgery indication in the fracture dislocation of the posterior wall of the acetabulum.

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ResumoIntrodução: a protrusão acetabular foi inicialmente descrita por Otto, em 1824. A incidência é maior no sexo feminino e a bilateralidade, mais comum, é maior nas protrusões de etiologia primária. Sotelo-Garza e Charnley definiram uma classificação que considera a distância da parede medial em relação à linha de Köhler.Objetivo: apresentar a classificação angular para protrusão acetabular e demonstrar sua aplicabilidade. Método: a classificação da Faculdade de Medicina do ABC (FMABC) foi determinada a partir da medida do ângulo P (ângulo de protrusão), formado pela intersecção de três linhas. Foram avaliadas radiografias de bacia em dois grupos de pacientes: o primeiro, com pacientes sem protrusão acetabular, em que foram definidos os valores de normalidade, e o segundo, com pacientes com protrusão acetabular. Destes, foram medidos o ângulo P e o tamanho da protrusão de acordo com Sotelo-Garza e Charnley, sendo os resultados comparados. Dezenove quadris com protrusão foram submetidos à artroplastia total e comparados os valores do ângulo P no pré e pós-operatório. Resultados: o valor médio do ângulo P, em pacientes sem protrusão acetabular, foi -1,22°. No segundo grupo, observou-se semelhança quando foram comparados os valores da classificação FMABC e os da classificação de Sotelo-Garza e Charnley. A comparação entre os valores do ângulo P pré e pós-operatórios resultou em diferença estatisticamente significante (p<0,001). A classificação angular foi dividida em leve, moderada e grave. Conclusões: o ângulo P foi sempre superior a zero nas protrusões acetabulares, os valores numéricos das duas classificações foram estatisticamente significativos, possibilitando a utilização dos mesmos valores da classificação de Sotello-Garza e Charnley para a classificação FMABC, e o uso de enxerto causou uma lateralização do componente acetabular. Palavras-chave:Deformidades articulares adquiridas; acetábulo; artroplastia. AbstractIntroduction: protrusio acetabuli was first described by Otto, in 1824. Its incidence is higher among women and the bilaterality, more common, is higher in