Assuntos

RESUMO

El objetivo de nuestro trabajo fue comparar dos grupos de pacientes tratados con trasplantes osteoarticulares del fémur distal en términos de evaluar: 1) el volumen del fémur distal del receptor y del trasplante, 2) la superficie articular de contacto del fémur distal del receptor y del trasplante, 3) el ángulo del valgo anatómico femoral del fémur distal del receptor y del trasplante. Materiales y métodos: se realizó una búsqueda retrospectiva entre 2002 y 2012 analizando a pacientes tratados con un trasplante osteoarticular de fémur distal. Se incluyó un total de 32 pacientes. Estos fueron divididos en dos grupos de acuerdo con el método de selección del trasplante: Grupo 1, conformado por 16 pacientes con trasplantes seleccionados mediante tomografía 2D y Grupo 2, 16 pacientes con trasplantes seleccionados a través de un método 3D. La evaluación fue realizada por un observador independiente y ciego para los dos grupos. Resultados: las diferencias en las pruebas de estimación de volumen y superficie articulares entre el donante y el receptor no fueron estadísticamente significativas (p>0,05). Sin embargo, la diferencia entre los ángulos de valgo del fémur receptor y el fémur donante, seleccionados por el método 2D fue significativa (p<0,05), mientras que la diferencia de estos ángulos en el método 3D no lo fue (p>0,05). Conclusión: el método de selección de un aloinjerto, mediante la utilización de un banco de huesos virtual 3D para la reconstrucción con un trasplante osteoarticular de femur distal, permite obtener una mejor alineación del miembro comparado con aquellos seleccionados solo con un método bidimensional. (AU)

The aim of our study was to compare two groups of patients treated with distal femur osteoarticular allograft in terms of: 1) the volume of the distal femur of the allograft and patient, 2) the articular surface contact, 3) the anatomical femoral valgus angle. Material and methods: a retrospective review was performed between 2002 and 2012 and all patients with an osteo-articular allograft of the distal femur were analysed. A total of 32 patients were included in the study. Patients were divided into two groups according to the selection method of the allograft: Group 1, 16 patients with allograft selected by 2D (CT) and Group 2, 16 patients selected through a 3D method. The evaluation was done by an independent and blind observer. Results: the differences in terms of volume estimation and joint surface contact between the donor allograft and patient distal femur were not statistically significant (p>0.05). However, the difference between the valgus angle showed significant differences between donor and patient femurs selected by the 2D method (p<0.05) but no difference in the group of patients selected by 3D method (p>0.05). Conclusion: the 3D method for allograft selection of the distal femur showed better results in limb alignment compared to 2D selection method. (AU)

Assuntos

RESUMO

The use of interactive surgical scenarios for virtual preoperative planning of osteotomies has increased in the last 5 years. As it has been reported by several authors, this technology has been used in tumor resection osteotomies, knee osteotomies, and spine surgery with good results. A digital three-dimensional preoperative plan makes possible to quantitatively evaluate the transfer process from the virtual plan to the anatomy of the patient. We introduce an exact definition of accuracy and precision of this transfer process for planar bone cutting. We present a method to compute these properties from ex vivo data. We also propose a clinical score to assess the goodness of a cut. A computer simulation is used to characterize the definitions and the data generated by the measurement method. The definitions and method are evaluated in 17 ex vivo planar cuts of tumor resection osteotomies. The results show that the proposed method and definitions are highly correlated with a previous definition of accuracy based in ISO 1101. The score is also evaluated by showing that it distinguishes among different transfer techniques based in its distribution location and shape. The introduced definitions produce acceptable results in cases where the ISO-based definition produce counter intuitive results.

Assuntos

RESUMO

Structural bone allograft has been used in bone defect reconstruction during the last fifty years with acceptable results. However, allograft selection methods were based on 2-dimensional templates using X-rays. Thanks to preoperative planning platforms, three-dimensional (3D) CT-derived bone models were used to define size and shape comparison between host and donor. The purpose of this study was to describe the workflow of this virtual technique in order to explain how to choose the best allograft using a virtual bone bank system. We measured all bones in a 3D virtual environment determining the best match. The use of a virtual bone bank system has allowed optimizing the allograft selection in a bone bank, providing more information to the surgeons before surgery. In conclusion, 3D preoperative planning in a virtual environment for allograft selection is an important and helpful tool in order to achieve a good match between host and donor.

RESUMO

Osteoarticular allograft is one possible treatment in wide surgical resections with large defects. Performing best osteoarticular allograft selection is of great relevance for optimal exploitation of the bone databank, good surgery outcome and patient's recovery. Current approaches are, however, very time consuming hindering these points in practice. We present a validation study of a software able to perform automatic bone measurements used to automatically assess the distal femur sizes across a databank. 170 distal femur surfaces were reconstructed from CT data and measured manually using a size measure protocol taking into account the transepicondyler distance (A), anterior-posterior distance in medial condyle (B) and anterior-posterior distance in lateral condyle (C). Intra- and inter-observer studies were conducted and regarded as ground truth measurements. Manual and automatic measures were compared. For the automatic measurements, the correlation coefficients between observer one and automatic method, were of 0.99 for A measure and 0.96 for B and C measures. The average time needed to perform the measurements was of 16 h for both manual measurements, and of 3 min for the automatic method. Results demonstrate the high reliability and, most importantly, high repeatability of the proposed approach, and considerable speed-up on the planning.

Assuntos

RESUMO

Tumor excision is the primary treatment of aggressive or recurrent benign bone tumors and malignant bone sarcomas. This requires a surgical resection with the potential for large residual osseous defects that could be reconstructed using fresh frozen allografts. Virtual bone banks enable the creation of databases allowing a 3D pre-surgery evaluation of such allgorafts, based on segmentation of DICOM-CT images. This study demonstrates the usefulness of patient specific 3D models for an accurate host-donor allograft match. We describe one way to select the best match according to size and shape. The results suggest that a robust and reliable technique has been established. Since it is difficult to plan an allograft on a distal femur deformed by the tumor, we propose to plan the surgery on the contralateral side. Our results support this limb symmetry hypothesis. The use of this measurement protocol enables accurate selection of allografts from a contralateral healthy femur 3D CT model achieving the best match possible considering the geometry of available allograft candidate femur specimens.

Assuntos