A Computational/Experimental Platform for Investigating Three- Dimensional Puzzle Solving of Comminuted Articular Fractures

Reconstructing highly comminuted articular fractures poses a difficult surgical challenge, akin to solving a complicated three-dimensional (3D) puzzle. Pre-operative planning using CT is critically important, given the desirability of less invasive surgical approaches. The goal of this work is to advance 3D puzzle solving methods toward use as a pre-operative tool for reconstructing these complex fractures. Methodology for generating typical fragmentation/dispersal patterns was developed. Five identical replicas of human distal tibia anatomy, were machined from blocks of high-density polyetherurethane foam (bone fragmentation surrogate), and were fractured using an instrumented drop tower. Pre- and post-fracture geometries were obtained using laser scans and CT. A semi-automatic virtual reconstruction computer program aligned fragment native (nonfracture) surfaces to a pre-fracture template. The tibias were precisely reconstructed with alignment accuracies ranging from 0.03-0.4mm. This novel technology has potential to significantly enhance surgical techniques for reconstructing comminuted intra-articular fractures, as illustrated for a representative clinical case

Advances in identifying osseous fractured areas and virtually reducing bone fractures

[ES]Esta tesis pretende el desarrollo de técnicas asistidas por ordenador para ayudar a los especialistas durante la planificación preoperatoria de una reducción de fractura ósea. Como resultado, puede reducirse el tiempo de intervención y pueden evitarse errores de interpretación, con los consecuentes beneficios en el tratamiento y en el tiempo de recuperación del paciente. La planificación asistida por ordenador de una reducción de fractura ósea puede dividirse en tres grandes etapas: identificación de fragmentos óseos a partir de imágenes médicas, cálculo de la reducción y posterior estabilización de la fractura, y evaluación de los resultados obtenidos. La etapa de identificación puede incluir también la generación de modelos 3D de fragmentos óseos. Esta tesis aborda la identificación de fragmentos óseos a partir de imágenes médicas generadas por TC, la generación de modelos 3D de fragmentos, y el cálculo de la reducción de fracturas, sin incluir el uso de elementos de fijación.[EN]The aim of this work is the development of computer-assisted techniques for helping specialists in the pre-operative planning of bone fracture reduction. As a result, intervention time may be reduced and potential misinterpretations circumvented, with the consequent benefits in the treatment and recovery time of the patient. The computer-assisted planning of a bone fracture reduction may be divided into three main stages: identification of bone fragments from medical images, computation of the reduction and subsequent stabilization of the fracture, and evaluation of the obtained results. The identification stage may include the generation of 3D models of bone fragments, with the purpose of obtaining useful models for the two subsequent stages. This thesis deals with the identification of bone fragments from CT scans, the generation of 3D models of bone fragments, and the computation of the fracture reduction excluding the use of fixation devices.Tesis Univ. Jaén. Departamento de Informática. Leída 19 de septiembre de 201

Computer assisted surgery for fracture reduction and deformity correction of the pelvis and long bones

Many orthopaedic operations, for example osteotomies, are not preoperative planned. The operation result depends on the experience of the operating surgeon. In the industry new developments are not longer curried out without CAD planning or computer simulations. Only in medicine the operation technology of corrective osteotomies are still in their infant stage in the last 30 years. Two dimensional analysis is not accurate that results in operation errors in the operating room. The surgeon usually obtains the preoperative information about the current bone state by radiographs. In case of complex operations (also inserting implants) planning is required. Planning based on radiographs has some system-dependent disadvantages like small accuracy, requirement of time for corrections ( distortions due to the projection) and restrictions, if complex corrections are necessary. Today the computer tomography is used as a solution. It is the only modality that allows to reach the accuracy and the resolution required for a good 3D-planning. However its a high dose rate for the patient is the serious disadvantage. Therefore in dilemma between the low dose rate and an adequate planning the first is often preferred. However in future it is expected that good operation results are guarantied only with implementation of 3D-planung. MR systems provide image information too, from which indirectly bones can be extracted. But due to their large distortions (susceptibility, non non-homogeneity of magnetic field), small spatial dissolution and the high costs, it is not expected that MRI represents an alternative in next time. The solution is the use of other image modalities. Ultrasound is here a good compromise both of the costs of the accuracy. In this work I developed an algorithm, which can produce 3D bone models from ultrasonic data. They have good resolution and accuracy compared with CT, and therefore can be used for 3D planning. In the work an improved procedure for segmenting bone surfaces is realised in combination with methods for the fusion for a three-dimensional model. The novelty of the presented work is in new approaches to realising an operation planning system, based on 3D computations, and implementing the intraoperative control by a guided ultrasound system for bone tracking. To realise these ideas the following tasks are solved: - bone modelling from CT data; - real-time extraction of bone surfaces from ultrasound imaging; - tracking the bone with respect to CT bone model. - integrating and implementing the above results in the development of an operation planning system for osteotomy corrections that supports on-line measurements, different types of deformity correction, a bone geometry design and a high level of automation. The developed osteotomy planning system allows to investigate the pathology, makes its analysis, finds an optimal way to realise surgery and provides visual and quantitative information about the results of the virtual operation. Therefore, the implementation of the proposed system can be considered as an additional significant tool for the diagnosis and orthopaedic surgery. The major parts of the planning system are: bone modelling from 3D data derived from CT, MRI or other modalities, visualisation of the elements of the 3D scene in real-time, and the geometric design of bone elements. A high level of automation allows the surgeon to reduce significantly the time of the operation plane development

Biomedical Paper Computer-Based Periaxial Rotation Measurement for Aligning Fractured Femur Fragments from CT: A Feasibility Study

A new computer-based method for measuring periaxial rotation of healthy and fractured femurs from preoperative CT during closed femoral fracture reduction surgery is described. The method provides a comparative quantitative measure to align the distal and proximal femur fragments based on periaxial rotation. The periaxial rotation is defined in terms of patient-specific bone features. An algorithm for automatically extracting these features from the CT based on this definition has been developed. The algorithm extracts the condyle landmarks and neck axis of the healthy bone, determines its periaxial rotation, and extrapolates this data, assuming mirror symmetry between the healthy and fractured bones, to measure periaxial rotation between the fractured fragments. Unlike existing techniques, the method requires minimal user intervention. In a feasibility study, the method was applied to five dry femurs and one patient data set, and simulated a reduction based on the periaxial measurements with satisfactory results. The experiments showed the measured angle on the fractured femur to be within 1–4.5 ° of that of the healthy bone. Comp Aid Surg 7:332–341 (2002). ©2003 Wiley-Liss, Inc. Key words: computer-aided orthopedic surgery; femoral fracture reduction; periaxial rotation measuremen