Objectives: To evaluate the accuracy of computer-assisted sacral screw fixation compared with conventional techniques in the dysmorphic versus normal sacrum.Design: Review of a previous study database.Setting: Database of a multinational study with 9 participating trauma centers.Patients: The reviewed group included 130 patients, 72 from the navigated group and 58 from the conventional group. Of these, 109 were in the nondysmorphic group and 21 in the dysmorphic group.Intervention: Placement of sacroiliac (SI) screws was performed using standard fluoroscopy for the conventional group and Brain-LAB navigation software with either 2-dimensional or 3-dimensional (3D) navigation for the navigated group.Main Outcome Measurements: Accuracy of SI screw placement by 2-dimensional and 3D navigation versus conventional fluoroscopy in dysmorphic and nondysmorphic patients, as evaluated by 6 observers using postoperative computerized tomography imaging at least 1 year after initial surgery. Intraobserver agreement was also evaluated.Results: There were 11.9% (13/109) of patients with misplaced screws in the nondysmorphic group and 28.6% (6/21) of patients with misplaced screws in the dysmorphic group, none of which were in the 3D navigation group. Raw agreement between the 6 observers regarding misplaced screws was 32%. However, the percent overall agreement was 69.0% (kappa = 0.38, P < 0.05).Conclusions: The use of 3D navigation to improve intraoperative imaging for accurate insertion of SI screws is magnified in the dysmorphic proximal sacral segment. We recommend the use of 3D navigation, where available, for insertion of SI screws in patients with normal and dysmorphic proximal sacral segments.

Osteoid osteoma is a benign bone tumor which was first described by Jaffe (1935). Histologically it consists of a centrally located nidus composed of osteoblasts and osteoid which is surrounded by an area of reactive sclerosis and/or periosteal new bone formation. Prostaglandins which are produced by the tumor induce a chronic inflammatory reaction and vasodilatation which results in stimulation of unmyelinated nerve endings in the nidus causing pain. This leads to the clinical symptoms of this lesion with local pain often worsening during the night, which is typically relieved by aspirin or other related nonsteroidal antiinflammatory drugs. Osteoid osteomas occurmore frequently in men than in women (2:1) and most patients, approximately 75%, suffering from osteoid osteomas are between 5 and 25 years old. Most commonly osteoid osteomas are found in the diaphysis of femur and tibia followed by humerus, radius, ulna, hand, and the verterbral spine. A malignant transformation of osteoid osteoma is not known.

Bei instabilen proximalen Tibiafrakturen kommt es infolge ungenügender Abstützung nicht selten zu Sekundärdislokationen mit konsekutiver Gelenksinkongruenz und Achsenfehlstellung. Doppelplattenosteosynthesen erhöhen zwar die Stabilität, sind aber wenig biologisch und führen leicht zu Wundheilungsproblemen. Neue Stabilisierungsverfahren wie das LISS (Less Invasive Stabilization System) und die LCP (Locked Compression Plate) ermöglichen eine winkelstabile und minimal invasive Osteosynthese. Dadurch können die Stabilität verbessert und Wundheilungsprobleme vermindert werden. Somit werden einfache Frakturen weiterhin mit den herkömmlichen Implantaten versorgt, bicondyläre Frakturen mit metaphysärer Trümmerzone und/oder ausgedehntem Weichteilschaden werden aber zunehmend mit minimal invasiven winkelstabilen Osteosyntheseverfahren stabilisiert.

Background Computer-assisted surgery (CAS) can act as an intraoperative ruler in high tibial osteotomy (HTO) to visualize continuously the leg during surgery. Questions The aim of the study is to evaluate the accuracy of CAS with respect to preoperative planning and postoper- ative deviation from the planned leg axis in HTO. In addition, the influence of surgeon experience as well as operation time and perioperative complications are analyzed. Methods A prospective multicenter study case series with follow-up at 6 weeks was performed in six centers. Medial open-wedge HTO with Tomofixwas done using com- puter assisted navigation technique with the Brainlab VV Osteotomy 1.0 module. Results Fifty-one patients with medial gonarthritis were treated with navigated HTO. The follow-up rate was 98%. The majority of HTO-CAS patients fell within the tolerated limit of ±3� for leg axis deviation, however, seven patients were reported with deviations outside of this range: three patients had deviations of(3� -4.5� and four patients(4.5� , respectively. Eight intraoperative complications were doc- umented, partially resulting from technical problems asso- ciated with the navigation system. During the 6-week follow-up period, three postoperative complications were experienced, all not associated with navigation technology. Conclusions In about 85% of cases, a perfect result in terms of deviation of the planned mechanical leg axis could be achieved. Computer assistance in HTO proved to be a helpful tool regarding intraoperative control of leg axis. Level of evidence Level I, High quality prospective study (all patients were enrolled at the same preoperative plan- ning point with C80% follow-up of enrolled patients).

BACKGROUND:Buried intraoral devices for distraction osteogenesis in mandibular deformities have numerous advantages, but success depends on the precise positioning of these devices. Although most centers nowadays use template-guided techniques for precise positioning, computer navigation has been described as a promising technique. Surgical navigation during device placement could become a viable method because it affords certainty in defining a device position.METHODS:A clinical situation was simulated by means of mounting a mandible model inside a phantom head. Screws were positioned according to a preoperative plan through transoral and transbuccal approaches, with both template-coded and freehand computer navigation.RESULTS:With template-coded navigation, the medium deviation from the planned position was 0.63 mm (range, 0.00-1.24 mm). With commercial freehand surgical computer navigation, the medium deviation was significantly higher at 0.98 mm (range, 0.00-3.13 mm).CONCLUSIONS:Computer-assisted surgery can provide a high level of accuracy in the region of the mandibular angle where precision is crucial for buried intraoral distraction devices. However, template-coded guidance does provide a significantly higher level of accuracy and therefore represents the gold standard.

BACKGROUND:The multifunctional image-guided therapy suite (MIGTS), a combined diagnostic and operating theatre, is currently the subject of considerable interest. This study investigated the effect of instituting a MIGTS on the emergency treatment of multiply injured patients.METHODS:This prospective controlled intervention study (MIGTS versus conventional treatment) included consecutive multiply injured trauma patients (Injury Severity Score of 16 or more) admitted between February 2003 and April 2005 to a university hospital. Main outcome measures were time to computed tomography (CT) and number of in-hospital transfers.RESULTS:A total of 168 patients were enrolled, 87 in the MIGTS and 81 in the control group. On average, CT was started at least 13 min sooner in the MIGTS group (P < 0.001), and these patients underwent fewer within-hospital transfers before arrival in the intensive care unit (median 2 versus 4 for controls; odds ratio -2.92, P < 0.001). Team members indicated increased satisfaction with the quality of the MIGTS procedure over the course of the study (P = 0.009). Thirty-day mortality rate (17 per cent for MIGTS versus 22 per cent for controls; P = 0.420) and long-term outcome did not differ between the two groups.CONCLUSION:Implementation of a MIGTS in the emergency treatment of multiple trauma significantly accelerated the procedure and reduced the number of in-hospital transports.REGISTRATION NUMBER:NCT0072213 (http://www.clinicaltrials.gov).

The clinical gold standard in orthopaedics for treating fractures with large bone defects is still the use of autologous, cancellous bone autografts. While this material provides a strong healing response, the use of autografts is often associated with additional morbidity. Therefore, there is a demand for off-the-shelf biomaterials that perform similar to autografts. Biomechanical assessment of such a biomaterial in vivo has so far been limited. Recently, the development of high-resolution peripheral quantitative computed tomography (HR-pQCT) has made it possible to measure bone structure in humans in great detail. Finite element analysis (FEA) has been used to accurately estimate bone mechanical function from three-dimensional CT images. The aim of this study was therefore to determine the feasibility of these two methods in combination, to quantify bone healing in a clinical case with a fracture at the distal radius which was treated with a new bone graft substitute. Validation was sought through a conceptional ovine model. The bones were scanned using HR-pQCT and subsequently biomechanically tested. FEA-derived stiffness was validated relative to the experimental data. The developed processing methods were then adapted and applied to in vivo follow-up data of the patient. Our analyses indicated an 18% increase of bone stiffness within 2 months. To our knowledge, this was the first time that microstructural finite element analyses have been performed on bone-implant constructs in a clinical setting. From this clinical case study, we conclude that HR-pQCT-based micro-finite element analyses show high potential to quantify bone healing in patients. Copyright (C) 2010 John Wiley & Sons, Ltd.

BACKGROUND:Distraction osteogenesis is a well known and frequently described technique in mandibular deformities. Buried intraoral devices have numerous advantages, but success hinges on precise positioning of the implants. Although computer navigation has repeatedly been described for craniofacial applications, research on navigating the mandibular region is scarce. Navigating the device placement for a mandibular distractor could become a viable method for distraction osteogenesis because of the possibility of certainty in achieving a defined device position.MATERIALS AND METHODS:A clinical situation was simulated by a mandible model mounted inside a phantom head. The screws were positioned according to a virtual plan through transoral and transbuccal approaches, with and without navigation.RESULTS:Without navigation, the mean deviation from the planned position was 4.9 mm (range, 0.9-10.7 mm), with a clear tendency to position the screws in the easy-to-access regions. With navigation, the mean deviation was significantly lower at 1.5 mm (range, 0.1-3.4 mm).CONCLUSIONS:Computer-assisted surgery can provide a high level of accuracy in the region of the mandibular angle, where precision is crucial for buried intraoral distraction devices.

This chapter on minimally-invasive percutaneous screw fixation of acetabular and sacral fractures will try to guide the reader through the process of understanding the biomechanics and classification of the specific injury he or she is investigating, recognizing and weighing the different conservative, minimallyinvasive and open treatment options and explaining how to perform some of the minimally-invasive techniques. Close collaboration between orthopedic surgeon and radiologist is strongly advised to provide the best possible service to your patients. The literature on fl uoroscopic, CT-based and navigated techniques is discussed and illustrated with examples from our own experience.

BACKGROUND:The utilisation and consequences of standardised operative procedures may importantly differ between different healthcare systems. This is the first investigation comparing the treatment and outcome of femoral shaft fractures stabilised with an identical implant between trauma centres in 2 continents (Europe, EU and South Africa, SA).METHODS:Following standardised introduction of the technique, the prospective, observational multicentre study enrolled 175 patients who underwent intramedullary fracture fixation using the antegrade femoral nail (AFN) for femoral shaft fractures. Eleven EU hospitals recruited 86 patients and 1 SA centre 89 patients in the study period. Comparison of epidemiologic data, operative characteristics as well as subjective (e.g., pain, SF-36) and objective (e.g., X-ray, range of motion [ROM]) 3-month and 1-year outcomes were performed (p<0.05).RESULTS:Compared to EU centres, several significant differences were observed in SA: (1) on average, patients operated on were younger, had less concomitant diseases and had more severe open fractures; (2) operative stabilisation was more often undertaken by young, unsupervised residents, with shorter operating and intraoperative fluoroscopy times; (3) mean hospital stay was shorter, with less recorded complications, but a higher loss to follow-up rate. Non- or malunion rates and subjective outcomes were similar for both groups, with the physical component of the SF-36 at the 1-year follow-up not fully restoring to baseline values.CONCLUSIONS:Our investigation demonstrates the importance of several major differences between 2 different regions of the world in the treatment of femoral shaft fractures, despite involving only high level trauma centres and using an identical implant. The intercontinental comparison of results from clinical studies should be interpreted very carefully considering the heterogeneity of populations and clinical settings.

BACKGROUND:Orthopedic trauma care relies on two-dimensional radiograms both before and during the operation. Understanding the three-dimensional nature of complex fractures on plain radiograms is challenging. Modern fluoroscopes can acquire three-dimensional volume datasets even during an operation, but the device limitations constrain the acquired volume to a cube of only 12-cm edge. However, viewing the surrounding intact structures is important to comprehend the fracture in its context. We suggest merging a fluoroscope's volume scan into a generic bone model to form a composite full-length 3D bone model.METHODS:Materials consisted of one cadaver bone and 20 three-dimensional surface models of human femora. Radiograms and computed tomography scans were taken before and after applying a controlled fracture to the bone. A 3D scan of the fracture was acquired using a mobile fluoroscope (Siemens Siremobil). The fracture was fitted into the generic bone models by rigid registration using a modified least-squares algorithm. Registration precision was determined and a clinical appraisal of the composite models obtained.RESULTS:Twenty composite bone models were generated. Average registration precision was 2.0 mm (range 1.6 to 2.6). Average processing time on a laptop computer was 35 s (range 20 to 55). Comparing synthesized radiograms with the actual radiograms of the fractured bone yielded clinically satisfactory results.CONCLUSION:A three-dimensional full-length representation of a fractured bone can reliably be synthesized from a short scan of the patient's fracture and a generic bone model. This patient-specific model can subsequently be used for teaching, surgical operation planning, and intraoperative visualization purposes.

BACKGROUND:Surgical navigation requires registration of the pre-operative image dataset with the patient in the operation theatre. Various marker and marker-free registration techniques are available, each bearing an individual level of precision and clinical practicability. In this study the precision of four different registration methods in a maxillofacial surgical setting is analyzed. MATERIALS AND METHODS:A synthetic full size human skull model was registered with its computer tomography-dataset using (a) a dentally mounted occlusal splint, (b) the laser surface scanning, (c) five facial bone implants and (d) a combination of dental splint and two orbital bone implants. The target registration error was computed for 170 landmarks spread over the entire viscero- and neurocranium in 10 repeats using the VectorVision2 (BrainLAB AG, Heimstetten, Germany) navigation system. Statistical and graphical analyses were performed by anatomical region. RESULTS:An average precision of 1mm was found for the periorbital region irrespective of registration method (range 0.6-1.1mm). Beyond the mid-face, precision linearly decreases with the distance from the reference markers. The combination of splint with two orbital bone markers significantly improved precision from 1.3 to 0.8mm (p<0.001) on the viscerocranium and 2.3-1.2mm (p<0.001) on the neurocranium. CONCLUSIONS:An occlusal splint alone yields poor precision for navigation beyond the mid-face. The precision can be increased by combining an occlusal splint with just two bone implants inserted percutaneously on the lateral orbital rim of each side.

Objectives: During complex image-guided orthopedic trauma procedures, repetitive fluoroscopic scout imaging is performed. A number of preparatory positioning images often must be taken to reproduce a comparable projection. These scout images have no intrinsic clinical relevance but nevertheless expose the patient and the surgical team to considerable radiation, which could be avoided. This study presents and validates a method to decrease intraoperative radiation. Methods: Precision, time requirements, and number of scout images for repositioning the fluoroscope, with and without navigation aid, were recorded on 20 test-rig and 3 phantom setups. A commercially available image-guided surgical navigation system (Vector Vision®, BrainLAB), originally designed for instrument navigation, was employed to register and retrieve the C-arm positions. A newly developed software computed the necessary moves to reposition the C-arm on an intuitive visual display. Results: Retrieving a given C-arm position with the conventional non-navigated technique required an average of 7 scout images (range, 3 to 12 images). In contrast, navigation-assisted repositioning did not necessitate a single scout image. Deviations from the original projection were minimal for both navigated (0.9 degrees, 95% CI 0.8 to 1.1 degrees) and non-navigated repositioning (0.8 degrees, 95% CI 0.7 to 0.9 degrees). Average positioning times were comparable when navigating the C-arm (46 seconds, 95% CI 41 to 51 seconds) and in scout image-based positioning (49 seconds, 95% CI 44 to 53 seconds). Conclusions: Navigated C-arm positioning avoids multiple scout images and yields sufficient precision for clinical deployment. Radiation exposure can be reduced considerably by a combination of instrument navigation and navigated C-arm positioning.

In order to maintain overall navigation accuracy established by a calibration procedure in our CT-based registration-free navigation system, the CT scanner has to repeatedly generate identical volume images of a target at the same coordinates. We tested the positioning accuracy of the prototype of an advanced workplace for image-guided surgery (AWIGS) which features an operating table capable of direct patient transfer into a CT scanner. Volume images (N = 154) of a specialized phantom were analysed for translational shifting after various table translations. Variables included added weight and phantom position on the table. The navigation system's calibration accuracy was determined (bias 2.1 mm, precision +/- 0.7 mm, N = 12). In repeated use, a bias of 3.0 mm and a precision of +/- 0.9 mm (N = 10) were maintainable. Instances of translational image shifting were related to the table-to-CT scanner docking mechanism. A distance scaling error when altering the table's height was detected. Initial prototype problems visible in our study causing systematic errors were resolved by repeated system calibrations between interventions. We conclude that the accuracy achieved is sufficient for a wide range of clinical applications in surgery and interventional radiology.

Surgical patient care is a complex organization task. On the one hand, it involves numerous specialties, e. g., radiologists, surgeons, anaesthesiologists, operation room nurses, auxiliary OR staff. On the other, it heavily relies on hospital logistics, e. g., OR scheduling, hospital warehouse management and accounting. Numerous individual computer applications assist the care team throughout the treatment process. Unfortunately, the stand-alone nature of these applications intrinsically hinders information transfer across specialities and between process steps. We have analyzed the peri-operative workflow in an orthopaedic trauma setting and identified bottle-necks in in-hospital information dissemination. We subsequently developed an integrated application to facilitate information processing along the peri-operative workflow. Our application merges innovative three-dimensional surgical planning with hospital warehouse management and logistics. Quality of patient care will increasingly depend on integrating existing medical systems to a central information turntable. It is thereby essential that such an application depicts the entire peri-operative treatment process. Process optimization through integration could likewise be applied to other surgical disciplines.

Both in radiology and in surgery, numerous applications are emerging that enable 3D visualization of data from various imaging modalities. In clinical practice, the patient's images are analyzed on work stations in the Radiology Department. For specific preclinical and educational applications, however, data from single patients are insufficient. Instead, similar scans from a number of individuals within a collective must be compiled. The definition of standardized acquisition procedures and archiving formats are prerequisite for subsequent analysis of multiple data sets. Focusing on bone morphology, we describe our concept of a computer database of 3D human bone models obtained from computed tomography (CT) scans. We further discuss and illustrate deployment areas ranging from prosthesis design, over virtual operation simulation up to 3D anatomy atlases. The database of 3D bone models described in this work, created and maintained by the AO Development Institute, may be accessible to research institutes on request.

Technology integration is an enabling technological prerequisite to achieve a major breakthrough in sophisticated intra‐operative imaging, navigation and robotics in minimally invasive and/or emergency diagnosis and therapy. Without a high degree of integration and reliability comparable to that achieved in the aircraft industry image guidance in its different facets will not ultimately succeed. As of today technology integration in the field of image‐guidance is close to nonexistent. Technology integration requires inter‐departmental integration of human and financial resources and of medical processes in a dialectic way. This expanded techno‐socio‐economic integration has profound consequences for the administration and working conditions in hospitals. At the university hospital of Basel, Switzerland, a multimodality multifunction sterile suite was put into operation after a substantial pre‐run. We report the lessons learned during our venture into the world of medical technology integration and describe new possibilities for similar integration projects in the future.

Matthews, Felix MD1; Trentz, Otmar MD2; Jacob, Augustinus Ludwig MD3; Kikinis, Ron MD1; Jupiter, Jesse B. MD4; Messmer, Peter MD2 Author Information

. Intra-articular fractures are commonly scanned by computer tomography. But even complex fractures located in the bone shaft are usually only diagnosed on 2D radiographs. The surgeon must therefore himself interpret the 2D pictures to determine fracture’s 3D configuration. Minimally invasive procedures that do not expose the fracture during surgery are increasing in popularity. Consequently, young surgeons will hardly ever see the true 3D configuration of the shaft fractures they are treating. This lack of opportunity to learn the correspondence between 2D radiogram and actual 3D fracture morphology is a cause of concern in surgical education. In this study we suggest a method to improve comprehension of 3D fracture morphology. We propose creating a concatenated 3D bone model by merging a short scan of the pertinent fracture with a generic intact bone model. Thus a full-length concatenated model is obtained that depicts both fracture and surrounding intact bone.