Comparative study of the quality of C-arm based 3D imaging of the talus

Malposition of extraosseous or intra-articular screws, e.g., in osteosyntheses of joint fractures or in the vicinity of joints, frequently remains undiscovered in intraoperative fluoroscopy and is only recognized on postoperative computed tomography (CT) scans. The aim of the study, therefore, was to assess the value of a new mobile C-arm three-dimensional imaging device in comparison with fluoroscopy, conventional radiographs, and CT scans using an extremity model. Screws were inserted ventrally in four anatomic lower leg specimens without talus fractures parallel to the longitudinal axis to simulate surgical management of fractures of the talus. The specimens supplied were examined with fluorscopy, conventional radiography, spiral CT, and the new three-dimensional imaging with the SIREMOBIL Iso-C3D. These four modalities were evaluated by ten radiologists and ten trauma surgeons and were compared regarding subjective image quality and position of the screws. The quality of information acquired with the SIREMOBIL Iso-C3D was equal to that of the CT examinations, although image quality was considered inferior to fluoroscopy, conventional radiography, and CT (p < 0.001). In contrast to the previous procedure with intraoperative fluoroscopy and subsequent postoperative X-ray control, the results obtained with the SIREMOBIL IsoC3D were superior. The SIREMOBIL Iso-C3D is useful for the intraoperative diagnosis of small joints with few artifacts producing osteosynthesis material, i.e., for recognizing the position of screws in the region of glenoid surfaces.     

Computerassistierte Verschraubung des hinteren Beckenrings

OBJECTIVE: Computer-assisted procedures have recently been introduced for navigated iliosacral screw placement. Currently there are only few data available reflecting results and outcome of the different navigated procedures which may be used for this indication. We therefore evaluated the features of a new 3D image intensifier used for navigated iliosacral screw placement compared to 2D fluoroscopic and CT navigation. MATERIALS AND METHODS: Twenty fixed human cadavers were used in this trial. Cannulated cancellous screws were percutaneously implanted in the supine position in four treatment groups. An optoelectronic system was used for the navigated procedures. Screw placement was postoperatively assessed by fluoroscopic 3D scan and CT. The target parameters of this investigation were practicability, precision as well as procedure and fluoroscopic time per screw. RESULTS: All navigated procedures revealed a significant loss of time compared to non-navigated screw placement (2D: p<0.001, 3D: p>0.05, CT: p<0.001). Simultaneously a significant decrease of radiation exposure time was observed in the navigated groups (p<0.001 each). The misplacement rate was 20% in the non-navigated and the 2D fluoroscopic navigated group each. Procedures providing 3D imaging of the posterior pelvis did not produce any screw misplacement (p>0.05). However, the CT procedure was associated with time-consuming registration and high rates of failed matching procedures. CONCLUSION: Our data show a clear benefit of using C-arm navigation for iliosacral screw placement compared with the CT-based procedure. While both fluoroscopy-based navigation procedures decrease intraoperative radiation exposure times, only 3D fluoroscopic navigation seems to improve the precision compared to non-navigated screw placement.     

计算机辅助外科手术的基本概念

目的讨论医用数字影像系统与计算机技术在骨科手术中的应用.方法总结目前计算机技术在骨科临床开发应用的几个组成部分及其应用.结果计算机辅助外科可以:①对患者的数字资料进行采集记录,从术前的CT、MRI和X线片来提取,从术中的X线透视或B超影像获得,从术中手术器械和骨组织上通过三维定位装置得到的定位与定向资料中汲取;②将术前影像资料与术中从解剖标志或从骨表面探取的数据进行配准、整合,或直接利用术中从B超图像截取的骨轮廓影像资料进行手术导航;③帮助医生进行准确的决策过程,采用各种信息,术中针对器械与骨组织的相互位置,在术前或术中的数字影像资料上模拟显示预设导航方案,包括器械的方位、轴线、定向、长度和直径等;④通过被动、主动及半主动系统帮助医生术中监控具体操作,准确地达到术前计划好的方案.结论计算机辅助骨科手术系统可以为术者提供具有安全性与准确性的手术技术,是一种优化手术治疗的步骤.     

Comparison of Radiation Exposure in Lumbar Pedicle Screw Placement With Fluoroscopy Vs Computer-Assisted Image Guidance With Intraoperative Three-Dimensional Imaging

Background/objective: Little is known about the long-term effects of chronic exposure to ionizingradiation. Studies have shown that spine surgeons may be exposed to significantly more radiation than thatobserved in surgery on the appendicular skeleton. Computer-assisted image guidance systems have beenshown in preliminary studies to enable accurate instrumentation of the spine. Computer-assisted image guidance systems may havesignificant application to the surgical management of spinal trauma and deformity. The objective of this study was to compare C-arm fluoroscopy and computer-assisted imageguidance in terms of radiation exposure to the operative surgeon when placing pedicle screw-rod constructsin cadaver specimens.

Methods: Twelve single-level (2 contiguous vertebral bodies) lumbar pedicle screw-rod constructs (48screws) in 4 fresh cadavers were placed using standard C-arm fluoroscopy and computer-assisted imageguidance (Stealth Station with lso-C^3D ).Pedicle screw-rod constructs were placed at L1-L2, L3-L4, and L5-S1 in 4 fresh cadaver specimens. Imaging was alternated between C-arm fluoroscopy and computer-assistedimage guidance with Stealth Station lso-C^3D. Radiation exposure was measured using ringand badge dosimeters to monitor the thyroid, torso, and index finger. Postprocedure CT scans were obtained to judge accuracy of screw placement.

Results: Mean radiation exposure to the torso was 4.33 ± 2.66 mRemfor procedures performed with standard fluoroscopy and 0.33 ± 0.82 mRem for procedures performed with computer-assisted image guidance. This difference was statistically significant (P = 0.012). Radiation exposure to the index finger and thyroid was negligible for all procedures. The accuracy of screw placement was similar for both techniques.

Conclusions: Computer-assisted image guidance systems allow for the safe and accurate placement ofpedicle screw-rod constructs with a significant reduction in exposure to ionizing radiation to the torso of theoperating surgeon.     

The use of intraoperative three-dimensional imaging (ISO-C-3D) in fixation of intraarticular fractures

INTRODUCTION: The purpose of this study was to analyse the applicability and advantages of the intraoperative use of a mobile isocentric C-arm with three-dimensional imaging (Siremobil ISO-C-3D) in fixation of intraarticular fractures. METHODS: After the fixation was judged to be satisfactory relying on the images provided by routine fluoroscopy, intraoperative CT visualisation with ISO-C-3D was performed to evaluate the fracture reduction and implant position. Intraoperative revision was performed based on the additional information ISO-C-3D provided beyond routine fluoroscopy. ISO-C-3D was used on a series of 72 closed-intraarticular fractures in 70 patients. Fracture distribution was: calcaneus (25), tibial plateau (17), tibial plafond (12), acetabulum (11), distal radius (3), ankle Weber-C (3) and femoral head (l). The primary outcome measure was revision rate after final ISO-C-3D data acquisition and prior to wound closure. Secondary objectives were to measure the additional time required for ISO-C-3D use and to determine the rate of further re-do surgeries. RESULTS: Eight out of 72 (11%) fracture fixations were judged by the surgeon to require intraoperative revision following ISO-C-3D imaging. Prior to leaving the operating room, the surgeon was satisfied with fracture alignment in all the procedures. The mean additional operative time using ISO-C-3D was 7.5 min (8.2% of the mean total operative time). No patient required re-do surgery. CONCLUSION: : Intraoperative three-dimensional visualisation of intraarticular fractures enables the surgeon to identify inadvertent malreductions or implant malpositions which may be overlooked by routine C-arm fluoroscopy and hence may eliminate the need for re-do procedures. ISO-C-3D adds little operative time and may preclude the need for pre-operative and post-operative CT-scans in selected cases.     

Intraoperative cone-beam CT for image-guided tibial plateau fracture reduction.

OBJECTIVES: A mobile isocentric C-arm was modified in our laboratory in collaboration with Siemens Medical Solutions to include a large-area flat-panel detector providing multi-mode fluoroscopy and cone-beam CT (CBCT) imaging. This technology is an important advance over existing intraoperative imaging (e.g., Iso-C(3D)), offering superior image quality, increased field of view, higher spatial resolution, and soft-tissue visibility. The aim of this study was to assess the system's performance and image quality in tibial plateau (TP) fracture reconstruction. METHODS: Three TP fractures were simulated in fresh-frozen cadaveric knees through combined axial loading and lateral impact. The fractures were reduced through a lateral approach and assessed by fluoroscopy. The reconstruction was then assessed using CBCT. If necessary, further reduction and localization of remaining displaced bone fragments was performed using CBCT images for guidance. CBCT image quality was assessed with respect to projection speed, dose and filtering technique. RESULTS: CBCT imaging provided exquisite visualization of articular details, subtle fragment detection and localization, and confirmation of reduction and implant placement. After fluoroscopic images indicated successful initial reduction, CBCT imaging revealed areas of malalignment and displaced fragments. CBCT facilitated fragment localization and improved anatomic reduction. CBCT image noise increased gradually with reduced dose, but little difference in images resulted from increased projections. High-resolution reconstruction provided better delineation of plateau depressions. CONCLUSION: This study demonstrated a clear advantage of intraoperative CBCT over 2D fluoroscopy and Iso-C(3D) in TP fracture fixation. CBCT imaging provided benefits in fracture type diagnosis, localization of fracture fragments, and intraoperative 3D confirmation of anatomic reduction.     

Ein Vergleich von C-Bogen-CT und Standardbildgebung an Osteosynthesen frakturierter Präparate des distalen Radius

BACKGROUND: The purpose of this study was to evaluate the value of C-arm CT imaging of the distal radius with standard patient positioning in intraoperative assessment of plate osteosynthesis. MATERIALS AND METHODS: Four complete distal radius specimens from human cadavers were fractured (type C), and internal fixation with palmar plates (stainless steel) was then carried out in each. On the basis of C-arm fluoroscopy, radiography and C-arm CT (Siremobil Iso-C3D, scans with forearm bones positioned parallel to the z-axis), 19 observers subsequently evaluated the positions of screws near the joint and any steps within the joint, after which the bones were surgically exposed and the imaging results checked against direct visual observations. RESULTS: No statistically significant differences were detected either between the modalities or between the evaluator groups. CONCLUSION: With standard patient positioning, the performance of C-arm CT was equivalent to and not better than that of current standard procedures, i.e. intraoperative fluoroscopy and postoperative radiography. Further studies should examine whether this holds true in clinical practice with representative patient collectives when titanium implants are used and/or optimized patient positioning is practised.     

Fluoroscopy-Based Surgical Navigation versus Fluoroscopic Guidance to Control Guide Wire Insertion for Osteosynthesis of Femoral Neck Fractures

AbstractBackground and Purpose: Long fluoroscopic times and related radiation exposure are a universal concern when C-arm fluoroscopy is used to guide percutaneous procedures. Fluoroscopy-based surgical navigation has been proposed as an alternative guidance method requiring limited fluoroscopic times to achieve precision. The purpose of this experimental study was to compare fluoroscopy-based surgical navigation with C-arm fluoroscopy for guidance with respect to the precision achieved, the fluoroscopic time, and the resources needed.Material and Methods: 114 guide wires were placed in 38 synthetic bone models using either C-arm fluoroscopy (group A) or fluoroscopy-based surgical navigation (group B) for guidance. Precision of guide wire placement was rated on the basis of an individual CT scan on all fracture models of both groups. The fluoroscopic time, the procedure time, and the number of attempts required to place the guide wires were documented as well.Results: An average fluoroscopic time of 26 s was needed with C-arm fluoroscopy to place three guide wires compared with an average fluoroscopic time of 2 s that was needed when fluoroscopy-based surgical navigation was used for guidance (p < 0.0001). Precision of guide wire placement and procedure times required to place the guide wires did not differ significantly between both groups. The number of attempts required for correct placement was found significantly reduced with fluoroscopy-based surgical navigation when compared with fluoroscopic guidance (p = 0.04).Conclusion: Fluoroscopic times to achieve precision are reduced with fluoroscopy-based surgical navigation compared with C-arm fluoroscopy. The impact of this new technique on minimally invasive, percutaneous procedures has to be evaluated in controlled prospective clinical studies.     

Isozentrischer C-Bogen

In addition to conventional C-arms which can be used for intraoperative imaging, C-arm image amplifiers with an option for three-dimensional imaging (ISO-C3D) are available to visualize reduction of fragments and positions of implants. In ten cadaver wrists intra-articular steps and intra-articular screw positions were simulated. Images obtained by conventional two-dimensional C-arm image amplifier, computed tomography and ISO-C3D were evaluated by four investigators using a questionnaire. For 2D image amplifier scans the investigators rated the quantity of the articular steps correctly in 45%, incorrectly in 51% and were uncertain in 4%. Concerning CT scans these values were 57, 40 and 3%, respectively. With a slow 190° ISO-C3D mode the investigators rated the steps correctly in 47%, incorrectly in 44% and were uncertain in 9%. The positions of the tip of the screw were rated correctly for 2D scans in 56%, incorrectly in 40% and were uncertain in 4%. For CT screw positions were assessed correctly in 40%, incorrectly in 43% and were uncertain in 17%. For ISO-C3D in fast 190° mode the rating was correct in 59%, wrong in 30% and uncertain in 11%. In the slow Iso-C3D mode the results were inferior with correct assessment in 51%, wrong results in 36% and uncertain evaluation in 13%. In our cadaveric study, ISO-C3D scans have been found valuable for intraoperative controls of implant positions and assessment of intra-articular steps.     

Comparison of novel machine vision spinal image guidance system with existing 3D fluoroscopy-based navigation system: a randomized prospective study

BACKGROUND CONTEXTThe use of spinal image guidance systems (IGS) has increased patient safety, accuracy, operative efficiency, and reduced revision rates in pedicle screw placement procedures. Traditional intraoperative 3D fluoroscopy or CT imaging produces potentially harmful ionizing radiation and increases operative time to register the patient. An IGS, FLASH Navigation, uses machine vision through high resolution stereoscopic cameras and structured visible light to build a 3D topographical map of the patient's bony surface anatomy enabling navigation use without ionizing radiation.PURPOSEWe aimed to compare FLASH navigation system to a widely used 3D fluoroscopic navigation (3D) platform by comparing radiation exposure and pedicle screw accuracy.DESIGNA randomized prospective comparative cohort study of consecutive patients undergoing open posterior lumbar instrumented fusion.PATIENT SAMPLEAdults diagnosed with spinal pathology requiring surgical treatment and planning for open posterior lumbar fusion with pedicle screws implanted into 1-4 vertebral levels.OUTCOME MEASURESOutcome measures included mean intraoperative fluoroscopy time and dose, mean CT dose length product (DLP) for preoperative and day 2 CT, pedicle screw accuracy by CT, estimated blood loss and revision surgery rate.METHODSConsecutive patients were randomized 1:1 to FLASH or 3D and underwent posterior lumbar instrumented fusion. Radiation doses were recorded from pre- and postoperative CT and intraoperative 3D fluoroscopy. 2 independent blinded radiologists reviewed pedicle screw accuracy on CT.RESULTSA total of 429 (n=210 FLASH, n=219 3D) pedicle screws were placed in 90 patients (n=45 FLASH, n=45 3D) over the 18-month study period. Mean age and indication for surgery were similar between both groups, with a non-significantly higher ratio of males in the 3D group.Mean intraoperative fluoroscopy time and doses were significantly reduced in FLASH compared to 3D (4.51±3.71s vs 79.6±23.0s, p<.001 and 80.9±68.1cGycm² vs 3704.1±3442.4 cGycm², p<.001, respectively). This represented a relative reduction of 94.3% in the total intraoperative radiation time and a 97.8% reduction in the total intraoperative radiation dose. Mean preoperative CT DLP and mean day 2 postoperative CT DLP were significantly reduced in FLASH compared to 3D (662.0±440.4mGy-cm vs 1008.9±616.3 mGy-cm, p<.001 and 577.9±294.3 mGy-cm vs 980.7±441.6 mGy-cm, p<.001, respectively). This represented relative reductions of 34.4% and 41.0% in the preoperative CT dose and postoperative total DLP, respectively.The FLASH group required an average of 1.2 registrations in each case with an average of 2447 (±961.3) data points registered with a mean registration time of 106s (±52.1). A rapid re-registration mechanism was utilized in 22% (n=10/45) of cases and took 22.7s (±11.3). Re-registration was used in 7% (n=3/45) in the 3D group.Pedicle screw accuracy was high in FLASH (98.1%) and 3D (97.3%) groups with no pedicle breach >2mm in either group (p<.001). EBL was not statistically different between the groups (p=.38). No neurovascular injuries occurred, and no patients required return to theatre for screw repositioning.CONCLUSIONSFLASH and 3D IGS demonstrate high accuracy for pedicle screw placement. FLASH showed significant reduction in intraoperative radiation time and dose with lower but non-significant blood loss. FLASH showed significant reduction in preoperative and postoperative radiation, but this may be associated to the lower number of males/females preponderance in this group. FLASH provides similar accuracy to contemporary IGS without requiring 3D-fluoroscopy or radiolucent operating tables. Reducing registration time and specialized equipment may reduce costs.     

Intraoperative 3D fluoroscopy in stereotactic surgery

Background  

Intraoperative localisation of a stereotactic probe remains challenging. Stereotactic X-ray, the “gold standard”, as well as intraoperative magnetic resonance (MRI) and computed tomography (CT), require a dedicated operating room (OR). Fluoroscopy with crosshairs confirms only grossly the target position. An alternative would be a mobile three-dimensional (3D) fluoroscopy C-arm. To our knowledge, this is the first report on 3D C-arm fluoroscopy to verify stereotactical trajectories. The objective was to assess the feasibility of using a 3D C-arm to verify the intraoperative trajectory and target.     

Odontoid screw placement using Isocentric 3-dimensional C-arm fluoroscopy

STUDY DESIGN: We describe the use of isocentric 3-dimensional fluoroscopy to place odontoid screws in 9 patients. OBJECTIVE: We wanted to show the benefits of using isocentric 3-dimensional fluroscopy in odontoid screw placement. SUMMARY OF BACKGROUND DATA: Odontoid screw fixation for treatment of type II odontoid fractures has gained popularity since its introduction in the early 1980s. During the last several years, a multitude of new techniques have improved the ease of odontoid screw placement, including biplanar fluoroscopy, cannulated screw systems, and beveled bedside-fixed retractor systems. The use of isocentric C-arm fluoroscopy can improve the ease and facilitate placement of odontoid screws. CLINICAL PRESENTATION: Nine patients, ranging in ages from 30 to 89 years, presented with type II odontoid fractures. All fractures were either nondisplaced or minimally displaced (<4 mm) and occurred as a result of acute trauma. No patient had evidence of transverse atlantal ligament disruption. METHODS: Isocentric 3-dimensional fluoroscopy, in conjunction with image-guided navigational software, was used to place 1 or 2 odontoid screws in each patient. Three-dimensional images were acquired intraoperatively, which were then reconstructed and uploaded to the navigational workstation. Screw trajectory was planned and performed with the use of tracked instruments. RESULTS: Successful screw placement, as judged by intraoperative computerized tomography, was attained in all 9 patients. CONCLUSIONS: Isocentric 3-dimensional fluoroscopy, in conjunction with an image-guided navigational software system, obviates the need for cumbersome biplanar fluoroscopy, allows for intraoperative image acquisition after surgical exposure, reduces intraoperative registration time, reduces both surgeon and patient radiation exposure, and allows immediate computerized tomographic imaging in the operating room to verify screw position.     

C臂CT在经导管动脉化疗栓塞术治疗肝脏恶性肿瘤中的应用

目的探讨平板探测器C臂CT在TACE治疗肝脏恶性肿瘤中的应用价值。方法 38例肝脏恶性肿瘤患者在常规DSA基础上接受C臂CT检查,观察C臂CT是否能提供更多影像信息及其对介入治疗方案的影响;对C臂CT图像进行伪影分级评分并对其中28例患者C臂CT图像与近期MSCT图像比较,评价其图像质量;分析观察者间一致性。结果与常规DSA比较,C臂CT为26例（26/38,68.42%）提供了更多的影像信息,9例（9/38,23.68%）最初通过常规DSA制定的介入治疗方案因而改变;C臂CT图像质量评分为2.68,稍差于MSCT。所有患者C臂CT图像均有不同程度伪影。在C臂CT图像质量、伪影等级评分、C臂CT是否提供额外影像信息及对介入治疗方案的影响方面,观察者之间有良好的一致性（Kendall＇s W系数分别为0.78、0.84、0.73及0.67）。结论平板探测器C臂CT可在常规DSA基础上提供更多的影像信息,有助于提高肝脏恶性肿瘤TACE的疗效及安全性。     

Klinische Erfahrungen mit dem Siremobil Iso-C3D-Bildwandler in der Beckenchirurgie

In pelvic and acetabular surgery intraoperative control of reduction and implant position is sometimes hard to achieve with conventional C-arm technology. The Siemens C-arm Iso-C(3D) imaging system enables axial cuts and two- or three-dimensional reconstructions to be generated. Following the good experience in surgery of the spine and extremities, its clinical applicability in pelvic surgery was evaluated in 30 patients in a prospective clinical trial. In all 20 patients with acetabular fractures reduction quality and implant position could be well assessed. In one postoperative examination an intraarticular screw placement was evident, which intraoperatively was not as clear and was revised. In one procedure an intraarticular fragment was visualized, and was extracted in the same procedure. In one procedure the use of the Iso-C(3D) system enabled the approach to be limited.In all ten pelvic ring injuries the osseous structures in the posterior pelvic ring could be visualized with an adequate image quality. Reduction quality and implant position could be assessed in all open and closed procedures. On two occasions the SI screws were navigated based upon the Iso-C(3D) dataset. Overall the use of the Iso-C(3D) system was successful in all cases. Image quality, which is clearly inferior to that of CT, was sufficient for the assessment of reduction quality and implant position. One revision was indicated, and one avoided. However, in spite of its advantages in pelvic surgery, handling, sterile covering and data transfer need to be improved. For bilateral pelvic injuries the image size is too small.     

骨科机器人辅助下脊柱椎弓根螺钉置入准确性与安全性的临床研究

目的:探讨骨科机器人与C形臂X线透视辅助下脊柱椎弓根螺钉置入的准确性与安全性.方法:对2019年1月至2020年8月采用外科治疗的36例脊柱疾患病例进行回顾性分析.36例患者中18例采用骨科机器人辅助下的椎弓根螺钉置入(观察组),男12例,女6例;年龄16～61 (38.44±3.60)岁;青少年脊柱侧弯1例,脊柱结核...     

Three-dimensional fluoroscopy for evaluation of articular reduction and screw placement in calcaneal fractures

BACKGROUND: Anatomic reconstruction of the posterior calcaneal facet after intra-articular fracture is one of the critical factors in achieving a good functional result. Intraoperative evaluation of fracture reduction and implant placement relies on direct view by standard fluoroscopy. We hypothesized that three-dimensional (3D) fluoroscopy is more accurate than conventional fluoroscopy, and equivalent to CT for determining fracture reduction and screw position in calcaneal fractures. METHODS: A Sanders type IIB fracture pattern was created in eight embalmed lower extremity cadaver specimens. First, the posterior facet was reduced with a step-off of 0 mm to 2 mm in 0.5-mm increments. All specimens had two dimensional (2D) fluoroscopy, 3D fluoroscopy with an Iso-C3D, and a CT scan. Next, screws were placed so they protruded into the subtalar and calcaneocuboid joint and through the medial wall. All specimens were imaged again. Three observers evaluated all imaging studies, and the sensitivities and specificities of each modality were determined. RESULTS: Both the Iso-C3D and the CT were more specific for anatomic reduction (75% and 100%, respectively) than fluoroscopy (62%). For the malreduced trials, the Iso-C3D and CT were both 100% sensitive, and the sensitivity of fluoroscopy was 63% (p < 0.001 for both). For the intra-articular screws, the Iso-C3D and CT were accurate in all cases (sensitivities = 100%), and fluoroscopy was accurate in five of the eight trials for both joints (sensitivities = 63%). Finally, with screws protruding through the medial wall, the sensitivity of fluoroscopy was 25%, for the Iso-C3D 88% (p = 0.02), and for CT was 100% (p = 0.003). CONCLUSIONS: Three-dimensional fluoroscopic imaging is more accurate than 2D fluoroscopy for detection of intra-articular incongruities and implant position and is similar to CT. CLINICAL RELEVANCE: This new technology may be particularly useful in assessing calcaneal fractures and may lead to improved fracture reduction, less implant misplacement, and improved patient outcomes.     

Perkutane navigierte Ballonreposition einer dislozierten Acetabulumfraktur

Kyphoplasty is a well proven surgical procedure for osteoporotic fractures in spine surgery. Anatomic reconstruction of the joint is the primary aim in the treatment of acetabular fractures. To achieve this, extensive approaches with entry related morbidity are usually needed. Percutaneous stabilisations are still limited for non- or minimally displaced fractures.For displaced acetabular fractures, there are percutaneous procedures described with intraoperative CT control or by the use of a 3D C-arm. The case of an anterior column posterior hemitranverse fracture with an articular step in the weight bearing area is presented. In this case, a kyphoplasty balloon was placed by use of 3D C-arm navigation. After 2D C-arm controlled fracture reduction, the supra-acetabular screw was inserted percutaneously using the previous 3D navigation data set.With the combination of kyphoplasty technique, intraoperative 3D C-arm control and 3D C-arm based navigation, this displaced acetabular fracture could be reduced and fixed percutaneously. Anatomic reconstruction of the joint remains the primary aim.     

Navigation Using Fluoro-CT Technology

Abstract Background: The mobile SIREMOBIL^® Iso-C^3D C-arm is a device that permits the intraoperative three-dimensional (3-D) representation of bony structures (multiplanar reconstructions). Linking to navigation makes it possible to transfer the generated 3-D data directly to the navigation system. The advantages of CT-based navigation with 3-D representation of bone structures are therefore combined with the advantages of inherent navigation with intraoperative imaging. The surgical instrument is immediately displayed in the image, i.e., without any complex manual registration procedure. Patients and Methods: Inherent navigation in 3-D images from the Iso-C^3D was successfully used for the first time in this study in a larger group of patients. 39 patients who intraoperatively underwent successful navigation in Iso-C^3D images were included in the study. Results: 143 drilling procedures were performed in the 39 patients. Pedicle instrumentations took place in 24 of the 39 patients. Eight patients underwent screw placements on the pelvic ring (sacroiliac joint screw placement, placement of anterior column screw, acetabulum osteosynthesis). Four patients underwent retrograde perforation of a talus cyst and filling with autologous cancellous bone, while one patient underwent screw osteosynthesis on the neck of the femur, and two patients underwent placement of an external fixator with a hinge at the elbow joint. One pedicle screw was found to be 2 mm out of position in the spinal group. All other screws/drillings were placed correctly. Additionally, in three patients intraoperative navigation had to be aborted due to hard- or software problems. In these cases, surgery was finished in conventional ways. Conclusion: The results herein for the extremities, spine, and pelvis are very encouraging and portend an advance in safety and quality in the operating room (OR). As compared to the conventional approach and other computer-assisted procedures (CT-based navigation, C-arm-based 2-D navigation), the lowest rate of incorrect placements and the lowest average fluoroscopy time were achieved during the placement of pedicle screws on the spine with Iso-C^3D navigation at a comparable average OR duration. Iso-C^3D navigation supports standardized work procedures in the OR.     

计算机导航系统和C臂机透视引导颈椎椎弓根螺钉内固定技术的临床对比研究

目的探讨颈椎（C1-C7）椎弓根螺钉内固定的可行性和两种不同置钉方法的精确性。方法通过术后进行X线摄片、CT或术后Iso-C断层扫描等方法,判断C臂机透视引导下置入的145枚和三维导航系统（CT三维导航或Iso—C术中三维导航）辅助下187枚颈椎椎弓根螺钉病例的置钉准确性。结果三维导航系统引导组螺钉置入满意率（97．9％,183／187）明显高于C臂机透视引导组（91．7％,133／145）（χ2=6．705,P=0．010）。且三维导航系统引导组位置不满意的4枚螺钉均发生于早期病例,导航系统使用熟练后未再出现置钉不满意的病例。两组病例均未出现明显的神经血管损伤并发症（C臂机透视引导组2例术后一过性上肢疼痛）。对三维导航系统引导组中25例进行术中导航操作时间和导航精确性的监测。CT三维导航术中工具注册和参考点照合时间平均3．5min（2—8rain）,位置误差率平均0．31mm（0．12—0．56mm,导航仪自动计算）;Iso—C术中三维导航图像采集和传输时间平均6．2min（5—7min）,每颗椎弓根螺钉定位针置入所需时间平均2min（1—3．5min）;术中只需进行2次C臂机透视印证螺钉定位针和螺钉置入的准确性。结论采用三维导航系统辅助,能显著提高椎弓根螺钉置入的精确性,其操作技术有待完善。     

椎弓根螺钉内固定术中X线测量椎弓根螺钉横断面倾角

目的探讨术中利用C形臂X线机测量椎弓根螺钉横断面倾角(STA)的临床应用价值。方法选取胸腰椎椎弓根螺钉内固定术患者43例,术中利用C形臂X线机正位像测量椎体旋转度(VRD)、椎弓根螺钉空间旋转度(SSR),并计算STA(STA=SSR-VRD);术后利用CT横断面图像测量椎弓根螺钉实际STA。选取同一术者手术的20例患者的20枚椎弓根螺钉(每例1枚),分别在初始位(目标显像在图像中央)、球管高移位、球管低移位、球管左移位、球管右移位、球管头移位、球管尾移位、球管头倾斜照位及球管尾倾斜位照位9个不同透视机投照位置下测量VRD、SSR并计算STA,分析测量者测量结果的内部差异性。另选取20例患者的20枚椎弓根螺钉,由3名不同医生依上述方法测量VRD、SSR并计算STA,分析测量者间测量结果的差异性。结果椎弓根螺钉CT测量STA范围为-4.5°~27.3°(内倾为正角度),术中X线机测量值与术后CT测量值差距为-2.7°~3.2°,2组间差异无统计学意义(P0.05)。测量者测量结果的内部差异性分析结果显示,球管左移或右移时VRD、SSR及STA测量值与初始位置测量值差异存在统计学意义(P0.05),其他不同位置测量值与初始位置测量值差异无统计学意义(P0.05)。测量者间差异性分析显示,3名医生测量结果差异无统计学意义(P0.05)。结论术中利用C形臂X线机能较准确地评估STA。当术者遇到置钉困难时,可利用该方法测量STA并指导置钉,提高术者置钉信心及手术安全性。