Computer assisted pelvic and acetabular surgery. Clinical experiences and indications

CT based navigation has been used in spine surgery since 1994. Several clinical studies could show an increase in precision compared to the conventional technique and thus nowadays the navigated pedicle screw placement is a routine procedure in many hospitals.Based upon the experience in spine surgery the CT based navigation module was used for percutaneous screw fixations in minimally displaced pelvic ring and acetabular fractures.After preclinical experimental trials the C-arm navigation was used for 19 screw fixations. The postoperative control of the screw position was performed with postop. X-ray and CT.Overall 23 of the 24 screws were placed correctly. In one SI screw the postoperative CT could reveal a ventral cortex perforation of the sacrum without any clinical symptoms.Based upon this limited clinical experience we see the indication for CT based navigation in minimally displaced acetabular fractures or in SI screw fixations in case of sacral dysplasia. The C-arm based navigation with adequate image quality is our method of choice for SI screw fixation in traumatic or degenerative instabilities, especially if reduction maneuvers are necessary.     

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 at the spine

Computer aided and computer navigated operative techniques have been used for the first time in neurosurgery and surgery of the spine. For computer aided surgery of the spine there are currently two different methods: CT-based and C-arm based techniques. The advantage of the CT-based technique is its accuracy especially in difficult anatomical regions like the cervical and upper thoracic spine, and the possibility of preoperative planning. The advantage of C-arm navigation is the broad intraoperative availability with the disadvantage of limited image quality in some regions of the spine eg, the upper thoracic spine. This last disadvantage has been dramatically improved by introducing 3-D C-arm navigation (ISO C 3-D, Siemens, GER). Generally, all methods enhance the precision of pedicle screw insertion. Clinical as well as experimental studies show an exact pedicle screw position using the computer navigated techniques in over 90% of cases. C-arm based navigational techniques are being constantly improved and the future will be CT-like images with instant intraoperative availability.     

BK 2112 Gonarthrose

This article presents an overview of the possibilities of navigated procedures in pelvic ring and acetabular fractures from our experimental and clinical experiences. First of all, various navigated procedures for sacroiliac (SI) screw fixation were assessed in cadaveric studies (n=80 screws) and compared with the conventional technique. Subsequently, clinical comparison was made of the 2D fluoroscopic navigated procedure (n=35) and the conventional technique (n=23) and by a retrospective survey all SI screw fixations from a 7-year period conducted in our hospital (n=139) were analyzed. Experimental studies in human cadaveric models (n=10 screws) for supra-acetabular percutaneous screw placement (parallel to the quadrilateral surface) via 3D-fluoroscopic navigated procedure were performed and compared with clinical case studies. Conclusion: we found a significant prolongation of the procedural time for navigated inserted iliosacral screws in comparison to those that were inserted by the conventional technique. In contrast, intraoperative fluoroscopic exposure time was decreased by approximately 50% by using the navigated technique. Furthermore, the failure rate in screw positioning was around four times higher using the conventional technique versus the navigated procedure. The failure rate increased significantly according to the practical experience of the surgeon. For acetabular surgery the 2D-fluoroscopic based navigation is a helpful tool, whereas the 3D-fluoroscopic navigation procedure reveals a high learning curve. While navigated iliosacral screw fixation is well-established, the use of navigation in acetabular surgery will remain limited, for the time being, to individual cases.     

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.     

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.     

Computer assisted surgery, 2001 development and prospects. Results of a congress at Reisensburg Castle, 23-24 November 2000]

The progress in computer assisted surgery (CAS) is influenced by new technologies in imaging as well as by the input of the users. At present, CAS procedures are established in dorsal spine instrumentation, prosthetics and long bone surgery. Present status and future of CAS was a topic of an expert meeting at the Reisensburg castle. Imaging will speed up in the future using multi-detector techniques. C-arm navigation will gain more information using the 3D technology intraoperatively. CT based navigation procedures are standard in spine and will be established in pelvic surgery. CAS in robotics at the moment means the use of robot-assistance. A new concept is the modality-based navigated surgery, which can be used at various skeletal locations. Visualization of patient data will improve using 3D semi-transparencies with real time update. In the future it will be mandatory to find algorithms to fuse the different possibilities and techniques. A new concept of surgical training is necessary to teach CAS procedures. Therefore discussion must go on to improve these systems.     

Computer-assisted surgery: developments and prospects in 2001. Results of a workshop at Schloss Reisenburg, 23-24 November 2000

The progress in computer assisted surgery (CAS) is influenced by new technologies in imaging as well as by the input of the users. At present, CAS procedures are established in dorsal spine instrumentation, prosthetics and long bone surgery. Present status and future of CAS was a topic of an expert meeting at the Reisensburg castle. Imaging will speed up in the future using multi-detector techniques. C-arm navigation will gain more information using the 3D technology intraoperatively. CT based navigation procedures are standard in spine and will be established in pelvic surgery. CAS in robotics at the moment means the use of robot-assistance. A new concept is the modality-based navigated surgery, which can be used at various skeletal locations. Visualization of patient data will improve using 3D semi-transparencies with real time update. In the future it will be mandatory to find algorithms to fuse the different possibilities and techniques. A new concept of surgical training is necessary to teach CAS procedures. Therefore discussion must go on to improve these systems.     

Verletzungen des Azetabulums

Anatomic reduction of the articular surface is essential in the definitive therapy of acetabular injuries. The required surgical approaches with extensive and deep exposure of the adjacent soft tissue may cause additional iatrogenic trauma. Computer-aided navigation based on 2D and 3D fluoroscopy is increasingly being applied for successful percutaneous screw fixation. Non-dislocated or minimally dislocated but unstable fractures are particularly suitable for navigation. The advantages of computer-assisted navigation are the improved accuracy of screw placement and reduced radiation exposure as well as protection of the soft tissue. Therefore, percutaneous navigated screw fixation is a promising alternative to conventional operative procedures in selected acetabular fractures considering the primary goals of anatomic reduction and rigid fixation allowing early exercises.     

Integrierte Navigation

BACKGROUND: Computer navigation systems have increasingly become part of the surgical routine due to the improvements of intraoperative visualization procedures. Because of limited space in the operating room and insufficient workflow, the project of integrated navigation had been started. METHODS: As the first step, the navigation system VectorVision2 and the second-generation fluoroscopic C-arm system Orbic 3D were integrated into one common trolley. In an experimental study the integrated navigation system was used to drill 160 pedicle screws. Afterwards the system was clinically evaluated in 11 surgical procedures. RESULTS: During the whole experimental study the system could be used for all 160 drilling procedures without any technical faults, causing a failure rate of 4.2%. For clinical evaluation the integrated navigation system was used in seven patients with navigated dorsal spine instrumentation, in three cases sacroiliac screws were placed, and in one case supra-acetabular screw osteosynthesis was performed for an acetabular fracture. In all cases the positioning of the screws was correct and no system failure occurred. CONCLUSIONS: The combination of the navigation system and the C-arm system in one common trolley is a major improvement of the surgical workflow. In the experimental study and the clinical trials the system worked extremely reliably and with high precision.     

Wirbelsäulenverletzungen und Unfallfolgezustände

The aim of computer-assisted navigation procedures is to increase the anatomical orientation intraoperatively, to improve the accuracy, to minimize the invasiveness and to reduce the emission of radiation. In the field of orthopedic surgery navigation has been used for over 15 years and these techniques are particularly widely used in spinal surgery. There are three major applications of navigation: CT-based (computed tomography) navigation which needs a preoperative CT scan, 2D navigation which is based on standard X-ray images of a C-arm during surgery and 3D navigation which requires an intraoperatively performed C-arm based 3D scan. Higher accuracy has been proven for instrumentation of the lumbar and cervical spine and reduced emission of radiation could be demonstrated. Higher accuracy for pedicle screw insertions of the thoracic spine is still not proven in prospective studies with sufficient numbers of pedicle screws. Navigation systems provide additional information for better anatomical orientation in spinal surgery and can reduce intraoperative fluoroscopy time. Intraoperative 3D scan technology with automatic registration is the perfect tool in spinal surgery today. Knowledge of the classical techniques remains crucial for the safety of patients.     

Navigation—Erfahrung zu Kosten und Nutzen

Navigation systems claim perfect implant positioning and a superior performance compared to the experienced surgeon. The aim is to achieve central pedicle screw positions or precise periacetabular/ISG screws. The costs of the navigation system are about € 200,000 while the C-arm costs about € 100,000. Clinical and experimental studies show a slightly increased precision in pedicle screw placement, more pronounced in the CT than in the C-arm based technique. Experimental data for the proximal femur show a reasonable accuracy. Use of the 3D ISO C-arm is the latest technique. The first clinical studies show a good intraoperative performance and sufficient accuracy in spinal and pelvic applications.In summary, navigation seems to improve accuracy in vivo, however, this is overrated in comparison with the producers data. The system has a clear learning curve and is time consuming. The new 3D ISO C-arm technique is promising and has a good cost/benefit ratio in terms of performance, visualization and accuracy.Nevertheless, these system are very expensive and do not represent a universal tool for trauma surgery. At present there is no reimbursement available for the technique.     

Computerassistierte Osteosynthesen am Beckenring

The number of computer-assisted osteosynthesis procedures of the pelvic ring is increasing. The use of navigation aims to improve accuracy and intraoperative visualization of the complex pelvic ring structures while minimizing invasiveness. 3D-fluoroscopic navigated percutaneous sacroiliac screw osteosynthesis fulfills these requirements. The use of a special 3D image intensifier provides high flexibility for the intraoperative 3D-data acquisition required for the navigation procedure. These multiplanar reformations enable reliable analysis of posterior pelvic ring structures, in particular following a repositioning maneuver. However, the size of the visualized image and the 3D-scan volume of the area of interest require significant improvement. Further applications and developments in computer-assisted surgery are to be expected in the future.     

Intra- and postoperative complications of navigated and conventional techniques in percutaneous iliosacral screw fixation after pelvic fractures: Results from the German Pelvic Trauma Registry

Background

Percutaneous iliosacral screw placement following pelvic trauma is a very demanding technique involving a high rate of screw malpositions possibly associated with the risk of neurological damage or inadequate stability. In the conventional technique, the screw's correct entry point and the small target corridor for the iliosacral screw may be difficult to visualise using an image intensifier. 2D and 3D navigation techniques may therefore be helpful tools.The aim of this multicentre study was to evaluate the intra- and postoperative complications after percutaneous screw implantation by classifying the fractures using data from a prospective pelvic trauma registry. The a priori hypothesis was that the navigation techniques have lower rates of intraoperative and postoperative complications.

Methods

This study is based on data from the prospective pelvic trauma registry introduced by the German Society of Traumatology and the German Section of the AO/ASIF International in 1991. The registry provides data on all patients with pelvic fractures treated between July 2008 and June 2011 at any one of the 23 Level I trauma centres contributing to the registry.

Results

A total of 2615 patients were identified. Out of these a further analysis was performed in 597 patients suffering injuries of the SI joint (187 × with surgical interventions) and 597 patients with sacral fractures (334 × with surgical interventions).The rate of intraoperative complications was not significantly different, with 10/114 patients undergoing navigated techniques (8.8%) and 14/239 patients in the conventional group (5.9%) for percutaneous screw implantation (p = 0.4242).Postoperative complications were analysed in 30/114 patients in the navigated group (26.3%) and in 70/239 patients (29.3%) in the conventional group (p = 0.6542). Patients who underwent no surgery had with 66/197 cases (33.5%) a relatively high rate of complications during their hospital stay. The rate of surgically-treated fractures was higher in the group with more unstable Type-C fractures, but the fracture classification had no significant influence on the rate of complications.

Discussion

In this prospective multicentre study, the 2D/3D navigation techniques revealed similar results for the rate of intraoperative and postoperative complications compared to the conventional technique. The rate of neurological complications was significantly higher in the navigated group.     

Rechnergestütztes Operieren bei Beckenverletzungen

For pelvic fractures, pre- and postoperative imaging includes spiral computed tomography, providing high resolution and accuracy. In conventional pelvic operations, these image data cannot be used directly. Intraoperative imaging is limited with fluoroscopy and visualization by the approaches. One solution in terms of precision and reduction of radiation exposure could be computer-assisted surgery (CAS). This method can be divided into navigation, which requires active registration, CT based navigation and registration-free fluoroscopy-based or Iso-C-3D-based navigation. Applications for CAS in the pelvis include sacroiliac screw osteosynthesis in pelvic ring fractures, navigated periacetabular screw fixation, and correction operations for malhealed pelvic ring fractures. Nowadays, CAS is still costly and frequently requires additional staff. However, it helps to reduce complications caused by implant placement. With the introduction of new health care requirements in Germany, this may be an economic argument as well. Current developments focusing on accurate navigated reduction will provide new indications for CAS, further decrease complication rates, and help to reduce the invasiveness of pelvis operations.     

Perkutane, 2D-fluoroskopisch navigierte Sakrumverschraubung in Rückenlage

OBJECTIVE: In pelvic surgery, computer-assisted procedures are currently used predominantly for percutaneous iliosacral screw placement. The aim of this study was to evaluate the possibilities and limits of a 2D-fluoroscopic navigated procedure used for this indication. METHODS: A consecutive series of patients with non or slightly displaced injuries of the posterior pelvic ring were prospectively investigated. Cannulated cancellous screws of 7.3 mm were percutaneously implanted in the supine position. The navigated procedure was performed using an active optoelectronical system and a 2D C-arm. Target parameters were practicability, precision and intraoperative radiation exposure time compared to patients treated using a non-navigated technique. RESULTS: In a 15 month period, 35 screws were implanted in 20 patients. The average procedure took 36.2+/-12.5 min (range 18-62 min), with a fluoroscopic time of 0.9+/-0.3 min (range 0.6-1.8 min) per screw. The displacement rate was 8% (n=3/35, CI 1.8-23.0). Compared to retrospectively selected patients treated using a non-navigated technique (n=13), a significant increase in procedure time (P=0.01), a significant decrease of radiation exposure time (P<0.001) and a decreased displacement rate (P>0.05) were observed in the navigated group. CONCLUSION: The 2D-fluoroscopic navigated procedure used in this study can be recommended for percutaneous stabilisation of non or minor displaced injuries of the posterior pelvis. This procedure reduces intraoperative radiation exposure and improves intraoperative orientation but does not crucially enhance the precision of screw placement compared to the non-navigated technique. Finally, it is limited by its poor image resolution and lack of three-dimensionality.     

Minimalinvasive Beckenchirurgie

The pelvis is the mechanical connection between the lower extremities and the spinal column. The aim of surgical treatment for pelvic and acetabular injuries is to compensate the strong mechanical forces needed here, without compromising wound healing and restricting muscle function due to additional soft tissue damage. In recent years, minimally invasive stabilizing techniques, which reduce surgical risks and recovery time as well as improving outcomes, have become increasingly established. The increased use of improved imaging modalities also plays a significant role here. Surgical errors can be avoided in the osteosynthesis of acetabular fractures by means of intraoperative visualization using 3D image converters. Navigated percutaneous pelvic sacroiliac screw fixation is the main procedure to be used for pelvic and acetabular navigation. New software enables a 2D representation of the hip area and a 3D calculation of instrument and implant positions, thereby reducing X-ray exposure and increasing intraoperative safety.     

Bildwandler-gestützte Navigation Eine experimentelle Studie zu Beckenverschraubungen

Within an experimental trial the new method of fluoroscopy based navigation was tested for percutaneous pelvic screw fixations. A regular C-arm was used and the navigation system developed by Medivision. In a first step appropriate C-arm projections were defined for five standardized screw positions. Then precision and fluoroscopy time of 60 screws in 6 artificial pelves were evaluated. For the sacroliacal screw in S1, S1 screw in S2, anterior column screw, posterior column screw and the supraacetabular ilium screw three to four appropriate projections were defined. These were all combinations of the known special pelvic views inlet/outlet and iliac/obturator. Using these standardized views the average fluoroscopy time was 6 seconds per screw. 51 screws (85%) were inserted correctly. In five cases there was a slight deviation without perforating the cortex, four times the cortex was perforated.     

Computer-assisted screw insertion into the first sacral vertebra using a three-dimensional image intensifier: results of a controlled experimental investigation

Currently there are few data available regarding the application and efficacy of computer-assisted procedures in the sacral spine. In order to optimize and standardize this procedure, a controlled experimental investigation has been performed. The aim of the study is to systematically assess the efficacy of a novel three-dimensional image intensifier used for navigated transiliac screw insertion into the first sacral vertebra. Screws were inserted iliosacrally into the first sacral vertebra of preserved human cadaver specimens. The instrument navigated procedure was performed with the Siremobil Iso-C^3D (Siemens Medical Solutions) and the Navigation System by Stryker. The accuracy and quality of the imaging procedure as well as the fluoroscopic exposure times were measured. These results were compared to three control groups (CT-based navigation, C-arm navigation, and fluoroscopic guidance). In each group a total amount of 20 screws was implanted. Screw position was postoperatively assessed by Iso-C^3D or CT-scan. The navigated procedure using the Iso-C^3D provided good feasibility characteristics without requiring a specific matching process. It revealed the shortest procedure time of all navigated procedures and significantly decreased fluoroscopic time compared to C-arm navigation and fluoroscopic guidance. Furthermore, Iso-C^3D navigation showed no screw malposition and was in this regard superior to C-arm navigated and fluoroscopic guided procedures. The quality of imaging was sufficient for accurate placement, but did not share the high-resolution level of CT-based navigation. These findings indicate that application of the Iso-C^3D for navigated transiliac screw insertion into S1 can be recommended as a feasible and safe technique, enabling the surgeon to reduce procedure and fluoroscopic time. Further progress in improving the quality of the Iso-C^3D image should be attempted.