Percutaneous iliosacral screw insertion: malpositioning and revision rate of screws with regards to application technique (navigated vs. Conventional)

Augmented reality simulation framework for minimally invasive orthopedic surgery

PURPOSE

Minimally invasive surgery (MIS) has emerged in clinical practice to minimize surgical trauma, providing patients with faster recovery, reduced pain and complications and enhanced aesthetic results compared to traditional surgery. However, this approach increase the risk of iatrogenic damage, i.e. the accidental injury to sensitive anatomical structures (eg. nerves and vascular strcuteres) not directly visible during a percutaneous access. Augmented reality (AR) can effectively mitigate these drawbacks by overlaying graphical information onto the surgical field and providing real-time feedback, offering support in training settings and clinical practice. Implementation challenges have limited the number of case studies in the scientific literature. This study presents a novel simulation paradigm for orthopedic surgery training, filling a gap in surgical skill development resources for trainees, and demonstrating the effectiveness of this approach.

METHODS

The proposed methodology provides a framework for building a cost-effective and easily reproducible surgical training simulation environment. To address the challenge of mental spatial navigation during MIS procedures, the framework's rationale is to address the challenge of mental spatial navigation during MIS procedures. A surgical gesture tracking system using a commercial depth camera for comfortable simulation was developed. The principles of the acquisition system, image processing, and spatial computation mechanics are detailed to illustrate the framework's applicability. Digital environments customization with game engines to simulate expensive medical instrumentation, such as the C-arm, is also demonstrated. The simulation platform comprises a Computer Vision (CV) module, an X-ray machine simulation module, and an AR module.

RESULTS

System validation involved analysis at different framework levels. From texture analysis of acquired images to application accuracy evaluation, the influence of various parameters on system performance is demonstrated. The simulation system is a valuable tool for learning minimally invasive procedures and for developers building AR systems for medical applications. The implementation is focused on the insertion surgical devices, including screws and K-wires. This is results in real application in minimizing the risk of iatrogenic injury to neural and vascular structures. To demonstrate the effectiveness of highly reproducible accuracy between real and virtual environment an analysis of errors and accuracies is illustrated at level of different subsystems. Measurement between comparative measurement between vernier caliper and simulation system methods shows a R>0.9 with a p<0.01. Application accuracy was evaluated using the following parameters. The relative point-to-point accuracy averaged 1.02mm with a standard deviation of 2.82mm. Future development includes clinical implementation and integration of advanced AI technologies.

Single trans-iliac trans-sacral screw (STITSS) versus dual iliosacral screws (ISS) in fixation of unstable pelvic ring disruptions

OBJECTIVE

To compare between single trans-iliac trans-sacral screw versus dual ilio-sacral screws in Management of unstable pelvic ring disruptions after achieving reduction, to facilitate union of the fracture and early mobilization.

METHODS

In a retrospective cohort study that was done in Assiut University hospital trauma unit between May 2018 to September 2020, 36 patients with unstable fracture pelvis were included in the study. Single trans-iliac trans-sacral screws were done in 16 cases while two ilio-sacral screws were done for the rest of cases. Age ranged from 18 to 57 years old, with exclusion of patients with spino-pelvic dissociation, comminuted fractures, chronic uncontrolled co-morbidities, bilateral sacral fractures. Follow up of the patients radiologically using plain X-ray and Computed Tomography scan to identify union of fractures were reported. Functional follow-up using Majeed score and Visual analogue scale were reported with allowance of weight bearing as tolerated.

RESULTS

The two groups were comparable in terms of baseline characteristics, including age, sex, and comorbidities. A significant difference was observed in Tile classification between the groups (P = 0.05), while there was no significant difference in Denis classification (P = 0.29). Operative parameters such as surgical time, fluoroscopy time, and blood loss were similar between the two groups (P > 0.05). Outcome analysis revealed that patients in the STITSS group experienced significantly less pain at six weeks post-surgery, with lower VAS scores (4.31 ± 0.87 vs. 6.38 ± 1.31; P = 0.000). However, by 3 and 6 months, the VAS scores showed no significant differences between the groups (P > 0.05). Additionally, functional outcomes measured by the Majeed score were significantly better in the STITSS group at six weeks (61.64 ± 8.55 vs. 53.15 ± 7.80; P = 0.037). Similar to pain scores, the Majeed scores equalized between the groups at 3 and 6 months, with no significant differences noted.

CONCLUSION

The study findings indicate that STITSS fixation offers better early outcomes in terms of pain relief and functional recovery compared to dual ilio-sacral screw fixation. Despite the technical challenges associated with STITSS, it allows for faster rehabilitation and a quicker return to functional activities. In the long term, however, both techniques demonstrate comparable results. Further research is needed to validate these findings and optimize fixation strategies for unstable pelvic fractures.

Iliosacral screw osteosynthesis - state of the art

Iliosacral screw osteosynthesis is a widely recognized technique for stabilizing unstable posterior pelvic ring injuries, offering notable advantages, including enhanced mechanical stability, minimal invasiveness, reduced blood loss, and lower infection rates. However, the procedure presents technical challenges due to the complex anatomy of the sacrum and the proximity of critical neurovascular structures. While conventional fluoroscopy remains the primary method for intraoperative guidance, precise preoperative planning using multiplanar reconstructions and three-dimensional volume rendering is crucial for ensuring accurate placement of iliosacral or transsacral screws. Particular attention must be given to the preoperative evaluation of both the iliosacral and transsacral corridors, as anatomical variations may restrict the available space for screw insertion. This review aims to highlight the essential aspects of sacroiliac osteosynthesis, with a focus on the critical role of thorough preoperative planning and its impact on achieving successful surgical outcomes.

TiRobot-assisted versus freehand femoral neck system placement in the treatment of femoral neck fractures: a systematic review and meta-analysis

The purpose of this study is to assess the safety and effectiveness of TiRobot-assisted treatment for femoral neck fractures, in comparison to traditional freehand treatment methods. Throughout the research process, we conducted an extensive literature search across numerous databases, including PubMed, EMBASE, Cochrane Library, Web of Science, China National Knowledge Infrastructure (CNKI), CQVIP, and Wanfang. Based on the literature screening criteria, we selected six studies, encompassing 358 cases of femoral neck fracture patients, for this meta-analysis. The study evaluated the effectiveness of TiRobot-assisted versus freehand placement of the Femoral Neck System (FNS). The results indicate that the TiRobot-assisted group demonstrated significant advantages in several surgical parameters. Specifically, the robot-assisted group showed superior outcomes regarding the frequency of guide pin insertion, frequency of X-ray fluoroscopy, operative time, invasive fixation time, intraoperative blood loss and incision length (MD < 0, p < 0.05). Furthermore, there was a significant difference in the Harris score, between the TiRobot-assisted group and the traditional freehand group (MD > 0, p < 0.05). However, the two groups had no significant differences concerning postoperative complications, fracture healing time, and fracture healing rate (p > 0.05). In conclusion, the comprehensive analysis suggests that the TiRobot-assisted technique has distinct advantages over the traditional freehand technique in treating femoral neck fractures. TiRobot-assisted technology, owing to its enhanced safety and efficacy, minimizes surgical trauma and expedites postoperative recovery.

Navigation and 3D-imaging in pelvic ring surgery: a systematic review of prospective comparative studies

BACKGROUND

Few literature reviews have been published focusing on navigation, robotic or pre-operative planning using 3D-imaging technology (3D-printing, 3D-planning). To our knowledge, no reviews have been performed to assess and compare all these modalities together versus control groups (conventional fluoroscopy) through high Randomized Control Trials (RCTs) and Prospective Control Studies (PCSs). The aim of this study was to assess and compare 3D-imaging technologies from pre-operative planning to per-operative navigation and robotic in the management of pelvic ring fractures through high level studies.

METHODS

A literature search was performed using PubMed, the Cochrane library and Google scholar using keywords up to December 2023. Only prospective comparative studies (RCT and PCS) were included. A total of 341 articles were identified, 39 articles were selected for full-text analysis leaving 7 articles included in this literature systematic review.

RESULTS

A trend towards improved precision in screw placement and reduction of radiation exposure without consequences in term of functional outcomes have been identified. No conclusions can be extrapolated regarding operative time and blood loss except for robotic which improve these parameters because robotic arm assistance help surgeons to correctly follow the planning based on 2D-fluoroscopy. Surgery duration and radiation dose are significantly reduced with robotic-arm assistance for the same reasons. With navigation the results have to be nuanced according to the experience of the surgical team. Interest of navigation is emphasized in sacral dysmorphism in comparison with conventional fluoroscopy. This highlights the benefits of navigation for ilio-sacral screw placement in difficult cases and less experimented teams.

CONCLUSION

High level studies which assess and compare 3D-imaging technologies from pre-operative planning to per-operative navigation and robotic in the management of pelvic ring fractures are low. To date and according to the present high level literature, navigation and 3D-technologies in pelvic ring surgery should be recommended for difficult cases.

LEVEL OF EVIDENCE, II

Systematic review of Level II studies.

Percutaneous Ilioilial Fixator Versus Percutaneous Iliosacral Screw in Managing Unstable Sacral Fractures: A Prospective Randomised Controlled Study

INTRODUCTION

Unstable sacral fractures with pelvic fractures are challenging to both surgeons and patients, particularly in the immediate post-injury phase and later when definitive fixation is undertaken. Percutaneous iliosacral screw fixation is widely regarded as the gold standard treatment for unstable sacral fractures without spinopelvic dissociation. Closed reduction and percutaneous fixation using iliosacral screws for sacral fractures provide early stabilisation without the need for extensive surgical exposure, thereby mitigating major complications associated with open surgical procedures. A new technique for stabilising unstable sacral fractures is the minimally invasive ilioilial fixator, also called a transiliac internal fixator (TIIF), which has gained more attention for its ability to address challenges associated with sacroiliac screw fixation. The objective of this study is to compare the functional, radiological, and surgical outcomes between the percutaneous iliosacral screw and the ilioilial fixator.

METHODS

A total of 51 patients with sacral fracture injuries sustained between August 2019 and November 2021 were included in this study, with 25 patients in Group A and 26 patients in Group B. Patient randomization was done using computer-generated randomization facilitated by Random Allocation Software (Mahmood Saghaei, Isfahan, Iran). All patients underwent the chosen intervention within 10 days of the trauma. Patients had follow-up at two weeks, six weeks, and 12 months post-treatment. The results of fixation were evaluated radiologically based on the Matta and Tornetta grading system and clinically using the Majeed pelvic scoring system. Complications were detected in both groups during follow-up visits.

RESULTS

The study found no statistically significant differences between the two patient groups in terms of final clinical assessment (p=0.79), radiological assessment (p=0.78), or the need for another operation (p=1.0). Moreover, there were no statistically significant differences between the groups with respect to complication rates (p=0.63) or the time of union (p=0.14). No differences were noted in terms of intraoperative blood loss (p=0.93) or operative time (p=0.34) but for longer incision length in the ilioilial fixator group (p<0.001) and an increased risk of intraoperative radiation exposure in the iliosacral screw group (p<00.1).

DISCUSSION

Although the iliosacral screw is considered a gold standard for unstable sacral fracture, a TIIF is a good alternative with a very satisfactory outcome.

CONCLUSION

Although the iliosacral screw still remains the gold standard for the management of sacral fractures, the ilioilial fixator emerges as a good alternative with comparable functional and radiological outcomes.

A novel biplanar positioning technique to guide iliosacral screw insertion: a retrospective study

PURPOSE

To evaluate the safety and benefits of the biplanar position technique on operative time, radiation exposure, and screw placement accuracy.

METHODS

In this study, we retrospectively evaluated the records of 64 patients with pelvic fractures (Tile B and C) between October 2020 and September 2021. According to the surgical methods selected by the patients, the patients were divided into a biplanar positioning technique group (biplanar group), a Ti-robot navigation group (Ti-robot group), and a traditional fluoroscopy-guided technique group (traditional group). Length of operation, blood loss, intra-operative radiation exposure fracture reduction, and the quality of screw positioning were compared among the three groups.

RESULTS

One hundred three screws were implanted in 64 patients (biplanar group 22, Ti-robot group 21, traditional group 21). The average operation time was significantly less in the biplanar group (26.32 ± 6.32 min) than in the traditional group (79.24 ± 11.31 min), but significantly more than in the Ti-robot group (15.81 ± 3.9 min). The radiation exposure was similar in the biplanar group (740.53 ± 185.91 cGy/cm2) and Ti-robot group (678.44 ± 127.16 cGy/cm2), both of which were significantly more than in the traditional group (2034.58 ± 494.54 cGy/cm2). The intra-operative blooding loss was similar in the biplanar group (12.76 ± 3.77 mL) and the Ti-robot group (11.92 ± 4.67 mL), both of which were significantly less than in the traditional group (29.7 ± 8.01 mL). The Screw perforation was slightly lower in the biplanar group (94.1%) than in the Ti-robot group (97.2%) but was significantly higher than in the traditional group (75.7%).

CONCLUSIONS

The biplanar positioning technique is as accurate and safe as computer-navigated systems for percutaneous iliosacral screw insertion, associated with shorter surgical time, lower intra-operative radiation exposure, and more accuracy compared to traditional fluoroscopy.

Robot-assisted versus conventional percutaneous sacroiliac screw fixation for posterior pelvic ring injuries: a systematic review and meta-analysis

PURPOSE

Robot-assisted pelvic screw fixation is a new technology with promising benefits on intraoperative outcomes for patients with posterior pelvic ring injuries. We aim to compare robot-assisted pelvic screw fixation to the traditional fluoroscopy-assisted technique with regards to intraoperative and postoperative outcomes.

METHODS

The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were used along with a search of electronic information to identify all studies comparing the outcomes of robot-assisted versus conventional screw fixation in patients with posterior pelvic ring injuries. Primary outcomes included operative duration (minutes), intraoperative bleeding (mL), fluoroscopy exposure and intraoperative drilling frequency. Secondary outcome measures included Majeed score, healing time (minutes) and rate (%), postoperative complications, screw positioning, incision length (cm) and guide wire insertion times (minutes). The random effects model was used for analysis.

RESULTS

Four observational studies including a total of 294 patients were identified. There was a significant difference between robot-assisted and conventional groups in terms of operative duration (MD = - 24.66, p < 0.05), intraoperative bleeding (MD = - 10.37, P < 0.05), fluoroscopy exposure (MD = - 2.15, P < 0.05) and intraoperative drilling frequency (MD = - 2.42, P =  < 0.05). For secondary outcomes, no significant difference was seen in Majeed score, healing time and rate and postoperative complications. The robot-assisted group had better screw positioning, smaller incision length, and shorter anaesthesia and guide wire insertion times.

CONCLUSIONS

Robot-assisted fixation has superior intraoperative outcomes compared to conventional fixation. Further studies are needed to look at postoperative outcomes as there is no significant difference in postoperative prognosis between the techniques.

Comparison of Three-Dimensional Navigation-Guided Percutaneous Iliosacral Screw and Minimally Invasive Percutaneous Plate for the Treatment of Zone II Unstable Sacral Fractures

OBJECTIVE

The percutaneous IS screws and the minimally invasive percutaneous plate are the most popular internal methods for Zone II unstable sacral fractures. However, the choice of fixation remains controversial for orthopaedic surgeons. The purpose of study was to evaluate and compare the clinical results of percutaneous iliosacral (IS) screw fixation under three-dimensional (3D) navigation and minimally invasive percutaneous plate fixation in the treatment of Zone II unstable sacral fractures.

METHODS

A retrospective study was performed, including 64 patients with Zone II unstable sacral fractures who underwent percutaneous IS screw fixation under 3D navigation (navigation group) and minimally invasive percutaneous plate fixation (plate group) from January 2011 and March 2021 in our department. The age, gender, fracture type, mechanism of injury, injury severity score (ISS), time from admission to operation, operative time, intraoperative blood loss, hospital stay, incision length, follow-up time, time to clinical healing, and complications were recorded and analyzed. Matta standard was used to assess fracture reduction outcomes. The Majeed function system assessed functional outcomes at the last follow-up.

RESULTS

The average follow-up time was (14.42 ± 1.57) months in the navigation group and (14.79 ± 1.37) months in the plate group. No statistical difference between the two groups in age, gender, fracture type, mechanism of injury, ISS, time from admission to operation, and time to clinical healing. However, significant differences were detected in operative time, intraoperative blood loss, hospital stay, and incision length (p < 0.001). According to Matta standard at 2 days postoperatively, the excellent and good rate was 91.42% in the navigation group, and it was 93.10% in the plate group. There was no significant difference between the two groups (p = 0.961). According to Majeed function system at the follow-up, the excellent and good rate was 97.14% in the navigation group, and 93.10% in the plate group. The difference between the two groups was not statistically significant (p = 0.748). There were no neurovascular injuries associated with this procedure. The incidence of complications was 44.82% (13/29) in the plate group, while 14.28% (5/35) in the navigation group (p = 0.007).

CONCLUSION

This study found that compared with minimally invasive percutaneous plate fixation, percutaneous IS screw fixation under 3D navigation is a suitable option for the treatment of Zone II unstable sacral fractures. This approach is characterized by its shorter operation time, less surgical trauma, less bleeding, less hospital time, and fewer complications.

Risk factors for screw breach and iatrogenic nerve injury in percutaneous posterior pelvic ring fixation

Background

Percutaneous screw fixation of the posterior pelvic ring is technically demanding and can result in cortical breach. The purpose of this study was to examine risk factors for screw breach and iatrogenic nerve injury.

Methods

A retrospective review at a single level-one trauma center identified 245 patients treated with 249 screws for pelvic ring injuries with postoperative computed tomography (CT) scans. Cortical screw breach, iatrogenic nerve injury, and associated risk factors were evaluated.

Results

There were 86 (35%) breached screws. The breach rate was similar between screw types (33% S1-iliosacral (S1-IS), 44% S1-transsacral (S1-TS), 31% S2-IS, and 30% S2-TS) and was not associated with patient characteristics, Tile C injuries, or corridor size or angle. The overall rate of screw revision for screw malpositioning was 1.2% (3/249). Iatrogenic nerve injuries occurred in 8 (3.2%) of the 249 screws. Screws that caused iatrogenic nerve injuries had greater screw breach distances (5.4 vs. 0 mm, MD 5, CI 2.3 to 8.7, p < 0.0001), were more likely to be S1-IS screws (88% vs. 47%, PD 40%, CI 7 to 58%, p = 0.006), more likely to be placed in Tile C injuries (75% vs. 44%, PD 31%, CI -3 to 55%, p = 0.04), and there was a trend for having a screw corridor size <10 mm (75% vs. 47%, PD 28, CI -6 to 52%, p = 0.06). Of the 7 iatrogenic nerve injuries adjacent to screw breaches, two nerve injuries recovered after screw removal, three recovered with screw retention, and two did not recover with screw retention.

Conclusion

Screw breaches were common and iatrogenic nerve injuries were more likely with S1-IS screws. Surgeons should maintain a high degree of caution when placing these screws and consider removal of any breached screw associated with nerve injury.

Computer-Assisted Surgical Navigation for Primary and Metastatic Bone Malignancy of the Pelvis: Current Evidence and Future Directions

Computer-assisted navigation and robotic surgery have gained popularity in the treatment of pelvic bone malignancies, given the complexity of the bony pelvis, the proximity of numerous vital structures, and the historical challenges of pelvic bone tumor surgery. Initial interest was on enhancing the accuracy in sarcoma resection by improving the quality of surgical margins and decreasing the incidence of local recurrences. Several studies have shown an association between intraoperative navigation and increased incidence of negative margin bone resection, but long-term outcomes of navigation in pelvic bone tumor resection have yet to be established. Historically, mechanical stabilization of pelvic bone metastases has been limited to Harrington-type total hip arthroplasty for disabling periacetabular disease, but more recently, computer-assisted surgery has been employed for minimally invasive percutaneous fixation and stabilization; although still in its incipient stages, this procedure is potentially appealing for treating patients with bone metastases to the pelvis. The authors review the literature on navigation for the treatment of primary and metastatic tumors of the pelvic bone and discuss the best practices and limitations of these techniques.

Comparison of Outcomes Following TiRobot-Assisted Sacroiliac Screw Fixation with Bone Grafting and Traditional Screw Fixation without Bone Grafting for Unstable Osteoporotic Sacral Fracture: A Single-Center Retrospective Study of 33 Patients

BACKGROUND This retrospective study from a single center aimed to compare patient outcomes following TiRobot-assisted sacroiliac screw fixation and bone grafting with traditional screw fixation without bone grafting in 33 patients with unstable osteoporotic sacral fracture (UOSF). MATERIAL AND METHODS Patients with UOSF were included and divided into 2 groups: a TiRobot-assisted surgical group with 18 patients (robot-aided sacroiliac screw fixation and bone grafting) and a standard surgical group with 15 patients (free-hand screw fixation without bone grafting). T values of bone mineral density (BMD) £-2.5 standard deviation (SD) were diagnosed as osteoporosis. Screw positioning and fracture healing time were evaluated. Functional outcomes were investigated at the final follow-up. RESULTS There were no statistically significant differences in screw positioning; however, there were satisfactory positioning rates in 94.4% (17/18) of patients in the TiRobot-assisted surgical group and 73.3% (11/15) in the standard surgical group. The advantages with TiRobot on surgical time of screw placement, fluoroscopy frequency, and total drilling times were noted (P=0.000). The nonunion rates were 5.6% (1/18) in the TiRobot-assisted surgical group and 33.3% (5/15) in the standard group (P=0.039). Healing time in the union cases had a significant difference (P=0.031). Functional outcome scores in the TiRobot-assisted surgical group were superior to that in the standard group (P=0.014). CONCLUSIONS The findings showed that TiRobot-assisted sacroiliac screw fixation and bone grafting was a safe and effective surgical treatment option that had a reduced radiation dose and improved fracture healing, when compared with standard screw fixation without bone grafting.

Optimal ilio-sacral screw trajectory in paediatric patients : a computed tomography study

Pelvic fixation during procedures performed to treat spinal deformities in paediatric patients remains challenging. No computed tomography studies in paediatric have assessed the optimal trajectory of ilio- sacral screws to prevent screw malposition. We used pelvic computed tomography from 80 children divided into four groups : females <10 and ≥10 years and males <10 and ≥10 years. A secure triangular corridor parallel to the upper S1 endplate was delineated based on three fixed landmarks. The optimal screw insertion angle was subtended by the horizontal and the line bisecting the secure corridor. Student’s t test was applied to determine whether the optimal screw insertion angle and/or anatomical parameters were associated with age and/or sex. Mean optimal angle was 32.3°±3.6°, 33.8°±4.7°, 30.2°±5.0°, and 30.4°±4.7° in the younger females, younger males, older females, and older males, respectively. The mean optimal angle differed between the two age groups (p=0.004) but not between females and males (p=0.55). Optimal mean screw length was 73.4±9.9 mm. Anatomical spinal canal parameters in the transverse plane varied with age (p=0.02) and with sex in the older children (p=0.008), and those in the sagittal plane varied with sex (p=0.04). Age affected ilio-sacral screw positioning, whereas sex did not. Several anatomical spinal canal parameters varied with age and sex. These results should help to ensure safe and easy ilio-sacral screw placement within a secure corridor.

Two-Dimensional Visualization of the Three-Dimensional Planned Sacroiliac Screw Corridor with the Slice Fusion Method

Insertion of sacro-iliac (SI) screws for stabilization of the posterior pelvic ring without intraoperative navigation or three-dimensional imaging can be challenging. The aim of this study was to develop a simple method to visualize the ideal SI screw corridor, on lateral two-dimensional images, corresponding to the lateral fluoroscopic view, used intraoperatively while screw insertion, to prevent neurovascular injury. We used multiplanar reconstructions of pre- and postoperative computed tomography scans (CT) to determine the position of the SI corridor. Then, we processed the dataset into a lateral two-dimensional slice fusion image (SFI) matching head and tip of the screw. Comparison of the preoperative SFI planning and the screw position in the postoperative SFI showed reproducible results. In conclusion, the slice fusion method is a simple technique for translation of three-dimensional planned SI screw positioning into a two-dimensional strict lateral fluoroscopic-like view.

[Minimally invasive stabilization of sacral fractures]

BACKGROUND

Sacral fractures can be of traumatic origin and can also occur as insufficiency fractures. While the therapeutic target of mechanically stable insufficiency fractures is mainly pain relief, mechanically unstable insufficiency fractures and traumatic sacral fractures following high-energy trauma require biomechanical stabilization. Various surgical strategies are available for this, whereby minimally invasive techniques are now preferred whenever possible.

OBJECTIVE

This article presents the clinical challenges and options for minimally invasive treatment of sacral fractures.

MATERIAL AND METHODS

Selected important study data are discussed and our own treatment approach is presented.

RESULTS

The most important minimally invasive techniques for operative treatment of sacral fractures are presented: sacroiliac screw osteosynthesis, lumbopelvic stabilization and sacroplasty. The selection of the surgical technique should be made on an individual basis. While sacroiliac screw osteosynthesis is the international gold standard, diverse authors have also published minimally invasive techniques for lumbopelvic stabilization. The latter enables a higher mechanical stability. In contrast, sacroplasty should only be used as an alternative treatment in insufficiency fractures. Comparative studies of the described techniques are still missing.

CONCLUSION

All surgical options have their indications. Nevertheless, the biomechanical stability which can be achieved differs widely. Therefore, an exact analysis should be carried out of what is necessary with respect to reduction and retention and what should be achieved when treating sacral fractures.

Anatomical conditions and patient-specific locked navigation templates for transverse sacroiliac screw placement: a retrospective study

Objective

To analyse the anatomical conditions of transverse sacroiliac screw (TSS) about the S1 and S2 segments in order to develop and validate a locked navigational template for TSS placement.

Methods

A total of 22 patients with sacral fractures were involved in this study from May 2018 to February 2019. Patients were divided into two groups according to the surgery procedure: locked template group and conventional group. The CT data of 90 normal sacra were analysed. The long axis, short axis and lengths of TSS, cancellous corridors were measured through 3D modelling. A patient-specific locked navigation template based on simulated screws was designed and 3D printed and then used to assist in TSS placement. The operative time and radiation times were recorded. The Matta criteria and grading score were evaluated. The entry point deviation of the actual screw placement relative to the simulated screw placement was measured, and whether the whole screw was in the cancellous corridor was ob`served.

Results

S1 screws with a diameter of 7.3 mm could be inserted into 69 pelvises, and S2 screws could be inserted in all pelvises. The S1 cancellous corridor had a long axis of 25.44 ± 3.32 mm in males and 22.91 ± 2.46 mm in females, a short axis of 14.21 ± 2.19 mm in males and 12.15 ± 3.22 mm in females, a corridor length of 153.07 ± 11.99 mm in males and 151.11 ± 8.73 mm in females, and a proportional position of the optimal entry point in the long axis of the cancellous corridor of 35.96 ± 10.31% in males and 33.28 ± 7.2% in females. There were significant differences in the corridor long axis and corridor short axis between sexes (p < 0.05), and there were no significant differences in corridor length and proportional position of the optimal entry point in the long axis of the cancellous corridor between sexes (p > 0.05). The S2 cancellous corridor had a long axis of 17.58 ± 2.36 mm in males and 16 ± 2.64 mm in females, a short axis of 14.21 ± 2.19 mm in males and 13.14 ± 2.2 mm in females, a corridor length of 129.95 ± 0.89 mm in males and 136.5 ± 7.96 mm in females, and a proportional position of the optimal entry point in the long axis of the cancellous corridor of 46.77 ± 9.02% in males and 42.25 ± 11.95% in females. There were significant differences in the long axis, short axis and corridor length (p < 0.05). There was no significant difference in the proportional position of the optimal entry point in the long axis of the cancellous corridor (p > 0.05). A total of 20 transversal sacroiliac screws were successfully implanted into 10 patients with the assistance of locked navigation templates, and a total of 24 transversal sacroiliac screws were successfully implanted into 12 patients under C-arm fluoroscopy. There was a significant difference in surgical time (88 ± 14.76 min vs 102.5 ± 17.12 min, p = 0.048), radiation times (11.5 ± 1.78 vs 54.83 ± 6.59, p < 0.05) and screw grading between two groups (nineteen screws in grade 0, one screw in grade 1 and 0 screws in grade 2 vs fourteen screws in grade 0, 8 screws in grade 1 and 2 screws in grade 2, p = 0.005). All screw entry point deviations were shorter than the short axis of the cancellous corridor, and all screws were located completely within the cancellous corridor.

Conclusion

Approximately 76% of males and females can accommodate screws with diameters of 7.3 mm in S1, and all persons can accommodate the same screw in S2. From the standard lateral perspective of the sacrum, the optimal entry point of the transverse screw is in the first 1/3 of the cancellous corridor for S1 and the centre of the cancellous corridor for S2. The patient-specific locked navigation template assisted in TSS placement with less operative time, less intraoperative fluoroscopy and higher safety of screw placement compared with traditional surgery.

Safety and efficacy of 2D-fluoroscopy-based iliosacral screw osteosynthesis: results of a retrospective monocentric study

Introduction

Iliosacral screw osteosynthesis is a well-accepted procedure for stabilization of sacral fractures and iliosacral (fracture) dislocations.

Materials and Methods

In this monocentric study, safety and efficacy of conventional 2D-fluoroscopic-guided iliosacral screw insertion were evaluated.

Results

During a 10-year period (2005–2014), 98 patients between the age of 18 and 65 years received 207 iliosacral screws in 101 procedures. Average patient age was 43.2 years. There were 46 Type B and 40 Type C injuries in the AO/OTA classification, nine patients had a fragility fracture of the pelvis. In three patients, primary radiological data were missing. The indication for surgical treatment was a sacral fracture in 97 patients, a pure iliosacral dislocation in 37 patients and a fracture-dislocation in 31 patients. 70 procedures were performed with the patient in supine position, 31 with the patient in prone position. Surgery was done in a minimal-invasive technique in 76 patients, in 22 patients an open reduction was necessary before screw insertion. 81 patients received a unilateral, 17 patients a bilateral screw osteosynthesis. 199 screws were inserted in S1, only eight screws in S2. 65 patients received two screws unilaterally, ten patients two screws bilaterally. There were no vascular or neurologic complications. During in-hospital stay, there were seven complications, which needed 12 operative revisions: three wound infections, two hematomas, one screw malalignment and one early screw loosening. In 28 patients with 56 iliosacral screws, a pelvic CT-scan was performed during follow-up. A penetration of a cortical layer was diagnosed in 20 of these screws. All penetrations were seen in double screw osteosynthesis of S1. In none of the patients, complaints could be explained by the malalignment of these screws. Five operative revisions were performed during follow-up: two for screw loosening, two for fracture healing problems and one for screw malalignment. Metal removal was performed in 39 patients with 75 screws. 2D-fluoroscopic-guided iliosacral screw osteosynthesis is a safe and efficient procedure in clinical practice.

Discussion

A thorough preoperative evaluation of the morphology of the upper sacrum and careful operative procedure are indispensable. Fluoroscopic views in AP, lateral, inlet and outlet must allow recognition of all anatomical landmarks. The indication for double screw osteosynthesis in S1 should be taken with caution. Screw malalignments do not inevitably correlate with complaints.

Comparative Study of Percutaneous Sacroiliac Screw with or without TiRobot Assistance for Treating Pelvic Posterior Ring Fractures

Objectives

To analyze the curative effect of TiRobot surgical robotic navigation and location system‐assisted percutaneous sacroiliac screw fixation and percutaneous sacroiliac screw by traditional fluoroscopy, and to summarize the safety and benefits of TiRobot.

Methods

A total of 91 patients with pelvic posterior ring fractures from December 2015 to February 2018 were included in this study. According to the surgical methods selected by the patients, the patients were divided into a TiRobot surgical robotic navigation and location system group (TiRobot group) and a percutaneous sacroiliac screw fixation group (traditional group). Statistical indicators included the number of sacroiliac screws, the time of planning the sacroiliac screw path, fluoroscopy frequency, fluoroscopy time, operation time, length of incision, blood loss, anesthesia time, the healing process of skin incisions, and fracture healing time. Fracture reduction was evaluated according to the maximum displacement degree at the inlet and outlet view X‐ray or CT. Matta standard was used to evaluate fracture reduction. At the last follow‐up, the Majeed function system was used to evaluate the function.

Results

All patients were followed up for 8 to 32 months. A total of 66 sacroiliac screws were implanted in the TiRobot group. A total of 43 sacroiliac screws were implanted in the traditional group. There were statistically significant differences in terms of fluoroscopy frequency, fluoroscopy time, operation time, incision length, anesthesia time, and blood loss between the two groups; the TiRobot group was superior to the traditional group. The healing time of the TiRobot group and the traditional group was 4.61 ± 0.68 months (range, 3.5–6.3 months) and 4.56 ± 0.78 months (range, 3.4–6.2 months), respectively, and there was no statistical difference. Postoperatively, by Matta standard, the overall excellent and good rate of fracture reduction was 89.28% and 88.57%, respectively. At the last follow‐up, by Majeed function score, the overall excellent and good rate was 91.07% and 91.43%. There was no statistical difference between the two groups.

Conclusion

Sacroiliac screw implantation assisted by TiRobot to treat the posterior pelvic ring fractures has the characteristics of less trauma, shorter operation time, and less blood loss. TiRobot has the characteristics of high safety and accuracy and has great clinical application value.

Rate of intraoperative problems during sacroiliac screw removal: expect the unexpected

BACKGROUND

The indications for sacroiliac screw (SI) removal have been under debate. Data on complication rates of SI screw removal is missing in the current literature. The objective of this study was to compare the rate of intra- and perioperative problems and complications during SI screw removal to those with SI screw fixation.

METHODS

A retrospective observational study with two interventions in the same cohort was performed. Consecutive patients who underwent both sacroiliac screw fixation for an isolated fracture of the pelvic ring and removal of the same implants between November 2008 and September 2015 (n = 19; age 57.3, SD 16.1 years) were included. Intraoperative technical problems, postoperative complications, duration of surgery, and radiation dose were analysed.

RESULTS

Intraoperative technical problems occurred in 1/19 patients (5%) during SI screw fixation and in 7/19 cases (37%) during SI screw removal (p = .021). Postoperative complications were seen in 3/19 patients after SI screw fixation and in 1/19 patients after SI screw removal (p = 0.128). The surgical time needed per screw was longer for screw removal than for implantation (p = .005). The amount of radiation used for the whole intervention (p = .845) and per screw (p = .845) did not differ among the two interventions.

CONCLUSIONS

Intraoperative technical problems were more frequent with SI screw removal than with SI screw fixation. Most of the intraoperative technical problems in this study were implant-related. They resulted in more surgical time needed per screw removed but similar radiation time.

Factors influencing the accuracy of iliosacral screw insertion using 3D fluoroscopic navigation

INTRODUCTION

The purpose of the present study was to determine which factors affect the positional accuracy of iliosacral screws inserted using 3D fluoroscopic navigation. Specifically, we asked: (1) does the screw insertion angle in the coronal and axial planes affect the positional accuracy of iliosacral screw insertion using 3D fluoroscopic navigation? (2) Is the positional accuracy of iliosacral screw insertion using 3D fluoroscopic navigation affected by the type of screw (transsacral versus standard iliosacral), site of screw insertion (S1 versus S2), patient position (supine versus prone), presence of a dysmorphic sacrum, or AO/OTA classification (type B versus C)?

MATERIALS AND METHODS

Twenty-seven patients with AO/OTA type B or C pelvic ring fracture were treated by percutaneous iliosacral screw fixation. A total of 55 screws were inserted into S1 or S2 using 3D fluoroscopic navigation combined with preoperative CT-based planning. The positional accuracy of screw placement was assessed by matching postoperative CT images with preoperative CT images. The distance between the central axis of the inserted screw and that of the planned screw placement was measured in the sagittal plane passing through the center of the vertebral body.

RESULTS

The mean deviation between the planned and the inserted screw position was 2.9 ± 1.7 mm (range 0-8.5 mm) at the vertebral body center. Multiple regression analysis showed that the screw insertion angle relative to the vertical line of the bone surface in the axial plane (β = 0.354, p = 0.013) and the use of a transsacral screw (β = 0.317, p = 0.017) were correlated with the positional accuracy of screw placement (adjusted R² = 0.276, p = 0.002).

CONCLUSIONS

A greater screw insertion angle relative to the vertical line on the bone surface and the use of transsacral screws increases the positional error of iliosacral screws inserted using 3D fluoroscopic navigation.

LEVEL OF EVIDENCE

Level IV, therapeutic study.

Posterior pelvic ring fractures: Intraoperative 3D-CT guided navigation for accurate positioning of sacro-iliac screws

INTRODUCTION

Posterior pelvic ring fractures frequently pose a problem of stability with an elevated risk of complications. The traditional method of percutaneous sacroiliac (SI) stabilization with the use of fluoroscopic image amplifiers demands a high degree of experience and has an elevated risk of screws' malpositioning.

HYPOTHESIS

Intraoperative 3D-CT scan coupled with a navigation system (O-Arm^©) can allow screw fixation accuracy while limiting the risk of complications for the treatment of posterior pelvic ring fractures.

MATERIAL AND METHODS

Patients with posterior pelvic ring fractures stabilized with percutaneous SI screws through O-Arm^© navigation from August 2008 to December 2017 were analyzed. A modified Gras classification was used to determine screws' positioning under CT visualization, and intraoperative and early postoperative complications were documented.

RESULTS

Among the 21 patients evaluated, 14 men and 7 women with a mean age of 57.8 years (range 25-91), receiving 39 screws, the rate of misplacement was low: 82% grade I, 15.4% grade II, and only 2.6% grade III. Only one patient underwent revision surgery, not because of misplacement but rather for a secondary implant loosening. No complications occurred in this series.

DISCUSSION

This study documented a large series of patients treated for pelvic ring fractures using the intraoperative 3D-CT O-Arm^© guided navigation. This surgical approach provided a precise and safe SI screw positioning with no complications.

LEVEL OF EVIDENCE

IV, Retrospective study.

Accuracy of sacroiliac screw placement with and without intraoperative navigation and clinical application of the sacral dysmorphism score

INTRODUCTION

Percutaneously-placed sacroiliac (SI) screws are currently the gold-standard fixation technique for fixation of the posterior pelvic ring. The relatively high prevalence of sacral dysmorphism in the general population introduces a high risk of cortical breach with resultant neurovascular damage. This study was performed to compare the accuracy of SI screw placement with and without the use of intraoperative navigation, as well as to externally validate the sacral dysmorphism score in a trauma patient cohort.

PATIENTS AND METHODS

All trauma patients who underwent sacroiliac screw fixation for pelvic fractures at a level 1 trauma centre over a 6 year period were identified. True axial and coronal sacral reconstructions were obtained from their pre-operative CT scans and assessed qualitatively and quantitatively for sacral dysmorphism - a sacral dysmorphism score was calculated by two independent assessors. Post-operative CT scans were then analysed for breaches and correlated with the hospital medical records to check for any clinical sequelae.

RESULTS

68 screws were inserted in 36 patients, most sustaining injuries from road traffic accidents (50%) or falls from height (36.1%). There was a male preponderance (83.3%) with the majority of the screws inserted percutaneously (86.1%). Intraoperative navigation was used in 47.2% of the patient cohort. 30.6% of the cohort were found to have dysmorphic sacra. The mean sacral dysmorphism scores were not significantly different between navigated and non-navigated groups. Three cortical breaches occurred, two in patients with sacral dysmorphism scores >70 and occurring despite the use of intraoperative navigation. There was no significant difference in the rates of breach between navigated and non-navigated groups. None of the breaches resulted in any clinically observable neurovascular deficit.

CONCLUSION

The sacral dysmorphism score can be clinically applied to a cohort of trauma patients with pelvic fractures. In patients with highly dysmorphic sacra, reflected by high sacral dysmorphism scores, intraoperative navigation is not in itself sufficient to prevent cortical breaches. In such patients it would be prudent to consider instrumentation of the lower sacral corridors instead.

Percutaneous Sacroiliac Screw Placement: A Prospective Randomized Comparison of Robot-assisted Navigation Procedures with a Conventional Technique

Background:

Sacroiliac (SI) screw fixation is a demanding technique, with a high rate of screw malposition due to the complex pelvic anatomy. TiRobot™ is an orthopedic surgery robot which can be used for SI screw fixation. This study aimed to evaluate the accuracy of robot-assisted placement of SI screws compared with a freehand technique.

Methods:

Thirty patients requiring posterior pelvic ring stabilization were randomized to receive freehand or robot-assisted SI screw fixation, between January 2016 and June 2016 at Beijing Jishuitan Hospital. Forty-five screws were placed at levels S1 and S2. In both methods, the primary end point screw position was assessed and classified using postoperative computed tomography. Fisher's exact probability test was used to analyze the screws’ positions. Secondary end points, such as duration of trajectory planning, surgical time after reduction of the pelvis, insertion time for guide wire, number of guide wire attempts, and radiation exposure without pelvic reduction, were also assessed.

Results:

Twenty-three screws were placed in the robot-assisted group and 22 screws in the freehand group; no postoperative complications or revisions were reported. The excellent and good rate of screw placement was 100% in the robot-assisted group and 95% in the freehand group. The P value (0.009) showed the same superiority in screw distribution. The fluoroscopy time after pelvic reduction in the robot-assisted group was significantly shorter than that in the freehand group (median [Q₁, Q₃]: 6.0 [6.0, 9.0] s vs. median [Q₁, Q₃]: 36.0 [21.5, 48.0] s; χ² = 13.590, respectively, P < 0.001); no difference in operation time after reduction of the pelvis was noted (χ² = 1.990, P = 0.158). Time for guide wire insertion was significantly shorter for the robot-assisted group than that for the freehand group (median [Q₁, Q₃]: 2.0 [2.0, 2.7] min vs. median [Q₁, Q₃]: 19.0 [15.5, 45.0] min; χ² = 20.952, respectively, P < 0.001). The number of guide wire attempts in the robot-assisted group was significantly less than that in the freehand group (median [Q₁, Q₃]: 1.0 [1.0,1.0] time vs. median [Q₁, Q₃]: 7.0 [1.0, 9.0] times; χ² = 15.771, respectively, P < 0.001). The instrumented SI levels did not differ between both groups (from S1 to S2, χ² = 4.760, P = 0.093).

Conclusions:

Accuracy of the robot-assisted technique was superior to that of the freehand technique. Robot-assisted navigation is safe for unstable posterior pelvic ring stabilization, especially in S1, but also in S2. SI screw insertion with robot-assisted navigation is clinically feasible.

Fluoroscopic iliosacral screw placement made safe

AIM

Unstable posterior pelvic ring injuries should be stabilised successfully by percutaneous iliosacral screwing. The intervention takes place under intraoperative fluoroscopic guidance. The inlet and outlet views are crucial and are performed by tilting the image intensifier. Safely interpreting fluoroscopic views can be challenging in certain clinical scenarios. We demonstrated on a series of patients howpreoperative CT scans can be used to anticipate the appropriate intraoperative inlet and outlet fluoroscopic views and positioning of the patient on the operating table, thereby avoiding possible operating table obstacles.

MATERIALS AND METHODS

We analysed at random 30 pelvic CT scans from patients of different ages and both sexes, utilising the sagittal reconstructions. Inlet and outlet angle measurements were calculated on the scans to determine the appropriate intraoperative inlet and outlet views.

RESULTS

The analysed CT scans showed an average inlet view of 22.3° (range 10.4°-39.8°) and an average outlet view of 42.3° (range 31.5°-53.1°). Sex and age had no influence on results. The calculated required free space under the operating table for unobstructed tilting of the C-arm was a minimum of 145cm.

CONCLUSION

The significant anatomic variations of the posterior pelvic ring have been well documented in the literature. The angles required to obtain appropriate intraoperative inlet and outlet views are not perpendicular and differ greatly from traditional settings, which directed the beam 45° caudally and 45° cranially. The fluoroscopic beam would need to be angled differently in each patient to obtain ideal cardinal views that ultimately assist in safe iliosacral screw placement. To avoid collision of the C-arm with the operating table, it is essential to provide secure free space under the operating table of at least 145cm.

[The new treatment procedures of the DGUV from the perspective of an injury type procedure (VAV) clinic]

The new treatment procedures of the German Statutory Accident Insurance (DGUV) have ramifications for the injury type procedure clinics (VAV) from medical, economic and structural aspects. Whereas the latter can be assessed as positive, the medical and economical aspects are perceived as being negative. Problems arise from the partially unclear formulation of the injury type catalogue, which results in unpleasant negotiations with the occupational insurance associations with respect to financial remuneration for services rendered. Furthermore, the medical competence of the VAV clinics will be reduced by the preset specifications of the VAV catalogue, which opens up an additional field of tension between medical treatment, fulfillment of the obligatory training and acquisition of personnel as well as the continually increasing economic pressure. From the perspective of the author, the relinquence of medical competence imposed by the regulations of the new VAV catalogue is "throwing the baby out with the bathwater" because many VAV clinics nationwide also partially have competence in the severe injury type procedure (SAV). A concrete "competence-based approval" for the individual areas of the VAV procedure would be sensible and would maintain the comprehensive care of insured persons and also increase or strengthen the willingness of participating VAV hospitals for unconditional implementation of the new VAV procedure.

Simple mathematical model of sacroiliac screws safe-zone-Easy to implement by pelvic inlet and outlet views

Percutaneous sacral screw fixation is the mainstay of posterior pelvic ring fixation. This study quantifies the accuracy of fluoroscopic screw placement using post-operative CT scans and redefines the fluoroscopic safe zone using a mathematical calculation obtained from Inlet and outlet images. The authors hypothesized that a mathematical calculation of screw placement within the ala will improve accuracy of screw placement. A retrospective review of consecutive patients admitted to a level 1 trauma center with pelvic fractures fixed with iliosacral screws from January 2011 to December 2014 was performed. Accuracy of screw placement was determined by comparing fluoroscopy to post-operative CT scans. A mathematical calculation of screw position within the sacral ala was applied to determine assess screw position and compared to CT findings. Ninety-four patients with 156 screws met inclusion criteria, of which 50 (32.0%) had a cortical breech on CT. The sensitivity and specificity of the inlet-outlet safe zone using mathematical calculation were 97.1% and 84.0%, respectively. The positive and negative predictive values were 92.7% and 93.3%, respectively. Overall accuracies of the radiographic inlet-outlet and lateral safe zones were 92.9% and 70.0%, respectively (p-value = 0.004). Sacral dysmorphism was not found to be associated with sacral cortical breech. A Simple mathematical calculation (screw position relative to percentage of bone width) on the inlet-outlet provides an accurate way to predict the accuracy of sacroiliac screws. The method is easy to implement, part of the surgery work-flow, and provides higher accuracy than relying on subjective interpretation of inlet, outlet, and lateral images. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:1478-1484, 2017.

Placement of iliosacral screws using 3D image-guided (O-Arm) technology and Stealth Navigation: comparison with traditional fluoroscopy

AIMS

We compared the accuracy, operating time and radiation exposure of the introduction of iliosacral screws using O-arm/Stealth Navigation and standard fluoroscopy.

MATERIALS AND METHODS

Iliosacral screws were introduced percutaneously into the first sacral body (S1) of ten human cadavers, four men and six women. The mean age was 77 years (58 to 85). Screws were introduced using a standard technique into the left side of S1 using C-Arm fluoroscopy and then into the right side using O-Arm/Stealth Navigation. The radiation was measured on the surgeon by dosimeters placed under a lead thyroid shield and apron, on a finger, a hat and on the cadavers.

RESULTS

There were no neuroforaminal breaches in either group. The set-up time for the O-Arm was significantly longer than for the C-Arm, while total time for placement of the screws was significantly shorter for the O-Arm than for the C-Arm (p = 0.001). The mean absorbed radiation dose during fluoroscopy was 1063 mRad (432.5 mRad to 4150 mRad). No radiation was detected on the surgeon during fluoroscopy, or when he left the room during the use of the O-Arm. The mean radiation detected on the cadavers was significantly higher in the O-Arm group (2710 mRem standard deviation (sd) 1922) than during fluoroscopy (11.9 mRem sd 14.8) (p < 0.01).

CONCLUSION

O-Arm/Stealth Navigation allows for faster percutaneous placement of iliosacral screws in a radiation-free environment for surgeons, albeit with the same accuracy and significantly more radiation exposure to cadavers, when compared with standard fluoroscopy.

TAKE HOME MESSAGE

Placement of iliosacral screws with O-Arm/Stealth Navigation can be performed safely and effectively. Cite this article: Bone Joint J 2016;98-B:696-702.

2D versus 3D fluoroscopy-based navigation in posterior pelvic fixation: review of the literature on current technology

PURPOSE

Percutaneous sacroiliac (SI) fixation of unstable posterior pelvic ring injuries is a widely accepted procedure. The complex sacral anatomy with narrow osseous corridors for SI screw placement makes this procedure technically challenging. Techniques are constantly evolving as a result of better understanding of the posterior pelvic anatomy. Recently developed tools include fluoroscopy-based computer-assisted navigation, which can be two-dimensional (2D) or three-dimensional (3D). Our goal is to determine the relevant technical considerations and clinical outcomes associated with these modalities by reviewing the published research. We hypothesize that 3D fluoroscopy-based navigation is safer and superior to its 2D predecessor with respect to lower radiation dose and more accurate SI screw placement.

METHODS

We searched four medical databases to identify English-language studies of 2D and 3D fluoroscopy-based navigation from January 1990 through August 2015. We included articles reporting imaging techniques and outcomes of closed posterior pelvic ring fixation with percutaneous SI screw fixation. Injuries included in the study were sacral fractures (52 patients), sacroiliac fractures (88 patients), lateral compression fractures (20 patients), and anteroposterior compression type pelvic fractures (8 patients). We excluded articles on open reduction of posterior pelvic ring injuries and solely anatomic studies. We then reviewed these studies for technical considerations and outcomes associated with these technologies.

RESULTS

Six studies were included in our analysis. Results of these studies indicate that 3D fluoroscopy-based navigation is associated with a lower radiation dose and lower rate of screw malpositioning compared with 2D fluoroscopy-based systems.

CONCLUSIONS

It may be advantageous to combine modern imaging modalities such as 3D fluoroscopy with computer-assisted navigation for percutaneous screw fixation in the posterior pelvis.

In-screw cement augmentation for iliosacral screw fixation in posterior ring pathologies with insufficient bone stock

BACKGROUND

Minimal invasive screw fixation is common for treating posterior pelvic ring pathologies, but lack of bone quality may cause anchorage problems. The aim of this study was to report in detail a new technique combining iliosacral screw fixation with in-screw cement augmentation (ISFICA).

DESCRIPTION OF TECHNIQUE

The patient was put under general anesthesia and placed in the supine position. A K-wire was inserted under inlet-outlet view to guide the fully threaded screw. The screw placement followed in adequate position. Cement was applied through a bone filler device, inserted at the screwdriver. The immediate control of cement distribution, accurate screw placement and potential leakage were obtained via intraoperative CT scan.

PATIENTS AND METHODS

Twenty consecutive patients treated with ISFICA were included in this study. The mean age was 74.4 years (range 48-98). Screw placement, possible cement leakage and screw positioning were evaluated via intraoperative CT scan. Postoperative neurologic deficits, pain reduction and immediate postoperative mobilization were clinically evaluated.

RESULTS

Twenty-six screws were implanted. All patients were postoperatively, instantly mobilized with reduced pain. No neurologic deficits were apparent postoperatively. No cement leakage occurred. One breach of the iliac cortical bone was noted due to severe osteoporosis. One screw migration was seen after 1 year and two patients showed iliosacral joint arthropathy, which led to screw removal.

CONCLUSION

ISFICA is a very promising technique in terms of safety, precision and initial postoperative outcome. Long-term outcomes such as lasting mechanical stability or pain reduction and screw loosening despite cement augmentation should be investigated in further studies with larger patient numbers.

Electromagnetic Real Time Navigation in the Region of the Posterior Pelvic Ring: An Experimental In-Vitro Feasibility Study and Comparison of Image Guided Techniques

Background

Electromagnetic tracking is a relatively new technique that allows real time navigation in the absence of radiation. The aim of this study was to prove the feasibility of this technique for the treatment of posterior pelvic ring fractures and to compare the results with established image guided procedures.

Methods

Tests were performed in pelvic specimens (Sawbones^®) with standardized sacral fractures (Type Denis I or II). A gel matrix simulated the operative approach and a cover was used to disable visual control. The electromagnetic setup was performed by using a custom made carbon reference plate and a prototype stainless steel K-wire with an integrated sensor coil. Four different test series were performed: Group OCT: Optical navigation using preoperative CT-scans; group O3D: Optical navigation using intraoperative 3-D-fluoroscopy; group Fluoro: Conventional 2-D-fluoroscopy; group EMT: Electromagnetic navigation combined with a preoperative Dyna-CT. Accuracy of screw placement was analyzed by standardized postoperative CT-scan for each specimen. Operation time and intraoperative radiation exposure for the surgeon was documented. All data was analyzed using SPSS (Version 20, 76 Chicago, IL, USA). Statistical significance was defined as p< 0.05.

Results

160 iliosacral screws were placed (40 per group). EMT resulted in a significantly higher incidence of optimal screw placement (EMT: 36/40) compared to the groups Fluoro (30/40; p< 0.05) and OCT (31/40; p< 0.05). Results between EMT and O3D were comparable (O3D: 37/40; n.s.). Also, the operation time was comparable between groups EMT and O3D (EMT 7.62 min vs. O3D 7.98 min; n.s.), while the surgical time was significantly shorter compared to the Fluoro group (10.69 min; p< 0.001) and the OCT group (13.3 min; p< 0.001).

Conclusion

Electromagnetic guided iliosacral screw placement is a feasible procedure. In our experimental setup, this method was associated with improved accuracy of screw placement and shorter operation time when compared with the conventional fluoroscopy guided technique and compared to the optical navigation using preoperative CT-scans. Further studies are necessary to rule out drawbacks of this technique regarding ferromagnetic objects.

Accuracy of computer-assisted iliosacral screw placement using a hybrid operating room

INTRODUCTION

In recent years hybrid operating rooms were established all over the world. In our setting we combined a 3D flat-panel c-arm (Artis zeego, Siemens) with a navigation system (BrainLab curve, BrainLab). This worldwide unique combination enables the surgeon to visualise an entire pelvis in CT-like image quality with a single 3D-scan. The aim of our study was to investigate, if utilisation of a hybrid operating room increases the accuracy of SI-screws in comparison to standard 3D-navigation.

MATERIAL AND METHODS

Retrospective, not randomised single centre case series at a level I trauma centre. Inclusion criterion was insertion of a percutaneous iliosacral screw using image-guidance in the hybrid operating room. 61 patients (35 female, 26 male) were included from June 2012 till October 2014. 65 iliosacral screws were inserted. Intraoperative 3D-scans and postoperative scans were examined to investigate screw placement. The results were compared to a preceding study performed in 2012 using conventional 3D-navigation. Statistical calculations were performed with Microsoft Excel 2011 and SPSS.

RESULTS

65 iliosacral screws were implanted. Two different types of screws were implanted: 1. "Standard" iliosacral screws stabilizing one joint/a unilateral fracture. 2. Single SI-screws stabilizing both SI-joints and if present a bilateral fracture. Forty one patients were included in group 1 (screws n=45). There was no perforation in 43 screws, grade 1 perforation in 2 screws. There was no grade 2 or 3 perforation in this group. Compared to the conventional 3D-navigated screws there was a highly significant difference (p<0.001). Twenty patients could be included in group 2. Eleven screws showed a complete intraosseous position. There was grade 1 perforation in 2 screws, grade 2 perforation in 5 screws and grade 3 perforation in 2 screws.

CONCLUSION

Improvements in image quality and enlargement of the display window lead to better intraoperative visualisation of the entire dorsal pelvis. Thereby the accuracy of computer-assisted iliosacral screws could be increased using a hybrid operating room. Furthermore difficult tasks like a single screw for both joints can be accomplished.

Percutaneous screw fixation of the iliosacral joint: optimal screw pathways are frequently not completely intraosseous

INTRODUCTION

In iliosacral screw fixation, the dimensions of solely intraosseous (secure) pathways, perpendicular to the ilio-sacral articulation (optimal) with corresponding entry (EP) and aiming points (AP) on lateral fluoroscopic projections, and the factors (demographic, anatomic) influencing these have not yet been described.

METHODS

In 100 CTs of normal pelvises, the height and width of the secure and optimal pathways were measured on axial and coronal views bilaterally (total measurements: n=200). Corresponding EP and AP were defined as either the location of the screw head or tip at the crossing of lateral innominate bones' cortices (EP) and sacral midlines (AP) within the centre of the pathway, respectively. EP and AP were transferred to the sagittal pelvic view using a coordinate system with the zero-point in the centre of the posterior cortex of the S1 vertebral body (x-axis parallel to upper S1 endplate). Distances are expressed in relation to the anteroposterior distance of the S1 upper endplate (in %). The influence of demographic (age, gender, side) and/or anatomic (PIA=pelvic incidence angle; TCA=transversal curvature angle, PID-Index=pelvic incidence distance-index; USW=unilateral sacral width-index) parameters on pathway dimensions and positions of EP and AP were assessed (multivariate analysis).

RESULTS

The width, height or both factors of the pathways were at least 7mm or more in 32% and 53% or 20%, respectively. The EP was on average 14±24% behind the centre of the posterior S1 cortex and 41±14% below it. The AP was on average 53±7% in the front of the centre of the posterior S1 cortex and 11±7% above it. PIA influenced the width, TCA, PID-Index the height of the pathways. PIA, PID-Index, and USW-Index significantly influenced EP and AP. Age, gender, and TCA significantly influenced EP.

CONCLUSION

Secure and optimal placement of screws of at least 7mm in diameter will be unfeasible in the majority of patients. Thoughtful preoperative planning of screw placement on CT scans is advisable to identify secure pathways with an optimal direction. For this purpose, the presented methodology of determining and transferring EPs and APs of corresponding pathways to the sagittal pelvic view using a coordinate system may be useful.

Assessment of pelvic injuries treated with ilio-sacral screws: injury severity and accuracy of screw positioning

PURPOSE

The aim of this study was to analyse possible indicative parameters for percutaneous ilio-sacral stabilisation and to identify parameters associated with screw misplacement.

METHODS

Cohort study, level I trauma centre.

INCLUSION CRITERIA

(1) unstable pelvic injury, (2) percutaneous ilio-sacral screws placement.

EXCLUSION CRITERIA

(1) sacral dysmorphy, (2) failed closed reduction, (3) navigated techniques. Indicative parameters were age, gender, body mass index, number of screws, screw angulation, fracture type and injury severity. End points were ilio-sacral screw position and associated complications. Screw placement accuracy was graded as follows: grade 0, no perforation; grade 1, perforation <2 mm; grade 2, perforation from 2 to 4 mm; grade 3, ≥4 mm perforation.

RESULTS

Between March 2008 and March 2013, 102 (53 women) patients were included (mean age, 48.5 ± 21.4 years). The Injury Severity Score (ISS) and New Injury Severity Score (NISS) were 18.9 ± 9.9 and 22.3 ± 22.3, respectively. The positions of 137 ilio-sacral screws were analysed. Of all screws, 87.6 % (120) were placed satisfactory (<2 mm perforation). The incidence of screw misplacement was significantly higher in the case of two unilateral S1 screws compared with a single screw (failure rate: two unilateral screws 23.1 % vs single screw 7.0 %; p < 0.05). Screw perforation anterior to the lateral mass (in-out-in) represented the most frequent malposition. Revision was necessary in three cases due to malpositioning. Furthermore, no major complication occurred.

CONCLUSIONS

We conclude, that twofold ilio-sacral screw positioning from one side increases the risk for screw misplacement. In this case, alternative techniques like navigation should be considered. Anterior screw perforation represents a common problem with a high incidence and warrants particular attention.

Percutaneous iliosacral screw fixation after osteoporotic posterior ring fractures of the pelvis reduces pain significantly in elderly patients

INTRODUCTION

Osteoporotic posterior ring fractures of the pelvis are common injuries in the elderly, but the treatment of these fractures still remains controversial. Percutaneous iliosacral screw fixation is one surgical option if conservative treatment cannot provide sufficient pain reduction. The aim of this study is to provide short-term results of elderly patients with percutaneous screw fixation.

METHODS

30 patients with posterior ring fractures were treated between 12/2009 and 01/2014 with percutaneous iliosacral screw fixation. Patients' mean age was 78.4 years. Concerning short-term outcome, we focused on initial pain level and postoperative pain reduction together with intra- and postoperative complications.

RESULTS

The average hospital stay was 23.7 days, with surgical treatment performed after an average of 9.2 days. 90% of our patients were female. All 30 patients had a lower level of pain at discharge compared with admission or immediately prior to surgery. The difference in pain level at admission compared with the pain level upon discharge showed a mean reduction from 6.8 to 1.8 with a statistically significant change (P≤0.001). 24 of 30 patients had no registered complications, one screw malpositioning with postoperative nerve irritation occurred.

DISCUSSION

Conventional percutaneous iliosacral screw fixation is a successful operative treatment for elderly patients with persistent lower back pain after unstable posterior ring fractures of the pelvis. Intra- and postoperative complications are rare, so this treatment can be regarded as a safe procedure.

LEVEL OF EVIDENCE

IV (retrospective study).

Correlating preoperative imaging with intraoperative fluoroscopy in iliosacral screw placement

Background

Percutaneous iliosacral screw placement can successfully stabilize unstable posterior pelvic ring injuries. Intraoperative fluoroscopic imaging is a vital component needed in safely placing iliosacral screws. Obtaining and appropriately interpreting fluoroscopic views can be challenging in certain clinical scenarios. We report on a series of patients to demonstrate how preoperative computed tomography (CT) imaging can be used to anticipate the appropriate intraoperative inlet and outlet fluoroscopic views.

Materials and methods

24 patients were retrospectively identified with unstable pelvic ring injuries requiring operative fixation using percutaneous iliosacral screws. Utilizing the sagittal reconstructions of the preoperative CT scans, anticipated inlet and outlet angle measurements were calculated. The operative reports were reviewed to determine the angles used intraoperatively. Postoperative CT scans were reviewed for repeat measurements and to determine the location and safety of each screw.

Results

Preoperative CT scans showed an average inlet of 20.5° (7°–37°) and an average outlet of 42.8° (30°–59°). Intraoperative views showed an average inlet of 24.9° (12°–38°) and an average outlet of 42.4° (29°–52°). Postoperative CT scans showed an average inlet of 19.4° (8°–31°) and an average outlet of 43.2° (31°–56°). The average difference from preoperative to intraoperative was 4.4° (−21° to 5°) for the inlet and 0.45° (−9° to 7°) for the outlet. The average difference between the preoperative and postoperative CT was 2.04° (0°–6°) for the inlet and 2.54° (0°–7°) for the outlet.

Conclusion

There is significant anatomic variation of the posterior pelvic ring. The preoperative CT sagittal reconstruction images allow for appropriate preoperative planning for anticipated intraoperative fluoroscopic inlet and outlet views within 5°. Having knowledge of the desired intraoperative views preoperatively prepares the surgeon, aids in efficiently obtaining correct intraoperative views, and ultimately assists in safe iliosacral screw placement.

Level of evidence

IV, Retrospective case series.

Retrieval of broken iliosacral screws: the power of a push screw

Percutaneous iliosacral screw fixation is a common technique that is widely used for unstable posterior pelvic ring disruptions. Complications of posterior percutaneous iliosacral screw fixation include implant malpositioning and hardware failure. Removal of iliosacral screws in broken or symptomatic hardware is sometimes necessary. To our knowledge, there are few reports addressing pelvic implant removal, and most of those report on anterior pelvic implants and symphyseal plates. There are no reports describing techniques for retrieval of broken iliosacral screws. We present two cases involving removal of broken sacroiliac screws, review the literature regarding iliosacral implant extraction, and identify important aspects of safe extraction of iliosacral screws and the potential complications associated with their retrieval. We further describe a novel and powerful technique to facilitate percutaneous removal of broken screw fragments, using a "push screw" to drive a broken screw fragment from a position buried in bone.

Fluoroscopically assisted computer navigation enables accurate percutaneous screw placement for pelvic and acetabular fracture fixation

Percutaneous fixation of pelvic and acetabular fractures are technically demanding procedures, and high rates of screw misplacement and potential neurovascular complications have been reported. One hundred and sixty two screws from a prospectively collected database were analysed to evaluate the accuracy of a fluoroscopically assisted computer navigated technique to insert a cannulated screw to treat pelvic and acetabular fractures. Actual screw position and trajectory with the intraoperative surgical plan stored in the navigation computer. The actual screw position differed from the surgical plan by a mean of 3.9 mm, with a mean 1.4 degree difference in screw trajectory. Post operative CT analysis of patients showed 10 screws perforated cortical bone. Our results show that the use of computer navigation can aid in the accurate placement of percutaneous screws along a predefined plan. It is still possible to incorrectly place a screw and great care needs to be taken with the surgical plan and also to understand the complex anatomy of the bony pelvis.

Intraoperative image-guided spinal navigation: technical pitfalls and their avoidance

Spinal instrumentation has made significant advances in the last two decades, with transpedicular constructs now widely used in spinal fixation. Pedicle screw constructs are routinely used in thoracolumbar-instrumented fusions, and in recent years, the cervical spine as well. Three-column fixations with pedicle screws provide the most rigid form of posterior stabilization. Surgical landmarks and fluoroscopy have been used routinely for pedicle screw insertion, but a number of studies reveal inaccuracies in placement using these conventional techniques (ranging from 10% to 50%). The ability to combine 3D imaging with intraoperative navigation systems has improved the accuracy and safety of pedicle screw placement, especially in more complex spinal deformities. However, in the authors' experience with image guidance in more than 1500 cases, several potential pitfalls have been identified while using intraoperative spinal navigation that could lead to suboptimal results. This article summarizes the authors' experience with these various pitfalls using spinal navigation, and gives practical tips on their avoidance and management.

Iliosacral screw insertion using CT-3D-fluoroscopy matching navigation

BACKGROUND

Percutaneous iliosacral screw insertion requires substantial experience and detailed anatomical knowledge to find the proper entry point and trajectory even with the use of a navigation system. Our hypothesis was that three-dimensional (3D) fluoroscopic navigation combined with a preoperative computed tomography (CT)-based plan could enable surgeons to perform safe and reliable iliosacral screw insertion. The purpose of the current study is two-fold: (1) to demonstrate the navigation accuracy for sacral fractures and sacroiliac dislocations on widely displaced cadaveric pelves; and (2) to report the technical and clinical aspects of percutaneous iliosacral screw insertion using the CT-3D-fluoroscopy matching navigation system.

METHODS

We simulated three types of posterior pelvic ring disruptions with vertical displacements of 0, 1, 2 and 3cm using cadaveric pelvic rings. A total of six fiducial markers were fixed to the anterior surface of the sacrum. Target registration error over the sacrum was assessed with the fluoroscopic imaging centre on the second sacral vertebral body. Six patients with pelvic ring fractures underwent percutaneous iliosacral screw placement using the CT-3D-fluoroscopy matching navigation. Three pelvic ring fractures were classified as type B2 and three were classified as type C1 according to the AO-OTA classification. Iliosacral screws for the S1 and S2 vertebra were inserted.

RESULTS

The mean target registration error over the sacrum was 1.2mm (0.5-1.9mm) in the experimental study. Fracture type and amount of vertical displacement did not affect the target registration error. All 12 screws were positioned correctly in the clinical series. There were no postoperative complications including nerve palsy. The mean deviation between the planned and the inserted screw position was 2.5mm at the screw entry point, 1.8mm at the area around the nerve root tunnels and 2.2mm at the tip of the screw.

CONCLUSION

The CT-3D-fluoroscopy matching navigation system was accurate and robust regardless of pelvic ring fracture type and fragment displacement. Percutaneous iliosacral screw insertion with the navigation system is clinically feasible.

Usefulness of intraoperative three-dimensional imaging in fracture surgery: a prospective study

BACKGROUND

Since its introduction, intraoperative three-dimensional (3D) imaging has enabled the analysis of articular fractures and implant positions during fracture surgery. The purpose of this study was to evaluate the usefulness of intraoperative 3D imaging in locating anatomic structures, correcting errors, and preventing revision surgery.

METHODS

Between March 2010 and November 2012, intraoperative 3D imaging was used during surgery for 109 fractures in 101 patients. Fluoroscopy was performed with the Iso-C3D (Siemens, Erlangen, Germany). We recorded the number of intraoperative revisions for adjustment of fracture reduction and correction of implant position for these fractures.

RESULTS

Cases comprised intra-articular fractures (55%), disruptions of the posterior pelvic ring (33%), and syndesmotic injury (12%). The intraoperative revision rate was 9.2% (10/109). When considered by fracture site, the revision rate was highest for syndesmotic injury (23.1%), followed by iliosacral fixation (8.3%) and intra-articular fractures (6.6 %). We changed the implant position in six cases, corrected the articular reduction in one case, and revised the malreduction of syndesmosis in three cases. No postoperative infection occurred in any of these cases.

CONCLUSIONS

Intraoperative 3D imaging is useful for correcting errors and may prevent a second operation. Three-dimensional imaging may be especially helpful in intra-articular fractures, iliosacral screw fixation, and syndesmotic injury.

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.

Malposition and revision rates of different imaging modalities for percutaneous iliosacral screw fixation following pelvic fractures: a systematic review and meta-analysis

INTRODUCTION

Percutaneous iliosacral screw placement following pelvic trauma is associated with high rates of revisions, screw malpositioning, the risk of neurological damage and inefficient stability. The correct entry point and the small target corridor may be difficult to visualize using only an image intensifier. Therefore, 2D and 3D image-based navigation and reconstruction techniques could be helpful tools. The aim of this systematic review and meta-analysis was to evaluate the best available evidence regarding the rate of malpositioning and revisions using different techniques for screw implantation, i.e., conventional, 2D and 3D image-based navigation and reconstruction techniques, CT navigation.

METHODS

A systematic review and meta-analysis were performed using the data available on Ovid Medline. 430 studies published between 1/1948 and 2/2011 were identified by two independent investigators. Inclusion criteria were percutaneous iliosacral screw fixation after traumatic pelvic fractures with included revision rate or positioning of the screw, language of the article English or German. Exclusion criteria were osteoporotic fracture, tumor, reviews, epidemiological studies, biomechanical/cadaveric studies, studies about operative technique. For statistical analysis the random effect model was used.

RESULTS

A total of 51 studies fulfilled the inclusion requirements describing 2,353 percutaneous screw implantations following pelvic trauma in 1,731 patients. The estimated rate of malposition was 0.1 % for 262 screws using CT navigation. This rate was significantly lower (p < 0.0001) than for the conventional technique with malposition rate of 2.6 % (total 1,832 screws). Using 2D and 3D image-based navigation and reconstruction techniques, the malposition rate was 1.3 % (total 445 screws). No significance was observed between the conventional and the 2D and 3D image-based navigation and reconstruction techniques. The rates of revision were not statistically significant with 2.7 % (1,832 implantations) in the conventional group, 1.3 % (445 implantations) in the group of 2D and 3D image-based navigation and reconstruction techniques and 0.8 % (262 implantations) using the CT navigation.

CONCLUSIONS

CT navigation has the lowest rate of screw malposition, but on the other hand it could not be used for all type of fractures where surgical procedures (reduction maneuvers, additional osteosynthetic procedures) are necessary. The 2D and 3D image-based navigation and reconstruction techniques provide encouraging results with slightly lower rate of complications compared to the conventional technique and are additional tools to enhance the precision and decrease the rate of revision.

Intraoperative computed tomography with integrated navigation in percutaneous iliosacral screwing

BACKGROUND

Iliosacral screw fixation has generally been accepted as a treatment for unstable pelvic fractures with posterior sacroiliac joint disruption despite a 2-16% rate of screw malposition. The integration of an intraoperative computed tomography (iCT) with a navigation system was utilized in percutaneous sacroiliac screwing to provide an alternative.

METHODS

From October 2010 to November 2011, thirteen patients presented pelvic fractures with posterior ring disruption (lateral compression type 2-3 [n=12] and vertical shear type [n=1] by Young-Burgess Classification) and underwent percutaneous iliosacral screwing using an iCT integrated with navigation system. The perioperative data and radiographic outcomes of the patients were collected and analyzed.

RESULTS

Navigation times ranged from 10 to 45min (mean of 21.2±10.6min). Radiation exposure to the skin utilizing integrated navigation system ranged from 23.5 to 28.1mGy (mean of 26.4±1.5mGy), and the dose associated with examining the screw position ranged from 22.5 to 26.8mGy (mean of 25.5±1.1mGy). Effective dose of radiation ranged from 9.26 to 17.43mSv (mean of 13.16±2.52mSv). The iCT demonstrated iliosacral screws in adequate position (i.e., no penetration or encroachment of the neuroforamen or cord). No neurologic or vascular injury occurred in these cases.

CONCLUSIONS

An iCT with an integrated navigation system provided accuracy for percutaneous iliosacral screwing. In addition, the accumulated dose was minimized for surgeons. However, effective dose of radiation in iCT with an integrated navigation system group was higher than fluoroscopic-assisted iliosacral screwing in hands of the same group of surgeons. No neurologic complications occurred. The iCT with an integrated navigation system provided an alternative to percutaneous iliosacral screwing.

Percutaneous iliosacral screwing in pelvic ring injury using three-dimensional fluoroscopy

BACKGROUND

Iliosacral screw fixation is a popular technique for treatment of unstable pelvic injuries involving the posterior ring. However, screw malposition may result in dangerous complications involving injury to adjacent neurovascular structures. This study was conducted in order to evaluate the results and efficacy of using three-dimensional fluoroscopy in the performance of iliosacral screw fixation.

METHODS

Twenty-nine patients (31 cases, two bilateral) who suffered injury to the pelvic ring requiring surgical treatment were included in this study. According to the Association for Osteosynthesis-Orthopaedic Trauma Association (AO-OTA) classification, there were 14 patients with type B, 13 patients with type C, and 2 patients with a bilateral sacral fracture. The mean age of patients was 39 years. Once the guide pin had been inserted, its safety was confirmed using three-dimensional fluoroscopy; screw fixation was then performed. Eighteen patients underwent percutaneous iliosacral screw fixation and anterior fixation, while 11 patents underwent screw fixation only. Postoperative computed tomography (CT) was performed for evaluation of the screw position, including any invasion into the sacral foramen or canal and neurovascular injury. The perforation of the screw was divided according to the location (sacral zones I, II, and III) and the degree (grade 0, no perforation; grade 1, perforation <2 mm; grade 2, perforation between 2 and 4 mm; grade 3, perforation >4 mm).

RESULTS

The mean operation time was 35.6 min, and the mean radiation exposure time was 85.9 s. For accurate location of the guide pin, one patient underwent three-dimensional reconstruction twice. None of the patients required reoperation or suffered any neurovascular injury. Although seven cases involved perforation, all were less than 2 mm (grade 0: 24 cases, grade 1: 7 cases).

CONCLUSIONS

When performing percutaneous iliosacral screw fixation in a patient with an unstable pelvic ring injury, use of three-dimensional fluoroscopy may allow for accurate location of the screw and result in fewer complications.

Current state of computer-assisted trauma surgery

Computer assisted surgery (CAS) was first used in neurosurgery. Currently, CAS has gained popularity in several surgical disciplines including urology and abdominal surgery. In trauma and orthopaedic surgery, computer assisted systems are used for fracture reduction, planning and positioning of implants as well as the accurate implantation of hip and knee prostheses. The patient's anatomy is virtualized and the surgical instruments integrated into the digitized image background, thus allowing the surgeon to navigate the surgical instruments and the bone in an improved, virtual visual environment. CAS improves overall accuracy, reducing intraoperative radiation exposure and minimizing unnecessary surgical dissection combined with increased patient and surgeon safety. However, limitations include prolonged surgical time, technical errors and cost implications. This article will outline the current state of computer assisted trauma surgery including its implications and specific challenges in orthopaedic trauma surgery.