CT-3D-fluoroscopy matching navigation can reduce the malposition rate of iliosacral screw insertion for less-experienced surgeons

Accuracy in navigated percutaneous sacroiliac screw fixation: a systematic review and meta-analysis

INTRODUCTION

Percutaneous sacroiliac screw fixation of pelvic fragility fractures is increasingly being used to maintain mobility and reduce pain in the elderly patient population. Traditionally, this is performed using 2D fluoroscopy. Several newer, navigated techniques have emerged that may further facilitate this procedure. It, however, remains unclear whether there is a benefit regarding accuracy, radiation exposure and complications of these new navigation techniques when compared to the traditional 2D fluoroscopy.

METHODS

A systematic review and meta-analysis were performed. PubMed, CENTRAL and Embase were searched for both randomized controlled trials and observational studies comparing new navigation techniques to 2D fluoroscopy for percutaneous sacroiliac screw fixation. Effect estimates were pooled (random effects) and presented as odds ratio, mean difference and standardized mean difference with a 95% confidence interval.

RESULTS

19 studies were included. The 2D fluoroscopy group had 642 patients and the new navigation group 663 patients. Accuracy was significantly higher in the new navigation group (OR 2.44, 95% CI 1.53-3.90), especially O-Arm, 3D CT and Robotic navigation. On average, accuracy was 82% in the 2D group and 92% in the new navigation group, which was significant. Also, fluoroscopy time (MD 71.89 s, 95% CI 51.37-92.41) and frequency (MD 17.22 images in total, 95% CI 7.73-26.70) were significantly reduced in the new navigation group. Complications are acceptably low, however, poorly reported in both groups.

CONCLUSION

This meta-analysis demonstrated a higher accuracy, lower fluoroscopic frequency and time for new navigation techniques compared to 2D fluoroscopy. More advanced navigation techniques, such as 3D CT and robotic navigation, appeared to be even better.

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.

Use of 3D Navigation Versus Traditional Fluoroscopy for Posterior Pelvic Ring Fixation

Unstable pelvic ring disruption is most commonly treated with closed reduction and percutaneous screw fixation. Traditional methods involve screw placement under fluoroscopic imaging, but with recent technologic advances, intraoperative 3D navigation can now be used to help with the insertion of sacroiliac screws. Various cadaver studies have shown that placement of sacroiliac screws under 3D navigation is more accurate than placement under traditional fluoroscopic guidance. This retrospective review of 134 patients evaluated the clinical use of 3D navigation vs traditional fluoroscopy for sacroiliac screw insertion at an urban level I trauma center. Analysis of surgical data showed a significantly longer imaging time with the conventional method compared with the more experimental 3D navigation (204.06 seconds vs 66.90 seconds, P<.01). Further, a significantly larger radiation dose to both the patient and the staff was seen with traditional fluoroscopy (80.1 mGy for each) compared with that of 3D navigation (39.0 mGy and 25.1 mGy, respectively). No statistically significant difference was seen for outcome or follow-up variables between the 2 extrapolated groups. These variables included length of hospital stay, infection, nerve injury, and hardware breakage. The authors advocate that 3D navigated sacroiliac screws are safe and effective for pelvic ring stabilization; this method may be especially applicable in certain difficult imaging situations, such as morbid obesity, bowel gas interference, and overlapping pelvic structures that make the sacral corridor difficult to discern with traditional 2D fluoroscopy. Safe placement of transiliac-transsacral screws (P<.01) occurred with 3D navigation, and there was a statistically significant increase in adequate screw placement in multiple sacral segments compared with single-level stabilization (P<.01). [Orthopedics. 2021;44(4):229-234.].

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.

Quantifying Radiation Exposure From Intraoperative Computed Tomography in Traditionally Safe Operating Room Zones

OBJECTIVES

To quantify the amount of radiation exposure from a commercially available computed tomography surgical imaging system that occurs in areas of the operating room that are generally believed to be safe and to correlate these amounts with established safety recommendations.

DESIGN

Experimental in vitro study.

SETTING

Standard hospital operating room at a Level 1 trauma center.

PARTICIPANTS

Radiation survey instruments at specified distances from an intraoperative computed tomography scanner. Represented positions were the location of the anesthesiologist (80 cm), the radiation technologist (180 cm), the substerile room (500 cm), the operating room door (600 cm), the next-room nursing station (960 cm), and the hallway (1000 cm).

INTERVENTION

Radiation survey instruments were systematically exposed by a protocol intended to imitate expected radiation scatter during operative room use.

MAIN OUTCOME MEASUREMENTS

Radiation exposure readings from radiation survey instruments.

RESULTS

The mean radiation exposure rates are reported. The mean exposure rate was highest at the anesthesiologist (2200 mrem/h), followed by the door (25.33 mrem/h), the technologist (21.0 mrem/h), the substerile room (8.2 mrem/h), the hallway (2.633 mrem/h), and then the next-room nursing station (1.557 mrem/h). The mean integrated doses per scan were 15.03 mrem for the anesthesiologist, 0.170 mrem for the technologist, 0.136 mrem at the door, 0.033 mrem in the substerile room, 0.014 mrem in the hallway, and 0.005 mrem at the next-door nursing station. The exposure was related both to distance from the machine and to orientation from the machine.

CONCLUSIONS

These results indicate that although there is measurable radiation exposure outside of the operating room, the magnitude is low enough to be clinically insignificant. This study provides data that reinforce the need to wear a protective gear or leave the room during the use of intraoperative computed tomography but unsuspecting surrounding staff need not worry about uninformed exposure.

O-arm navigation for sacroiliac screw placement in the treatment for posterior pelvic ring injury

PURPOSE

This study aims to investigate the application value of O-arm navigation system in sacroiliac screw placement for the treatment of unstable pelvic ring injury.

METHODS

A total of 40 patients (mean age = 30.75 ± 14.99 years, 25 males, 15 females) were included. From January 2016 to July 2018, 40 patients with posterior pelvic ring injury treated in our hospital were included. Of them, 19 patients underwent O-arm navigation for screw placement (O-arm group) while the other 21 received C-arm fluoroscopy guidance (C-arm group) for sacroiliac screw placement. Intraoperative outcomes and the outcome of screw placement were compared between groups. The quality of radiological images was assessed by Matta's radiological outcome grade. The outcome of complex pelvic fracture treatment was evaluated by Majeed Functional score.

RESULTS

All demographic and clinical characteristics were comparable between the two groups. Compared with the C-arm groups, the O-arm group had a shorter surgery time (33.19 ± 3.14 vs. 48.35 ± 4.38 min, P < 0.001), a higher overall good outcome "excellent + good" rate of screw placement (95.45% vs. 73.91%, P < 0.05), and a significantly higher Majeed Functional score better outcome of complex pelvic fracture treatment at 1 and 3 months postoperation (both P < 0.05).

CONCLUSION

Our results demonstrated that O-arm navigation system is feasible and safe for the treatment of posterior pelvic ring injury and can effectively improve the accuracy and safety of sacroiliac screw placement, shorten the operation time, and help rapid postoperative functional recovery.

Early Clinical Result of Computerized Navigated Screw Fixation in Treatment of Fragility Pelvic Fracture

Introduction:

Minimal invasive fixation of fragility pelvic fracture is feasible with advancement of computerized navigation. However, the clinical outcomes compared with conservative care were seldom mentioned.

Method:

This is a retrospective study comparing the outcomes of elderly with stable pelvic fracture treated conservatively or operatively using computerized navigation. Outcome parameters included pain score, analgesics requirement, length of hospital stay and complication(s), if any.

Result:

Operations were performed in 15 patients from July 2017 to November 2018. A retrospective cohort of 37 patients who were treated conservatively was recruited. In the operative group, it showed a statistically significant reduction in analgesics consumption at 4-week time only. There was significant improvement in pain score at 1-week, 4-week and 3-month time. Patients showed earlier return to premorbid walking status. No major surgical complication was noted.

Conclusion:

Treating fragility pelvic fracture with computerized navigated screw fixation achieve better pain control, reduction in analgesics requirement and earlier mobilization.

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.

Comparing the Efficiency, Radiation Exposure, and Accuracy Using C-Arm versus O-Arm With 3D Navigation in Placement of Transiliac-Transsacral and Iliosacral Screws: A Cadaveric Study Evaluating an Early Career Surgeon

OBJECTIVES

To compare the efficiency, radiation exposure to surgeon and patient, and accuracy of C-arm versus O-arm with navigation in the placement of transiliac-transsacral and iliosacral screws by an orthopaedic trauma fellow, for a surgeon early in practice.

METHODS

Twelve fresh frozen cadavers were obtained. Preoperative computed tomography scans were reviewed to assess for safe corridors in the S1 and S2 segments. Iliosacral screws were assigned to the S1 segment in dysmorphic pelvises. Screws were randomized to modality and laterality. An orthopaedic trauma fellow placed all screws. Time of procedure and radiation exposure to the cadaver and surgeon were recorded. Three fellowship-trained orthopaedic trauma surgeons rated the safety of each screw on postoperative computed tomography scan.

RESULTS

Six normal and 6 dysmorphic pelvises were identified. Eighteen transiliac-transsacral screws and 6 iliosacral screws were distributed evenly between C-arm and O-arm. Average operative duration per screw was significantly shorter using C-arm compared with O-arm (15.7 minutes ± 6.1 vs. 23.7 ± 8.5, P = 0.014). Screw placement with C-arm exposed the surgeon to a significantly greater amount of radiation (3.87 × 10 rads vs. 0.32 × 10, P < 0.001) while O-arm exposed the cadaver to a significantly greater amount of radiation (0.03 vs. 2.76 rads, P < 0.001). Two S2 transiliac-transsacral screws (1 C-arm and 1 O-arm) were categorized as unsafe based on scoring. There was no difference in screw accuracy between modalities.

CONCLUSIONS

A difference in accuracy between modalities could not be elucidated, whereas efficiency was improved with utilization of C-arm, with statistical significance. A statistically significant increase in radiation exposure to the surgeon using C-arm was found, which may be clinically significant over a career. The results of this study can be extrapolated to a fellow or surgeon early in practice. The decision between use of these modalities will vary depending on surgeon preference and hospital resources.

Traumatic Sacral Fractures: Navigation Technique in Instrumented Stabilization

BACKGROUND

Sacral fractures are a challenge regarding treatment and classification. Surgical techniques using spinal navigation systems can improve treatment, especially if used in collaboration among different specialists.

METHODS

Between 2015 and 2017, we treated 25 consecutive cases of sacral fracture. Twelve patients (48%) underwent mechanical ventilation due to hypovolemic shock for severe thoracoabdominal trauma; bleeding was blocked with pelvic packing in 9 cases (36%) and transcatheter embolization in 2 cases (8%). External fixation was used in 7 cases (28%). In 20 cases (80%) spinal fractures were associated. All patients were operated on using spinal navigation by a team of neurosurgeons and orthopedic surgeons.

RESULTS

The mean time from first observation to surgery was 18 days (range 8-31). Surgical treatment consisted of iliosacral fixation in 19 cases (76%) and spinopelvic fixation in 6 cases (24%). The mean number of screws for spinopelvic fixation was 9.67 (range 6-17) with a mean operation time of 323.67 minutes (range 247-471); in iliosacral osteosynthesis the mean screw number was 1.37 (range 1-3) and mean surgical time was 78.93 minutes (range 61-130). Postoperative computed tomography showed the correct screw placement. Wound infection occurred in 2 cases (8%), managed with vacuum-assisted closure therapy; in 1 case (4%) a sacral screw was removed for decubitus.

CONCLUSIONS

Navigation systems in instrumented spinopelvic and sacropelvic reconstruction provide greater safety, reducing learning times and malpositioning. Multidisciplinary management allows us to achieve optimal results, especially when the sacral fracture is combined with spinal and pelvic lesions. The use of navigation systems could represent an important advancement.

Technical Considerations and Fluoroscopy in Percutaneous Fixation of the Pelvis and Acetabulum

Surgical treatment of the pelvic ring and acetabulum continues to evolve. Improved imaging technology and means for closed reduction have meant that percutaneous techniques have gained popularity in the treatment of the pelvic ring and, more recently, in the acetabulum. Potential benefits include decreased soft-tissue dissection, blood loss, and surgical time. However, these are technically demanding procedures that require substantial expertise from both the surgeon and the radiographer. This article details the necessary fluoroscopic views and general methods used in percutaneous techniques around the pelvis and acetabulum. Despite most studies reporting good-to-excellent clinical and radiographic results, further work is needed to facilitate standardization and optimization of these outcomes.

The Role of Intraoperative Navigation in Orthopaedic Surgery

An orthopaedic surgeon's knowledge of anatomical landmarks is crucial, but other modalities supplement this by providing guidance and feedback to a surgeon. Advances in imaging have enabled three-dimensional visualization of the surgical field and patient anatomy, whereas advances in computer technology have allowed for real-time tracking of instruments and implants. Together, these innovations have given rise to intraoperative navigation systems. The authors review these advances in intraoperative navigation across orthopaedic subspecialties, focusing on the most recent evidence on patient outcomes and complications, the associated learning curve, and the effects on operative time, radiation exposure, and cost. In spine surgery, navigated pedicle screw placement may increase accuracy and safety, especially valuable when treating complex deformities. Improved accuracy of pelvic and peri-articular tumor resection and percutaneous fixation of acetabular and femoral neck fractures has also been achieved using navigation. Early applications in arthroscopy have included surface-based registration for tunnel positioning for anterior cruciate ligament reconstruction and osteochondroplasty for femoro-acetabular impingement. Navigated arthroplasty techniques have addressed knee gap balancing and mechanical axis restoration as well as acetabular cup and glenoid baseplate positioning. Among these orthopaedic subspecialties, significant variation is found in the clinical relevance and dedication to research of navigation techniques.

[Precise sacroiliac joint screw insertion without computed tomography, digital volume tomography or navigation systems]

OBJECTIVE

Improvement of sacroiliac positioning of screws by detailed preoperative planning with a DICOM (Digital Imaging and Communications in Medicine-the international standard to store and process medical imaging information) workstation in the absence of advanced technical facilities like intraoperative computer tomography (CT), digital volume tomography (DVT) or a navigation system.

INDICATIONS

Mono- or bilateral non- or minor displaced, longitudinal sacral fractures type Denis I and II and pelvic ring fractures (Orthopedic Trauma Association) OTA type B possibly in combination with a ventral procedure.

CONTRAINDICATIONS

Displaced sacral fractures type Denis II and III, fractures with central comminution and circulatory unstable patients to be stabilized in the context of emergency care.

SURGICAL TECHNIQUE

Preoperative calculation of virtual conventional standard view X‑rays with the CT dataset using common DICOM software (e.g., Siemens via® or Sectra®). Typical landmarks such as screw entry point and end point are projected into the virtual X‑rays. Intraoperative navigation is performed by comparing the virtual standard views with fluoroscopic images of the C‑arm, thereby, simplifying the operative procedure.

POSTOPERATIVE MANAGEMENT

Postoperative CT scan, pain adapted partial weight bearing and X‑rays of the pelvic ring after 6 and 12 weeks.

RESULTS

Over a 13 month period, an orthopedic surgeon inserted 26 sacroiliac screws in 19 patients utilizing the described method. Postoperative CT scans revealed that all except three screws were precisely positioned without any bone perforation. Of these three screws one had a grade one perforation and two had a grade two perforation according to Smith. No revision was necessary and no neurological deficits were detected. The operating time was on average 33 min and duration of radiation 3.8 min.

Sacroiliac screw versus a minimally invasive adjustable plate for Zone II sacral fractures: a retrospective study

OBJECTIVE

Fracture line of the sacrum always involves the Zone II region because sacral foramina are anatomically and physiologically weak regions of the sacrum. The purpose of this study is to compare the therapeutic effects of a sacroiliac screw and a minimally invasive adjustable plate (MIAP) for Zone II sacral fractures.

METHODS

Patients with unilateral Zone II sacral fractures fixed with a unilateral sacroiliac screw or MIAP from August 2009 to January 2016 were recruited into this study and were divided into two groups: group A (sacroiliac screw) and group B (MIAP). Surgical time, blood loss, frequency of intraoperative fluoroscopy, and relative complications were reviewed. Radiographs and CT scans were routinely acquired to evaluate the fracture displacement and reduction quality. Fracture healing was evaluated in the radiographs at each follow-up. Functional outcome was assessed based upon the Majeed scoring system at the final follow-up.

RESULTS

Thirty-one patients in group A and thirty-nine patients in group B were included in this study. No significant differences in average surgical time (P = 0.221) or blood loss (P = 0.234) were noted between group A and group B. The mean frequency of intraoperative fluoroscopy was 15.74±2.98 in group A and 6.08±1.94 in group B (P = 0.000). All fractures healed well within four months in all patients, and the healing time exhibited no significant difference between the two groups (P = 0.579). Satisfactory rates of reduction quality and functional outcome were not statistically different between the two groups (P > 0.05). The complication rate was 16.13% (5/31) in group A and 5.13% (2/39) in group B (P = 0.222).

CONCLUSION

MIAP has a fixation effect and exhibits reduction potential for Zone II sacral fractures. Favourable radiographic and functional results could be obtained through the MIAP technique, which is easy to conduct without pre-contouring. Compared with the unilateral S1 sacroiliac screw technique, repeated projections and iatrogenic sacral injury can be avoided.

A novel computer navigation method for accurate percutaneous sacroiliac screw implantation: A technical note and literature review

The purpose of this study was to assess the accuracy of percutaneous sacroiliac screw (PSS) placement assisted by screw view model of navigation system for treatment of sacroiliac fractures.Data pertaining to 18 consecutive patients with posterior pelvic ring fracture who received sacroiliac screw fixation between January 2015 and July 2018 at the Second Hospital of Jilin University were retrospectively analyzed. Kirschner wires were placed under the guidance of navigation's screw view mode. The position of the screws was evaluated by computed tomography (CT) scan postoperatively. Fracture dislocation of sacroiliac joint was measured in axial, sagittal, and coronal views of 3 dimensional (3D) CT images preoperatively, postoperatively and at the last follow-up visit. The duration of trajectory planning, guide wire implantation time, screw placement time, intraoperative blood loss, and incidence of screw loosening and clinical complications were also assessed.A total of 27 screws were placed unilaterally or bilaterally into segments S1 or S2. Screw placement was rated as excellent for 88.9% of screws (n = 24), good for 7.4% (n = 2), and poor for 3.7% (n = 1). Preoperatively, the average fracture dislocation of sacroiliac joint on axial, sagittal, and coronal views was 14.3 mm, 9.6 mm, and 7.4 mm, respectively, and the corresponding postoperative figures were 5.6 mm, 3.2 mm, 4.1 mm, respectively. The corresponding correction rates were 60.8%, 66.7%, and 44.6%, respectively. The mean duration of trajectory planning was 6.5 min (2.7-8.9 min). Mean screw implantation time was 32 min (range, 20-53 min), and the mean guide wire implantation time was 3.7 min (range, 2.1-5.3 min). No clinical complications such as neurovascular injury, infection or screw loosening were observed on follow-up.The PSS placement under guidance of screw view model of navigation is a convenient, safe and reliable method.

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.

A novel patient-specific three-dimensional-printed external template to guide iliosacral screw insertion: a retrospective study

Background

Iliosacral screw fixation is a popular method for the management of posterior pelvic ring fractures or dislocations, providing adequate biomechanical stability. Our aim in this study was to describe the use of a new patient-specific external template to guide the insertion of iliosacral screws and to evaluate the efficacy and safety of this technique compared with the conventional fluoroscopy-guided technique.

Methods

This was a retrospective study of patients with incomplete or complete posterior pelvic ring disruptions who required iliosacral screw fixation. For analysis, patients were divided into two groups: the external template group (37 screws in 22 patients) and the conventional group (28 screws in 18 patients). The operative time per screw, radiation exposure time and the rate of screw perforation (accuracy) were compared between groups. In the external template group, the difference between the actual and planned iliosacral screw position was also compared.

Results

In the conventional group, the average operative time per screw was 39.7 ± 10.6 min, with an average radiation exposure dose of 1904.0 ± 844.5 cGy/cm², with 4 cases of screw perforation. In the external template group, the average operative time per screw was 17.9 ± 4.7 min, with an average radiation exposure dose of 742.8 ± 230.6 cGy/cm² and 1 case of screw perforation. In the template group, the mean deviation distance between the actual and planned screw position was 2.75 ± 1.0 mm at the tip, 1.83 ± 0.67 mm in the nerve root tunnel zone and 1.52 ± 0.48 mm at the entry point, with a mean deviation angle of 1.73 ± 0.80°.

Conclusions

The external template provides an accurate and safe navigation tool for percutaneous iliosacral screw insertion that could decrease the operative time and radiation exposure.

Intraoperative CT and Surgical Navigation for Iliosacral Screws: Technique for Patients With Sacral Dysmorphism

Percutaneous iliosacral screw (IS) fixation for pelvic ring injuries with the use of an O-arm imaging system has been associated with decreased procedure time and improved accuracy of IS screw placement compared with the use of fluoroscopic guidance. Specifically, patients with sacral dysmorphism require identification of safe bony sacral corridors, using specific anatomical measurements, to decrease the likelihood of complications such as screw perforation. Intraoperative computed tomography imaging and navigation can aid in safe and accurate IS screw fixation in patients with difficult anatomy.

Percutaneous screw fixation of the iliosacral joint: A case-based preoperative planning approach reduces operating time and radiation exposure

INTRODUCTION

A preoperative planning approach for percutaneous screw fixation of the iliosacral joint provides specific entry points (EPs) and aiming points (APs) of intraosseous screw pathways (as defined by CT scans) for lateral fluoroscopic projections used intraoperatively. The potential to achieve the recommended EPs and APs, to obtain an ideal screw position (perpendicular to the iliosacral joint), to avoid occurrence of extraosseous screw misplacement, to reduce the operating time and the radiation exposure by utilizing this planning approach have not been described yet.

METHODS

On preoperative CT scans of eight human cadaveric specimen individual EPs and APs were identified and transferred to the lateral fluoroscopic projection using a coordinate system with the zero-point in the center of the posterior cortex of the S1 vertebral body (x-axis parallel to upper S1 endplate). Distances were expressed in relation to the anteroposterior distance of the S1 upper endplate (in%). In each specimen on one side a screw was placed with provided EP and AP (New Technique) whereas at the contralateral side a screw was placed without given EP and AP (Conventional Technique). Both techniques were compared using postoperative CT scans to assess distances between predefined EPs and APs and the actually obtained EPs and APs, screw angulations in relation to the iliosacral joint in coronal and axial planes and the occurrence of any extraosseous screw misplacement. The "operating time (OT)" and the "time under fluoroscopy (TUF)" were recorded. Statistical analysis was performed by the Wilcoxon signed-rank test.

RESULTS

EPs were realized significantly more accurate using the new technique in vertical direction. The screw positions in relation to the iliosacral joint showed no significant difference between both techniques. Both techniques had one aberrantly placed screw outside the safe corridor. The (mean±SD) "OT" and the (mean±SD) "TUF" were significantly decreased using the new technique compared to the conventional technique (OT: 7.6±2min versus 13.1±5.8min, p=0.012; TUF: 1.5±0.8min versus 2.2±1.1min).

CONCLUSION

The presented preoperative planning approach increases the accuracy in percutaneous screw fixation of the iliosacral joint, reduces operating time and minimizes radiation exposure to patient and staff.

Accurate fixation of plates and screws for the treatment of acetabular fractures using 3D-printed guiding templates: An experimental study

OBJECTIVE

To investigate the feasibility of the use of 3D-printed guiding templates for accurate placement of plates and screws for internal fixation of acetabular fractures.

METHODS

3D models of the pelvises of 14 adult cadavers were reconstructed using computed tomography (CT). Twenty-eight acetabular fractures were simulated and placement positions for plates and screw trajectories were designed. Bending module was obtained by 3D cutting; guiding template was manufactured using 3D printing, and the plate was pre-bent according to the bending module. Plates and screws were placed in cadaveric pelvises using the guiding template, and 3D model was reconstructed using CT. The designed and real trajectories were matched using 3D registration including the coordinates (entry and exit points) of designed trajectory. The number of qualified points with different accuracy levels was compared using Chi-squared test.

RESULTS

Sixty-four plates and 339 screws were placed with no cortical breach. The absolute difference of the X, Y, and Z coordinates between the designed and real entry points were 0.52±0.45, 0.43±0.36, and 0.53±0.44mm, respectively. The corresponding values for the exit points were 0.83±0.67, 1.22±0.87, and 1.26±0.83mm, respectively. With an accuracy degree ≥1.9mm for the entry points and ≥3.8mm for the exit points, there was no significant difference between the designed and the real trajectories.

CONCLUSION

The 3D-printed guiding template helped achieve accurate placement of plates and screws in the pelvis of adult cadavers.

[Percutaneous internal fixation of pelvic fractures. German version]

BACKGROUND

Percutaneous internal fixation of pelvic fractures is increasing in popularity with multiple new techniques reported.

OBJECTIVES

The purpose of this article is to outline the imaging, indication, planning, equipment, surgical technique and complications of these methods.

METHODS

A review of the literature is provided and the techniques for anterior and posterior pelvic stabilization are discussed.

RESULTS

High-quality preoperative CT scans are essential in planning for this technique. The anterior internal fixator ("InFix") is an effective method for stabilizing the anterior ring and should be usually used in conjunction with posterior fixation. Good technique avoids neurovascular injury, which can be a devastating complication. The retrograde anterior column screw (RACS) is a technique that can be used in most patients, although in smaller patients smaller screw diameters may be needed. The entry point for the screw is more lateral in women than men. Iliosacral screws (ISS) are an effective method of posterior stabilization and can be placed using 2D or 3D fluoroscopy, computer navigation or CT navigation.

CONCLUSION

Percutaneous fixation of pelvic fractures requires high-quality imaging and can be aided by computer navigation. Safe techniques are reproducible; however, not all patients and fracture patterns can be treated using these techniques.

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.

Fluoroscopic Views for a More Accurate Placement of Iliosacral Screws: An Experimental Study

OBJECTIVES

Misperception on the fluoroscopic image showing a well-placed iliosacral (IS) screw can occur, when the screw is in reality misplaced. The purpose of this study was to demonstrate and highlight examples of misperception and suggest alternative inlet and outlet views to confirm adequate IS screw placement.

METHODS

We used 9 different pelvic plastic models. In 8 of those models, IS screws were purposely misplaced: exiting anterior at the midportion of the S1 body, exiting at the lateral aspect of the anterior S1 body, abutting posterior to S1 body, exiting posterior to the S1 body, exiting superior to the far-side of the sacral ala, exiting superior to the S1 body, exiting partially in the S1 foramen, exiting completely in the S1 foramen. One model was used as control with correct screw placement. Different outlet and inlet views were tested to accurately detect important anatomic landmarks and avoid fake phenomenon (FP) using 3 different angles.

RESULTS

Misperception occurred in 3 models: (1) penetration at the midportion of the anterior border of S1, (2) penetration of the superior sacrum ala, and (3) partial penetration of S1 foramen. In the first situation, misperception could be avoided when the "anterior inlet view" was obtained. In the other 2 situations, misperception could be avoided using specific outlet views herein described.

CONCLUSIONS

Our findings highlight that misperception can occur using standard inlet and outlet views. We suggest using 2 variations of the inlet views and 3 variations of the outlet views to avoid misperception in clinical practice.

Stereotactic guidance for navigated percutaneous sacroiliac joint fusion

Arthrodesis of the sacroiliac joint (SIJ) for surgical treatment of SIJ dysfunction has regained interest among spine specialists. Current techniques described in the literature most often utilize intraoperative fluoroscopy to aid in implant placement; however, image guidance for SIJ fusion may allow for minimally invasive percutaneous instrumentation with more precise implant placement. In the following cases, we performed percutaneous stereotactic navigated sacroiliac instrumentation using O-arm^® multidimensional surgical imaging with StealthStation^® navigation (Medtronic, Inc. Minneapolis, MN). Patients were positioned prone and an image-guidance reference frame was placed contralateral to the surgical site. O-arm® integrated with StealthStation® allowed immediate auto-registration. The skin incision was planned with an image-guidance probe. An image-guided awl, drill and tap were utilized to choose a starting point and trajectory. Threaded titanium cage(s) packed with autograft and/or allograft were then placed. O-arm® image-guidance allowed for implant placement in the SIJ with a small skin incision. However, we could not track the cage depth position with our current system, and in one patient, the SIJ cage had to be revised secondary to the anterior breach of sacrum.

Three-dimensional navigation is more accurate than two-dimensional navigation or conventional fluoroscopy for percutaneous sacroiliac screw fixation in the dysmorphic sacrum: a randomized multicenter study

OBJECTIVES

To evaluate the accuracy of computer-assisted sacral screw fixation compared with conventional techniques in the dysmorphic versus normal sacrum.

DESIGN

Review of a previous study database.

SETTING

Database of a multinational study with 9 participating trauma centers.

PATIENTS

The reviewed group included 130 patients, 72 from the navigated group and 58 from the conventional group. Of these, 109 were in the nondysmorphic group and 21 in the dysmorphic group.

INTERVENTION

Placement of sacroiliac (SI) screws was performed using standard fluoroscopy for the conventional group and BrainLAB navigation software with either 2-dimensional or 3-dimensional (3D) navigation for the navigated group.

MAIN OUTCOME MEASUREMENTS

Accuracy of SI screw placement by 2-dimensional and 3D navigation versus conventional fluoroscopy in dysmorphic and nondysmorphic patients, as evaluated by 6 observers using postoperative computerized tomography imaging at least 1 year after initial surgery. Intraobserver agreement was also evaluated.

RESULTS

There were 11.9% (13/109) of patients with misplaced screws in the nondysmorphic group and 28.6% (6/21) of patients with misplaced screws in the dysmorphic group, none of which were in the 3D navigation group. Raw agreement between the 6 observers regarding misplaced screws was 32%. However, the percent overall agreement was 69.0% (kappa = 0.38, P < 0.05).

CONCLUSIONS

The use of 3D navigation to improve intraoperative imaging for accurate insertion of SI screws is magnified in the dysmorphic proximal sacral segment. We recommend the use of 3D navigation, where available, for insertion of SI screws in patients with normal and dysmorphic proximal sacral segments.

LEVEL OF EVIDENCE

Therapeutic level I.

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.