Correlating preoperative imaging with intraoperative fluoroscopy in iliosacral screw placement

Simplifying the Orientation of S1 Iliosacral Screws for Placement in the Dysmorphic Sacrum

BACKGROUND

Determining the proper iliosacral screw orientation in a dysmorphic S1 sacral segment using a C-arm is difficult, and pelvic computed tomography (CT) is often necessary for the preoperative planning. On the preoperative pelvic axial CT section, the intended screw trajectory can be delineated intraosseously along the axis of the oblique osseous corridor. An inherently accurate orientation would be determined by 2 factors: (1) the trajectory is in the pelvic transverse plane, and (2) it is oriented relative to the coronal plane at a patient-specific angle, which should be measured preoperatively. Based on the above reasoning, we aimed to simplify and verify the orientation.

METHODS

After establishing the starting point on the sacral lateral view, we tested a method of simplifying the guidewire orientation: placing the guidewire in the pelvic transverse plane and then manipulating it to be angled relative to the coronal plane at the preoperatively measured patient-specific angle. The guidewire orientation should then be reproducibly accurate on the pelvic outlet and inlet views. The feasibility and safety of our method were verified through computer-simulated virtual surgical procedures in 95 dysmorphic sacra and clinical surgical procedures in 12 patients. The primary outcome parameters were the guidewire orientation and screw placement accuracy.

RESULTS

Using our method, the S1 guidewire orientation was reproducibly accurate on the pelvic outlet and inlet views in all of the virtual and clinical surgical procedures. Ninety-five virtual S1 screws (1 screw in each left hemipelvis) were placed intraosseously in the pelvic transverse plane. Fourteen unilateral S1 screws were placed intraosseously in the pelvic transverse plane in the 12 patients (2 patients had double screws) without iatrogenic injuries.

CONCLUSIONS

The guidewire orientation can be simplified by placing the guidewire in the pelvic transverse plane and replicating the preoperatively measured patient-specific angle between the guidewire and the coronal plane. After establishing the starting point on the sacral lateral view, our simplified manipulation yields a reproducibly accurate orientation on the pelvic outlet and inlet views.

LEVEL OF EVIDENCE

Therapeutic Level III . See Instructions for Authors for a complete description of levels of evidence.

Freehand Placement of a Transiliac-Transsacral Screw for Fixation of Posterior Pelvic Ring Injuries

OBJECTIVE

There are many advantages to stabilize the posterior pelvic ring injuries with a transiliac-transsacral (TITS) screw percutaneously. To identify the correct entry point and insert a guidewire accurately for a TITS screw, we propose a method of specifying the optimal entry point, and introduce a technique of enabling freehand placement of a guidewire with fluoroscopic guidance.

METHODS

In this retrospective study, 116 patients who underwent pelvic CT scans and pelvic lateral radiographs at our institution from January 2020 to April 2022 were enrolled. The optimal entry point for a TITS screw was formulated in the strict mid-sagittal CT plane, and then transferred to the pelvic lateral radiograph relying on the sacral cortexes which were easily visible even in the poor fluoroscopy. The relative position of this point to other anatomical markers was checked to confirm its feasibility as an entry point. With the method to locate the entry point, 18 patients suffered the posterior pelvic ring injuries were treated with TITS screws through hammering a reverse Kirschner wire (K-wire) to insert a guidewire assisted by a canula, followed by the validation of the screw placement accuracy.

RESULTS

The transferred point in radiograph was consistently beneath the sacral alar slope, and located posteroinferior to the iliac cortical density (ICD) and anterosuperior to the sacral nerve root tunnel in all 116 patients. In clinical practice, 18 TITS screws were successfully placed in 18 patients without cortex violation. The average operative time for each screw was 20.11 ± 6.29 min, with an average of 14.11 ± 6.81 fluoroscopic shots per screw. At the 3-month follow-up, fracture healing was confirmed in all patients. The average Majeed score was 89.61 ± 6.90 at the final follow-up.

CONCLUSIONS

It's feasible to identify an entry point for a TITS screw based on the sacral cortexes, and hammering a reverse K-wire assisted by a percutaneous kyphoplasty (PKP) canula is a safe and practical technique for guidewire insertion.

Upper sacral segment fixation with converging iliosacral screws: A technical trick for preoperative planning and case series

INTRODUCTION

There are some situations where pelvic surgeons may want to place iliosacral screws with differing trajectories (Sacroiliac and Sacral styles) but may not be able to because of overlapping trajectories.

HYPOTHESIS

Sacroiliac and Sacral style screws can be placed in S1 in select patients by using a preoperative planning technique off the 3D reconstructed surface rendered preoperative CT scan.

MATERIALS/METHODS

Retrospective review of all patients receiving iliosacral screws using the described technique.

RESULTS

Six patients received iliosacral screws using the described technique. When the preoperative planning technique demonstrated feasibility, all screws were able to be safely placed.

DISCUSSION

Placing Sacroiliac and Sacral style screws within S1 may be ideal in some injury patterns. The described technique allows pelvic surgeons facile in iliosacral screw techniques to preoperatively plan for this construct.

LEVEL OF EVIDENCE

VI; Retrospective case series.

Assessment of sacral osseous fixation pathways for same-level dual transiliac-transsacral screw insertion

INTRODUCTION

The purpose of this study is to (1) describe a pre-operative planning technique using non-reformatted CT images for insertion of multiple transiliac-transsacral (TI-TS) screws at a single sacral level, (2) define the parameters of a sacral osseous fixation pathway (OFP) that will allow for insertion of two TI-TS screws at a single level, and (3) identify the incidence of sacral OFPs large enough for dual-screw insertion in a representative patient population.

METHODS

Retrospective review at a level-1 academic trauma center of a cohort of patients with unstable pelvic injuries treated with two TI-TS screws in the same sacral OFP, and a control cohort of patients without pelvic injuries who had CT scans for other reasons.

RESULTS

Thirty-nine patients had two TI-TS screws at S1. Eleven patients, all with dysmorphic osteology, had two TI-TS screws at S2. The average pathway size in the sagittal plane at the level the screws were placed was 17.2 mm in S1 vs 14.4 mm in S2 (p = 0.02). Twenty-one patients (42%) had screws that were intraosseous and 29 (58%) had part of a screw that was juxtaforaminal. No screws were extraosseous. The average OFP size of intraosseous screws was 18.1 mm vs. 15.5 mm for juxtaforaminal screws (p = 0.02). Fourteen millimeters was used as a guide for the lower limit of the OFP for safe dual-screw fixation. Overall, 30% of S1 or S2 pathways were ≥ 14 mm in the control group, with 58% of control patients having at least one of the S1 or S2 pathways ≥ 14 mm.

CONCLUSIONS

OFPs ≥ 7.5 mm in the axial plane and 14 mm in the sagittal plane on non-reformatted CT images are large enough for dual-screw fixation at a single sacral level. Overall, 30% of S1 and S2 pathways were ≥ 14 mm and 58% of control patients had an available OFP in at least one sacral level.

Imaging of Pelvic and Acetabular Trauma: Part 1, Osseous Findings

Pelvic ring injuries and acetabular fractures are complex injuries and are often challenging to treat for a number of reasons. Orthopaedic trauma surgeons critically evaluate pelvic radiographs and CT images to generate an appropriate detailed injury and patient-specific preoperative plan. There are numerous crucial osseous details that surgeons should be aware of. Often, some of the most important factors that affect patients in treatment timing decisions, assessing reduction strategies, and deciding and inserting fixation constructs may be subtle on preoperative imaging. The radiographic and CT imaging findings covered subsequently should be sought out and appreciated preoperatively. Combining all the available osseous information helps the surgeon predict potential pitfalls and adjust surgical plans before incision. Ensuring a methodical and meticulous imaging review allows for the development of a detailed preoperative plan and helps avoid intraoperative missteps. This process will inherently streamline the surgical procedure and optimize the patient's surgical care. Maximizing the accuracy of the preoperative planning process can streamline the treatment algorithm and ultimately contribute to the best possible clinical outcome.

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.

Sacroiliac screws fixation navigated with three-dimensional printing personalized guide template for the treatment of posterior pelvic ring injury: A case report

Objective

Pelvic injuries refer to the disruption of the inherent structural and mechanical integrity of the pelvic ring. Sacroiliac screw fixation technique is often used for the treatment of posterior pelvic ring injury, which is prone to the iatrogenic injury. Various attempts were proposed to avoid iatrogenic injuries, while the executing processes are usually too cumbersome. The patient-personalized guide template based on 3D printing technology has been considered as a promising method, which can achieve lower deviation and higher accuracy in a simple and convenient way. We reported the first case of posterior pelvic ring injury using 3D printing personalized guide template with the verification of intraoperative CT.

Methods

The subject was a 74-year-old female with posterior pelvic ring injury. Two patient-specific guide templates were customized based on 3D printing technology, one for S1 and the other for S2. We used the guide templates for navigation to place the sacroiliac screws. The placement of screws was verified by intraoperative CT. Intraoperative and postoperative variables were collected.

Results

The technique helped us successfully insert the sacroiliac screws into the safe zone. The intraoperative blood loss was 23.03 ml, and the duration of operation was 62 min. The exposure dose during CT scanning was 7.025 mSv. The assessment of screws position was excellent. Furthermore, there was no sign of any functional impairment postoperatively.

Conclusion

Sacroiliac screws fixation with the assistance of 3D printing personalized guide template under the verification of intraoperative CT may be a promising method to treat posterior pelvic ring injuries.

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.

TiRobot‑assisted versus conventional fluoroscopy-assisted percutaneous sacroiliac screw fixation for pelvic ring injuries: a meta‑analysis

BACKGROUND

The TiRobot is the only robot that has been reported in the literature for posterior pelvic injuries. We aim to compare TiRobot-assisted pelvic screw fixation with the conventional fluoroscopy-assisted percutaneous sacroiliac screw fixation.

METHODS

We conducted a meta-analysis to identify studies involving TiRobot‑assisted versus conventional percutaneous sacroiliac screw fixation for pelvic ring injuries in electronic databases, including Web of Science, Embase, PubMed, Cochrane Controlled Trials Register, Cochrane Library, Highwire, CBM, CNKI, VIP, and WanFang database, up to April 2022. The following keywords were used: "TiRobot," "robot," "robotic," "pelvic fracture," "screw fixation," "percutaneous," and "pelvic ring injury." Pooled effects of this meta-analysis were calculated using STATA SE version 15.0.

RESULTS

Compared with conventional fluoroscopy-assisted percutaneous sacroiliac screw fixation, TiRobot will result in less radiation exposure time of screw implantation (P = 0.000), less frequency of intraoperative fluoroscopy (P = 0.000), fewer guide wire attempts (P = 0.000), less intraoperative blood loss (P = 0.005), better screw accuracy (P = 0.011), better Majeed score (P = 0.031), and higher overall excellent and good rates of Majeed score (P = 0.018). However, there were no significant differences in terms of operative time (P = 0.055), fracture healing time (P = 0.365), and overall excellent and good rate of reduction accuracy (P = 0.426) between the two groups.

CONCLUSION

TiRobot-assisted fixation has less intraoperative fluoroscopy and intraoperative blood loss, superior screw accuracy, and Majeed score compared with conventional percutaneous sacroiliac screw fixation. TiRobot has no significant effect on operative time, fracture healing time, and reduction accuracy. Given the relevant possible biases in our meta-analysis, we required more adequately powered and better-designed RCT studies with long-term follow-up to reach a firmer conclusion.

Modified Lumbopelvic Technique Using S1 Pedicle Screws for Spinopelvic Dissociation U-Type and H-Type Sacral Fractures With Kyphotic Deformity

Spinopelvic dissociation injuries are complex injuries defined as discontinuity between the appendicular and axial skeleton. Fracture patterns are variable, but U-type and H-type fractures are common and often present with kyphotic deformity along with translational displacement and impaction. The ideal method of fixation has not been established for these injuries. The goals of treatment include restoration of alignment, stability, and neural decompression as needed. Traditional methods of lumbopelvic fixation have spanned the upper sacral fracture site. Our novel modified method of lumbopelvic fixation directly instruments the S1 body. This allows for direct manipulation of the fracture which we theorize improves reduction and increases stability across the fracture. This article characterizes the injury patterns, outlines the modified technique, and reports the clinical and radiographic outcomes of our modified lumbopelvic fixation technique and construct.

The Utility of the Hyperinlet View in Posterior Fixation of Pelvic Ring Injuries

Percutaneous pelvic fixation has evolved into a widely used, safe, and effective treatment option in the management of pelvic ring injuries. Proper preoperative and intraoperative radiographic evaluation of these injuries is critical to ensure safe placement of fixation of the pelvis. Traditional intraoperative views for posterior pelvic ring fixation include the pelvic inlet and outlet views. We propose that the intraoperative use of a hyperinlet view, which uses additional cranial tilt relative to the traditional inlet view, is helpful to better delineate the spinal canal and thereby better define the posterior limit of the osseous fixation pathway of the upper sacral segments. This study illustrates the use of this novel radiographic view and presents a patient cohort in which it was effectively used.

Differences in Accuracy and Radiation Dose in Placement of Iliosacral Screws: Comparison between 3D and 2D Fluoroscopy

Percutaneous iliosacral screw fixation is a widely accepted method of stabilizing the posterior pelvic ring. Recently developed tools such as 3D-navigated fluoroscopy and computed navigation seem to prevent a surgeon from conducting screw misplacement. The study aimed to comparatively assess the introduction of sacroiliac screw placement using 2D and 3D fluoroscopy in terms of accuracy and radiation exposure. Iliosacral screws were introduced in 37 patients using 2D (group N1) and in 36 patients using 3D fluoroscopy (group N2) techniques. Overall, 61 and 56 screws were introduced in groups N1 and N2, respectively. Screw placement accuracy was assessed using postoperative computed tomography and Smith’s scale. Intraoperative radiation exposure was also assessed. No differences were noted between groups in terms of screw positioning accuracy and radiation dose. Both 2D and 3D fluoroscopy provide good visualization for safely placing percutaneous iliosacral joint screws. Using 3D fluoroscopy-based navigation in comparison with 2D fluoroscopy is not advantageous.

Is the Iliac Cortical Density Similarly Positioned in the Developing Pediatric Pelvis?

OBJECTIVES

The iliac cortical density (ICD) is a critical fluoroscopic landmark for pelvic percutaneous screw placement. Our purpose was to evaluate the ICD as a landmark in pediatrics and quantify the diameter of osseous pathways for 3 screw trajectories: iliosacral (IS) at S1 and transiliac-transsacral (TSTI) at S1 and S2.

METHODS

Two hundred sixty-seven consecutive pelvic CT scans in children 0-16 years of age were analyzed. ICD and S1 vertebral heights were measured at multiple regions along S1. Their height and corresponding ratios, as well as osseous screw corridor dimensions were compared between age groups and by the dysmorphic status.

RESULTS

In the nondysmorphic pelvises, S1 height, ICD height, and the ICD to S1 height ratio increased across age groups for all locations (P < 0.001). All 3 screw pathway diameters increased with age (P < 0.001). In the dysmorphic group, there was no increase in ICD to S1 height ratio with age. Except for the age 0-2 group, the ICD to S1 height ratios were significantly larger in the nondysmorphic group. In the dysmorphic group, S1 TSTI pathway remained narrow with age, whereas IS at S1 and TSTI at S2 had a significant increased diameter with age (P < 0.001).

CONCLUSION

The ICD is a useful fluoroscopic landmark for percutaneous screw placement in the pediatric pelvis. For nondysmorphic pelvises, the ICD to S1 height ratio, as well as osseous corridors for IS, TSTI at S1, and TSTI at S2 screw trajectories increase significantly with age. The margin for safe screw placement in S1 is smaller for younger and dysmorphic pelvises.

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.].

Techniques for predicting and avoiding unintentional biplanar movements during iliosacral screw placement

The technique for placing iliosacral screws typically involves the surgeon using an inlet and outlet view as the primary means for assessing the anteroposterior and craniocaudal position of the guidewire, respectively. However, because these views are rarely, if ever, orthogonal to one another, this technique will inevitably lead to unintentional biplanar movements. These unintentional movements, in turn, require correction, which can increase operating room and fluoroscopic time. Here we calculate the degree and magnitude of these unintentional movements. Additionally, we provide a simple technique for minimizing or eliminating them altogether.

Is the Implant in Bone? The Accuracy of CT and Fluoroscopic Imaging for Detecting Malpositioned Pelvic Screw and SI Fusion Implants

BACKGROUND

Spine fusions to the pelvis have been associated with increased strain to the sacroiliac joint (SI) and possibly continued postoperative low back pain. To minimize this, concomitant SI joint fusion at the time of lumbopelvic fixation has been advocated. This requires concomitant placement of sacral alar iliac screws (S2AI) for lumbopelvic fixation and triangular titanium rods (TTR) for the SI joint fusion. Traditionally, surgeons have mostly relied on fluoroscopic images to confirm final implant position and patient safety after pelvic instrumentation, although computer tomography (CT) has also been used.

METHODS

We wanted to know which imaging modality, if any, was superior in helping to identify malpositioned implants during concomitant lumbopelvic fixation and SI joint fusion. We instrumented pelvic sawbones models with S2AI screws, TTR's, or both in the correct anatomic positions or malpositioned variants that led to known cortical breaches. Pelvic models were then imaged with fluoroscopy and CT, and the images assessed by blinded reviewers (spine surgeons and a musculoskeletal radiologist) for the presence of cortical breaches, the identity of the breached implant, and its direction. The responses of the blinded reviewers were then compared to the known position of the implants and Kappa coefficient calculated to determine agreement.

RESULTS

We found that thorough evaluation of implant position with multiple fluoroscopic views (kappa 0.641) or CT imaging (kappa 0.906) allowed reviewers to assess implant position, identity, and breach direction.

CONCLUSION

These findings suggest that intraoperative CT imaging allows surgeons to make the best decision regarding implant position prior to leaving the operating room, thus potentially improving patient safety and unplanned returns to the operating room.Level of Evidence: V.

Posterior pelvic ring bone density with implications for percutaneous screw fixation

BACKGROUND

Although the second (S2) and third (S3) sacral segments have been established as potential osseous fixation pathways for screw fixation, the S2 body has been demonstrated to have inferior bone density when compared to the body of the first (S1) sacral segment. Caution regarding the use of iliosacral screws at this level has been advised as a result. As transiliac-transsacral screws traverse the lateral cortices of the posterior pelvis, they may be relying on bone with superior density for purchase, which could obviate this concern. The objective of this study was to compare the bone density of the posterior ilium and sacroiliac joint to that of the sacral body at the first (S1), second (S2), and third (S3) sacral levels.

MATERIALS AND METHODS

A retrospective case series was performed, reviewing the CT scans of 100 patients without prior pelvic trauma. Each CT was confirmed to have available osseous fixation pathways at the first (S1), second (S2), and third (S3) sacral segments. The bone density of the posterior ilium/sacroiliac joint (PISJ) and sacral body (SB) was measured using the embedded standardized Hounsfield units (HU) tool at each sacral level.

RESULTS

The average S2 PISJ bone density (320.1) was significantly higher than the S1 (286.5) and S3 (278.9) PISJ (p < 0.0001) and S1 and S3 PISJ was not statistically different. The S1 sacral body bone density (231.1) was significantly higher than the S2 (182.1) and S3 (126.8) bone density (p < 0.0001). The PISJ bone density is greater than the sacral body at every sacral level (p < 0.0001).

CONCLUSION

The S2 PISJ bone density is significantly greater than S1. The S1, S2, and S3 PISJ bone density is greater than the sacral body at all sacral levels, and the S1 body has higher bone density than the S2 and S3 bodies. These differences in bone density may have implications for the stability of posterior pelvic ring fixation constructs with regard to screw purchase.

LEVEL OF EVIDENCE

Level III-Case cohort series.

Vertical Shear Pelvic Ring Injury Adjacent to Retained Pelvic Hardware: A Case Report

CASE

A 47-year-old obese woman presented with a vertical shear (VS) pelvic ring injury after a motor vehicle accident around her previous posterior pelvic hardware. The patient underwent closed reduction with percutaneous posterior screw fixation using combined fluoroscopy and O-arm (Medtronic).

CONCLUSION

A rare case of VS pelvic injury with indwelling posterior pelvic hardware does not automatically preclude placement of percutaneous sacroiliac and transiliac-transsacral screws. Combining fluoroscopic imaging and O-arm enables safe screw placement, saving patients from invasive surgeries.

Computerised Tomography Analysis of Pelvic Inlet and Outlet Fluoroscopic View Angles

BACKGROUND

Pelvic inlet and outlet fluoroscopy views are routinely used in operative treatment of posterior pelvic ring injuries. In this study, we aimed to evaluate the angles of pelvic inlet and outlet fluoroscopic view, their differences with hip flexion and the correlation of these differences with sacral slope changes.

MATERIALS AND METHODS

Sagittal reconstructions of 100 lumbopelvic CT were used to measure sacral slope, pelvic inlet and outlet view angles. The range of pelvic inlet-outlet view angles and their relation with age, sex and sacral slope were analyzed. In ten of these 100 patients, who were undergone a second CT imaging, hips were passively flexed to 60° to change pelvic tilt. The difference in sacral slope and pelvic inlet-outlet view angles in different positions were compared.

RESULTS

Mean angles for inlet view, outlet view and sacral slope were 28.9, 41.4 and 37.0, respectively. There was no difference between males and females (p > 0.05). Pelvic outlet angles had a negative correlation with age (p < 0.05). Sacral slope changes with hip flexion showed a negative correlation with inlet angles and positive correlation with outlet angles (p < 0.05). The differences in sacral slope, pelvic inlet and outlet view angles between two measurements were equal.

CONCLUSIONS

The pelvic inlet and outlet view angles shows a wide range without a standard so we suggest preoperative CT scan to plan the optimal angles before pelvic ring surgery. The difference in these angles due to pelvic tilt during the surgery may be corrected by measuring the sacral slope difference.

Comparative study of sacroiliac screw placement guided by 3D-printed template technology and X-ray fluoroscopy

OBJECTIVE

To compare the clinical effect of 3D-printed template technology with X-ray fluoroscopy in assisting surgery for sacroiliac screws placement.

DESIGN

Institutional review board-approved retrospective analysis.

PATIENTS

The clinical data of 31 cases of sacroiliac complex injury between January 2015 and December 2016 were analyzed. There were 16 patients, males 11 and females 5, who underwent surgery assisted by 3D-printed template in template group, and that of contemporaneous 15 patients, males 11 and females 4, who underwent traditional surgery were gathered as fluoroscopy group. All those patients were followed up for more than 6 months.

MAIN OUTCOME MEASURES

The operation time and X-ray fluoroscopy times for each screw placement, and the Matta and Majeed score were analyzed and the difference between the two group was tested.

RESULTS

All cases were followed up for 6-20 months, average 11.4 ± 0.6 months. In template group, 19 screws were implanted. Each screw spent 25-38 min, average 27.2 ± 5.3 min, and need 2-5 times fluoroscopy, average 2.7 ± 0.5. The fracture reduction quality was evaluated by Matta score scale: excellent 10, well 4, fair 2, good rate 87.5%; and pelvic function were evaluated by Majeed score scale: excellent 11, well 3, fair 2, and good rate 87.5%. In fluoroscopy group, 17 screws were implanted. Each screw spent 45-70 min, average 60.3 ± 5.8 min, and needs 11-23 times fluoroscopy, average 15.4 ± 3.5. The fracture reduction quality was evaluated by Matta score scale: excellent 7, well 6, fair 2, and good rate 86.7%; and pelvic function was evaluated by Majeed score scale: excellent 6, well 6, fair 3, and good rate 80.0%. The difference in operation time, X-ray fluoroscopy times between template group and fluoroscopy group had statistical significance. But the Matta and Majeed score had no difference between two groups.

CONCLUSION

Compared with traditional surgery, 3D-printed template technology-assisted surgery for sacroiliac screws placement in sacroiliac complex injury patients possesses advantage such as shortened operation time and reduced X-ray exposure times. This technology improves the safety profile of this operation and should be further studied in future clinical applications.

Are Routine Postoperative Computer Tomography Scans Warranted for All Patients After Operative Fixation of Pelvic Ring Injuries?

OBJECTIVE

To evaluate the efficacy of routine postoperative computed topography (CT) scan after percutaneous fixation of unstable pelvic ring injuries.

DESIGN

Retrospective chart review.

SETTING

Level I Trauma Center.

PATIENTS/PARTICIPANTS

A total of 362 consecutive patients underwent operative fixation of unstable pelvic ring injuries during the study period.

INTERVENTION

Postoperative CT scan of the pelvis was obtained in 331 (91%) of the 362 patients treated operatively for unstable pelvic ring injuries.

MAIN OUTCOME MEASUREMENTS

Revision surgery based on routine postoperative CT scan.

RESULTS

Two patients (0.55%) returned to the operating room on the basis of postoperative CT scans due to malpositioned implants. There were no significant differences of age, sex, body mass index, Injury Severity Score, mechanism of injury, smoking status, or diabetes status between those who did and did not undergo revision surgery. A dysmorphic pelvis was identified in 154 (47%) patients. Both patients undergoing revision surgery were determined to have a dysmorphic pelvis while no patients with normal pelvic anatomy returned to the operating room based on postoperative CT (2/154, 1.3% vs. 0/177, 0%, P = 0.22).

CONCLUSIONS

Although there remains a role for postoperative CT scans in the appropriately selected patient, in the hands of experienced orthopaedic traumatologists, patients with adequate intraoperative fluoroscopy and a nondysmorphic pelvis may not require routine postoperative three-dimensional imaging.

LEVEL OF EVIDENCE

Diagnostic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Preoperative planning and safe intraoperative placement of iliosacral screws under fluoroscopic control

OBJECTIVE

Preoperative planning of the starting point and safe trajectory for iliosacral screw (SI screw) fixation using CT scans for safe and accurate fluoroscopically controlled percutaneous SI screw placement.

INDICATIONS

Transalar and transforaminal sacral fractures. SI joint disruptions and fracture-dislocations. Non- or minimally displaced spinopelvic dissociation injuries.

CONTRAINDICATIONS

Transiliac instabilities. Sacral fractures with neurological impairment requiring decompression. Relevant residual displacement after closed reduction attempts. Insufficient fluoroscopic visualization of the anatomical landmarks of the upper sacrum.

SURGICAL TECHNIQUE

Preoperative planning of the starting point and the safe screw trajectory using CT scans and two-dimensional multiplanar reformation tools. Fluoroscopically guided identification of the starting point using the lateral view according to preoperative planning. Advancing the guidewire under fluoroscopic control using inlet and outlet views according to the planned trajectory. Predrilling and placement of 6.5 mm cannulated screws.

POSTOPERATIVE MANAGEMENT

Weightbearing as tolerated using crutches. Immediate CT scan in case of postoperative neurological impairment. Generally no screw removal.

RESULTS

Fifty-nine screws were placed in 34 patients using the described technique. There were 2 cases of screw malpositioning (anatomical landmarks inadequately identified and fluoroscopically controlled SI screw fixation should thus not have been performed at all; in a case with sacral dysmorphism, preoperative planning suggested a posterior and/or caudal S1 starting point, respectively, but intraoperatively, selection of a different starting point and screw trajectory resulted in screw malpositioning with iatrogenic L5 nerve palsy).

Comparison of Efficacy between 3D Navigation-Assisted Percutaneous Iliosacral Screw and Minimally Invasive Reconstruction Plate in Treating Sacroiliac Complex Injury

The clinical efficacy was compared between 3D navigation-assisted percutaneous iliosacral screw (3DPS) and minimally invasive reconstruction plate (MIRP) in treating sacroiliac complex injury and the surgical procedures of 3DPS were introduced. A retrospective analysis was performed on 49 patients with sacroiliac complex injury from March 2013 to May 2017. Twenty-one cases were treated by 3DPS, and 28 cases by MIRP. Intraoperative indexes as operative time, blood loss, incision length, length of hospital stay and postoperative complications were respectively documented. Quality of reduction was postoperatively evaluated by Matta radiological criteria, and clinical effect was assessed by Majeed scoring criteria at the last follow-up. Operative time and hospital stay were significantly shortened, and blood loss, and incision length were significantly reduced in 3DPS group as compared with those in MIRP group (P<0.05). No statistically significant difference was found between 3DPS group and MIRP group in the assessment of reduction and function (P>0.05). It was concluded that both 3DPS and MIRP can effectively treat the sacroiliac complex injury, and 3DPS can provide an accurate, safe and minimally invasive fixation with shorter operative time and hospital stay.

Intra- and interrater reliabilities and a method comparison of 2D and 3D techniques in cadavers to determine sacroiliac screw loosening

Sacroiliac (SI) screw loosening may indicate persistent instability, non-union and contribute to pain. Yet, there is no reliable objective measurement technique to detect and monitor SI screw loosening. In 9 cadaveric pelvises one of two SI screw was turned back approximately 20 mm and subsequently assessed by optical measurement, fluoroscopy and a 3D scan using an image intensifier. CTs were segmented and a contour-based registration of the 3D models and the fluoroscopies was performed to measure SI backing out (X-ray module). Three independent observers performed measurements with three repetitions. Deviation of the measurement techniques to the 3D scan, intra- and interrater reliabilities and method equivalence to the 3D scan were assessed. The X-ray module and two fluoroscopic measurement techniques yielded a difference less than 5 mm compared to the 3D scan and equivalence to the 3D scan. Intrarater reliability was for two observers and almost all techniques very good. Three fluoroscopic measurement techniques and optical measurements displayed a very good interrater reliability. The 3D scan and X-ray module yielded the most precise values for SI screw loosening but only the fluoroscopic measurement of the inlet lateral loosening displayed a good reliability and equivalence to the 3D scan.

When and How to Operate Fragility Fractures of the Pelvis?

Fragility fractures of the pelvis (FFP) are an entity with an increasing frequency. The characteristics of these fractures are different from pelvic ring fractures in younger adults. There is a low energy instead of a high energy trauma mechanism. Due to a specific and consistent decrease of bone mineral density, typical fractures in the anterior and posterior pelvic ring occur. Bilateral sacral ala fractures are frequent. A new classification system distinguishes between four categories with increasing loss of stability. The subtypes represent different localizations of fractures. The primary goal of treatment is restoring mobility and independency. Depending on the amount of instability, conservative or surgical treatment is recommended. The operative technique should be as less invasive as possible. When the broken posterior pelvic ring is fixed operatively, a surgical fixation of the anterior pelvic ring should be considered as well. FFP Type I can be treated conservatively. In many cases, FFP Type II can also be treated conservatively. When conservative treatment fails, percutaneous fixation is performed. FFP Type III and FFP Type IV are treated operatively. The choice of the operation technique is depending on the localization of the fracture. Iliosacral screw osteosynthesis, transsacral bar osteosynthesis, transiliac internal fixation, and iliolumbar fixation are alternatives for stabilization of the posterior pelvic ring. Plate osteosynthesis, retrograde transpubic screw, and anterior internal fixation are alternatives for stabilization of the anterior pelvic ring. Postoperatively, early mobilization, with weight bearing as tolerated, is started. Simultaneously, bone metabolism is also analyzed and its defects compensated. Medical comorbidities should be identified and treated with the help of a multidisciplinary team.

Useful Intraoperative Technique for Percutaneous Stabilization of Bilateral Posterior Pelvic Ring Injuries

Treating patients with bilateral posterior pelvic ring injuries can be challenging. Placement of transiliac-transsacral style screws in available S1 or S2 osseous fixation pathways is becoming an increasingly common fixation method for these unstable injuries. We propose a percutaneous technique that sequences reduction and stabilization of 1 hemipelvis with at least 1 transiliac-transsacral screw and then uses the existing transiliac-transsacral screw and accompanying guide wires to assist in temporary stabilization and definitive fixation of the second hemipelvis.

Is S3 a Viable Osseous Fixation Pathway?

OBJECTIVES

To report the incidence of patients with a third sacral segment (S3) osseous fixation pathway (OFP) that could accommodate a transiliac-transsacral screw.

DESIGN

Retrospective case series.

SETTING

Regional Level 1 Trauma Center.

PATIENTS/PARTICIPANTS

A total of 250 patients without pelvic trauma from January 2017 to February 2017 were included.

INTERVENTION

The axial and sagittal reconstruction images of each patient's computed abdomen and pelvis tomography (CT) scans were reviewed.

MAIN OUTCOME MEASUREMENTS

Each CT was evaluated for the presence of sacral dysmorphism and whether an S3 OFP that could accommodate an intraosseous transiliac-transsacral screw exists.

RESULTS

There were 130 of the 250 patients (52%) with sacral dysmorphism. Overall, 38 of the 250 patients (15.2%) had an S3 OFP that could accommodate a 7.0-mm transiliac-transsacral style screw. When narrowed to patients who had an S3 OFP, 38 of 153 patients (24.8%) could accommodate a 7.0-mm transiliac-transsacral screw. Specific to the 38 patients with an adequate S3 OFP, 34 of 38 patients (89.5%) were noted to have sacral dysmorphism.

CONCLUSIONS

Our study demonstrates that 15.2% of patients have an S3 OFP large enough to accommodate an intraosseous implant. Patients who have sacral dysmorphism are more likely to have an adequate S3 OFP. Additional studies are needed to quantify the S3 OFP, understand the bone quality of the S3 segment and accompanying biomechanical implications, and investigate the anatomical concerns associated with S3 screw placement.

LEVEL OF EVIDENCE

Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

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 Retrograde-Antegrade-Retrograde Technique for Successful Placement of a Retrograde Superior Ramus Screw

Stabilization of pelvic ring injuries and certain acetabular fractures using percutaneous techniques is becoming increasingly more common. Intramedullary superior ramus screw fixation is beneficial in both injury types. While implants can be placed in an antegrade or retrograde direction, parasymphyseal ramus fractures benefit from retrograde implant insertion. In some patients, the parabolic osseous anatomy or obstructing soft tissues of the anterior pelvis or thigh can prevent appropriate hand and instrumentation positioning for appropriate retrograde ramus screw insertion through the entire osseous fixation pathway. Instead of abandoning medullary fixation, we propose a technique utilizing cannulated screws to successfully place retrograde screws in this distinct clinical scenario.

[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.

A Useful Preoperative Planning Technique for Transiliac-Transsacral Screws

Stabilization of posterior pelvic ring injuries is increasingly performed using percutaneously placed iliosacral and transiliac-transsacral screws. Understanding the unique and specific anatomical variations present in each patient is paramount. Multiple methods of evaluating potential osseous fixation pathways for screw placement exist, but many require specific imaging protocols, specialized software, or modification of data. Not all surgeons and institutions have access to these options for a variety of reasons. A simple technique to preoperatively plan for safe transiliac-transsacral screws is proposed.

Bowel preparation prior to percutaneous ilio-sacral screw insertion: is it necessary?

PURPOSE

The aim of this study was to compare the outcomes of ilio-sacral (IS) screw fixation with and without the use of bowel preparation, in terms of obtaining adequate visualisation, malpositioning of screw requiring revision surgery and neurovascular injury.

METHODS

A retrospective case control study was performed. We reviewed 74 consecutive cases of IS screw fixation performed at our institution within the last 5 years. We included all patients who had undergone percutaneous IS screw fixation. Two groups, one consisting of patients who underwent bowel preparation prior to surgery (Group 1) and one consisting of patients who had no bowel preparation (Group 2), were compared in terms of the above outcomes. There were 37 patients in each group. The mean age in Group 1 was 41 years (17-63) and in Group 2 was 47 years (12-89).

RESULTS

In Group 1 there were two procedures abandoned due to poor visualisation. In Group 2 there were no cases abandoned for poor visualisation. There were two nerve injuries in Group 1 and no nerve injuries in Group 2. Revision surgery was performed in four patients in Group 1-for malposition, persistent buttock pain, sciatic nerve palsy and inadequate fixation while one revision performed in Group 2 for persistent buttock pain.

CONCLUSION

Based on these results, we conclude that bowel preparation is not necessary to obtain adequate visualisation for safe and accurate percutaneous IS screw insertion. In fact, in Group 1 two procedures were abandoned and there was higher incidence of complications. Therefore, it would appear that this treatment arm should be abandoned all together. Further studies to prove it conclusively and explain the reasons are required.