Percutaneous fixation of pelvic ring disruptions

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.

Results of open reduction internal fixation versus percutaneous iliosacral screw fixation for unstable pelvic ring injuries: retrospective study of 36 patients

INTRODUCTION

Surgical stabilization of posterior pelvic ring fractures can be achieved by closed reduction and percutaneous fixation (CRPF) or by open reduction and internal fixation (ORIF). The aim of the present study is to compare the clinical results of both methods.

MATERIAL AND METHODS

Medical records of 36 patients consecutively operated for unstable pelvic ring injuries were retrospectively reviewed. We compared 22 patients treated with CRPF versus 14 patients stabilized by using ORIF between 2007 and 2017. The Majeed and Pohlemann scores were used to evaluate postoperative functional outcomes. Complications like blood loss, infection rate, Neurological injury, the operative time and the length of hospital stay were analyzed.

RESULTS

The median Majeed pelvic score was 87 points for the CRPF technique compared with 69 points for the ORIF technique. The median Pohlemann score, operative time and length of hospitalization were similar between the two groups. The median blood loss for the CRPF technique was 300 ml compared to 500 ml for the ORIF technique. CRPF and ORIF procedure had each one neurological lesion. There was one case of infection in the ORIF group and none in the CRPF group. No measurements except for the blood loss have reached the significance threshold.

CONCLUSION

The CRPF technique shows a clear decrease in blood loss. There was no statistically significant difference in the functional results, infection rate, neurological injury, operative time and hospital stay between both techniques.

Percutaneous removal of sacroiliac screw following iatrogenic neurologic injury in posterior pelvic ring injury: A case report

INTRODUCTION

Percutaneous sacroiliac fixation is an effective minimally invasive method for posterior pelvic ring stabilization. Screw misplacement, and subsequent neurologic injury are two well described complications. Managing those complications however is under-reported.

CASE

A young female, sustained an unstable pelvic ring injury as a victim of motor vehicle collision. Following percutaneous sacroiliac screw fixation, she complained of L5 nerve root radiculopathy, and muscle weakness. Percutaneous removal of the screw after a wait period for fracture union resulted in immediate symptoms relief.

DISCUSSION

Safe sacroiliac screw placement is technically demanding requiring good understanding of sacral complex morphology and its anatomic variants. Risk of screw misplacement, and potential neurologic injury increases in dysmorphic sacra, or with inaccurate fracture reduction. Advances in intraoperative imaging modalities have been introduced in an attempt to improve accurate screw insertion. Literature is scarce with reports discussing removal of sacroiliac screw. Technique of screw retrieval is also controversial.

CONCLUSION

This case addresses management of an iatrogenic neurologic complication following percutaneous sacroiliac screw fixation. Our experience showed that, percutaneous retrieval of an intact misplaced sacroiliac screw is achievable, resulting in complete resolution of neurologic symptoms.

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.

Surgery for Unilateral Sacral Fractures: Are the Indications Clear?

OBJECTIVES

To evaluate unilateral sacral fractures and compare those treated operatively versus nonoperatively to determine indications for surgery.

DESIGN

Prospective, multicenter, observational study.

SETTING

Sixteen trauma centers.

PATIENTS/PARTICIPANTS

Skeletally mature patients with pelvic ring injury and unilateral zone 1 or 2 sacral fractures and without anteroposterior compression injuries.

MAIN OUTCOME MEASUREMENTS

Injury plain anteroposterior, inlet, and outlet radiographs and computed tomography scans of the pelvis were evaluated for fracture displacement.

RESULTS

Three hundred thirty-three patients with unilateral sacral fractures and a mean age of 41 years with a mean Injury Severity Score of 15 were included. Ninety-two percent sustained lateral compression injuries, and 63% of all fractures were in zone 1. Thirty-three percent of patients were treated operatively, including all without lateral compression patterns. Operative patients were more likely to have zone 2 fractures (54%) and to have posterior cortical displacement (29% vs. 6.2%), both with P < 0.001. Over 60% of all patients had no posterior displacement. Mean rotational displacements comparing the injured side versus the intact side were no different for patients treated operatively compared with those treated nonoperatively.

CONCLUSIONS

Most unilateral sacral fractures are minimally or nondisplaced. Many patients with radiographically similar fractures were treated operatively and nonoperatively by different surgeons. This suggests an opportunity to develop consistent indications for treatment.

LEVEL OF EVIDENCE

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

CT-guided fixation of pelvic fractures after high-energy trauma, by interventional radiologists: technical and clinical outcome

OBJECTIVE

The aim of our study was to evaluate screw placement accuracy, safety, complications, and clinical outcomes including functional and pain score, in 32 patients treated with CT-guided pelvic ring fixation after high-energy trauma.

MATERIALS AND METHODS

Consecutive patients who were treated by CT-guided fixation of sacral or acetabular fractures after high-energy trauma were included. All procedures were performed under general anesthesia, with dual CT and fluoroscopic guidance, by interventional radiologists. Fractures were minimally displaced or reduced unstable posterior pelvic ring disruptions, with or without sacroiliac disjunction (Tile B or C) and minimally displaced acetabular fractures. The primary outcome evaluated was screw accuracy. Secondary outcomes included patient radiation exposure, duration of the procedure, complications, clinical functional score (Majeed score), and pain scale (VAS, visual analog scale) evaluation during a follow-up period from 4 to 30 months postoperatively.

RESULTS

Thirty-two patients were included (mean age 46) and 62 screws were inserted. Screw placement was correct in 90.3% of patients (95% of screws). Mean procedure duration was 67 min and mean patient radiation exposure was 965 mGy cm. Mean follow-up was 13 months and no complications were observed. The mean Majeed score at final follow-up was 84/100 and the mean VAS was 1.6/10.

CONCLUSION

This technique is an effective and safe procedure in specific cases of pelvic ring and acetabulum fractures. It allows accurate screw placement in a minimally invasive manner, leading to effective management of poly-traumatized patients.

KEY POINTS

• CT-guided pelvic ring fixation, including sacroiliac and acetabular fractures, is an effective and safe procedure. • It allows accurate and minimally invasive screw placement, leading to effective management of poly-traumatized patients. • Multidisciplinary cooperation is essential to ensure efficiency and safety.

A Locked Sacroiliac Joint Dislocation Requiring Open Reduction: A Case Report

CASE

Vertically unstable pelvic ring injuries are often associated with sacroiliac (SI) joint subluxations or dislocations. The following report describes an irreducible SI joint dislocation where the ilium was locked in a position superior to the sacrum. This injury was refractory to initial closed reduction techniques and ultimately required an open reduction.

CONCLUSIONS

This report demonstrates the limitations of closed manipulation for some vertically unstable pelvic ring injuries. It is critical to have a strong understanding of the anatomy and typical manipulations to succeed in both closed and open SI joint reduction attempts.

A novel percutaneous crossed screws fixation in treatment of Day type II crescent fracture-dislocation: A finite element analysis

Objective

Day type II crescent fracture–dislocation is a subtype of pelvic lateral compression injury. At present, there is still a controversy on the operative approach and fixation technique. We have put forward closed reduction and percutaneous crossed screws fixation for treating type-II crescent fracture–dislocation. Finite element analysis is used to compare the biomechanical properties between percutaneous crossed screws and other internal fixations.

Methods

A three-dimensional finite element model of Day type-II crescent fracture–dislocation was simulated using 5 implants, including double anterior plates (Model A), one posterior plate and one iliac screw (Model B), one sacroiliac joint screw (Model C), crossed one iliac screw and one sacroiliac joint screw (Model D), and crossed two iliac screws and one sacroiliac joint screw (Model E). 600-N stress was applied to S1 vertebral end-plate. To evaluate the biomechanical properties, the stress distribution and displacement distribution of the pelvis, stress distribution of the crescent fragment and stress distribution of plate and cannulated screw were recorded and analyzed.

Results

Under the loading of 600N, the maximum pelvic displacements in the finite element model were compared as follows: model E (0.070 ​mm), model D (0.071 ​mm), model A (0.080 ​mm), model C (0.096 ​mm), and model B (0.112 ​mm). The maximum displacements of crescent fragment were compared as follows: model E (0.018 ​mm), model B (0.022 ​mm), model D (0.023 ​mm), model A (0.030 ​mm), and model C (0.043 ​mm). The maximum stress of all implants were compared as follows: model D (90.01 ​Mpa), model E (81.60 ​Mpa), model C (69.07 ​Mpa), model A (56.51 ​Mpa), model B (18.29 ​Mpa). Model E and model D could provide better mechanical support for whole pelvic.

Conclusions

With sufficient biomechanical stability and minimally invasive advantage, percutaneous crossed screw fixation is a recommended treatment for Day Type-II Crescent Fracture–dislocation. It is recommended to fix crescent fracture fragment and sacroiliac joint simultaneously during the operation. If it is difficult to fix the both position, the sacroiliac joint is preferentially fixed.

The translational potential of this article

There is a controversy on the operative approach and fixation technique of Day type-II crescent fracture–dislocation. This article proves that percutaneous crossed screw fixation is a recommended treatment for Day type-II crescent fracture–dislocation by finite element analysis.

Effectiveness of closed reduction and percutaneous fixation of isolated sacral fractures. Functional outcomes and sagittal alignment after 3.6 years in 20 patients

BACKGROUND

Displaced U- or H-shaped sacral fractures (Roy-Camille Grade II or III) are treated at our institution by early transcondylar traction and manual countertraction, hyperlordosis induced by a pad positioned under the lumbo-sacral junction, and percutaneous ilio-sacral screw fixation. The objective of this study was to evaluate the outcome of this technique used in a level 1 trauma centre. Hypothesis Our early reduction technique provides anatomical reduction of U- or H-shaped sacral fractures by correcting the sagittal malalignment due to the intra-sacral kyphosis, thereby obviating the need for decompression laminectomy and improving neurological outcomes.

MATERIAL AND METHODS

We retrospectively evaluated 20 patients treated for U- or H-shaped sacral fractures using our original reduction technique followed by percutaneous fixation only. Mean follow-up was 42.4 months. Mean displacement of the S1 posterior wall was measured on computed tomography scans obtained before and after surgery. Pelvic incidence (PI) and measured lumbar lordosis (LLm) were evaluated on standard radiographs before surgery and on stereoradiographs after surgery. Expected lumbar lordosis (LLe) was computed as LLe=PI+9°. A 25% or greater difference between LLe and LLm defined lumbo-pelvic mismatch. At last follow-up, functional outcomes were assessed based on the Majeed score and the Iowa Pelvic Score (IPS), and a neurological examination was performed.

RESULTS

Mean S1 posterior wall displacement in the sagittal and axial planes was 64% and 64.8%, respectively, before surgery versus 5.6% and 15.2%, respectively, after surgery. At last follow-up, LLm was 63.5° and the LLe-LLm difference was 11.2%; only 3 (15%) patients had lumbo-pelvic mismatch at last follow-up. The mean Majeed score and IPS values were 86.6 and 79, respectively, and lumbo-pelvic mismatch correlated significantly with a worse functional outcome defined as a Majeed score below 75 (p=0.0087). At last follow-up, the neurological dysfunctions were improved in 90% of patients, and 70% of patients had achieved a full neurological recovery.

DISCUSSION/CONCLUSION

Given these encouraging findings, we advocate early reduction and percutaneous fixation of U- or H-shaped sacral fractures. Although technically demanding, this method restores the normal pelvic parameters and improves neurological function.

LEVEL OF EVIDENCE

IV, retrospective observational study.

Interactive Flying Frustums (IFFs): spatially aware surgical data visualization

PURPOSE

As the trend toward minimally invasive and percutaneous interventions continues, the importance of appropriate surgical data visualization becomes more evident. Ineffective interventional data display techniques that yield poor ergonomics that hinder hand-eye coordination, and therefore promote frustration which can compromise on-task performance up to adverse outcome. A very common example of ineffective visualization is monitors attached to the base of mobile C-arm X-ray systems.

METHODS

We present a spatially and imaging geometry-aware paradigm for visualization of fluoroscopic images using Interactive Flying Frustums (IFFs) in a mixed reality environment. We exploit the fact that the C-arm imaging geometry can be modeled as a pinhole camera giving rise to an 11-degree-of-freedom view frustum on which the X-ray image can be translated while remaining valid. Visualizing IFFs to the surgeon in an augmented reality environment intuitively unites the virtual 2D X-ray image plane and the real 3D patient anatomy. To achieve this visualization, the surgeon and C-arm are tracked relative to the same coordinate frame using image-based localization and mapping, with the augmented reality environment being delivered to the surgeon via a state-of-the-art optical see-through head-mounted display.

RESULTS

The root-mean-squared error of C-arm source tracking after hand-eye calibration was determined as [Formula: see text] and [Formula: see text] in rotation and translation, respectively. Finally, we demonstrated the application of spatially aware data visualization for internal fixation of pelvic fractures and percutaneous vertebroplasty.

CONCLUSION

Our spatially aware approach to transmission image visualization effectively unites patient anatomy with X-ray images by enabling spatial image manipulation that abides image formation. Our proof-of-principle findings indicate potential applications for surgical tasks that mostly rely on orientational information such as placing the acetabular component in total hip arthroplasty, making us confident that the proposed augmented reality concept can pave the way for improving surgical performance and visuo-motor coordination in fluoroscopy-guided surgery.

Surgical Fixation of Geriatric Sacral U-Type Insufficiency Fractures: A Retrospective Analysis

OBJECTIVES

To define the incidence of sacral U-type insufficiency fracture and describe management of a consecutive series of patients with this injury.

DESIGN

Retrospective analysis.

SETTING

Single Level II trauma center.

PATIENTS/PARTICIPANTS

Sixteen adult patients with sacral U-type insufficiency fractures treated over a 36-month period.

INTERVENTION

Patients were indicated for percutaneous screw fixation of the posterior pelvis if they had posterior pelvic pain that prohibited mobilization.

MAIN OUTCOME MEASUREMENTS

Visual analog scale for pain, distance ambulated on postoperative day 1, and change in sacral kyphosis.

RESULTS

The sacral U-type insufficiency fracture incidence was 16.7% (19/114); average patient age was 75 years. Delayed surgery was performed after primary nonoperative treatment had failed in 62.5% (10/16) at an average 83 days postinjury. Acute surgery was performed in 37.5% (6/16) at an average 5 days postinjury. Distance ambulated on postoperative day 1 was 114.4 feet [95% confidence interval (CI) (50.6, 178.2)] and 88.7 feet [95% CI (2.8, 174.6)] in the delayed and acute surgery groups, respectively, P = 0.18. Change in visual analog scale for pain was -3.2 [95% CI (-5.0, -1.4)] and -3.7 [95% CI (-7.0, -0.4)] in the delayed and acute surgery groups, respectively, P = 0.15. Change in sacral kyphosis from presentation to surgery was 12.3 degrees [95% CI (6.7, 17.9)] and 0.3 degrees [95% CI (-0.2, 0.9)] in the delayed and acute surgery groups, respectively, P < 0.01. Minimum follow-up was 12 months.

CONCLUSIONS

Treatment of sacral U-type insufficiency fractures by percutaneous screw fixation permits early mobilization, provides rapid pain relief, and prevents progressive deformity.

LEVEL OF EVIDENCE

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

[Treatment of unstable pelvic fractures by cannulated screw internal fixation with the assistance of three-dimensional printing insertion template]

Objective

To evaluate the effectiveness of unstable pelvic fractures treated by cannulated screw internal fixation with the assistance of three-dimensional (3D) printing insertion template.

Methods

The clinical data of 10 patients who underwent surgical treatment for unstable pelvic fractures by cannulated screw internal fixation with the assistance of 3D printing insertion template between May 2015 and June 2016 were retrospectively analysed. There were 7 males and 3 females with an average age of 37.5 years (range, 20-58 years). The causes of injury included falling from height in 5 cases, crushing from heavy load in 1 case, and traffic accidents in 4 cases. The interval from injury to admission was 1-5 hours (mean, 3.1 hours). The fracture situation included 6 cases of sacral fracture, 1 case of right sacroiliac joint dislocation, and 3 cases of iliac bone fracture. There were 10 cases of superior and inferior pubic rami fracture, including 3 cases on the left side (2 cases of suprapubic fracture adjacent to symphysis pubis), 2 cases on the right side, and 5 cases on the bilateral. All fractures were classified according to the Tile system, there were 4 cases of type B2, 1 of type B3, 4 of type C1, and 1 of type C2. The radiological outcome was evaluated by Matta scale, and the positions of the iliosacral screw and superior pubic ramus screw were evaluated according to 3D reconstruction of CT postoperatively. The functional outcome was evaluated by Majeed function scale.

Results

The average time of each screw implantation was 30 minutes, and the average blood loss per screw incision was 50 mL. The time of implantation of each sacroiliac screw was 24-96 seconds (mean, 62 seconds), and the time of implantation of each suprapubic screw was 42-80 seconds (mean, 63.2 seconds). The hospitalization duration was 17-90 days (mean, 43.7 days). All incisions healed by first intention. All patients were followed up 12-22 months (mean, 15.6 months). The radiological outcome was excellent in 8 cases and good in 2 cases according to Matta scale; and 3D reconstruction of CT demonstrated that all the 9 iliosacral screws were placed as type Ⅰ, and all the 13 suprapubic ramus screws were placed as grade 0 on the first postoperative day. No complication such as neurovascular injury, screw back out or rupture, or secondary fracture displacement was observed during the follow-up. At 6 months after operation, the X-ray films showed good fracture healing in all the 10 patients. The functional outcome was excellent in 9 cases and good in 1 case according to Majeed scale at 1 year after operation. One patient sustained Tile C2 pelvic disruption complicated with L ₅ nerve root injury achieved complete nervous functional recovery at last follow-up.

Conclusion

It has advantages of precise screw insertion and lower risk of neurovascular injury to treat unstable pelvic fractures by cannulated screw internal fixation with the assistance of 3D printing insertion template, which can be a good alternative for the treatment of unstable pelvic fractures.

Biomechanical evaluation of location and mode of failure in three screw fixations for a comminuted transforaminal sacral fracture model

Background

Pelvic ring–comminuted transforaminal sacral fracture injuries are rotationally and vertically unstable and have a high rate of failure.

Objective

Our study purpose was to use three-dimensional (3D) optical tracking to detect onset location of bone–implant interface failure and measure the distances and angles between screws and line of applied force for correlation to strength of pelvic fracture fixation techniques.

Methods

3D relative motion across sacral–rami fractures and screws relative to bone was measured with an optical tracking system. Synthetic pelves were used. Comminuted transforaminal sacral–rami fractures were modelled. Each pelvis was stabilised by either (1) two iliosacral screws in S1, (2) one transsacral screw in S1 and one iliosacral screw in S1 and (3) one trans-alar screw in S1 and one iliosacral screw in S1; groups 4–6 consisted of fixation groups with addition of anterior inferior iliac pelvic external fixator. Eighteen-instrumented pelvic models with right ilium fixed simulate single-leg stance. Load was applied to centre of S1 superior endplate. Five cycles of torque was initially applied, sequentially increased until permanent deformation occurred. Five cycles of axial load compression was next applied, sequentially increased until permanent deformation occurred, followed by axial loading to catastrophic failure. A Student t test was used to determine significance (p < 0.05).

Results

The model, protocol and 3D optical system have the ability to locate how sub-catastrophic failures initiate. Our results indicate failure of all screw-based constructs is due to localised bone failure (screw pull-in push-out at the ipsilateral ilium–screw interface, not in sacrum); thus, no difference was observed when not supplemented with external fixation.

Conclusion

Inclusion of external fixation improved resistance only to torsional loading.

Translational Potential of this Article

Patients with comminuted transforaminal sacral–ipsilateral rami fractures benefit from this fixation.

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

INTRODUCTION

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

PATIENTS AND METHODS

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

RESULTS

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

CONCLUSION

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

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

Background:

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

Methods:

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

Results:

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

Conclusions:

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

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.

3D printing-based minimally invasive cannulated screw treatment of unstable pelvic fracture

Background

Open reduction and internal fixation of pelvic fractures could restore the stability of the pelvic ring, but there were several problems. Minimally invasive closed reduction cannulated screw treatment of pelvic fractures has lots advantages. However, how to insert the cannulated screw safely and effectively to achieve a reliable fixation were still hard for orthopedist. Our aim was to explore the significance of 3D printing technology as a new method for minimally invasive cannulated screw treatment of unstable pelvic fracture.

Methods

One hundred thirty-seven patients with unstable pelvic fractures from 2014 to 2016 were retrospectively analyzed. Based on the usage of 3D printing technology for preoperative simulation surgery, they were assigned to 3D printing group (n = 65) and control group (n = 72), respectively. These two groups were assessed in terms of operative time, intraoperative fluoroscopy, postoperative reduction effect, fracture healing time, and follow-up function. The effect of 3D printing technology was evaluated through minimally invasive cannulated screw treatment.

Results

There was no significant difference in these two groups with respect to general conditions, such as age, gender, fracture type, time from injury to operation, injury cause, and combined injury. Length of surgery and average number of fluoroscopies were statistically different for 3D printing group and the control group (p < 0.01), i.e., 58.6 vs. 72.3 min and 29.3 vs. 37 min, respectively. Using the Matta radiological scoring systems, the reduction was scored excellent in 21/65 cases (32.3%) and good in 30/65 cases (46.2%) for the 3D printing group, versus 22/72 cases (30.6%) scored as excellent and 36/72 cases (50%) as good for the control group. On the other hand, using the Majeed functional scoring criteria, there were 27/65 (41.5%) excellent and 26/65 (40%) good cases for the 3D printing group in comparison to 30/72 (41.7%) and 28/72 (38.9%) cases for the control group, respectively. This suggests no significant difference between these two groups about the function outcomes.

Conclusion

Full reduction and proper fixation of the pelvic ring and reconstruction of anatomical morphology are of great significance to patients’ early functional exercise and for the reduction of long-term complications. This retrospective study has demonstrated the 3D printing technology as a potential approach for improving the diagnosis and treatment of pelvic fractures.

Trial registration

The study was retrospectively registered at the Chinese Clinical Trial Registry, number: ChiCTR-TRC-17012798, trial registration date: 26 Sept. 2017.

Safe Zone Quantification of the Third Sacral Segment in Normal and Dysmorphic Sacra

OBJECTIVE

To quantify the osseous anatomy of the dysmorphic third sacral segment and assess its ability to accommodate internal fixation.

DESIGN

Retrospective chart review of a trauma database.

SETTING

University Level 1 Trauma Center.

PATIENTS

Fifty-nine patients over the age of 18 with computed tomography scans of the pelvis separated into 2 groups: a group with normal pelvic anatomy and a group with sacral dysmorphism.

MAIN OUTCOME MEASUREMENTS

The sacral osseous area was measured on computed tomography scans in the axial, coronal, and sagittal planes in normal and dysmorphic pelves. These measurements were used to determine the possibility of accommodating a transiliac transsacral screw in the third sacral segment.

RESULTS

In the normal group, the S3 coronal transverse width averaged 7.71 mm and the S3 axial transverse width averaged 7.12 mm. The mean S3 cross-sectional area of the normal group was 55.8 mm. The dysmorphic group was found to have a mean S3 coronal transverse width of 9.49 mm, an average S3 axial transverse width of 9.14 mm, and an S3 cross-sectional area of 77.9 mm.

CONCLUSIONS

The third sacral segment of dysmorphic sacra has a larger osseous pathway available to safely accommodate a transiliac transsacral screw when compared with normal sacra. The S3 segment of dysmorphic sacra can serve as an additional site for screw placement when treating unstable posterior pelvic ring fractures.

A New Modified Method for Inserting Iliosacral Screw versus the Conventional Method

Study Design

Methodological study.

Purpose

To our knowledge, this is the first study to introduce a new modified method for inserting iliosacral screws and to compare its results with those of a conventional method.

Overview of Literature

Previous techniques, such as open reduction and internal fixation, are associated with perioperative hemorrhage, postoperative infection, and neurological deficits. Although percutaneous iliosacral screw insertion confers the advantage of being minimally invasive, leading to less blood loss and a low postoperative infection rate, it harbors the risk of screw malpositioning due to narrow sacral proportions and a high interindividual variability.

Methods

Nine cadaveric pelvises were included in this study, with one hemipelvis of each being assigned to the new modified method and the other to the conventional iliosacral screw insertion method. In the new modified method, the guidewire entry point was determined using a lateral sacral X-ray. To do so, we first identified the anterosuperior quadrant of the S1 body on one hemipelvis. The anterosuperior quadrant was further divided into four imaginary quadrants, and the guidewire was inserted into the posteroinferior quadrant. The guidewire trajectory was perpendicular to the sagittal plane so that the guidewire resembled a single point in the lateral sacral view. Guidewires were inserted into corresponding hemipelves using the conventional method as described in the literature. Subsequently, an axial computed tomography scan with 1-mm fine cuts was obtained, and sagittal and coronal views were reconstructed. The distance of the guidewire from the sacral canal, anterior sacral cortex, and first sacral foramen was measured in axial, sagittal, and coronal views. The minimum measurement among different views was defined as the safety index of the insertion methods. The conventional and new modified methods were then compared in terms of safety and duration of the procedure.

Results

The minimum distance of the guidewire from the S1 foramen and anterior sacral cortex was not significantly different between the two methods. However, the minimum distance between the guidewire and sacral canal was significantly greater in the new modified method than in the conventional method. The duration of guidewire insertion was significantly shorter in the new modified method than in the conventional method.

Conclusions

This new modified method of iliosacral screw insertion could be safely and simply implemented while taking less surgical time than the conventional methods.

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.

Robotically Assisted Long Bone Biopsy Under MRI Imaging: Workflow and Preclinical Study

RATIONALE AND OBJECTIVES

Our research team has developed a magnetic resonance imaging (MRI)-compatible robot for long bone biopsy. The robot is intended to enable a new workflow for bone biopsy in pediatrics under MRI imaging. Our long-term objectives are to minimize trauma and eliminate radiation exposure when diagnosing children with bone cancers and bone infections. This article presents our robotic systems, phantom accuracy studies, and workflow analysis.

MATERIALS AND METHODS

This section describes several aspects of our work including the envisioned clinical workflow, the MRI-compatible robot, and the experimental setup. The workflow consists of five steps and is intended to enable the entire procedure to be completed in the MRI suite. The MRI-compatible robot is MR Safe, has 3 degrees of freedom, and a remote center of motion mechanism for orienting a needle guide. The accuracy study was done in a Siemens Aera 1.5T scanner with a long bone phantom. Four targeting holes were drilled in the phantom.

RESULTS

Each target was approached twice at slightly oblique angles using the robot needle guide for a total of eight attempts. A workflow analysis showed the average time for each targeting attempt was 32 minutes, including robot setup time. The average 3D targeting error was 1.39 mm with a standard deviation of 0.40 mm. All of the targets were successfully reached.

CONCLUSION

The results showed the ability of the robotic system in assisting the radiologist to precisely target a bone phantom in the MRI environment. The robot system has several potential advantages for clinical application, including the ability to work at the MRI isocenter and serve as a steady and precise guide.

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.

Percutaneous iliosacral screw fixation in unstable pelvic fractures

Surgical treatment of unstable pelvic fractures Type C, has a vertical instability that is not controlled by traction and supine; therefore, orthopedic and functional treatments undertaken by default are sources of complications. The closed reduction with percutaneous sacroiliac fixation solves the problem of vertical instability; but at the cost of learning the method. Five patients with unstable pelvic fractures; were treated by percutaneous sacroiliac fixation. This reliable and useful method in the stabilization of unstable pelvic fractures. Good functional results are predictable based on the severity of pelvic fractures and associated injuries. The low rates of complications and the minimally invasive nature are the advantages of this method.

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.

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.

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

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

Optimization of technique for insertion of implants at the supra-acetabular corridor in pelvis and acetabular surgery

The technique for application of implants at the sciatic buttress has been well described in the pelvic and acetabular fracture reconstruction literature. We described a new use of the inlet–obturator oblique view for the identification of the anterior inferior iliac spine, which is the entry point of implants, and we provide a detailed fluoroscopic and radiographic description of this view. A small series of 15 patients who underwent an application of an anterior inferior pelvic external (supra-acetabular) fixator via this technique is presented. We consider the use of the obturator oblique for the identification of the entry point unnecessary, and we advocate for the use of only the inlet–obturator oblique and iliac oblique views when implants are applied to the sciatic buttress.

Open reduction internal fixation versus percutaneous iliosacral screw fixation for unstable posterior pelvic ring disruptions

BACKGROUND

Surgical stabilization of posterior pelvic ring fractures can be achieved by either open or closed methods. They all provide a comparable biomechanical stability. The aim of the present study is to compare the clinical results of both techniques for treating posterior pelvic ring injuries.

MATERIAL AND METHODS

Seventy patients operated for unstable posterior pelvic ring disruptions were retrospectively reviewed. We compared 35 patients treated by open reduction internal fixation (ORIF group) versus 35 patients stabilized by using closed reduction and percutaneous iliosacral screw fixation (CRIF group) under fluoroscopic guidance.

RESULTS

According to pelvic outcome scoring system of Pohlemann et al., 28 patients out of the ORIF group obtained good or excellent results (20 excellent and 8 good), five fair and two poor. In the CRIF group, 30 patients obtained good or excellent results (25 excellent and 5 good), four fair and one poor (P=0.64). The average intraoperative blood loss in the ORIF group was 500cc with average blood transfusion of 2units (1000cc) compared to blood loss 150cc in the CRIF group, with average blood transfusion of 1unit (500cc) (P=0.002). No intraoperative complications were reported in the ORIF group while operative guide wires were broken in two cases in the CRIF group (P=0.16). There were no neurological complications observed in the ORIF group, but one radiculopathy (L5 root palsy) occurred in the CRIF group (P=0.317). In the ORIF group, three patients had superficial wound infection and one patient had deep infection while in the CRIF group, we noted only one case of deep infection (P=0.083).

CONCLUSION

No difference was noticed between ORIF and CRIF. The technical decision is variable according to time of surgery, fracture types, patient general condition, skin condition, presence of ipsilateral fractures of the acetabulum and feasibility of the closed reduction. More studies are needed to identify prognostic factors related to quality of the reduction. We need for creation of decisional algorithm for ORIF versus CRIF.

LEVEL OF EVIDENCE

Level 4.

How to obtain and identify the acetabular anterior column axial view projection in patients?

PURPOSE

This study aims at sharing our experience as how to obtain and identify axial view image of the acetabular anterior column in patients.

METHODS

Pelvic computed tomography data of six normal adults were used to reconstruct three-dimensional (3D) models. The transparency of each 3D model was downgraded at the view perpendicular to the cross section of the anterior column axis to simulate the anterior column axial view image. Fluoroscopy was performed in all patients to obtain the anterior column axial view image in the operating room. Each fluoroscopic image was compared with the corresponding simulation image to analyze potential anatomic landmarks that were helpful to identify the translucent area (projection of the screw path) in the patients.

RESULTS AND CONCLUSIONS

To obtain ideal anterior column axial fluoroscopic image, the patient should be positioned supine with the leg of "abnormal side" straight and contralateral side flexion, abduction, and external rotation; the C-arm machine should be placed at the caudal end of the operation table with the C-arm fluoroscopic intensifier first positioned at the pelvic lateral view and then tilted approximately 30° toward the "abnormal side" and rotated approximately 45° toward the caudal end of the operation table. To identify the translucent area on the anterior column axial view fluoroscopic image obtained from the patient, the greater sciatic notch, the true pelvis edge, and the acetabulum should be identified first and the translucent area is located in the area surrounded by these three anatomic landmarks.

Are two retrograde 3.5 mm screws superior to one 7.3 mm screw for anterior pelvic ring fixation in bones with low bone mineral density?

Objectives

Osteosynthesis of anterior pubic ramus fractures using one large-diameter screw can be challenging in terms of both surgical procedure and fixation stability. Small-fragment screws have the advantage of following the pelvic cortex and being more flexible.

The aim of the present study was to biomechanically compare retrograde intramedullary fixation of the superior pubic ramus using either one large- or two small-diameter screws.

Materials and Methods

A total of 12 human cadaveric hemipelvises were analysed in a matched pair study design. Bone mineral density of the specimens was 68 mgHA/cm³ (standard deviation (sd) 52). The anterior pelvic ring fracture was fixed with either one 7.3 mm cannulated screw (Group 1) or two 3.5 mm pelvic cortex screws (Group 2). Progressively increasing cyclic axial loading was applied through the acetabulum. Relative movements in terms of interfragmentary displacement and gap angle at the fracture site were evaluated by means of optical movement tracking. The Wilcoxon signed-rank test was applied to identify significant differences between the groups

Results

Initial axial construct stiffness was not significantly different between the groups (p = 0.463). Interfragmentary displacement and gap angle at the fracture site were also not statistically significantly different between the groups throughout the evaluated cycles (p ⩾ 0.249). Similarly, cycles to failure were not statistically different between Group 1 (8438, sd 6968) and Group 2 (10 213, sd 10 334), p = 0.379. Failure mode in both groups was characterised by screw cutting through the cancellous bone.

Conclusion

From a biomechanical point of view, pubic ramus stabilisation with either one large or two small fragment screw osteosynthesis is comparable in osteoporotic bone. However, the two-screw fixation technique is less demanding as the smaller screws deflect at the cortical margins.

Cite this article: Y. P. Acklin, I. Zderic, S. Grechenig, R. G. Richards, P. Schmitz, B. Gueorguiev. Are two retrograde 3.5 mm screws superior to one 7.3 mm screw for anterior pelvic ring fixation in bones with low bone mineral density? Bone Joint Res 2017;6:8–13. DOI: 10.1302/2046-3758.61.BJR-2016-0261.

Percutaneous screws CT guided to fix sacroiliac joint in tile C pelvic injury. Outcomes at 5 years of follow-up

INTRODUCTION

The treatment of the sacroiliac joint (SIJ) vertical instability is a matter of current discussions and remains controversial. The aim of our study is the evaluation of the surgical management of SIJ vertical instability involving the use of cannulated screws introduced under CT guidance and local anesthesia.

MATERIALS AND METHODS

In the set time frame of 7 years, 96 poly-trauma patients with Tile's type C fracture of the pelvis with vertical instability of the SIJ were treated. The average distance between the two stumps was 73.4 mm (range: 43-100 mm). All patients were treated with anterior stabilization and subsequent stabilization with cannulated screws (Asnis® Stryker® 6 mm, an average length of 70 mm; range from 55 to 85 mm) of the sacroiliac fracture. The clinical and radiological follow-up was performed with follow-up plain radiograph and Majeed score (from 1 to 60 months after injury).

RESULTS

The consolidation of pelvic fractures was obtained after an average of 63 days. The average Majeed score was as follows: 96 points at 1 month, 84 points at 3 months, 62 points at 6 months, 44 points at 12 months, 42 points at 24 months, 32 points at 36 months, 28 points at 48 months and 28 points at 60 months. Complications were as follows: not fatal deep vein thrombosis in five cases, skin infection at the entry point of the screws in six cases, screw breakage in one case and loosening of the screws in one case. Radiological evidence of fracture consolidation was achieved on average at 63 days. Forty-seven patients managed to get back to their pre-trauma employment at the end of the convalescence period.

CONCLUSIONS

Our results suggest that the stabilization of SI Tile type C fracture/dislocations with CT-guided percutaneous cannulated screws is a valid and feasible management option and associated with a low complication rate.

The Effect of Transiliac-Transsacral Screw Fixation for Pelvic Ring Injuries on the Uninjured Sacroiliac Joint

OBJECTIVE

To evaluate the functional outcomes and pain in patients with unilateral posterior pelvic ring injuries treated with transiliac-transsacral screw fixation compared with unilateral iliosacral screw fixation.

DESIGN

Retrospective comparative study.

SETTING

Three academic level 1 trauma centers.

PATIENTS/PARTICIPANTS

From a group of 866 patients with pelvic ring injuries treated surgically, 86 patients with unilateral pelvic ring injuries treated with transiliac-transsacral screws and 97 patients treated with unilateral iliosacral screws were identified. Thirty-six patients treated with transiliac-transsacral fixation and 26 patients treated with unilateral iliosacral screws met the inclusion criteria and participated.

INTERVENTION

Patients were treated surgically for unstable pelvic ring injuries with either unilateral iliosacral screws or transiliac-transsacral screws at the discretion of the treating surgeon.

MAIN OUTCOME MEASUREMENT

Majeed Pelvic Score.

RESULTS

There was no significant difference in Majeed Pelvic Scores between patients treated with transiliac-transsacral screws and those treated with unilateral iliosacral screws (72.8 ± 23.7 vs. 70.4 ± 19.0, P = 0.66). There was no difference in side-specific Numeric Rating Scale pain scores between patients treated with transiliac-transsacral screws and those treated with unilateral iliosacral screws on the injured side (2.5 ± 3.1 vs. 2.0 ± 2.4, P = 0.46) or the uninjured side (1.7 ± 2.8 vs. 0.8 ± 1.7, P = 0.12). Mean follow-up was greater than 3 years with no difference between the groups (mean 1270 vs. 1242 days, P = 0.84).

CONCLUSIONS

Treatment of unilateral pelvic ring injuries with transiliac-transsacral screws does not adversely affect or improve patient outcomes or subjective pain scores when compared with those treated with unilateral iliosacral screws.

LEVEL OF EVIDENCE

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

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.

Zone 2 sacral fractures managed with partially-threaded screws result in low risk of neurologic injury

BACKGROUND

Zone 2 sacral fractures account for 34% of sacral fractures with reported neurological deficit in 21-28% of patients. The purpose of this study was to examine the risk factors for neurological injury in zone 2 sacral fractures. The authors hypothesized that partially thread iliosacral screws did not increase incidence of neurologic injury.

METHODS

A retrospective review of consecutive patients admitted to a level 1 trauma center with zone 2 sacral fractures requiring surgery from September 2010 to September 2014 was performed. Patients were excluded if no neurologic exam was available after surgery. Fractures were classified according to Denis and presence/absence of comminution through the neural foramen was noted. Fixation schema was recorded (sacral screws or open reduction and internal fixation with posterior tension plate). Any change in post-operative neurological exam was documented as well as exam at last clinic encounter.

RESULTS

90 patients met inclusion criteria, with zone 2 fractures and post-operative neurological exam. No patient with an intact pre-operative neurologic exam had a neurological deficit after surgery. 86 patients (95.6%) were neurologically intact at their last follow-up examination. Four patients (4.4%) had a neurological deficit at final follow-up, all of them had neurological deficit prior to surgery. 81 patients were treated with partially threaded screws of which 1 (1.2%) had neurological deficit at final follow-up. Fifty-seven fractures (63.3%) were simple fractures and 33 fractures (36.7%) were comminuted. All four patients with neurological deficit had comminuted fractures. The association between neurologic deficit in zone 2 sacral fracture and fracture comminution was found to be statistically significant (p-value=0.016). No nonunion was observed in this cohort.

CONCLUSIONS

The use of partially threaded screws for zone 2 sacral fractures is associated with low risk for neurologic injury, suggesting that compression through the fracture does not cause iatrogenic nerve damage. The low rate of sacral nonunion can be attributed to compression induced by the use of partially threaded compression screws. There is a strong association between zone 2 comminution and neurologic injury.

Biomechanical comparison of plate and screw fixation in anterior pelvic ring fractures with low bone mineral density

INTRODUCTION

Osteosynthesis of anterior pubic ramus fractures can be challenging, especially in poor bone quality. The aim of the present study was to compare plate and retrograde endomedullary screw fixation of the superior pubic ramus with low bone mineral density (BMD).

MATERIALS AND METHODS

Twelve human cadaveric hemi-pelvises were analyzed in a matched pair study design. BMD of the specimens was 35±30mgHA/cm(3), as measured in the fifth lumbar vertebra. A simulated two-fragment superior pubic ramus fracture model was fixed with either a 7.3-mm cannulated retrograde screw (Group 1) or a 10-hole 3.5-mm reconstruction plate (Group 2). Cyclic progressively increasing axial loading was applied through the acetabulum. Relative interfragmentary movements were captured using an optical motion tracking system.

RESULTS

Initial axial construct stiffness was 424±116.1N/mm in Group 1 and 464±69.7N/mm in Group 2, with no significant difference (p=0.345). Displacement and gap angle at the fracture site during cyclic loading were significantly higher in Group 1 compared to Group 2. Cycles to failure, based on clinically relevant criteria, were significantly lower in Group 1 (3469±1837) compared to Group 2 (10,226±3295) (p=0.028). Failure mode in Group 1 was characterized by screw cutting through the cancellous bone. In Group 2 the specimens exclusively failed by plate bending.

CONCLUSIONS

From biomechanical point of view, pubic ramus stabilization with plate osteosynthesis is superior compared to a single retrograde screw fixation in osteoporotic bone. However, the extensive surgical approach needed for plating must be considered.

Pelvic ring injuries

Pelvic ring injuries exhibit a wide spectrum of severity; at times devastating with potentially serious immediate and long-term consequences. The anatomical and mechanistic basis of the injured pelvis is described. The non-operative and surgical management of pelvic ring disruption in the acute and definitive care settings is discussed. As emphasized here, basic principles, the mechanism of injury and pattern of instability help guide management.

Correct Positioning of Percutaneous Iliosacral Screws With Computer-Navigated Versus Fluoroscopically Guided Surgery in Traumatic Pelvic Ring Fractures

OBJECTIVES

To assess the correct positioning of iliosacral screw in patients with unstable traumatic pelvic ring injury by comparing fluoroscopically guided computer-navigated surgery (CNS) with conventional fluoroscopy (CF) through reviewing postoperative computed tomography (CT) and clinical indicators.

DESIGN

A comparative multicenter cohort study.

SETTING

Two level I Trauma Centers in the Netherlands.

PATIENTS

The computer-navigated group (n = 56) and the CF group (n = 24) were comparable regarding age (mean, 43 years), sex (58%, male), body mass index (25 kg/m), injury severity score (27), injury-to-surgery interval (7 days), and Orthopaedic Trauma Association classification (40% 61-B, 60% 61-C).

MAIN OUTCOME MEASUREMENTS

The position of the iliosacral screws was evaluated on postoperative CT. In addition, clinical morbidity and reoperation were assessed.

RESULTS

In the CNS group, a total of 111 screws were placed (2.0 per patient), of which 83% were placed correctly. In the CF group, 39 screws (1.6 per patient) were placed, 82% of them correctly.Inadequate fixation included neural foramina hit [12 screws (11%) in the CNS group versus 3 screws (8%) in the CF group, P = 0.76] and extraosseous dislocation [7 screws (6%) vs. 4 screws (10%), respectively, P = 0.47]. Five patients required reoperation, all in the CNS group, P = 0.32. We observed more adequate positioning with increased surgical experience, P = 0.12.

CONCLUSIONS

In contrast to what has been suggested by previous studies, we found no benefit from computer-navigated iliosacral screw fixation compared with fluoroscopically guided surgery regarding the correct positioning of iliosacral screw on postoperative CT and related morbidity.

LEVEL OF EVIDENCE

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

Preclinical usability study of multiple augmented reality concepts for K-wire placement

PURPOSE

In many orthopedic surgeries, there is a demand for correctly placing medical instruments (e.g., K-wire or drill) to perform bone fracture repairs. The main challenge is the mental alignment of X-ray images acquired using a C-arm, the medical instruments, and the patient, which dramatically increases in complexity during pelvic surgeries. Current solutions include the continuous acquisition of many intra-operative X-ray images from various views, which will result in high radiation exposure, long surgical durations, and significant effort and frustration for the surgical staff. This work conducts a preclinical usability study to test and evaluate mixed reality visualization techniques using intra-operative X-ray, optical, and RGBD imaging to augment the surgeon's view to assist accurate placement of tools.

METHOD

We design and perform a usability study to compare the performance of surgeons and their task load using three different mixed reality systems during K-wire placements. The three systems are interventional X-ray imaging, X-ray augmentation on 2D video, and 3D surface reconstruction augmented by digitally reconstructed radiographs and live tool visualization.

RESULTS

The evaluation criteria include duration, number of X-ray images acquired, placement accuracy, and the surgical task load, which are observed during 21 clinically relevant interventions performed by surgeons on phantoms. Finally, we test for statistically significant improvements and show that the mixed reality visualization leads to a significantly improved efficiency.

CONCLUSION

The 3D visualization of patient, tool, and DRR shows clear advantages over the conventional X-ray imaging and provides intuitive feedback to place the medical tools correctly and efficiently.

Immediate percutaneous sacroiliac screw insertion for unstable pelvic fractures: is it safe enough?

OBJECTIVES

The purpose of this study was to compare the results of immediate and delayed percutaneous sacroiliac screws surgery for unstable pelvic fractures, regarding technical results and complication rate.

DESIGN

Retrospective study.

SETTING

The study was conducted at the Soroka University Medical center, Beer Sheva, Israel, which is a level 1 trauma Center.

PATIENTS

108 patients with unstable pelvic injuries were operated by the orthopedic department at the Soroka University Medical Center between the years 1999-2010. A retrospective analysis found 50 patients with immediate surgery and 58 patients with delayed surgery. Preoperative and postoperative imaging were analyzed and data was collected regarding complications.

INTERVENTION

All patients were operated on by using the same technique-percutaneous fixation of sacroiliac joint with cannulated screws.

MAIN OUTCOME MEASUREMENTS

The study's primary outcome measure was the safety and quality of the early operation in comparison with the late operation.

RESULTS

A total of 156 sacroiliac screws were inserted. No differences were found between the immediate and delayed treatment groups regarding technical outcome measures (P value = 0.44) and complication rate (P value = 0.42).

CONCLUSIONS

The current study demonstrated that immediate percutaneous sacroiliac screw insertion for unstable pelvic fractures produced equally good technical results, in comparison with the conventional delayed operation, without additional complications.

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.

A simple approach for the preoperative assessment of sacral morphology for percutaneous SI screw fixation

BACKGROUND

Percutaneous sacroiliac screw fixation under fluoroscopic control is an effective method for posterior pelvic ring stabilization. However, sacral dysmorphism has a high risk of L5 nerve injury. This study describes a simple method for the preoperative assessment of the sacral morphology using CT scans with widely available tools.

MATERIALS AND METHODS

CT scans of 1000 patients were analyzed. True inlet, outlet, and lateral views of the sacrum were obtained using a two-dimensional reconstruction tool to align the sacrum in a reproducible manner. Corridor morphology in the inlet view was measured to calculate different morphological types: (1) Ascending type, (2) Horizontal type, and (3) Descending type. In a second step, the corridor was analyzed for the presence of an anterior indentation of the sacrum between the SI joint and the midsagittal plane with proximity to the nerve root L5, which, therefore, may be harmed during screw misplacement.

RESULTS

A notch was found in the majority of cases with relative frequencies ranging from 69 % (upper quartile of S1) to 95 % (upper quartile of S2). Descending types were, by far, the most frequent corridor type with one exception: In the upper quartile of S1, the ascending type was the most frequent corridor (71 %). Horizontal types were less frequent with a relative incidence between 2 and 14 %.

DISCUSSION

This study should increase the awareness for sacral dysmorphism, emphasize the importance of a preoperative assessment of the osseous corridor, and provide a simple method for the preoperative assessment with widely available tools.

Computer-aided pelvic reduction frame for anatomical closed reduction of unstable pelvic fractures

Traditional closed reductions of unstable pelvic fractures are mainly performed by surgeons using manual manipulation and subjective verification based on intra-operative roentgenography. It is difficult to perform an accurate closed reduction because of a lack of adequate knowledge of the displacement patterns and an inability to apply the reduction in correct direction. Using the concept of the remote center of motion mechanism and computer-aided design software, we developed a pelvic reduction frame for use in anatomical closed reductions of unstable pelvic fractures. With three-dimensional reconstruction technique and the matrix algorithm, the spatial orientation of the displaced hemipelvis can be calculated and deconstructed into several rotational and translational movements that can be completed with the frame. To verify the accuracy of this system, the rotations were repeated 10 times in arbitrary degrees and directions. After the matrix is calculated, the displaced hemipelvis can be reduced to the anatomical position using our frame. The maximum residual translational and rotational displacements were less than 5 mm and 4 degrees, which indicated the accuracy of this system. The maximum average residual translation and rotation were 1.87 mm in Z-axis (ranging: 4.63-0.1 mm) and 1.1 degrees around Y-axis (ranging: 3.81-0.13 degrees), respectively. Only the Z-axial translation showed a statistically significant difference (p < 0.05). In conclusion, the proposed pelvic reduction frame could be a useful tool for the anatomical reduction of unstable pelvic fractures.

Do Safe Radiographic Sacral Screw Pathways Exist in a Pediatric Patient Population and Do They Change With Age?

OBJECTIVES

Iliosacral screw pathways in the first (S1) and second (S2) sacral segments are commonly used for adult pelvic ring stabilization. We hypothesize that radiographically "safe" pathways exist in pediatric patients.

SETTING

Academic level I Trauma Center.

PATIENTS

All patients between ages 2 and 16 years with a computed tomography scan including the pelvis obtained over a 6-week period (174 children, mean age 10.8 ± 3.9 years; 90 boys, 84 girls).

INTERVENTION

The width and height at the "constriction point" in 3 safe screw pathways were measured bilaterally by 3 orthopaedists (resident, trauma fellow, trauma attending). Pathways corresponding to: (1) an "iliosacral" screw at S1, a "trans-sacral trans-iliac" (TSTI) screw at S1, and a TSTI screw at S2.

MAIN OUTCOME MEASUREMENTS

(1) Mean width and height of pathways, (2) interrater reliability coefficient, (3) availability of pathways greater than 7 mm, (4) growth of pathways with age, (5) sacral morphology.

RESULTS

The interrater reliability coefficient was above 0.917 for all measurements. Radiographically safe pathways were available for 99%, 51%, and 89% of children for iliosacral screws at S1 (width 16.4 ± 2.8 mm, height 15.1 ± 3.3 mm), TSTI screws at S1 (width 7.2 ± 4.9 mm, height 8.3 ± 5.6 mm), and TSTI at S2 (width 9.3 ± 2.2 mm, height 11.5 ± 2.7 mm), respectively.

CONCLUSIONS

Contrary to our hypothesis, almost all children aged 2-16 had a radiographically safe screw pathway for an iliosacral screw at S1, and most of the children had an available pathway for a TSTI screw at S2. However, only 51% had a pathway for a TSTI screw at S1.

Percutaneous Screw Fixation of Crescent Fracture-Dislocation of the Sacroiliac Joint

Crescent fracture-dislocation of the sacroiliac joint (CFDSIJ) is a type of lateral compression pelvic injury associated with instability. Open reduction and internal fixation is a traditional treatment of CFDSIJ. However, a minimally invasive method has never been reported. The purpose of this study was to assess the outcome of closed reduction and percutaneous fixation for different types of CFDSIJ and present their clinical outcome. The authors reviewed 117 patients diagnosed with CFDSIJ between July 2003 and July 2013. Closed reduction and percutaneous fixation was performed in 73 patients. Treatment selection was based on Day's fracture classification. For type I fractures, fixation perpendicular to the fracture line were performed. For type II fractures, crossed fixation was performed. For type III fractures, fixation was performed with iliosacral screws. Forty-four patients were treated by open reduction and plate fixation. Demographics, fracture pattern distribution, blood loss, incision lengths, revision surgeries, radiological results, and functional scores were compared. All 117 patients were followed for more than 6 months (mean, 14 months [range, 6-24 months]). Blood loss, extensive exposure, duration of posterior ring surgery, duration of hospital stay, and infection rates were lower in the closed group (P<.01). Patients in the closed group achieved better functional performance (P<.01). There were no significant differences in reduction quality (P=.32), revision surgery rates (P=.27), and iatrogenic neurologic injuries (P=.2) between the 2 groups. The authors' results indicate that closed reduction and percutaneous fixation is a safe and effective surgical method for CFDSIJ.

Percutaneous Sacroiliac Screw Fixation of the Posterior Pelvic Ring

Percutaneous sacroiliac (SI) screw fixation is indicated for unstable posterior pelvic ring injuries, sacral fractures, and SI joint dislocations. This article provides a review of indications and contraindications, preoperative planning, imaging techniques and relevant anatomy, surgical technique, complications and their management, and outcomes after SI screw insertion.

Comparison of reconstruction plate screw fixation and percutaneous cannulated screw fixation in treatment of Tile B1 type pubic symphysis diastasis: a finite element analysis and 10-year clinical experience

Objective

The objective of this study is to compare the biomechanical properties and clinical outcomes of Tile B1 type pubic symphysis diastasis (PSD) treated by percutaneous cannulated screw fixation (PCSF) and reconstruction plate screw fixation (RPSF).

Materials and Methods

Finite element analysis (FEA) was used to compare the biomechanical properties between PCSF and RPSF. CT scan data of one PSD patient were used for three-dimensional reconstructions. After a validated pelvic finite element model was established, both PCSF and RPSF were simulated, and a vertical downward load of 600 N was loaded. The distance of pubic symphysis and stress were tested. Then, 51 Tile type B1 PSD patients (24 in the PCSF group; 27 in the RPSF group) were reviewed. Intra-operative blood loss, operative time, and the length of the skin scar were recorded. The distance of pubic symphysis was measured, and complications of infection, implant failure, and revision surgery were recorded. The Majeed scoring system was also evaluated.

Results

The maximum displacement of the pubic symphysis was 0.408 and 0.643 mm in the RPSF and PCSF models, respectively. The maximum stress of the plate in RPSF was 1846 MPa and that of the cannulated screw in PCSF was 30.92 MPa. All 51 patients received follow-up at least 18 months post-surgery (range 18–54 months). Intra-operative blood loss, operative time, and the length of the skin scar in the PCSF group were significantly different than those in the RPSF group. No significant differences were found in wound infection, implant failure, rate of revision surgery, distance of pubic symphysis, and Majeed score.

Conclusion

PCSF can provide comparable biomechanical properties to RPSF in the treatment of Tile B1 type PSD. Meanwhile, PCSF and RPSF have similar clinical and radiographic outcomes. Furthermore, PCSF also has the advantages of being minimally invasive, has less blood loss, and has shorter operative time and skin scar.

Minimally-invasive fixation for anterior pelvic ring disruptions

Pelvic fractures are usually the result of high-energy trauma. In addition to the underlying disruption of the pelvic ring extensive damage to the surrounding soft tissue envelope might be present. Different fixation techniques have been developed including open plating, external fixation and transramus intraosseous screw fixation. Recently another method has been reported the so called pelvic Bridge or Infix technique. In this short review article the different techniques of pelvic fixation are described.