Iliac screw for reconstructing posterior pelvic ring in Tile type C1 pelvic fractures

Calculation of CT ideal screw path and safety angle before percutaneous sacroiliac screw placement

INTRODUCTION

Percutaneous sacroiliac screw placement is the main surgical approach to treat unstable posterior pelvic ring injuries. Intraoperative fluoroscopic imaging is an important part of safe sacroiliac screw placement. However, how to determine the right perspective view is challenging. We developed a trigonometric algorithm to verify how preoperative pelvic computed tomography (CT) can be used to predict ideal screw path and safety angle.

MATERIALS AND METHODS

The normal pelvic CT data of 30 volunteers from our hospital between September 2021 and June 2023 were collected, and analyzed and reconstructed using Materialise Mimics 21.0. The angle between the cross-sectional ideal screw path and the horizontal plane (∠α), the angles of the pelvic inlet and outlet on the sagittal plane (∠1, ∠2), and the insertion angles of virtual screws at the inlet and outlet (∠a, ∠b) were measured. The ideal insertion angles (∠A, ∠B) and safety angles of the screws at the pelvic inlet and outlet were calculated using trigonometric functions.

RESULTS

The virtual screw insertion angle ∠a of 30 pelvises measured at the inlet was 18.57 ± 4.33°, and the ideal screw angle ∠A calculated using trigonometric functions was 18.72 ± 4.71° (range, 13.84 ± 0.75°-23.36 ± 0.98°). The difference between the measurement and calculation was only 0.15 ± 0.19° and not significant. The angle ∠b of the virtual screw insertion measured at the outlet was 25.37 ± 5.13°, and the ideal screw angle ∠B calculated using trigonometric functions was 25.58 ± 4.93 ° (range, 19.02 ± 0.88°-31.31 ± 1.01°). The difference between the measurement and calculation was only 0.20 ± 0.13° and not significant. The distance e from the optimal screw insertion point to the vertical line through the anterior superior iliac spine is 32.34 ± 1.76 mm, and the distance f to the horizontal line through the posterior superior iliac spine is 28.61 ± 0.81 mm.

CONCLUSIONS

During preoperative planning, trigonometric calculations were used to determine the ideal screw placement angles and safety angle at the inlet and outlet of the screw path. Combined with intraoperative C-arm fluoroscopy, individualized screw insertion can help orthopedic surgeons quickly and accurately obtain intraoperative images and accurately determine the direction of screw insertion.

Efficacy and safety of conventional biplanar and triangulation method for sacroiliac screw placement in the treatment of unstable posterior pelvic ring fractures: A real-world retrospective cohort study

PURPOSE

The fixation method commonly employed worldwide for treating unstable fractures of the posterior pelvic ring is the percutaneous iliosacral screw technique. However, prolonged operation time and frequent fluoroscopies result in surgical risks. This study aimed to investigate whether a new triangulation method could reduce operative and fluoroscopy times and increase the accuracy of screw placement.

METHODS

This study is a real-world retrospective cohort analysis that examined a patient cohort who underwent percutaneous iliosacral screw fixation between January 1, 2019 and December 31, 2022. Inclusion criteria were patients (1) diagnosed with posterior pelvic ring instability who underwent pelvic fracture closed reduction and percutaneous S1 transverse-penetrating iliosacral screw placement and (2) aged >18 years. Exclusion criteria were: (1) combined proximal femoral fractures, (2) severe soft tissue injury in the surgical area, (3) incomplete imaging data, and (4) declining to provide written informed consent by the patient. The patients were divided into 2 groups according to the screw insertion method: conventional and triangulation methods. Screw placement and fluoroscopy times recorded by the C-arm were compared between the 2 methods. The accuracy of screw placement was evaluated by Smith grading on postoperative CT. Normality tests were conducted to assess the distribution of the quantitative variables and the Chi-square test was used to compare the qualitative variables.

RESULTS

The study included a total of 94 patients diagnosed with posterior pelvic ring instability, who underwent percutaneous iliosacral screw placement. The patients were divided into 2 groups: 46 patients treated with the conventional surgical method and 48 patients received the triangulation method. The operation time (61.13±9.69 vs. 35.77±6.27) min and fluoroscopy frequency times (52.15±9.29 vs 24.40±4.04) of the triangulation method were significantly reduced (p<0.001).

CONCLUSIONS

The use of a triangular positioning technique for the surface positioning of percutaneous iliosacral screws could reduce the operative time and fluoroscopy frequency. And screw placement accuracy using this new method was comparable to that using other conventional methods.

Experimental study of fractures of the posterior pelvic ring C1.1 using LC-II screws and internal fixation by plate

INTRODUCTION

To compare the biomechanical outcomes of C1.1 posterior pelvic ring fractures treated with different numbers of LC-II screws and plate internal fixation.

MATERIALS AND METHODS

Nine adult preserved pelvic specimens were used. After being measured by bone densitometry, the specimens were randomly divided into 3 groups of 3 pelvic specimens each. The C1.1 pelvic fractures were generated by iliac osteotomies and anterior pelvic ring osteotomies. The fractures were fixed and randomly divided into three groups: (1) one LC-II screw, (2) two LC-II screws, and (3) two reconstruction plates. The anterior pelvic rings were all fixed with pubic branch screws. A biomechanical testing machine loaded all specimens vertically, recording the displacement and ultimate load of the specimens to quantify the stiffness.

RESULTS

When loads up to 1000 N were applied, the displacement of the iliac bone was close between the one LC-II screw and the two LC-II screw group specimens; (P > 0.05); when loads such as 1000 N, 1200 N and 1400 N were applied, there was no significant difference in displacement between the plate fixation group and the two LC-II screw fixation group (P > 0.05), both of which were superior to the one LC-II screw fixation group (P < 0.05). There was no significant difference in compressive stiffness between the two LC-II screw fixation groups and the plate fixation group (P > 0.05), and both were superior to the one LC-II screw fixation group (P < 0.05) the ultimate load of both the two LC-II screws and the steel plate is greater than that of one LC-II screw (1.74 times the ultimate load of one LC-II screw for the two LC-II screws and 1.83 times the ultimate load of one LC-II screw for the steel plate).

CONCLUSION

For posterior pelvic ring fractures of type C1.1, placement of two LC-II screws provides comparable posterior pelvic ring stability compared to reconstructed plates. At loads below 1000 N, one LC-II screw fixation and two LC-II screws were comparable in restoring posterior pelvic ring stability.

Safe surgical corridor for iliosacral screw placement in unstable pelvic fractures: a computed-tomography-guided validation study of the "triangulation method"

BACKGROUND

The percutaneous iliosacral screw technique represents a global standard fixation method for unstable fractures of the posterior pelvic ring. However, the inaccurate positioning of iliosacral screws is associated with a significant risk of severe intra-operative complications. Therefore, this study aimed to investigate the relationship between the skin entry point of the transverse iliosacral screw of the first sacral vertebral body and the anterior superior iliac spine and the greater trochanter of the femur using computed-tomography-guided validation.

METHODS

Overall, 91 consecutive patients admitted to a tertiary referral center in China for posterior pelvic ring fixation via the "triangulation method" using computed-tomography-guided validation between January 1, 2020, and December 31, 2020, were included in this retrospective observational cohort study. Modeling and simulated iliosacral screw placement were performed using the Mimics software. The distance between the three points of interest was measured, and their relationship in a rectangular coordinate system was determined. Patients were categorized according to gender, body mass index, and femoral rotation angle to investigate the factors affecting the positional relationship between the three points.

RESULTS

An equilateral triangular relationship was observed between the positioning points of the transverse iliosacral screw, anterior iliac spine, and greater trochanter. Additionally, 95% of the entry points were within a circle radius centered 12 mm at the apex of an equilateral triangle comprising the anterior superior iliac spine and the greater trochanter as the base. The entry point in the femoral external rotation was more dorsal than that in the internal femoral rotation. Furthermore, the entry point in females was more rostral than that in males, and the entry point in overweight patients was more dorsal than that in normal-weight patients.

CONCLUSIONS

The skin entry point of the percutaneous iliosacral screw can be located by drawing an equilateral triangle from the anterior superior iliac spine and the greater trochanter as the base to the dorsum end of the patient's head. In summary, this retrospective cohort study validated the safety and efficacy of the "triangulation methods" for percutaneous fixation of unstable posterior pelvic ring injuries.

Minimally invasive stabilization of posterior pelvic ring injuries through transiliac internal fixator versus Iliosacral screw: A prospective comparative cohort study

INTRODUCTION

Longitudinal sacral fractures are usually a matter of controversy regarding decision-making for reduction, fixation, and approach. Percutaneous and minimally invasive techniques present perioperative difficulties, but with fewer postoperative complications compared to open techniques. The objective of this study was to compare the functional as well as radiological outcomes of the Transiliac Internal fixator (TIFI) versus Iliosacral screw (ISS) fixation of sacral fractures applied percutaneously in a minimally invasive technique.

METHODS

A Prospective comparative cohort study was conducted in a level 1 trauma center in a university hospital. The study included 42 patients with complete sacral fractures, 21 patients have been allocated to each group (TIFI group & ISS group). The clinical, functional, as well as radiological data, were collected and analyzed for the 2 groups.

RESULTS

The mean age was 32 (18 -54 years), and the mean follow-up was 14 (12 -20 months). There was a statistically significant difference in favor of the TIFI group regarding a shorter operative time (P = 0.04) as well as less fluoroscopy time (P = 0.01) whereas there was less blood loss in the ISS group (P = 0.01). Both the mean Matta's radiological score, the mean Majeed score as well as the pelvic outcome score were comparable between the 2 groups with no statistically significant difference.

CONCLUSION

This study suggests that both TIFI and ISS through a minimally invasive technique represent valid methods for sacral fracture fixation with a shorter operative time, less radiation exposure in TIFI and less blood loss in the ISS. However, the functional, as well as radiological outcomes, were comparable between the 2 groups.

Does minimally invasive percutaneous transilial internal fixator became an effective option for sacral fractures? A prospective study with novel implantation technique

AIM

To assess radiological and functional outcomes of transilial internal fixator (TIFI) for treatment of sacral complete transforaminal fractures with a novel implantation technique that decrease wound irritation problems in addition to facilitating easy application of reduction methods beside showing the best entry points, screw trajectories and angles.

METHODS

A Prospective case series from 2019 to 2021 was conducted at university hospital including 72 patients with Denis type 2 sacral fractures. The operative and fluoroscopy time, reduction, implantation techniques, postoperative radiological and functional data were collected and evaluated with minimum follow-up of 12 months.

RESULTS

The mean initial fracture displacement was 4.42 mm while mean postoperative maximum residual fracture displacement was 2.8 mm, Radiological outcome assessed using Matta's grading at the final follow-up visit with 63 cases scored as Excellent,7 cases as Good, 2 cases as fair. Functional outcome using Majeed scoring shows 64 cases of Excellent grading and 8 cases were Good. Short operative and fluoroscopy time, easy reduction techniques, few skin problems were recorded.

CONCLUSION

TIFI through a minimally invasive technique represents a valid method for dealing with transforaminal sacral fractures. TIFI provides a rigid fixation for posterior ring injuries with few risks regarding iatrogenic nerve injury, avoiding different variations of upper sacral osseous anatomy or sacral dysmorphism. In addition, there is no necessity for high quality fluoroscopy for visualization of sacral foramina intraoperatively, decreasing risk of radiation exposure, unlike other methods of fixation as iliosacral screws. Our novel modification for implantation technique provides few risks for postoperative and wound complications.

Patient-reported physical functioning and quality of life after pelvic ring injury: A systematic review of the literature

BACKGROUND

Pelvic ring injuries are one of the most serious traumatic injuries with large consequences for the patients' daily life. During recent years, the importance of the patients' perception of their functioning and quality of life following injury has increasingly received attention. This systematic review reports on self-reported physical functioning and quality of life after all types of pelvic ring injuries.

METHODS

The online databases MEDLINE-PubMed and Ovid-EMBASE were searched for studies published between 2008 and 2019 to identify published evidence of patient-reported physical functioning and quality of life after which they were assessed for their methodological quality.

RESULTS

Of the 2577 articles, 46 were reviewed in full-text, including 3049 patients. Most studies were heterogeneous, with small cohorts of patients, a variety of injury types, treatment methods and use of different, often non-validated, outcome measures. The overall methodological quality was moderate to poor. Nine different PROMs were used, of which the Majeed Pelvic Score (MPS), SF-36 and EQ-5D were the most widely used. Mean scores respectively ranged from 75-95 (MPS), 53-69 (SF-36, physical functioning) and 0.63-0.80 (EQ-5D).

CONCLUSIONS

Physical functioning and quality of life following pelvic ring injuries seem fair and tend to improve during follow-up. However, differences in patient numbers, injury definition, treatment strategy, follow-up duration and type of PROMs used between studies hampers to elucidate the actual effects of pelvic ring injuries on a patient's life.

IMPLICATIONS OF KEY FINDINGS

Physicians and researchers should use valid and reliable patient-reported outcome instruments on large cohorts of patients with properly defined injuries to truly evaluate physical functioning and quality of life after pelvic ring injuries.

SYSTEMATIC REVIEW REGISTRATION NUMBER

PROSPERO International prospective register of systematic reviews; registration number CRD42019129176.

Biomechanical comparison of minimally invasive treatment options for Type C unstable fractures of the pelvic ring

BACKGROUND

The definite treatment of pelvic C fractures presents a widely discussed issue and undergoes continuous evolution. While the stabilization of the posterior ring has been studied extensively, the fixation of the anterior pelvic ring continuous to be rarely investigated. The importance of the simultaneous stabilization however lays in the earlier mobilization and prevention of long-term damage to the pelvis. Therefore we investigated four combinations of minimally invasive fixation techniques for unstable type C1-3 pelvic injuries and aimed to answer the following research questions: (1) what combination of fixation methods yields the highest stiffness and the least displacement? (2) Is the combination of a single sacroiliac screw (SI-screw) with a transiliac internal fixator (TIFI) a reasonable alternative to two SI-screws? (3) Is a modified unilateral anterior fixation comparable to a retrograde transpubic screw?

HYPOTHESIS

Minimally invasive fixation techniques provide sufficient biomechanical stability for type C pelvic fractures.

METHODS

Thirty synthetic full pelvises were divided into 5 groups, of which 4 groups were assigned a different osteosynthesis method and one was an intact pelvis used as reference (group 1: internal fixator+2 sacroiliac screws, group 2: internal fixator+transiliac internal fixator+1 sacroiliac screw, group 3: retrograde transpubic screw+2 sacroiliac screws, group 4: retrograde transpubic screw+transiliac internal fixator+1 sacroiliac screw). The pelvises underwent a protocol of cyclic loading between 100N and 200N, during which they were subjected to compression loads while the position of the fracture fragments was measured every 30 milliseconds. Displacement and stiffness were calculated for statistical analysis.

RESULTS

The minimally invasive fixation methods investigated in this study all provide sufficient biomechanical stability without one method being superior to the others (p [anterior displacement]=0.61 and p [posterior displacement]=0.88). Group 3 was allowed the least displacement (1.8±0.2mm for anterior and posterior fracture) for the treatment of a C1.3 fracture. The other fixation methods displayed the following dislocations (mm) of the anterior pelvic ring: group 1: 1.9±0.3, group 2: 2.1±0.4, group 4: 2.0±0.5. Posteriorly, the displacements (mm) were the following: group 1: 1.8±0.6, group 2: 1.9±0.2, group 4: 2.0±0.5.

DISCUSSION

The minimally invasive fixation methods investigated in this study all provide sufficient biomechanical stability without one method being superior to the others since differences were not significant regarding anterior and posterior displacements. Even if not significantly, we could reveal that out of all the methods tested the combination of 2 SI-screws with a retrograde transpubic screw (group 3) displayed the least displacement and highest stiffness. These techniques could therefore potentially improve patient's clinical outcome by reducing the surgical invasiveness and procedure time while providing sufficient biomechanical stability.

LEVEL OF EVIDENCE

III, comparative in vitro study.

Inaccuracies in the Use of the Majeed Pelvic Outcome Score: A Systematic Literature Review

OBJECTIVES

To evaluate the accuracy with which the Majeed Pelvic Score has been reported in the English literature.

DATA SOURCES

Databases used to search for literature were PubMed, Embase, and Ovid, restricted to English language from inception to October 2, 2018.

STUDY SELECTION

Search words used were: Majeed, pelvis, and outcome.

DATA EXTRACTION

Articles were assessed for descriptions of scoring and proper reporting of Majeed Pelvic Outcome Score.

DATA SYNTHESIS

Descriptive statistics were used to report the outcome of our findings.

CONCLUSIONS

Ninty-two English articles were identified. Twenty-four (26%) articles were identified as including methodology related to the use and scoring of the Majeed Pelvic score. The remaining 68 presented mean Majeed scores with no methodological information. None (0/92) discussed how the range of possible scores for the most severe function was applied. Six (7%) reported adjusted scores for patients not working. Three (3%) included a discussion of the scores as adjusted for patients working before injury compared with those not working. Ten (11%) addressed the categorization of scores by excellent to poor describing what raw scores defined those categories. We observed poor accuracy and notable inconsistency in the use and reporting of the Majeed Pelvic Outcome Score in the literature. These data demonstrate that interpretation and comparison of research reporting this score should be done cautiously. Future studies should include specific information as to how the Majeed instrument calculated to allow for verification of the presented scores and subsequent conclusions.