Morphometric analysis of the anterior column of the acetabulum and safety of intramedullary screw fixation for its fractures in Indian population: a preliminary report

The automatic pelvic screw corridor planning for intact pelvises based on deep learning deformable registration

Percutaneous screw fixation technique in pelvic trauma surgery is an extremely challenging operation that typically requires a trial-and-error insertion process under the guidance of continuous intraoperative X-ray. This process can be simplified by utilizing surgical navigation systems. Understanding the complexity of the intraosseous pelvis corridor is essential for establishing the optimal screw corridor, which further facilitates preoperative planning and intraoperative application. Traditional screw corridor search algorithms necessitate traversing the entrance and exit areas of the screw and calculating the distance from the corridor axis to the bone surface to ascertain the location of the screw. This process is computationally complex, and manual measurement by the physician is time consuming, labor intensive, and empirically dependent. In this study, we propose an automated planning algorithm for pelvic screw corridors based on deep learning deformable registration technology, which can efficiently and accurately identify the optimal screw corridors. Compared to traditional methods, the innovations of this study include: (1) the introduction of corridor safety range constraints on screw positioning, which enhances search efficiency; (2) the application of deep learning deformable registration to facilitate the automatic annotation of the screw entrance and exit areas, as well as the safety range of the corridor; and (3) the development of a highly efficient algorithm for optimal corridor searching, quickly determining the corridor without traversing the entrance and exit areas and enhancing efficiency via a vector-based diameter calculation method. The whole framework of the algorithm consists of three key components: atlas generation module, deformable registration and optimal corridor searching strategy. In the experiments, we test the performance of the proposed algorithm on 198 intact pelvises for calculating the optimal corridor of anterior column corridor and S1 sacroiliac screws. The results show that the new algorithm can increase the corridor diameter by 2.1%-3.3% compared to manual measurements, while significantly reducing the average time from 1038s and 3398s to 18.9s and 26.7s on anterior column corridor and S1 sacroiliac corridor, respectively, compared to the traditional screw searching algorithm. This demonstrates the advantages of the algorithm in terms of efficiency and accuracy. However, the current method is validated only on intact pelvises; further research is required for pelvic fracture scenarios.

Dependable Automated Approach for Measuring the Retrograde Superior Ramus Screw Corridor in Pelvic Fracture Fixation

BACKGROUND

Precise measurement of the intraosseous corridor within the superior pubic ramus is essential for the accurate percutaneous placement of a retrograde superior ramus screw (SRS). However, conventional manual measurement methods are often subjective, leading to variations in results among observers. Our goal was to develop an automated and dependable method for determining the retrograde SRS corridor.

METHODS

We developed an automated technique that utilized a computed tomography (CT) image-based search algorithm to identify the retrograde SRS corridor with the maximum diameter. We evaluated the reliability of this automated approach in comparison to a manual method using 17 pelves. Subsequently, we used both methods to measure the diameter, length, and orientation of the retrograde SRS corridor in 204 pelves in a Chinese population and assessed the intra- and interobserver agreement of each method by calculating the root-mean-square error (RMSE) and constructing Bland-Altman plots. We determined the screw applicability (percentages of hemipelves that could be treated with specific sizes of screws) for each method. Additionally, we investigated potential factors influencing the corridor, such as sex, age, height, and weight, through regression analysis.

RESULTS

The intra- and interobserver intraclass correlation coefficients (ICCs) for the automated method (0.998 and 0.995) were higher than those for the manual approach (0.925 and 0.918) in the assessment of the corridor diameter. Furthermore, the diameter identified by the automated method was notably larger than the diameter measured with the manual method, with a mean difference and RMSE of 0.9 mm and 1.1 mm, respectively. The automated method revealed a significantly smaller corridor diameter in females than in males (an average of 7.5 and 10.4 mm, respectively). Moreover, use of the automated method allowed 80.6% of the females to be managed with a 4.5-mm screw while a 6.5-mm screw could be utilized in 19.4%, surpassing the capabilities of the manual method. Female sex had the most substantial impact on corridor diameter (β = -0.583).

CONCLUSIONS

The automated method exhibited better reliability than the manual method in measuring the retrograde SRS corridor, and showed a larger corridor diameter for screw placement. Females had a significantly smaller corridor diameter than males. Given the intricate nature of the automated approach, which entails utilizing different software and interactive procedures, our current method is not readily applicable for traumatologists. We are working on developing integrated software with the goal of providing a more user-friendly solution for traumatologists in the near future.

LEVEL OF EVIDENCE

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

Description of Standardized Planes and Angles for Percutaneous Supra-acetabular Screw Placement

BACKGROUND

Percutaneous screw fixation for pelvic fractures has become a minimally invasive alternative to an open operation. The complex anatomy of the pelvis renders this procedure challenging. The objective of this study was to assess standardized angles and dimensions of safety zones within a 3 D computed tomography model for optimal supra-acetabular screw placement.

METHODS

Computed tomography scans of 107 patients that suffered major trauma without showing any bone injury of the pelvis were collected. Using a software-based analysis, raw computed tomography data were transformed into 3 D models to set standardized landmarks and determine the possible insertion corridor.

RESULTS

Screws not exceeding a length of 97 mm in females and 106.4 mm in males were, in 95% of the evaluated cases, insertable without cortical bone penetration. The safety zone was 6.6 mm for females and 7.9 mm for males. Screws not exceeding these diameters were safely insertable in 95% of the cases. For the midsagittal plane, the angle was 36.4 ± 5.1 on the left and 34.7 ± 2.9 on the right (p = 0.008). For the anterior pelvic plane, the angle was 31.3 ± 4.5° on the left and 34.0 ± 4.8° on the right (p = 0.008).

CONCLUSIONS

Percutaneous fixation using supra-acetabular screws is a promising method to treat simple supra-acetabular fractures. These results may improve its safe utilization and could facilitate its broader clinical application.

A standard canulated screw may not fit up to 1/3 of the patients treated percutaneously for anterior column acetabular fractures-A pilot study

A proper evaluation of the narrowings and length of the anterior acetabular column would offer better predictability and precision for implant insertion in the case of an acetabular fracture.

OBJECTIVE

To determine the diameter and length of the safety corridor of the anterior column of the acetabulum in patients with available pelvic computed tomography (CT), analyze the obtained measurements against those of a standard 6.5-mm implant, and verify possible sex differences regarding these measurements. A secondary aim was to develop a method for measurement of the anterior column of the acetabulum based on CT images.

MATERIALS AND METHODS

In 200 CT scans of hemipelvises we measured the diameter of two areas of narrowing and the length of the safety corridor of the anterior column. The images were submitted to multiplanar reformatting adjusted to a plane orthogonal to the bone corridor, drawn at the level of the superior pubic ramus.

RESULTS

Measurement #1 had a mean value of 8.12 (2.27) mm in the overall sample and median values of 9.03 (7.76-10.48) mm in men and 6.77 (5.44-7.19) mm in women. Measurement #2 had a mean value of 7.29 (2.19) mm and median values of 8.23 (7.18-9.82) mm in men and 5.9 (4.65-7.19) mm in women. Measurement #3 had a mean value of 109.53 (13.66) mm in the overall sample and median values of 117.17 (112.9-122.9) mm in men and 100.91 (90.95-111.17) mm in women (p<0.001 all three measurements). Measurement #1 was smaller than 6.5 mm in 22.5% of the patients (of whom 90% were women). Measurement #2 was smaller than 6.5 mm in 35% of the patients (of whom 80% were women).

CONCLUSIONS

This study proposed an anatomic evaluation of the anterior column of the acetabulum using conventional CT images The areas of narrowing in the anterior column had an average of 8.12 mm at the level of the pubic tubercle and 7.29 mm at the level of the acetabular fossa. The mean length of the safety corridor was 109.53 mm. In 35% of the cases, a 6.5 mm percutaneous screw would have violated the cortical bone of the safety corridor.

A computed tomography (CT) based morphometric study of superior pubic ramus anatomy among Arabs to determine safe intramedullary pubic rami screw insertion

PURPOSE

To assess the morphometric variables of the superior pubic ramus in an Arab/ Middle Eastern population to establish a safe pubic screw fixation technique.

METHODS

Cross-sectional retrospective analysis of computed tomography (CT) pelvic images. Morphometric data were extracted including; on pubic ramus length, insertion angles, potential danger zones and ramus diameters. The correlation between pubic rami diameter and patient demographics was also analyzed.

RESULTS

A total of 231 participants were included (45% female). The mean pubic ramus length was 104 mm in females and 127 mm in males. The narrowest canal diameters at the para-symphyseal area were; 7.35 mm (males) and 4.75 mm (females). The mediolateral insertion angle was 49.4° in females and 41.8° in males. The cephalic-caudal angle was 49.9° in males and 42.1° in females. The mean distance from the lateral ilium entry point to the joint articular surface was 23.5 mm in males and 19.9 mm in females. The symphysis pubis to tubercle exit point was higher in females than males (24.2 mm vs 16.6 mm, respectively). There was a significant positive correlation between age and pubic ramus diameters in all age groups.

CONCLUSION

The results from this study suggest that percutaneous pubic rami screw fixation using the standard 6.5 or 7.3 mm cannulated screw system may potentially be unsafe in female Arab patients. This subset of patients may require alternative non-cannulated screws (3.5-4.5 mm) or plate options. Further, female patients may have a higher risk of acetabular joint penetration, while males have a potentially higher risk of pudendal nerve injury.

Navigation Template Design and the Anatomic Measurement for Anterograde Transpubic Screws

OBJECTIVE

For pelvic ring fractures, screw fixation became a popular technique for its good biomechanical performance. The safe insertion of anterograde the transpubic screw is important for patients with anterior pelvic ring fractures. This paper is to research the anatomical parameters of the anterograde transpubic screw corridor and evaluate the safety of anterograde transpubic screw placement assisted by the assembled navigation template.

METHODS

Fifty subjects with normal pelvic, 25 men and 25 women, age from 20 to 60 were enrolled, and their ilium were 3D reconstructed. The ilium was divided into zone I, zone II and zone III. Zone I and zone III was defined as medial and lateral to the obturator foramen, respectively. Zone II is located between zones I and III. The corridor A is formed by zone I and zone II and corridor B is formed by zone I, zone II and zone III. The diameter and length of the inner circle, the distance from the center of the inner circle to the posterior superior and to the inferior iliac spine of corridor A and corridor B were measured, respectively. Nine patients with pelvic fractures underwent anterograde transpubic screw and transverse sacroiliac screw placement assisted by the assembled navigation template and were retrospectively analyzed. Operation time, blood loss, incision length and fluoroscopy times were recorded. Grading score and Matta score were evaluated after surgery.

RESULTS

In the 50 subjects, the diameter of corridor A was 11.16 ± 2.13 mm, and that of corridor B was 8.54 ± 1.52 mm. The length of corridor A was 86.39 ± 9.35 mm, and that of corridor B was 117.05 ± 5.91 mm. The surface distance from the screw entry point to the posterior superior iliac spine in corridor A was 109.31 ± 11.06 mm, and that in corridor B was 127.86 ± 8.23 mm. The surface distance from the screw entry point to the posterior inferior iliac spine in corridor A was 91.16 ± 10.34 mm, and that in corridor B was 106.92 ± 7.91 mm. A total of 18 sacroiliac transverse screws and 11 anterograde transpubic screws were inserted assisted by assembled navigation templates for nine patients. The average operation time was 108.75 ± 25.71 min, the blood loss was 141.11 ± 50.21 ml, the incision length was 14 ± 4.62 cm, and the intraoperative fluoroscopy was 17.89 ± 4.01 times.

CONCLUSION

Transpubic screw corridor can be obtained by 3D reconstruction. For the majority of patients, the anterograde pubic ramus corridor accommodated a 6.5 mm diameter screw. It is safe to use anterograde transpubic screw placement assisted by an assembled navigation template.

[Digital study of the ideal position of lag screw internal fixation in the anterior column of the acetabulum]

Objective

To find the ideal position of lag screw internal fixation in the anterior column of acetabulum by digital technology, and measure its related parameters, so as to improve the accuracy of lag screw implantation.

Methods

The CT scan data of 266 semi-pelvic raw in 133 cases (78 males and 55 females, aged 18-65 years old with an average age of 42 years) were collected between January 2019 and January 2020 to compose three-dimensional models. According to the relationship between the peripheral bone cortex of the anatomical channel and the lag screw, a new standard for the ideal position of lag screw fixation in the anterior column of acetabulum was proposed to simulate the implantation of the screw. After the screw was in the ideal position, the following indicators were measured: the maximum allowable diameter of the virtual screw (the diameter of the cylinder up to the new standard, R), the length (the distance between the center of the nail point on both sides, L); the position of the retrograde nail point (the interval between the nail insertion points and the midpoint of the pubic symphysis and the pubic tubercle, respectively, D1 and D2) and the position of the antegrade nail insertion point (the distance between the nail insertion point and the anterior superior iliac spine, the major ischial notch, and the vertical distance between the nail insertion point and the apex of the posterior upper edge of the acetabulum, respectively, D3, D4, D5); and the direction of the virtual screw at the ideal position (the angle between the screw and the horizontal plane, sagittal plane, and coronal plane, respectively, ∠β, ∠γ, ∠δ) were calculated.

Results

The maximum allowable diameter of virtual screws was 5.70-14.10 mm for males, with an average of 9.25 mm; for females, it was 4.40-10.40 mm with an average of 7.29 mm. The antegrade insertion point of the anteroposterior acetabular lag screw was located at 2.0-2.5 cm above the apex of the acetabulum, which was almost the same distance from the anterior superior iliac spine and the ischial notch, about 5 cm; the insertion point of the retrograde implant was located at the pubic bone 2.5-3.0 cm below the nodule. When the acetabular anterior column screw was in the ideal position, there was no significant difference in the comparison of ∠β and ∠γ between the male and the female ( P>0.05), and the differences in the other indicators were significant ( P<0.05). Except for D4 and ∠β showing no significant difference between the left and right sides ( P>0.05), the differences in the other indicators were significant ( P<0.05).

Conclusion

In the bony channel of the anterior column of the acetabulum, all males can accommodate screws with a diameter of <5.70 mm, and females can accommodate screws with a diameter of <4.40 mm. The anterograde or retrograde screw insertion points are different for male and female. The use of digital technology to individually measure the appropriate screw parameters can improve the accuracy and stability of the lag screw internal fixation for acetabular anterior column fractures.