A feasibility study of pelvic morphology for curved implants

Design of Proposed Software System for Prediction of Iliosacral Screw Placement for Iliosacral Joint Injuries Based on X-ray and CT Images

One of the crucial tasks for the planning of surgery of the iliosacral joint is placing an iliosacral screw with the goal of fixing broken parts of the pelvis. Tracking of proper screw trajectory is usually done in the preoperative phase by the acquisition of X-ray images under different angles, which guide the surgeons to perform surgery. This approach is standardly complicated due to the investigation of 2D X-ray images not showing spatial perspective. Therefore, in this pilot study, we propose complex software tools which are aimed at making a simulation model of reconstructed CT (DDR) images with a virtual iliosacral screw to guide the surgery process. This pilot study presents the testing for two clinical cases to reveal the initial performance and usability of this software in clinical conditions. This model is consequently used for a multiregional registration with reference intraoperative X-ray images to select the slide from the 3D dataset which best fits with reference X-ray. The proposed software solution utilizes input CT slices of the pelvis area to create a segmentation model of individual bone components. Consequently, a model of an iliosacral screw is inserted into this model. In the next step, we propose the software CT2DDR which makes DDR projections with the iliosacral screw. In the last step, we propose a multimodal registration procedure, which performs registration of a selected number of slices with reference X-ray, and based on the Structural Similarity Index (SSIM) and index of correlation, the procedure finds the best match of DDR with X-ray images. In this pilot study, we also provide a comparative analysis of the computational costs of the multimodal registration upon various numbers of DDR slices to show the complex software performance. The proposed complex model has versatile usage for modeling and surgery planning of the pelvis area in fractures of iliosacral joints.

Computer-aided automatic planning and biomechanical analysis of a novel arc screw for pelvic fracture internal fixation

BACKGROUND AND OBJECTIVE

The sacroiliac joint screw is a common fixation method for pelvic posterior ring fractures. The complex anatomical structure around the pelvis makes it impossible to find a suitable fixed path, which increases the difficulty of surgical operation. In this paper, we propose an automatic planning algorithm based on a computer-aided internal arc fixation channel for pelvic fractures for the first time.

METHODS

A channel generation algorithm based on seed derived points was designed, and the optimal channel was selected by scoring rules based on 3D erode algorithm for the generated channel. The biomechanical properties of the internal arc fixation screw and traditional internal straight fixation screw in three postures were compared using biomechanical finite element analysis.

RESULTS

The proposed algorithm verified the existence of a more adaptable internal arc fixation channel and can quantitatively plan a relatively optimal constant-curvature internal arc fixation channel in pelvises of ten adults. Significantly high stresses concentrated around the interaction region between the screws and bone may increase the risk of bone fractures and screw loosening in the long term. The experimental results show that the internal arc fixation screw has better strain and deformation performance than the internal straight fixation screw.

CONCLUSIONS

A novel arc internal fixation method for pelvic fractures was proposed to improve the safety and stability of screw fixation of pelvic fracture. The nonparametric test proved that the sacroiliac dislocation model repaired by internal arc fixation screw was significantly different from that repaired by internal straight fixation screw. The computer-aided automatic planning algorithm provides the possibility of robot-assisted pelvic fracture fixation.

Lateral compression type 1 (LC1) pelvic ring injuries: a spectrum of fracture types and treatment algorithms

Lateral compression type 1 (LC1) fractures are the commonest pelvic ring injury. However, they represent a heterogenous spectrum of injury mechanisms and fracture patterns, resulting in a lack of strong evidence for a universally agreed treatment algorithm. Although consensus exists that LC1 fractures have a preserved posterior ligamentous complex and are vertically stable, controversy persists around defining internal rotational instability. As such, treatment strategies extend from routine non-operative management through to dynamic imaging such as examination under anaesthetic (EUA) or stress radiographs to guide fixation algorithm. Multiple protocols sit between these two, all with slightly different thresholds for advocating surgery or otherwise, exemplifying a broad lack of consensus that is not seen for other, more severe, grades of pelvic ring injury. In the following review we discuss the evolving concepts of pelvic ring instability and management, starting from a historical perspective, through to current trends and controversies in LC1 fracture treatment. Emerging directions for research and emerging pharmacological and surgical treatments/technologies are also considered and expert commentary from 3 leading centres provided. The distinction is made between LC1 fracture arising from high-energy trauma and those following low-energy falls from standing height (so-called fragility fractures of the pelvis-FFP), since these two patient groups have different functional requirements and medical vulnerabilities. Issues pertaining to FFP are considered separately.

Intramedullary Stabilization of Pubic Ramus Fractures in Elderly Patients With a Photodynamic Bone Stabilization System (IlluminOss)

Introduction:

A photodynamic bone stabilization system (PBSS) is a percutaneous operating method that provides intramedullary stabilization. The purpose of the study was to assess the clinical and radiological outcome after treatment of pubic ramus fractures with the PBSS.

Materials and Methods:

In a retrospective study, patients with osteoporotic pubic ramus fractures were included. The patients were treated with the PBSS in a percutaneous method. In the routine follow-up examination, pain was measured with the visual analog scale (VAS) and the type of mobilization was verified. Computer tomography of the pelvis was carried out in the follow-up examination (mean of 7.5 months after surgery) to investigate bone healing.

Results:

A total of 32 patients (25 females and 7 males) were included in the study. The average hospital stay was 16.5 ± 7.9 days (range: 5-37 days) and the mean operation time was 116.8 ± 47.1 minutes (range: 33-255 minutes). Two cases of wound infections and 1 case of misplacement of the PBSS implant with revision surgery have been documented. The mean VAS score for pelvic/hip pain at the day of inpatient discharge was 4.4 ± 1.4 (range: 2-7). A total of 25 patients could attend the follow-up examination 7.5 ± 1.7 months (range: 6-14) after the procedure, reporting a mean VAS for pelvic/hip pain of 3.0 ± 2.2 (range: 0-8). A total of 11 patients could walk without an orthopedic walking device, 7 patients needed underarm crutches, 6 patients used a walker-rollator, and 1 patient was immobilized. Consolidated pubis ramus fractures were described in 24 (96%) cases.

Discussion:

The results of our study reveal adequate clinical and radiological outcomes after treatment of osteoporotic pubic ramus fractures with the PBSS. This is the first study investigating the outcome after treating pubic ramus fractures with the PBSS.

Conclusion:

Based on our findings, the PBSS is an alternative to known techniques for the stabilization of the pubic ramus.

Ultrasound-guided supra-acetabular pin placement in pelvic external fixation: description of a surgical technique and results

INTRODUCTION

Pelvic fracture in trauma patients can lead to hemodynamic instability. External fixation is a treatment capable of stabilizing these injuries in the context of damage control surgery. Supra-acetabular pin offers the greater biomechanical stability but requires the use of intraoperative fluoroscopy. The aim of this study was to analyze our results for an ultrasound-guided supra-acetabular pinning.

MATERIAL AND METHODS

Cross-sectional study with cadaveric specimens. Ultrasound-guided pin placement assessed by fluoroscopy and dissection.

RESULTS

Fourteen ultrasound-guided supra-acetabular pins were placed in seven cadaveric specimens. Excellent placement in all cases, evaluated with radiological control. Good qualitative bone fixation after dissection. One femoral cutaneous nerve was not found during anatomic dissection and was assumed injured.

CONCLUSION

Ultrasound-guided supra-acetabular pin placement is a feasible and effective technique. Our study indicates that pin placement without intraoperative fluoroscopy is feasible without compromising the reliability of its placement.