Periacetabular osteotomy through the pararectus approach: technical feasibility and control of fragment mobility by a validated surgical navigation system in a cadaver experiment

Simultaneous reduction and fixation of concomitant acetabular fracture and ipsilateral sacroiliac joint injury through the pararectus approach: a technical report and early radiological outcome

PURPOSE

Osteosynthesis for acetabular fractures with ipsilateral sacroiliac joint (SIJ) injuries remains challenging for orthopedic surgeons, despite the evolution of surgical approaches, such as the pararectus approach, and treatment sequences. The study aimed to describe the details of the treatment of acetabular fracture with ipsilateral SIJ injury by the pararectus approach and to report its surgical outcomes.

METHODS

We retrospectively assessed patients with acetabular fractures and ipsilateral SIJ injuries undergoing osteosynthesis by the pararectus approach over a three-year period. Evaluation parameters of the quality of reduction of both acetabulum and pelvis injuries were, among others, Matta's criteria, Lefaivre's criteria, inlet/outlet ratios, and maximal gap measured on computed tomography (CT) scans.

RESULTS

Ten patients (seven men and three women) were enrolled. Pelvic ring injuries classified as AO B2.3 and acetabular fractures involving two columns were the most common fractures, accounting for 70% and 60%, respectively. Radiological evaluation for pelvic ring injury revealed three excellent and seven good results according to Matta's criteria, as well as five excellent, three good, and one fair results according to Lefaivre's criteria. Inlet and outlet ratios were between 0.84-1.06 and 0.93-1.60, respectively. The distance of the sacroiliac joints significantly improved postoperatively in both axial and coronal views (P = 0.002). Further, the maximal articular gap and step-off of acetabular fractures on axial, coronal, and sagittal view CT scans showed statistically significant improvements after osteosynthesis.

CONCLUSION

Simultaneous reduction and fixation of acetabular fractures with ipsilateral SIJ injuries using the pararectus approach achieved satisfactory radiological outcomes.

LEVEL OF EVIDENCE

IV.

TRIAL REGISTRATION

Retrospectively registered.

Pararectus approach to the AO B2.2 pelvic fracture: early functional and radiological outcomes

PURPOSE

The pararectus approach is used to treat acetabular fractures; however, it remains unclear whether it can be used to treat pelvic fractures. This study aimed to examine the outcomes of patients with a pelvic ring fracture treated with this approach.

METHODS

Seven patients with AO B2.2 pelvic fractures treated with the pararectus approach were included. Patients' pain was assessed pre- and postoperatively with a numerical rating scale. Radiological evaluations included inlet and outlet ratios and pelvic symmetry. Functional outcomes, including Merle d'Aubigné and Majeed scores, were also recorded for 12 months.

RESULTS

One patient experienced obturator nerve neuropraxia. Pain scores ranged from 2.3-8.0 to 2.0-3.1 points before and after surgery, respectively. Radiological findings revealed satisfactory outcomes. The maximal gap of the affected ilium reduced from 8.6-20.2 to 0-3.4 mm, from 6.8-17.9 to 0-4.4 mm, and from 3.7-20.3 to 0-3.2 mm in the axial, sagittal, and coronal views, respectively. Based on multiple evaluations, functional outcomes were improved for all patients.

CONCLUSION

The pararectus approach can be used safely and satisfactorily to treat AO B 2.2 pelvic fractures.

BU-Net: Brain Tumor Segmentation Using Modified U-Net Architecture

The semantic segmentation of a brain tumor is of paramount importance for its treatment and prevention. Recently, researches have proposed various neural network-based architectures to improve the performance of segmentation of brain tumor sub-regions. Brain tumor segmentation, being a challenging area of research, requires improvement in its performance. This paper proposes a 2D image segmentation method, BU-Net, to contribute to brain tumor segmentation research. Residual extended skip (RES) and wide context (WC) are used along with the customized loss function in the baseline U-Net architecture. The modifications contribute by finding more diverse features, by increasing the valid receptive field. The contextual information is extracted with the aggregating features to get better segmentation performance. The proposed BU-Net was evaluated on the high-grade glioma (HGG) datasets of the BraTS2017 Challenge—the test datasets of the BraTS 2017 and 2018 Challenge datasets. Three major labels to segmented were tumor core (TC), whole tumor (WT), and enhancing core (EC). To compare the performance quantitatively, the dice score was utilized. The proposed BU-Net outperformed the existing state-of-the-art techniques. The high performing BU-Net can have a great contribution to researchers from the field of bioinformatics and medicine.

Fast and automatic periacetabular osteotomy fragment pose estimation using intraoperatively implanted fiducials and single-view fluoroscopy

Accurate and consistent mental interpretation of fluoroscopy to determine the position and orientation of acetabular bone fragments in 3D space is difficult. We propose a computer assisted approach that uses a single fluoroscopic view and quickly reports the pose of an acetabular fragment without any user input or initialization. Intraoperatively, but prior to any osteotomies, two constellations of metallic ball-bearings (BBs) are injected into the wing of a patient's ilium and lateral superior pubic ramus. One constellation is located on the expected acetabular fragment, and the other is located on the remaining, larger, pelvis fragment. The 3D locations of each BB are reconstructed using three fluoroscopic views and 2D/3D registrations to a preoperative CT scan of the pelvis. The relative pose of the fragment is established by estimating the movement of the two BB constellations using a single fluoroscopic view taken after osteotomy and fragment relocation. BB detection and inter-view correspondences are automatically computed throughout the processing pipeline. The proposed method was evaluated on a multitude of fluoroscopic images collected from six cadaveric surgeries performed bilaterally on three specimens. Mean fragment rotation error was 2.4 ± 1.0 degrees, mean translation error was 2.1 ± 0.6 mm, and mean 3D lateral center edge angle error was 1.0 ± 0.5 degrees. The average runtime of the single-view pose estimation was 0.7 ± 0.2 s. The proposed method demonstrates accuracy similar to other state of the art systems which require optical tracking systems or multiple-view 2D/3D registrations with manual input. The errors reported on fragment poses and lateral center edge angles are within the margins required for accurate intraoperative evaluation of femoral head coverage.

Computer assistance in hip preservation surgery-current status and introduction of our system

INTRODUCTION

Preservation surgery of the hip with open or arthroscopic approach has always been challenging as complex 3-D anatomy and limited surgical access make intraoperative evaluation difficult. Recent advances in computer technology offer a wide range of innovative solutions with a goal to improve accuracy and safety of corrective procedures on human joints.

METHOD

The author critically reviews currently available literature in the field of computer assistance in hip preservation surgery. Basic features of unique planning software and navigation surgical system used in treatment of femoroacetabular impingement and hip dysplasia are introduced.

RESULTS

Currently available software provides preoperative identification of hip deformity on CT-based 3-D model and planning of the surgical correction using kinematic protocols. Real-time intraoperative 3-D orientation is possible, and execution of surgical correction can be performed either with navigation of surgical tools or with printed templates. Computer assistance in hip preservation surgery is in the developing phase. First clinical experiences of its use in treatment of femoroacetabular impingement, hip dysplasia, hip tumors, and avascular necrosis of the femoral head are promising.

CONCLUSION

Computer assistance has been applied for treatment of several hip disorders. Technical advances are suggested and quality basic studies and clinical trials are encouraged for the novel technology to become more user friendly and widely accepted.

Retrospective Motion Correction in Multishot MRI using Generative Adversarial Network

Multishot Magnetic Resonance Imaging (MRI) is a promising data acquisition technique that can produce a high-resolution image with relatively less data acquisition time than the standard spin echo. The downside of multishot MRI is that it is very sensitive to subject motion and even small levels of motion during the scan can produce artifacts in the final magnetic resonance (MR) image, which may result in a misdiagnosis. Numerous efforts have focused on addressing this issue; however, all of these proposals are limited in terms of how much motion they can correct and require excessive computational time. In this paper, we propose a novel generative adversarial network (GAN)-based conjugate gradient SENSE (CG-SENSE) reconstruction framework for motion correction in multishot MRI. First CG-SENSE reconstruction is employed to reconstruct an image from the motion-corrupted k-space data and then the GAN-based proposed framework is applied to correct the motion artifacts. The proposed method has been rigorously evaluated on synthetically corrupted data on varying degrees of motion, numbers of shots, and encoding trajectories. Our analyses (both quantitative as well as qualitative/visual analysis) establish that the proposed method is robust and reduces several-fold the computational time reported by the current state-of-the-art technique.

Pose Estimation of Periacetabular Osteotomy Fragments With Intraoperative X-Ray Navigation

OBJECTIVE

State-of-the-art navigation systems for pelvic osteotomies use optical systems with external fiducials. In this paper, we propose the use of X-ray navigation for pose estimation of periacetabular fragments without fiducials.

METHODS

A two-dimensional/three-dimensional (2-D/3-D) registration pipeline was developed to recover fragment pose. This pipeline was tested through an extensive simulation study and six cadaveric surgeries. Using osteotomy boundaries in the fluoroscopic images, the preoperative plan was refined to more accurately match the intraoperative shape.

RESULTS

In simulation, average fragment pose errors were 1.3 ° /1.7 mm when the planned fragment matched the intraoperative fragment, 2.2 ° /2.1 mm when the plan was not updated to match the true shape, and 1.9 ° /2.0 mm when the fragment shape was intraoperatively estimated. In cadaver experiments, the average pose errors were 2.2  ° /2.2 mm, 3.8 ° /2.5 mm, and 3.5  ° /2.2 mm when registering with the actual fragment shape, a preoperative plan, and an intraoperatively refined plan, respectively. Average errors of the lateral center edge angle were less than 2 ° for all fragment shapes in simulation and cadaver experiments.

CONCLUSION

The proposed pipeline is capable of accurately reporting femoral head coverage within a range clinically identified for long-term joint survivability.

SIGNIFICANCE

Human interpretation of fragment pose is challenging and usually restricted to rotation about a single anatomical axis. The proposed pipeline provides an intraoperative estimate of rigid pose with respect to all anatomical axes, is compatible with minimally invasive incisions, and has no dependence on external fiducials.

Anatomical variants of the rectus femoris motor innervation

Adult periacetabular osteotomy (PAO) was originally performed through the classic Smith-Petersen approach for optimal operative visibility and acetabular fragment correction. Evolution towards an abductor-sparing technique significantly lowered the post-operative morbidity. The rectus-sparing approach represents a step further, but the innervation of the rectus femoris is theoretically more at risk. Although the topographic anatomy of the femoral nerve has been well described, it was never studied with specificity to surgical landmarks. The femoral nerve’s spatial relation with the anterior-inferior iliac spine (AIIS) and the amount of possible dissection in the rectus femoris and iliopsoas interval is uncertain. Seven formalin-preserved human cadaveric specimens without history of inguinal injury or surgery were dissected using the distal limb of an iliofemoral approach. The level of entry of motor innervation was measured and number of branches to the rectus femoris was noted. The average longitudinal distance from the AIIS to the first motor nerve to the rectus femoris was 8.6 ± 1.4 cm. The number of branches varied between 1 and 4 with the most common innervation pattern being composed of two segments. Dissection medial to the rectus femoris should not be carried out further than 7 cm distal to the AIIS and stretching of that interval during surgical exposure should be done cautiously. The clinical efficiency of the rectus-sparing approach should be studied further in order to confirm its advantage over the classic direct anterior approach. The study provides a better understanding of the localization and the anatomical variations of the structures encountered at the level of and below the AIIS. It also assesses the relative risk of denervation of the rectus femoris during PAO through the rectus-sparing approach. The authors recommend that the dissection medial to the rectus femoris should be carried out no further than 7 cm distal to the AIIS and stretching of that interval during surgical exposure should be done cautiously.

Preoperative planning for redirective, periacetabular osteotomies

Redirective, periacetabular osteotomies (PAO) represent a group of surgical procedures for treatment of developmental dysplasia of the hip (DDH) in skeletally mature and immature patients. The ultimate goal of all procedures is to reduce symptoms, improve function and delay or prevent progression of osteoarthritis. During the last two decades, the understanding of the underlying pathomechanisms has continuously evolved. This is mainly attributable to the development of the femoroacetabular impingement concept that has increased the awareness of the underlying three-dimensional complexity associated with DDH. With increasing knowledge about the pathobiomechanics of dysplastic hips, diagnostic tools have improved allowing for sophisticated preoperative analyses of the morphological and pathobiomechanical features, and early recognition of degenerative changes, which may alter the long-term outcome. As redirective, PAO are technically demanding procedures, preoperative planning is crucial to avoid intraoperative obstacles and to sufficiently address the patient-specific deformity. Although conventional radiography has been used for decades, it has not lost its primary role in the diagnostic work-up of patients with DDH. Furthermore, an increasing number of modern imaging techniques exists allowing for assessment of early cartilage degeneration (biochemical magnetic resonance imaging) as well as 3D planning and computer-based virtual treatment simulation of PAO. This article reviews the literature with regard to the current concepts of imaging of DDH, preoperative planning and treatment recommendations for redirective, PAO.