Seong-Wook Jang

The Effect of Notchplasty on Tunnel Widening in Anterior Cruciate Ligament Reconstruction

PURPOSE To investigate changes in femoral tunnel diameter, dimension, and volume after anterior cruciate ligament reconstruction with notchplasty. METHODS Porcine knee specimens were divided into 2 groups of 10 specimens each. Group A did not receive notchplasty. A 2-mm notchplasty was conducted in group B. Seven-millimeter-diameter femoral tunnels were drilled and a doubled flexor digitorum profundus tendon was inserted and fixed with an EndoButton (Smith & Nephew, Andover, MA) in each knee specimen. Samples were mounted on a materials testing machine. Each group was preloaded at 10 N and subjected to 20 loading cycles (between 0 and 40 N), followed by 1,000 loading cycles in the elastic region (between 10 and 150 N). High-resolution computed tomography with 1.0-mm slices was conducted with all samples before and after testing. A 3-dimensional model was constructed to evaluate the degree of the tunnel change. RESULTS In group B the mean longest diameter and dimension of the femoral tunnel significantly increased after the test (P = .005 and P = .001, respectively). The volumetric loss of bony structure after the test in group B was significantly greater than that in group A (P = .039). Meanwhile, no significant difference was found before and after the test in terms of tunnel diameter, dimension, and volumetric loss around the tunnel in group A. CONCLUSIONS The intra-articular orifice of the femoral tunnel was enlarged after the uniaxial cyclic loading test after notchplasty. An enlarged tunnel orifice may lead to a discrepancy between the tunnel and the graft at the tunnel aperture. CLINICAL RELEVANCE The data may have an implication that suspensory fixation with a notchplasty has a negative effect on the full graft accommodation at the tunnel aperture. Aperture widening may affect graft positioning, leading to subtle changes in graft biomechanics and laxity.

Computed Tomographic Image Analysis Based on FEM Performance Comparison of Segmentation on Knee Joint Reconstruction

The demand for an accurate and accessible image segmentation to generate 3D models from CT scan data has been increasing as such models are required in many areas of orthopedics. In this paper, to find the optimal image segmentation to create a 3D model of the knee CT data, we compared and validated segmentation algorithms based on both objective comparisons and finite element (FE) analysis. For comparison purposes, we used 1 model reconstructed in accordance with the instructions of a clinical professional and 3 models reconstructed using image processing algorithms (Sobel operator, Laplacian of Gaussian operator, and Canny edge detection). Comparison was performed by inspecting intermodel morphological deviations with the iterative closest point (ICP) algorithm, and FE analysis was performed to examine the effects of the segmentation algorithm on the results of the knee joint movement analysis.

Development of epiduroscopy training simulator using haptic master device

Epiduroscopy is one of the widely implemented procedures in effective diagnosing and curing lumbago patients. Such endoscopic surgery requires much skill to control the surgical instruments well. Therefore, this paper proposes an epiduroscopy training simulator using a haptic master device. The proposed training simulator calculates forces using virtual fixture implemented in a catheter insertion path. The calculated forces are provided as haptic feedback to a user through the haptic master device, and the user is trained to catheter insertion path of expert through the haptic feedback.

A Study on Tracking and Augmentation in Mobile AR for e-Leisure

Recently, a mobile augmented reality (AR) system with AR technology that requires high performance has become popular due to the improved performance of smartphones. In particular, mobile AR that directly interacts with outdoor environments has been in development because of increasing interest in e-leisure due to improvements in living standards. Therefore, this paper aims to study tracking and augmentation in mobile AR for e-leisure. We analyzed the performance of human body tracking application implemented in a mobile system (smartphone) using three methods (marker-based, markerless, and sensor-based) for the feasibility examination of human body tracking in mobile AR. Furthermore, game information augmentation was examined through the implementation of mobile AR using two methods (marker- and sensor-based).

A Real-Time Video Abstraction Technique for AR Content Synthesis on Android Platform

In this paper, we offer an efficient real-time video abstraction technique that enables interaction with the real-world environment using a smart device for combining augmented reality (AR) and virtual content. The conventional video abstraction technique is inappropriate for the real-time processing of AR content. Therefore, real-time video abstraction through the GPU approach is necessary to minimize the CPU processing of AR content. The methods other than the abstraction technique using the Open GL-ES shader have constraints regarding hardware and the dependency of AR content data. Consequently, this paper proposes a real-time video abstraction technique using the Open GL-ES shader. The proposed real-time video abstraction technique is a method for minimizing the disharmony between virtual and real-world content occurring on AR performing in the limited computing resources of a smart device. To do this, we performed research on video abstraction and applied three filtering algorithms (Sobel operator, Striped pattern-based toon, Non-boundary-based color quantization). In addition, we considered the applicability of AR content through real-time video abstraction experiments using adjusted and monitoring parameters.

An evaluation on CT image acquisition method for medical VR applications

Recent medical virtual reality (VR) applications to minimize re-operations are being studied for improvements in surgical efficiency and reduction of operation error. The CT image acquisition method considering three-dimensional (3D) modeling for medical VR applications is important, because the realistic model is required for the actual human organ. However, the research for medical VR applications has focused on 3D modeling techniques and utilized 3D models. In addition, research on a CT image acquisition method considering 3D modeling has never been reported. The conventional CT image acquisition method involves scanning a limited area of the lesion for the diagnosis of doctors once or twice. However, the medical VR application is required to acquire the CT image considering patients’ various postures and a wider area than the lesion. A wider area than the lesion is required because of the necessary process of comparing bilateral sides for dyskinesia diagnosis of the shoulder, pelvis, and leg. Moreover, patients’ various postures are required due to the different effects on the musculoskeletal system. Therefore, in this paper, we perform a comparative experiment on the acquired CT images considering image area (unilateral/bilateral) and patients’ postures (neutral/abducted). CT images are acquired from 10 patients for the experiments, and the acquired CT images are evaluated based on the length per pixel and the morphological deviation. Finally, by comparing the experiment results, we evaluate the CT image acquisition method for medical VR applications.