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Featured researches published by Sang Gyo Seo.


Foot & Ankle International | 2015

Correlation between static radiographic measurements and intersegmental angular measurements during gait using a multisegment foot model.

Dong Yeon Lee; Sang Gyo Seo; Eo Jin Kim; Sung Ju Kim; Kyoung Min Lee; Daniel C. Farber; Chin Youb Chung; In Ho Choi

Background: Radiographic examination is a widely used evaluation method in the orthopedic clinic. However, conventional radiography alone does not reflect the dynamic changes between foot and ankle segments during gait. Multiple 3-dimensional multisegment foot models (3D MFMs) have been introduced to evaluate intersegmental motion of the foot. In this study, we evaluated the correlation between static radiographic indices and intersegmental foot motion indices. Methods: One hundred twenty-five females were tested. Static radiographs of full-leg and anteroposterior (AP) and lateral foot views were performed. For hindfoot evaluation, we measured the AP tibiotalar angle (TiTA), talar tilt (TT), calcaneal pitch, lateral tibiocalcaneal angle, and lateral talcocalcaneal angle. For the midfoot segment, naviculocuboid overlap and talonavicular coverage angle were calculated. AP and lateral talo-first metatarsal angles and metatarsal stacking angle (MSA) were measured to assess the forefoot. Hallux valgus angle (HVA) and hallux interphalangeal angle were measured. In gait analysis by 3D MFM, intersegmental angle (ISA) measurements of each segment (hallux, forefoot, hindfoot, arch) were recorded. Results: ISAs at midstance phase were most highly correlated with radiography. Significant correlations were observed between ISA measurements using MFM and static radiographic measurements in the same segment. In the hindfoot, coronal plane ISA was correlated with AP TiTA (P < .001) and TT (P = .018). In the hallux, HVA was strongly correlated with transverse ISA of the hallux (P < .001). Conclusion: The segmental foot motion indices at midstance phase during gait measured by 3D MFM gait analysis were correlated with the conventional radiographic indices. Clinical Relevance: The observed correlation between MFM measurements at midstance phase during gait and static radiographic measurements supports the fundamental basis for the use of MFM in analysis of dynamic motion of foot segment during gait.


Clinics in Orthopedic Surgery | 2015

Demineralized Bone Matrix Injection in Consolidation Phase Enhances Bone Regeneration in Distraction Osteogenesis via Endochondral Bone Formation

Ji-Beom Kim; Dong Yeon Lee; Sang Gyo Seo; Eo Jin Kim; Ji Hye Kim; Won Joon Yoo; Tae-Joon Cho; In Ho Choi

Background Distraction osteogenesis (DO) is a promising tool for bone and tissue regeneration. However, prolonged healing time remains a major problem. Various materials including cells, cytokines, and growth factors have been used in an attempt to enhance bone formation. We examined the effect of percutaneous injection of demineralized bone matrix (DBM) during the consolidation phase on bone regeneration after distraction. Methods The immature rabbit tibial DO model (20 mm length-gain) was used. Twenty-eight animals received DBM 100 mg percutaneously at the end of distraction. Another 22 animals were left without further procedure (control). Plain radiographs were taken every week. Postmortem bone dual-energy X-ray absorptiometry and micro-computed tomography (micro-CT) studies were performed at the third and sixth weeks of the consolidation period and histological analysis was performed. Results The regenerate bone mineral density was higher in the DBM group when compared with that in the saline injection control group at the third week postdistraction. Quantitative analysis using micro-CT revealed larger trabecular bone volume, higher trabecular number, and less trabecular separation in the DBM group than in the saline injection control group. Cross-sectional area and cortical thickness at the sixth week postdistraction, assessed using micro-CT, were greater in the regenerates of the DBM group compared with the control group. Histological evaluation revealed higher trabecular bone volume and trabecular number in the regenerate of the DBM group. New bone formation was apparently enhanced, via endochondral ossification, at the site and in the vicinity of the injected DBM. DBM was absorbed slowly, but it remained until the sixth postoperative week after injection. Conclusions DBM administration into the distraction gap at the end of the distraction period resulted in a significantly greater regenerate bone area, trabecular number, and cortical thickness in the rabbit tibial DO model. These data suggest that percutaneous DBM administration at the end of the distraction period or in the early consolidation period may stimulate regenerate bone formation and consolidation in a clinical situation with delayed bone healing during DO.


Journal of Foot and Ankle Research | 2014

Repeatability of a multi-segment foot model with 15-marker set in normal adults

Sang Gyo Seo; Dong Yeon Lee; Ji-Beom Kim; Seong Hyun Kim; Hye Sun Park; Hyo Jeong Yoo; Sung Ju Kim; Jihyeung Kim; Kyoung Min Lee; Chin Youb Chung; In Ho Choi

Several 3D multi-segment foot models (MFMs) have been introduced for the in vivo analysis of dynamic foot kinematics [1,2]. However, there is scanty evidence available to support their clinical use. Considering the potential of MFM to assess the function in foot pathology, there is a need for simple, reproducible and reliable multi-segment foot models. The purpose of this study was to assess the reliability of a simple MFM with 15-marker set. Twenty healthy adults mean aged 28.9 years (10 males and 10 females) were tested. Eight markers of 15-marker set were placed in foot to evaluate segmental foot motion. Three representative strides from five separate trials were used for analysis from each session. Kinematic data of foot segmental motion was collected and tracked using the Foot3D Multi-Segment Software (Motion Analysis Co., Santa Rosa. CA). Retests were performed in the same manner with an interval of 4 weeks. Coefficients of multiple correlation (CMC) and intra-class correlation (ICC) were calculated in order to assess the inter-trial and inter-session repeatability. Inter-segment foot angles from healthy adults from a MFM with 15-marker set showed a narrow range of variability during the whole gait cycle. The mean inter-trial ICC (± Standard deviation) was 0.981 (± 0.010), which was interpreted as excellent. The mean inter-trial CMC (± Standard deviation ) was 0.948 (± 0.027), which was interpreted as excellent or very good repeatability. The mean inter-session ICC (±SD) was 0.886 (± 0.047) and the mean inter-session CMC (±SD) was 0.801 (± 0.077), which were interpreted as excellent or very good repeatability. The lowest repeatability was in the transverse plane at the forefoot and the most consistent finding was observed at the sagittal plane of the hallux and hindfoot (Table ​(Table1,1, Figure ​Figure11). Table 1 Repeatability of foot kinematics Figure 1 Walking kinematics for the 1st and 2nd visit (average with a range representing 2 standard deviations). Each row shows the motion of each segment: hallux, hindfoot, arch, forefoot, medial forefoot, lateral forefoot motion. Each column represents motion ... We demonstrated a MFM with 15-marker set had high inter-trial and inter-session repeatability, especially in sagittal plane motion. We thought this MFM would be applicable to evaluation of the motion of the foot segment during gait.


Journal of Foot and Ankle Research | 2014

Template-based landmark and region mapping of bone

Jae-Il Kim; Sang Gyo Seo; Dong Yeon Lee; Jinah Park

Background The shape morphology using 3D surface models has been recently emerged for biomechanics research, such as the quantitative assessment of bone deformity with clinical factors [1] and the correlation analysis between bone shape and joint motion [2]. In the bone shape morphology, the morphological difference of the bones across subjects is quantified by the geometric measures, such as the curvature of the articular surface and the relative bone orientation in joints, defined with the anatomical landmarks and regions on the bone surface. However, the landmark and region determination on individual cases is a difficult and time-consuming task, because of the various size and shape of the bones and operator’s errors. In this paper, we propose an automated landmark and region mapping method based on a non-rigid template-toimage registration. The template model is a triangular mesh including the generic shape of the target. It also encodes the landmarks and regions as a subset of the points in the triangular mesh. For the landmark and region mapping to individual bones, the template model is nonrigidly deformed by a Laplacian deformation framework [3]. This framework derives the point transformation into the image boundary while minimizing the distortion of the point distribution in the template model. This behavior of the deformation framework helps to trace the positions of the anatomical landmarks and regions across subjects.


Foot & Ankle Orthopaedics | 2016

Weight-Bearing 3D Foot Model Reconstruction From Standing Radiographs Using Deformable Surface Fitting Method

Sang Gyo Seo; Jae-Il Kim; Chang Hyun Ryu; Eo Jin Kim; Doojae Lee; Dong Yeon Lee; Jinah Park

Category: Basic Sciences/Biologics Introduction/Purpose: Although weight-bearing CT of the foot and ankle definitely reflect the morphology of joint and foot deformity, it is hard to obtain the standing CT due to difficulty of availability. The purpose of this study is to introduce a semi- automatic method based on a deformable surface fitting for achieving the weight-bearing 3D model reconstruction from standing radiographs for foot and ankle. Methods: Our method is based on a Laplacian surface deformation framework using a template model of foot bones. As pre- processing step, we obtained template surface meshes having the average shapes of foot bones from standing CT images (Planmed Verity® CT scanner) in 10 normal volunteers. First, 3D standing CT was obtained by Planmed Verity® CT scanner and used as gold standard of reconstruction for one patient with flatfoot. Second, in the reconstruction step, the surface meshes are deformed following guided user inputs (talus 6, calcaneus 8 in lateral, talus 6, calcaneus 6 in anteroposterior standing radiograph) with geometric constraints to recover the target shapes of patients while preserving average bone shape and smoothness as much as possible. Finally, we compared reconstructed 3D model to original standing CT images. Results: In this study, the comparison results indicate that the obtained reconstruction is close to the actual standing foot and ankle geometry. We present the accuracy and robustness of our method via comparison between the reconstructed 3D models and the original bone surfaces Conclusion: Weight-bearing 3D foot model reconstruction from standing radiographs is concise and the effective method for analysis of foot joint alignment and deformity.


Journal of Foot and Ankle Research | 2014

Gender differences in segmental foot motions during gait using 3D multi-segment foot model

Sang Gyo Seo; Dong Yeon Lee; Ji-Beom Kim; Seong Hyun Kim; Hye Sun Park; Hyo Jeong Yoo; Sung Ju Kim; Jihyeung Kim; Kyoung Min Lee; Chin Youb Chung; In Ho Choi

in female than in male. The stride length, the step width, and the step time were significantly longer in male. The speed and the proportion of stance phase were not significantly different (Table 1). The range of segmental motion (hallux, forefoot, hindfoot) and arch data were recorded during the gait and compared between male and female. The both genders had similar patterns of segmental foot motions. The range of sagittal motion and coronal angulation of the hallux was greater during gait in females. The range of motion on the hindfoot was also greater in females. The male had higher adjusted arch height and arch index. However, the range of adjusted arch height was larger in females (Figure 1). We demonstrated that there was a substantial temporal pattern of the foot segmental motion in normal adults. We also presented that


Journal of Foot and Ankle Research | 2014

Temporal pattern in segmental motions of the foot in healthy senile adults: comparison between young and senile healthy adults.

Sang Gyo Seo; Dong Yeon Lee; Ji-Beom Kim; Seong Hyun Kim; Hye Sun Park; Hyo Jeong Yoo; Sung Ju Kim; Jihyeung Kim; Kyoung Min Lee; Chin Youb Chung; In Ho Choi

The incidence of foot and ankle disease increases as the age increases [1,2]. However, there was no report about differences of foot motion between senile person and young adults. The purpose of this study is to analyze distinctions according to age in segmental foot motion using 3D multi-foot model from healthy senior and young adults. One hundred senile (50 males, 50 females) and young adults (50 males, 50 females) were tested by 3D multi-foot model with 15-markers. The cadence, speed, stride length, step width, step time, and stance phase were analyzed. The maximum and minimal values and motions of 3-planes of hallux, forefoot, hindfoot, and arch were compared between senile and young adults. The cadence, speed, stride length, and step width were lower in senior. The stance phase was longer (Table​(Table1).1). In female, sagittal motion of all segment were more limited and hindfoot was more unstable in senior (Figure ​(Figure1).1). In male, sagittal motion of hallux and forefoot were lower in senior (Figure ​(Figure2).2). Hallux valgus of male and female was more severe in senior during gait. Arch height was no difference (Figure ​(Figure3).3). In 3D foot gait analysis, the differences between senior and young adults were apparent. In summary, foot motion in senior had limited range of motion during gait. And hallux valgus in senior was more severe. But arch height was not diminished. The understanding about changes of foot segmental motion depending on age will suggest more correct approach in degenerative foot and ankle disease. Table 1 Basic gait parameters in senile adults Figure 1 Comparison of the mean foot segmental motion between senile and young adults in female. Figure 2 Comparison of the mean foot segmental motion between senile and young adults in male. Figure 3 Comparison of the mean foot segmental motion between male and female in senior.


Journal of Foot and Ankle Research | 2014

Correlation between radiography and motions of foot and ankle during gait using 3D multi-segment foot model.

Dong Yeon Lee; Sang Gyo Seo; Ji-Beom Kim; Sung Ju Kim; In Ho Choi

Results The following are the findings. Firstly, the total time taken for forward breakfall of the martial arts showed 1.53±0.04 s for skilled, and 1.41±0.06s for unskilled subjects (p<.01). Second, during forward breakfall of the martial arts, the skilled subjects came up with significantly faster impact velocity in the primary point of impact (E2) (p<.001), but the unskilled subjects showed significantly faster impact velocity in the secondary point of impact (E3) (p<.001). Third, the forward breakfall of the martial arts did not show any difference between left and right side in the reaction force, but unskilled subjects proved a significantly greater forward and backward reaction force in the secondary point of impact(E3) both right and left sides (right: p<.01, left: p<.001). The skilled subjects showed a significantly greater vertical reaction force in the primary point of impact (E2) (right: p<.001, left: p<.001), and unskilled subjects showed a larger vertical reaction force in the secondary point of impact (E3), respectively (right: p<.01, left: p<.05).


Journal of Foot and Ankle Research | 2014

Repeatability of a multi-segment foot model with a 15-marker set in healthy adults

Sang Gyo Seo; Dong Yeon Lee; Hyuk Ju Moon; Sung Ju Kim; Jihyeung Kim; Kyoung Min Lee; Chin Youb Chung; In Ho Choi


Journal of Foot & Ankle Surgery | 2015

Validity, Reliability, and Responsiveness of the Korean Version of American Academy of Orthopedic Surgeons Foot and Ankle Questionnaire

Ji-Beom Kim; Je Kyun Kim; Sang Gyo Seo; Dong Yeon Lee

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Dong Yeon Lee

Seoul National University Hospital

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In Ho Choi

Seoul National University

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Ji-Beom Kim

Seoul National University Hospital

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Sung Ju Kim

Seoul National University Hospital

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Chin Youb Chung

Seoul National University Bundang Hospital

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Kyoung Min Lee

Seoul National University Bundang Hospital

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Jihyeung Kim

Seoul National University

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Eo Jin Kim

Seoul National University Hospital

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Hye Sun Park

Seoul National University Hospital

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Hyo Jeong Yoo

Seoul National University Hospital

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