• Maxillofacial Plastic and Reconstructive Surgery
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• v.21 no.2
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• pp.131-138
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• 1999

The purpose of this study is to evaluate the effects of resorbable plate in the healing process of mandibular fracture. Reduction and rigid fixation was carried out on the artificial mandibular fracture site of the rabbits, using a resorbable screw, 1.5mm in diameter and 4.0mm in length, and an absorbable plate 1.5mm in thickness(Lactosorb$^{(R)}$). En block tissue specimens with plate were taken from the rabbits at 4, 6, 8, and 10 weeks intervals and specimen were observed with light microscope under the hematoxylin-eosin staining, to observe the inflammatory reaction and tissue healing process. The following conclusions were drawn: 1. The subject displayed good healing with no signs of detachment of the fixation plate. 2. At 4 weeks, the plate was covered by the connective tissue. Then at 6 weeks, bone regeneration was discovered around the plate. 3. During the period of healing, no inflammatory reaction or foreign body reaction, as a result of using resorbable plate, were observed. 4. At 8 weeks, the initial phase of the absorption of the plate was observed. Then at 10 weeks, macrophage were observed around the plate, indicating the absorption phase was in process. From the above results, it can be determined that when the resorbable plate is applied to rabbit, full recuperation occurs naturally in the absence of inflammatory reaction and foreign body reaction. The selected study is clinically valuable in proving this procedure.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.21 no.1
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• pp.60-64
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• 1999

Recently, for the reconstruction of bony defect and cosmetic improvement, many graft materials and implants have been widely used in the various surgical situations. The alloplastic materials have many advantages such as simplicity of operation, no additional need of surgery, and easy manipulation. The $Medpor^{TM}$(porous high-density polyethylene, Porex Co., USA) was initially studied in 1972 for surgical implant and introduced as an implant material for oral and maxillofacial region by Sauer and King in 1988. This material permits full ingrowth of bone into the implants, substantially increasing the implant's incorporation into the recipient site. It can be shaved during the surgery, which results in an improvement and prefabricated various size and shapes to fit into the surgical defect. The $Medpor^{TM}$ was used in 32 patients from 1995 to 1997 at the maxillofacial region. It was used for paranasal augmentation in 24 cases, for malar augmentation in 2 cases, for infraorbital augmentation in 2 cases, for mandibular angle augmentation in 2 cases, for mandibular body augmentation in 2 cases, for chin vertical augmentation in 1 case. It was mainly fixed with miniplate or screw. There were few complications except one infection and one exposure of the implant.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.31 no.2
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• pp.127-135
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• 2009

Objectives : The titanium fixation system has been used in orthognathic surgery for fixation of bone segments usually, but the biodegradable fixation system was developed and also being used. The strongest point in the biodegradable system is that no extra operation should be needed to remove fixation materials. In spite of this merit, oral & maxillofacial surgeons hesitate to use this system in fracture or orthognathic surgery. In this study, as we got some clinical experiences, we'd like to report the result of clinical study using the biodegradable fixation system in orthognathic surgery. Patients and Methods : A total of 35 patients composed of 17 males and 18 females with 25 osteotomies in maxilla and 34 osteotomies in mandible were fixated with the biodegradable fixation system(Inion $CPS^{(R)}$). We investigated methods of stabilization, fixation time, and complications on the basis of the method as above. Results : Four 2mm thick L shaped plates with 7 holes of which 1 hole was removed were fixed in maxilla with six $2.0{\times}7mm$ screws. Three $2.5{\times}16{\sim}18mm$ screws were used to fix superior ramus area and one mandibular angle area in mandible. It took about 27.4 minutes in maxilla, 25.3 minutes in mandible to perform the fixation which took longer time than the titanium system(9.5 minutes in maxilla, 8 minutes in mandible). Generally, there was no problem except 9 cases in which there were some complications. Conclusions : In most cases, the biodegradable fixation system can be used without problem in usual orthognathic surgery. But, this system is inferior to the titanium fixation one in some respects such as fixation time, size, and physical property. Some supplementations for such weak points as aforementioned should be needed for the universal use of biodegradable materials.

• Journal of Biomedical Engineering Research
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• v.23 no.5
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• pp.385-390
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• 2002

Nowadays, there are many attempts to develop domestic medical-equipments. In this study, it is performed to developed a new vertebral fusion device. The basic models are a rectangular-frame type and a screw type which are generally used for the patients. The main purpose of the development of a new device is to reduce the amount of bone taken out for the insertion of a device to vertebral disc and this paper is focused on th concept of a new device shape. In the results, two types are devised. One is a folding type and the other is a separate-push-in type device both are in primitive stage. However, in a folding type there are mechanical pins and the analysis of pins and the lock system is still in study and needs some time. Therefore a separate-push-in type is introduced in this study mainly and a prototype and 3-D finite element model are made and experimented and stress analyzed. From the results it is considered that it is stable for the basic loading condition of vertebra, however, it is required to develop a supporting operational equipment for the convenience of the operation in practice.

• Journal of Biomedical Engineering Research
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• v.22 no.1
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• pp.69-80
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• 2001

본 연구에서는 환자의 골다공증 유무에 따른 내고정 장치 시술 직후 및 융합 후의 안정성을 평가하기 위해 다양한 하중 모드에서 C5-C6 운동분절의 생체역학적 거동을 분석하였다. 이러한 목적으로 먼저, C5-C6 경추부의 유한요소 모델을 구현하여 검증하였다. 모델의 결과는 기존 실험치와 유사하여 신뢰성이 부여되었다. 검증된 모델은 Smith-Robinson 방식으로 골이식물을 삽입한 후 전방 내고정 장치를 적용한 시술 상황을 재현하기 위해 수정되었다. 수정된 모델은 두 종류로 구현되었다. (1) 첫 번째 모델에서는, 시술 직후의 상황을 재현하기 위해 골이식물과 종판의 경계면에 접촉요소를 사용하였다. (2)두 번째 모델에서는 완전히 융합된 상황을 나타내기 위해 골이식물을 종판에 고정하였다. 골다공증의 효과를 예측하기 위하여 두 모델의 해면골에 대한 탄성계수를 변화시켰다(정상: 100MPa, 골다공증: 40MPa). 각 모델의 C5 주체의 상위면에 73.6N의 압축 하중을 가한 후에 108Nm의 굴곡/신전, 굽힘, 비틀림 하중을 가하였으며, C6 추체의 하단면은 모든 방향에 대하여 구속하였다. 전체적인 결과에 있어서 상대적 회전운동, 미끄럼운동, 골이식물 내에서의 von Mises 응력의 경우 정상 모델에 비해 골다공증 모델에서 증가함을 보였으며, 특히 시술 직후의 모델에서 비틀림 하중이 가해진 경우, 상대적 회전운동 및 미끄럼 운동이 가장 높게 예측되었다. 이는 골다공증환자에게 전방 내고정 장치를 시술한 경우 골이식물의 파단 및 유합의 실패가 비틀림 하중에서 발생할 수 있음을 나타낸다. 해면골의 von Mises 응력은 시술 직후에 골다공증 모델의 모든 하중 모드에서, 유합 후에는 굽힘 하중 외의 모든 하중에서 ultimate strength를 초과하는 것으로 나타나 골다공증 환자에게 screw의 해리가 발생할 가능성이 높은 것으로 예측되었다. 따라서 골다공증 환자에게 과도한 운동이 발생하지 않도록 하기 위해서 시술 후 세심한 주의와 halo 같은 견고한 정형술이 필요할 것으로 사료된다.

• Journal of Korean Neurosurgical Society
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• v.39 no.4
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• pp.260-264
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• 2006

Objective : The retrospective study is undertaken to report clinical results of anterior cervical interbody fusion with an intradiscal cage with an integrated plate [PCB cervical plating system]. Methods : 38 patients underwent anterior cervical interbody fusion with PCB cervical plating system and followed $6{\sim}24\;months$. The authors investigated overall surgical results; clinical outcome, fusion rate, change of interspace height & lordotic angle, and complications. Results : No complication was observed during the operation. Clinical improvement was identified in 34 cases [89.5%]. Bone fusion observed in 44 out of 49 sites [90.7%]. After operation, the interspace height increased from $5.4{\pm}1.3mm$ to $7.8{\pm}1.5mm$ and maintained $7.4{\pm}1.1mm$ and, interspace angle went up from $4.2{\pm}0.7^{\circ}$ to $4.8{\pm}1.1^{\circ}$ and maintained $4.6{\pm}$0.9^{\circ}. The loosening of screw was observed in 6 cases, one of which had reoperation because of the expulsion of the device accompanied. Conclusion : PCB cervical plating system could restore interbody height and lordosis in anterior cervical interbody fusion. But, if the insertion of the spacer is not precise, the frequencies of hardware failure are relatively high. It is considered necessary for the operator to be careful in the procedure.

• Clinics in Shoulder and Elbow
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• v.24 no.3
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• pp.125-134
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• 2021

Background: To evaluate clinical and radiological outcomes of bony increased offset-reverse total shoulder arthroplasty (BIO-RSA) in the Asian population at mid-term follow-up. Methods: From June 2012 to August 2017 at a single center, 43 patients underwent BIO-RSA, and 38 patients with minimum 2 years follow-up were enrolled. We evaluated the clinical and radiological outcomes, and complications at the last follow-up. In addition, we divided these patients into notching and no-notching groups and compared the demographics, preoperative, and postoperative characteristics of patients. Results: Visual analogue scale, American Shoulder and Elbow Surgeons, University of California-Los Angeles Shoulder Scale, and Simple Shoulder Test scores improved significantly from preoperative (5.00, 3.93, 1.72, 3.94) to postoperative (1.72, 78.91, 28.34, 7.66) (p<0.05) outcomes. All range of motion except internal rotation improved significantly at the final follow-up (p<0.05), and the bone graft was well-incorporated with the native glenoid in all patients (100%). However, scapular notching was observed in 20 of 38 patients (53%). In the comparison between notching and no-notching groups (18 vs. 20 patients), there were no significant differences in demographics, radiological parameters, and clinical outcomes except acromion-greater tuberosity (AT) distance (p=0.003). Intraoperative complications included three metaphyseal fractures and one inferior screw malposition. Postoperative complications included ectopic ossification, scapular neck stress fracture, humeral stem relaxation, and late infection in one case each. Conclusions: BIO-RSA showed improved clinical outcomes at mid-term follow-up in Asian population. However, we observed higher scapular notching compared to the previous studies. In addition, adequate glenoid lateralization with appropriate humeral lengthening (AT distance) might reduce scapular notching.

• Journal of Korean Orthopaedic Sports Medicine
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• v.8 no.1
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• pp.26-32
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• 2009

Purpose: This study was performed to compare the strength of ligamentous attached sites of cadaveric distal femur and to obtain reliable biomechanical data to use in ligamentous reconstruction or augmentation. Materials and Methods: Fifteen cadaveric distal femurs were used for this study. After measuring the bone density, 5.0 mm cannulated screw (Experiment 1) or reconstructed porcine ligament (Experiment 2) was inserted into the each ligamentous attached sites of anterior cruciate ligament (ACL), posterior cruciate ligament (PCL), medial collateral ligament (MCL) and lateral collateral ligament (LCL). In experiment 2, reconstructed porcine graft was fixed with bioabsorbable screw in ligamentous insertion sites. And we measured the maximal pullout force of each ligamentous attached sites of cadaveric distal femur. Results: Average bone mineral density was $1.205{\pm}0.137\;g/cm^2$ in experiment 1, $1.236{\pm}0.089\;g/cm^2$ in experiment 2, which showed no statistically significant differences. In experiment 1, average pull-out strength of ACL, PCL, MCL and LCL group were $519.1{\pm}111.7$ N, $638.9{\pm}144.4$ N, $169.7{\pm}56.0$ N, $225.6{\pm}61.5$ N respectively. In experiment 2, the average pull-out strength were $310.6{\pm}31.0$ N, $379.9{\pm}47.4$ N, $104.0{\pm}14.4$ N, $131.5{\pm}21.9$ N respectively. In experiment 1, there was no significant difference between ACL and PCL group and between MCL and LCL group. However, the maximal pullout strength of MCL and LCL group were significantly lower than that of ACL and PCL group (p<0.01). Experiment 2 showed the same results of experiment 1. Conclusion: Because stiffness of MCL and LCL attached sites are much lower than that of ACL and PCL attached sites, we may consider augmented fixation in ligamentous reconstructions of MCL and LCL.

• Journal of Dental Rehabilitation and Applied Science
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• v.26 no.2
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• pp.179-195
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• 2010

In the internal connection system, the loading transfer mechanism within the inner surface of the implant and also the stress distribution occuring to the mandible can be changed according to the abutment form. Therefore it is thought to be imperative to study the difference of the stress distribution occuring at the mandible according to the abutment form. The purpose of this study was to assess the loading distributing characteristics of three different abutments for GS II$^{(R)}$ implant fixture(Osstem, Korea) under vertical and inclined loading using finite element analysis. Three finite element models were designed according to three abutments; 2-piece Transfer$^{TM}$ abutment made of pure titanium(GST), 2-piece GoldCast$^{TM}$ abutment made of gold alloy(GSG), 3-piece Convertible$^{TM}$ abutment with external connection(GSC). This study simulated loads of 100N in a vertical direction on the central pit(load 1), on the buccal cusp tip(load 2) and $30^{\circ}$ inward inclined direction on the central pit(load 3), and on the buccal cusp tip(load 4). The following results were obtained. 1. Without regard to the loading condition, greater stress was concentrated at the cortical bone contacting the upper part of the implant fixture and lower stress was taken at the cancellous bone. 2. When off-axis loading was applied, high stress concentration observed in cervical area. 3. GSG showed even stress distribution in crown, abutment and fixture. GST showed high stress concentration in fixture and abutment screw. GSC showed high stress concentration in fixture and abutment. 4. Maximum von Mises stress in the surrounding bone had no difference among three abutment type. In GS II$^{(R)}$ conical implant system, different stress distribution pattern was showed according to the abutment type and the stress-induced pattern at the supporting bone according to the abutment type had no difference among them.

• The Journal of Korean Academy of Prosthodontics
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• v.48 no.2
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• pp.122-127
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• 2010

Purpose: The objective of this study was to investigate the effects of calcium phosphate coated titanium implant surface on bone response and implant stability at early stage of healing period of 3 weeks and later healing period of 6 weeks. Material and methods: A total of 24 machined, screw-shaped implants (Dentium Co., Ltd., Seoul, Korea) which dimensions were 3.3 mm in diameter and 5.0 mm in length, were used in this research. All implants (n = 24), made of commercially pure (grade IV) titanium, were divided into 2 groups. Twelve implants (n = 12) were machined without any surface modification (control). The test implants (n = 12) were anodized and coated with thin film (150nm) of calcium phosphate by electron-beam deposition. The implants were placed on the proximal surface of the rabbit tibiae. The bone to implant contact (BIC) ratios was evaluated after 3 and 6 weeks of implant insertion. Results: The BIC percentage of calcium phosphate coated implants ($70.8{\pm}18.9%$) was significantly higher than that of machined implants ($44.1{\pm}16.5%$) 3 weeks after implant insertion (P = 0.0264). However, there was no significant difference between the groups after 6 weeks of healing (P > .05). Conclusion: The histomorphometric evaluation of implant surface revealed that; 1. After 3 weeks early healing period, bone to implant contact (BIC) percentage of calcium phosphate coated implants (70.8%) was much greater than that of surface untreated machined implants (44.1%) with P = 0.0264. 2. After 6 weeks healing period, however, BIC percentage of calcium phosphate coated implants group (79.0%) was similar to the machined only implant group (78.6%). There was no statistical difference between two groups (P = 0.8074). 3. We found the significant deference between the control group and experimental group during the early healing period of 3 weeks. But no statistical difference was found between two groups during the later of 6 weeks.